A motion tracker arrangement, a scanner system and a method of motion tracking of a subject having a body part located in a scanning scene

Abstract

A motion tracker arrangement for motion tracking of a body part of a subject in a scanning scene of a scanner, comprising a mirror arrangement with at least one primary mirror; an imaging arrangement with at least one imaging device; and a computer system. The mirror arrangement is adapted for redirecting light reflected from a target surface region of the subject. The imaging arrangement is adapted to receive light reflected by the mirror arrangement towards the imaging arrangement, wherein the redirected light comprises at least two portions of light representing at least a part of the target surface region. The imaging arrangement is adapted for recording consecutive digital images of the light portions and for generating and transmitting consecutive image data sets representing the digital images to the computer system. The respective portions of light have different travelling paths. The computer system is configured for processing the image data sets and for generating 3D data representing at least a portion of the target surface region.

Description

[0001] TRAC-P7 -78499

[0002] 1

[0003] A MOTION TRACKER ARRANGEMENT, A SCANNER SYSTEM AND A METHOD OF MOTION TRACKING OF A SUBJECT HAVING A BODY PART LOCATED IN A SCANNING SCENE

[0004] TECHNICAL FIELD

[0005] 5 The present invention relates to a scanner system comprising a scanner, such as a medical scanner and a motion tracker arrangement for tracking a subject having a body part located in a scanning scene of the scanner. The invention also relates to method of motion tracking using such motion tracker arrangement.

[0006] BACKGROUND

[0007] Over the last decade, numerous methods for motion tracking of a subject during a medical scanning in a medical scanner such as a magnetic resonance imaging (MRI) scanner, a positron emission tomography (PET) scanner or a combined MRI / PET scanner have been developed in particular for medical brain scanning: however, head motion during scanning pertains to be a significant problem causing artefacts

[0008] 15 and significantly reducing image quality. Also for scanning of other body parts of a subject, such as heart scanning or lung scanning, undesired motions of the subject during the scanning procedure may severely reduce the scanning quality.

[0009] Known methods include external tracking systems as well as image based motion tracking. Some external tracking systems use markers attached to the subjects head.

[0010] 20 This potentially introduces errors and complicates the process of preparing the subject for the scan and therefore reduces the usability in clinical practice. Generally, the known tracking system tracks a surface region of an object during a scanning procedure and apply detected motions for correcting the medical scanning images or to identify if a motion exceeds a threshold that indicates that the medical scanning result may be unacceptable. The operator may then restart the scanning procedure thereby saving time and reducing cost.

[0011] However, generally metallic parts and electrically active components should be avoided in a scanning scene of a medical scanner such as a MRI scanner or a PET scanner since such elements may severely disturb the scanning or may even make

[0012] 30 the scanning impossible. TRAC-P7 -78499

[0013] 2

[0014] To overcome this different systems and methods have been provided making the motion tracking possibly without disturbing the scanning.

[0015] US2017143271 describes a tracking apparatus wherein cameras are integrated in a device housing shielding the camera from the scene. The cameras are arranged to

[0016] 5 view through RF shielded openings. This solution is rather expensive and complex and the shielding may not be sufficient to avoid disturbing the scanning. In addition, this solution does not allow retrofitting on already existing medical scanners.

[0017] US2016287080 describes a method and apparatus for surface scanning in medical imaging. The surface scanning apparatus comprises an image source, a first optical

[0018] 10 fiber bundle comprising first optical fibers having proximal ends and distal ends, and a first optical coupler for coupling an image from the image source into the proximal ends of the first optical fibers, wherein the first optical coupler comprises a plurality of lens elements including a first lens element and a second lens element, each of the plurality of lens elements comprising a primary surface facing a distal end of the first optical coupler, and a secondary surface facing a proximal end of the first optical coupler. This solution is working well, but the cost of the fiber bundles provides that the system becomes rather expensive. In addition, the fiber bundle may provide that the tracking system only allow tracking a very narrow surface area of the target and only using a wavelength range defined by the fibers transmission band.

[0019] 20 EP 3564962 discloses a magnetic resonance imaging system wherein machine learning is applied for determining a prediction of a motion artifact level based on detected motion artifacts present in a sub set of the MRI data.

[0020] DISCLOSURE OF THE INVENTION

[0021] An object of the invention is to provide a motion tracker arrangement, which is

[0022] 25 effective for motion tracking of a subject, such as motion tracking of a body portion of a subject during a scanning procedure and where the motion tracking may be performed with a high accuracy.

[0023] In an embodiment, it is an object to provide a scanner system comprising a motion tracker arrangement, which is effective for motion tracking of a subject during a

[0024] 30 scanning procedure and where the motion tracking may be performed with a high accuracy. TRAC-P7 -78499

[0025] 3

[0026] In an embodiment, it is an object to provide a motion tracker arrangement and / or a scanner system, which alleviates at least one of the above discussed drawbacks and which in addition is fast. In an embodiment, it is an object to provide a method of motion tracking with a high tracking quality during a scanning procedure.

[0027] 5 These and other objects have been solved by the invention or embodiments thereof as defined in the claims and / or as described herein below.

[0028] It has been found that the invention or embodiments thereof have a number of additional advantages, which will be clear to the skilled person from the following description.

[0029] 10 The inventors of the present invention has realized that a surprisingly accurate and effective motion tracking may be obtained by a completely new architecture involving free space propagation of reflected light to an imaging arrangement. This new architecture ensures both a motion tracking with a desired high accuracy and a motion tracking that may be performed a feasible cost.

[0030] The invention comprises a motion tracker arrangement adapted for motion tracking of a subject comprising a body part located in a scanning scene of a scanner, wherein the body part, such as a brain, a knee, a hand or any other body part of the subject may be subjected to a scanning procedure and wherein the scanner is suitable for performing a scanning procedure of the body part.

[0031] 20 The motion tracker arrangement comprises

[0032] • a mirror arrangement comprising at least one primary mirror;

[0033] • an imaging arrangement comprising at least one imaging device; and

[0034] • a computer system.

[0035] The mirror arrangement is adapted for redirecting light reflected from at least one

[0036] 25 target surface region of the subject. The imaging arrangement is adapted to receive light reflected by the mirror arrangement. The redirected light comprises at least two portions of light, wherein each of the at least two portions of light comprises light representing at least a surface part of the target surface region, wherein the mirror arrangement are adapted for redirecting the at least two portions of light towards

[0037] 30 the imaging arrangement. TRAC-P7 -78499

[0038] 4

[0039] The imaging arrangement is adapted for recording consecutive digital images of the respective light portions redirected towards the imaging arrangement and for generating and transmitting consecutive image data sets representing the respective consecutive recorded digital images to the computer system.

[0040] 5 The respective portions of light have different travelling paths from being reflected from the mirror arrangement to being recorded by at least one of the at least one imaging device of the imaging arrangement.

[0041] The computer system is configured for processing the respective consecutive image data sets and for generating 3D data representing at least a portion of the at least

[0042] 10 one target surface region.

[0043] Advantageously, the computer system is configured for processing the respective consecutive image data sets and for generating 3D data in real time. The generating 3D data may advantageously be in the form of 3D data as a function of time. The 3D data as a function of time may in an embodiment be projected to a display e.g. in the form of a 3D video.

[0044] In an embodiment the computer system is configured for processing the respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of the at least one target surface region, preferably a 3D surface representation of at least a portion of the at least one target

[0045] 20 surface region comprises at least one of the surface parts of the at least one target surface region.

[0046] In an embodiment at least two, such as each of the at least two portions of light comprises light represents a common part of the target surface region.

[0047] Where each of the at least two portions of light comprises light represents a common

[0048] 25 part of the at least one target surface region, the computer system may be configured for processing the respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of the at least one target surface region, the at least one 3D surface representation of at least a portion of the at least one target surface region comprising the common part of the

[0049] 30 at least one target surface region. TRAC-P7 -78499

[0050] 5

[0051] The term "subject" is herein used to mean any subject capable of moving, preferably a living subject, preferably a mammal such as a human being. The terms "subject" and "patient" are used interchangeable.

[0052] Often only a part of the subject is subjected to the motion tracking, such part is

[0053] 5 herein referred to as a body part. Advantageously, the body part comprises a body portion subjected to medical scanning in the scanner. Advantageously, the body portion is an internal portion of the body part, such as a brain portion of a head, a joint portion of a knee, a heart or lung portion of a chest and etc.

[0054] The surface region of the subject may advantageously be a surface region of the

[0055] 10 body part in question. The surface region is advantageously selected to be a characteristic surface area, such as a surface area with a curvature and / or a color and / or structure variation, such as a surface area comprising the nasal bridge where the body part comprises a head or a surface area comprising a nipple where the body part comprises a part of the chest. The surface region of the subject may comprise a landmark providing a reliable and simple identifiable anatomical point, a configuration of points and / or a geometrical and / or structure. The term "landmark" is herein used to mean a selected, identifiable anatomical point(s), feature(s), geometrical, colored and / or any other characteristic visual structure of the subject, such as on the body part of the subject. The landmark may be a natural landmark of

[0056] 20 the subject, such as a nasal bridge, a bone structure or a nipple and / or an artificial landmark, such as one or more applied marks or visible unit(s), such as a reflector plate.

[0057] In an embodiment the at least one surface region comprises two or more surface regions, such as a surface region above a knee and a surface region below a knee

[0058] 25 where the body part is a knee region or a left face region and a right face region where the body portion is a head.

[0059] The motion tracker arrangement may advantageously be suitable for a markerless motion tracking i.e. without adding any markings on or at the subject or the body part of the subject.

[0060] 30 Advantageously, the at least one target surface region comprises or consists of a surface region of the body part located in the scanning scene where the at least one TRAC-P7 -78499

[0061] 6 target surface region is free of artificial marker element(s), such as markings and / or marker plates.

[0062] The subject or at least the body part of the subject is located in the scanner by being located in the scanner scene, i.e. the area where the scanner may perform scanning.

[0063] 5 The motion tracker may advantageously be configured for performing motion tracking in real time.

[0064] The phrase "real time" is herein used to mean that the time from recording respective of the consecutive digital images to generating the 3D data representing at least a portion of the target surface region of the respective consecutive digital

[0065] 10 images is 1 second or less, such as 0.1 second or less, such as 0.01 second or less.

[0066] Where the motion tracking is performed in real time, one or more scanning parameter of the medical scanner may be adjusted, preferably in real time, in dependence of the motion tracking in real time, such as adjusting the a magnetic field in MRI scanning, the radio waves and / or the sequences thereof an well as

[0067] 15 optionally performing reacquisition of fraction(s) of a scanning procedure.

[0068] Where the motion tracking indicates a movement beyond what is correctable, the scanning may in an embodiment be stopped by the scanner receiving an alert from the motion tracker arrangement or be stopped by an operator, e.g. for restarting the entire scanning procedure. Thereby both time and cost may be saved and the patient

[0069] 20 need not be subjected to rescanning at a later stage, since the scanning error is immediately observed.

[0070] The term "computer system" is herein used to mean one single computer or a plurality of computers in data connection, wireless, by wire and / or via the internet, wherein the term "computer" means a machine or device is capable of processing

[0071] 25 data at least partly based on instructions provided by a software and / or hardware program. It has the ability to accept data (input), process it, and then produce outputs.

[0072] The term "configured for" are used to mean "programmed for" and / or taught e.g. by machine learning which may be a supervised or non-supervised machine learning. TRAC-P7 -78499

[0073] 7

[0074] It should be emphasized that the term "comprises / comprising" when used herein is to be interpreted as an open term, i.e. it should be taken to specify the presence of specifically stated feature(s), such as element(s), unit(s), integer(s), step(s) component(s) and combination(s) thereof, but does not preclude the presence or

[0075] 5 addition of one or more other stated features.

[0076] Throughout the description or claims, the singular encompasses the plural and the plural encompasses the singular unless otherwise specified or required by the context. For example the term "a target surface" or "the target surface" includes the terms "at least one target surface" and "the at least one target surface".

[0077] 10 The "an embodiment" should be interpreted to include examples of the invention comprising the feature(s) of the mentioned embodiment.

[0078] The term "about" is generally used to include what is within measurement uncertainties. When used in ranges the term "about" should herein be taken to mean that what is within measurement uncertainties is included in the range.

[0079] 15 The term "substantially" should herein be taken to mean that ordinary product variances and tolerances are comprised. All features of the invention and embodiments of the invention as described herein, including ranges and preferred ranges, may be combined in various ways within the scope of the invention, unless there are specific reasons not to combine such features.

[0080] 20 The scanning scene is defined as the space in which the scanner is adapted for scan, such as the space for a body part subjected to a scanning procedure.

[0081] The scanner is advantageously a medical scanner, such as an X-ray scanner a MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner, a Bone densitometry (DXA), a Magneto-Encephalo-Graphy (MEG) scanner and / or any combinations

[0082] 25 thereof.

[0083] The scanner may be a scanner with a tunnel (also referred to as a bore) defining the scanning scene. In this type of scanner the support for supporting a subject may be a movable bearing, which may be pulled out of the tunnel for easy access of the subject. The tunnel is often very narrow, such as with a bore diameter of 100 cm or

[0084] 30 less, such as about 60 cm. TRAC-P7 -78499

[0085] 8

[0086] In an embodiment, the scanner is an open sided scanner, such as an open sided MRI scanner, which allow claustrophobic patients / subjects more comfort and also allow overweight patients / subjects to be scanned

[0087] In an embodiment, the scanner is an upright scanner allowing the subject to stand

[0088] 5 up or sit upright during a scanning procedure.

[0089] In an embodiment, where least two of the light portions comprises light representing a common part of the target surface region, the mirror arrangement and the imaging arrangement are configured for providing that the common part of the target surface region represented by each of the at least two portion of light is adapted to be

[0090] 10 recorded to form at least 0.05 % of one or more of the recorded image, such as at least 0.1 %, such as at least 1 % of one or more of the recorded image, preferably in terms of clout points and / or pixels.

[0091] As it will be described further below, the recorded image may be in the form of pixels and / or a light structured pattern, such as cloud points.

[0092] 15 The mirror arrangement may comprise one or more primary mirrors. Where the mirror arrangement has only one flat primary mirror, it is preferred that the imaging arrangement comprises at least two imaging devices.

[0093] The imaging arrangement may comprise one or more imaging devices. Where the imaging arrangement has only one single imaging devices, it is preferred that the

[0094] 20 mirror arrangement comprises at least one curved primary mirror, at least one curved intermediate mirror and / or at least two flat primary mirrors.

[0095] In an embodiment, the mirror arrangement comprises at least two primary mirrors and / or the imaging arrangement comprises at least two imaging devices.

[0096] Where the mirror arrangement has only one primary mirror, the primary mirror may for example have a distortion of 5 % or more, such as 10 % or more determined according to the standard JIS D 5705 93rd Edition, October 20, 2021 e.g. in the form of a curved primary mirror, such as a convex primary mirror. Where the single primary mirror is a flat primary mirror it is advantageously located to redirect the light portions with an angle to the primary mirror plane which is at least 15° different

[0097] 30 from perpendicular to the primary mirror plane, such as at least 25°, such as at least TRAC-P7 -78499

[0098] 9

[0099] 30°, such as at least 35°, such as at least 40° different from perpendicular to the primary mirror plane.

[0100] In an embodiment, the primary mirror arrangement comprises N primary mirrors, wherein N is an integer from 1 to 10, such as up to 4.

[0101] 5 As indicated the one or more primary mirrors may be flat or curved. The curved primary mirror may be curved with a single curving radius, such as a one directional convex primary mirror or with multiple curving radius, such as parabolic primary mirror. In an embodiment, the primary mirror may comprise local bends, such as with two flat primary mirror section connected to each other via ca curved edge portion.

[0102] Using one or more flat primary mirrors may ensure a simpler pre-calibration and / or simpler computer processing than where curved primary mirrors is applied. However, using curved primary mirrors may enabling use of smaller primary mirrors and / or less primary mirrors, such as a single primary mirror.

[0103] 15 In an embodiment, the mirror arrangement comprises at least one flat primary mirror, such as at least two flat primary mirrors or more. Where there are two primary flat mirrors the two flat primary mirrors or mirror sections may advantageously be interconnected to have a fixed angle between the two flat mirrors or mirror sections.

[0104] 20 In an embodiment, where the mirror arrangement comprises a single flat primary mirror, the single flat primary mirror may advantageously be located above or beside the scanning scene and with a mirror plane angled to redirect light from the scene towards an exit of the scanner or towards a scanner boundary wall of the scanner within a distance to the exit not exceeding 1 m, such as not exceeding 0.5 m, such as not exceeding 0.3 m. Optionally the imaging arrangement comprises at least one imaging device located at or integrated in the scanner boundary wall for receiving the redirected light. For example, the imaging arrangement comprises two imaging devices located at or integrated in the scanner boundary wall at a distance to each other for receiving respective portions of light of the redirected light.

[0105] 30 In an embodiment, the mirror arrangement comprises a single flat primary mirror located to redirect light from the scene towards an exit of the scanner and wherein TRAC-P7 -78499

[0106] 10 the camera arrangement comprises two imaging devices located at a distance to each other and outside the scanner for receiving respective portions of light of the redirected light. The two imaging devices may for example be fixed to the scanner boundary wall via a fixture to be located outside the scanner, e.g. at a location about

[0107] 5 1.8 m above floor level, such as at least 2 m above floor level.

[0108] In an embodiment, where the mirror arrangement comprises a single flat primary mirror with a primary mirror surface for redirecting the light reflected from the target surface and wherein the primary mirror advantageously comprises light absorbing features at the primary mirror surface to provide the redirected light to be a redirected structured light, preferably comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character, wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths.

[0109] 15 The light absorbing features may for example be shaped as cloud points and / or to form redirected cloud points.

[0110] In an embodiment, the motion tracker arrangement comprises a projector arranged for projecting a structured light beam onto the at least one target surface region of the subject and at least a portion of the structured light beam is redirected via the

[0111] 20 mirror arrangement to the imaging arrangement. Thereby providing the redirected light to be or comprise a redirected structured light. The redirect structured light may preferably comprise optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character, wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths, e.g. in the form of cloud points.

[0112] In an embodiment, the mirror arrangement comprises two or more flat primary mirrors each having a flat mirror plane, wherein two or more of the flat primary mirrors are orientated such that their respective flat mirror planes are intersecting

[0113] 30 each other, preferably to provide that their respective normal vectors have an angle of from 2° to 50°, such as an angle of from 2° to 30°, such as an angle from 5° to 25°, such as an angle from 10° to 20°. TRAC-P7 -78499

[0114] 11

[0115] In an embodiment, the mirror arrangement comprises at least one convex primary mirror, such as at least two convex primary mirrors, optionally the one or more convex primary mirrors comprises one or more spherical primary mirrors and / or one or more convex parabolic primary mirrors.

[0116] 5 The convex primary mirror may be a one-directional convex primary mirror, a twodirectional convex primary mirror or a multi-directional convex primary mirror, such as a parabolic primary mirror, a hyperbolic primary mirror or an ellipsoidal primary mirror, wherein the curving in the respective directions may be equal or different

[0117] In an embodiment, the convex primary mirror is a convex spherical primary mirror.

[0118] In an embodiment, the convex primary mirror has a varying radius of curvature, such as a radius of curvature varying as a function of distance to the vertex, such as a convex parabolic primary mirror.

[0119] Depending on the distance between the imaging arrangement and or an intermediate mirror for receiving the redirected light, thee at least one convex

[0120] 15 primary mirror comprises a focal length of from 1 mm to 5 m, such as from 0.5 cm to 2 m, such as from 1 cm to 1 m.

[0121] In an embodiment, the at least one convex primary mirror comprises a radius of curvature of from 1 cm to 10 m, such as from 2 cm to 5 m, such as from 5 cm to 2 m.

[0122] Where the mirror arrangement comprises at least two primary mirrors, the at least two primary mirrors may conveniently be located or adapted to be located with a minimum distance to each other of from 1 mm to 1 m, such as up to 20 cm, optionally the primary mirrors are fixed with the minimum distance.

[0123] Optionally, the primary mirrors are fixed with the minimum distance by being fixed to

[0124] 25 each other, by being fixed to the scanner boundary wall and / or by being fixed in an armature.

[0125] By providing the two or more primary mirrors with a fixed distance and / or orientation to each other, the calibration of the primary mirrors and the processing of the TRAC-P7 -78499

[0126] 12 computer system may be simpler, thereby enabling a motion tracker arrangement with a very fast and accurate motion tracking

[0127] In an embodiment, the at least one primary mirror of the mirror arrangement is located in an armature. By having the at least one primary mirror in an armature, the

[0128] 5 calibration may be even simpler and further makes it relatively simple to retrofitting the motion tracker arrangement in an already existing medical scanners.

[0129] Preferably, the mirror arrangement comprises a plurality of primary mirrors located in the armature. The one or more primary mirror(s) may preferably be adjustable anchored in the armature, such as a common armature comprising several primary mirrors. The armature is preferably free of ferromagnetic material.

[0130] In an embodiment, the one or more primary mirrors may be mounted in the armature to be is displaceable and / or tunable, for ensure a correct pre-calibration. Thereby an armature with one or more primary mirrors may be installed to form part of a motion tracker arrangement in a relatively simple way. As described further

[0131] 15 below, the primary mirrors in an armature may optionally be pre-calibrated before installation.

[0132] In an embodiment, the at least one primary mirror of the mirror arrangement is adapted to be located in the scene of the scanner, preferably, the two or more primary mirrors are adapted to be located in the scene at respective viewing

[0133] 20 distances to at least one of the respective surface parts and / or the common part of the at least one target surface region, wherein the respective viewing distances is determined from a center point of the respective mirrors to a center point of the common part of the at least one target surface region and / or to the surface part represented by the portion of light redirected by the respective mirrors, wherein the respective viewing distances may be equal or different from each other, such as from 1 cm to 1 m, such as from 2 cm to 25 cm, optionally the respective viewing distances differs at most 10 cm from each other, such as at most 5 cm from each other.

[0134] In an embodiment, the at least one primary mirror of the mirror arrangement is adapted to be located in the scene of the scanner. Where there are two or more

[0135] 30 primary mirrors, the two or more primary mirrors may be adapted to be located in the scene at respective viewing distances to the common target surface region, TRAC-P7 -78499

[0136] 13 wherein the respective viewing distances is determined from a center point of the respective mirrors to a center point of the common target surface region. The respective viewing distances may be equal or different from each other, such as from 1 cm to 1 m, such as from 2 cm to 25 cm, optionally the respective viewing distances

[0137] 5 differs at most 10 cm from each other, such as at most 5 cm from each other.

[0138] In an embodiment, the mirror arrangement is configured for transmitting data representing the pose, such as a valid calibration pose, of one or more of the at least one primary mirror to the computer system.

[0139] In an embodiment, the imaging arrangement is configured for transmitting data representing the pose such as a valid calibration pose, of one or more of the at least one imaging device to the computer system.

[0140] In an embodiment, the at least one primary mirror of the mirror arrangement, comprises at least one primary mirror temporally or permanently mounted to an RF coil, a scanner bore and / or or a patient table (also referred to as a bearing). The RF

[0141] 15 coil may for example comprise one or more through openings into the location in the scene adapted for the body part to be scanned, where the at least one primary mirror may be located to redirect light portion or portions passing from the at least one target surface region of the subject and through the one or more through openings. In an embodiment the RF coil comprises two or more through openings

[0142] 20 and where at least two primary mirrors are mounted to the RF coil to redirect light portions that have passed through respective of the at least two through openings. For example one primary mirror may redirect one of the light portions and another one of the primary mirror may redirect another one of the light portions, wherein the respective light portions that have passed through the respective of the two or more through openings represents distinct surface parts of the at least one target surface region of the subject.

[0143] In an embodiment, the motion tracker system comprises at least one mirror sensor adapted for detecting the pose of one or more of the at least one primary mirror and or the armature, where the armature preferably comprises at least one primary

[0144] 30 mirror and / or one or more intermediate mirrors. The at least one mirror sensor may preferably be located at a fixed location relative to the scanner, such as to a fixed TRAC-P7 -78499

[0145] 14 location of the scanner, such as to a scanner wall portion of a scanner, such as a scanner bore, a floor and / or a ceiling of the scanner.

[0146] The pose, also referred to as the valid calibration pose, of the respective primary mirrors and optionally the armature may be determined by a pre-calibration

[0147] 5 procedure as described below.

[0148] The at least one mirror sensor may conveniently comprise at least one of an IR sensor (e.g. IR LED, IR photodiode, IR camera), an ultrasound sensor and / or a time of flight sensor. The mirror sensor(s) is / are preferably immune to magnetic interference. The mirror sensor(s) is / are preferably free of ferromagnetic material and / components.

[0149] In an embodiment, the at least one mirror sensor is configured for transmitting an alarm signal if detecting that a primary mirror of the at least one primary mirror and / or the armature is deviating from a valid calibration pose, such as a precalibration pose, thereby the motion tracker arrangement may immediately alert a

[0150] 15 user if one or more of the primary mirrors has been moved to be out of conformation with the valid calibration pose and thereby the operator may stop the scanning procedure and provide that the pose of the one of more primary mirror and / or of the armature is / are corrected to be in conformation with the valid calibration pose.

[0151] Advantageously, the at least one mirror sensor is configured for transmitting

[0152] 20 instruction to a user to modify the pose of the at least one primary mirror and / or armature that has been detected to deviate from a valid calibration pose, to be in conformation with the valid calibration pose.

[0153] In an embodiment, each of the at least one primary mirror and / or the armature is associated to a step motor for adjusting pose of the respective primary mirrors and the armature and wherein the at least one mirror sensor is configured for transmitting instruction to the at least one step motor, to modify the pose of the at least one primary mirror and / or armature that has been detected to deviate from a valid calibration pose, to provide the at least one primary mirror and / or armature to be in conformation with the valid calibration pose.

[0154] 30 In an embodiment, the motion tracker is pre-calibrated e.g. as described below, providing one or more of the at least one primary mirror of the mirror arrangement TRAC-P7 -78499

[0155] 15 and / or one or the armature and / or one or more of the at least one imaging device to be in respective valid calibration pose, preferably to provide each of the at least one primary mirror of the mirror arrangement to be in respective valid pose, such as providing at least the armature to be in a valid calibration pose.

[0156] 5 Advantageously, the mirror arrangement is adapted to be arranged to provide that the respective portions of light reflected from the target surface region and redirected by the respective primary mirrors to the imaging arrangement represents different Field of views (FOVs) of the at least one target surface region, preferably of at least one of the common part and / or of the respective surface parts of the at least one target surface region. Thereby very accurate 3D data, e.g. in the form 3D data sets as a function of time may be generated by the computer system.

[0157] The mirror arrangement and the imaging arrangement of the motion tracker arrangement may preferably be arranged such that the travelling paths of the respective portions of light travelling from at least one of the common part and / or of

[0158] 15 the respective surface parts of the at least one target surface region via reflection by the respective primary mirrors to the imaging arrangement have equal travelling lengths or the travel lengths may differ, such as up to 100%, such as up to 10 % from the shortest travelling path of the travelling paths.

[0159] The respective travelling paths may be determined as the length of a path that light

[0160] 20 from a center point of the at least one of the common part and / or of the respective surface parts of the at least one target surface region passes to it is impinging onto the imaging arrangement - e.g. determined by providing a light spot at the center point of the at least one of the common part and / or of the respective surface parts of the at least one target surface region and determine the length to reaching the at least one imaging device of the imaging arrangement. This may for example be determined using a time of flight sensor.

[0161] In an embodiment, the mirror arrangement is adapted to be arranged to provide that the travelling paths of the respective portions of light travelling from the target surface region via reflection by the respective primary mirrors to the imaging

[0162] 30 arrangement, comprises different center travel axes from the at least one of the common part and / or of the respective surface parts of the at least one target surface region to the imaging arrangement. TRAC-P7 -78499

[0163] 16

[0164] Preferably the travelling paths of the respective portions of light travelling from the target surface region via reflection by the respective primary mirrors to the imaging arrangement comprises different center travel axes from the at least one of the common part and / or of the respective surface parts of the at least one target surface

[0165] 5 region to the respective primary mirrors. Preferably, at least one of the different center travel axes from the at least one of the common part and / or of the respective surface parts of the at least one target surface region to the respective primary mirrors has an angle of at least 5°, such as least 10, such as least 20°, such as least 25° relative to another one of the different center travel axes from the at least one of the common part and / or of the respective surface parts of the at least one target surface region to the respective primary mirrors.

[0166] The center travelling axis of a portion of light is determined as the intensity-weighted average position of the cross-section of the light portion along the travelling path of the light portion.

[0167] 15 The mirror arrangement may comprise one or more intermediate mirrors adapted for redirecting at least one of the light portions between one of the primary mirror(s) and the imaging arrangement.

[0168] The intermediate mirror may have any shape and may be located inside or outside the scene. Examples of suitable intermediate mirrors may include convex

[0169] 20 intermediate mirror(s), concave intermediate mirror(s) or flat or angular mirror(s). In an embodiment, the mirror arrangement comprises one or more intermediate concave mirrors arranged for focusing at least one of the portions of light, e.g. towards the at least one imaging arrangement.

[0170] The mirror arrangement may further comprise one or more lens or lens arrangements for focusing one or each of the respective light portion(s).

[0171] An intermediate mirror is especially beneficial for ensuring an accurate direction of a light portion to the imaging arrangement. For example, where the at least one primary mirror is located such that it may not be capable of redirecting the one or more portions of light directly to be received by the imaging arrangement with a

[0172] 30 desired accuracy, it may be beneficial to arrange an intermediate mirror optically between the primary mirror and the at least one imaging device of the imaging TRAC-P7 -78499

[0173] 17 arrangement. This is in particular beneficial where the scene of the medical scanner is relatively narrow and / or where there is no direct line between the primary mirror ant a imaging devices of the imaging arrangement, optionally because the imaging arrangement is located remotely in relation to an entrance / exit of the medical

[0174] 5 scanner to ensure unhindered entrance / exit of a subject.

[0175] Advantageously the imaging device(s) of the imaging arrangement is selected from one or more digital cameras, one or more time-of-flight (ToF) cameras and combinations thereof.

[0176] In an embodiment the one or more digital cameras comprises at least one eventbased camera, such as a neuromorphic camera, a dynamic vision sensor (DVS), or silicon retina camera.

[0177] The one or more digital imaging devices may advantageously have frame rate (fps) of at least 1 frame / second preferably at least 5, such as at least 10, such as at least 30, such as at least 60 frames / second. In an embodiment, the at least one imaging

[0178] 15 device is a 60 fps imaging devices or a 30 fps imaging device.

[0179] The one or more ToF cameras may for example comprise one or more continuous wave (CW) ToF cameras, one or more pulsed ToF cameras, one or more phase-shift TOF cameras, one or more flash ToF Cameras and / or one or more line scan ToF Cameras. Advantageously, the at least one ToF camera comprises an indirect ToF

[0180] 20 camera such as a CW ToF camera and / or a phase-shift TOF camera.

[0181] Where the imaging arrangement comprises at least one ToF camera, the ToF cameras generate both depth information and intensity data which are recorded at the consecutive digital images and from which the 3D representation of at least the portion of the target surface region of the subject, preferably as a function of time, is generated.

[0182] Where the imaging devices comprises one or more ToF cameras are applied, the at least two light portions of light need not comprise light representing a common part of the target surface region of the subject.

[0183] Thus, in an embodiment where the imaging devices comprises one or more ToF

[0184] 30 cameras, the at least two portions of light, each representing at least a surface part TRAC-P7 -78499

[0185] 18 of the at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject, such as distinct surface parts of the at least one target surface region of the subject with no overlap.

[0186] 5 Where the imaging devices comprises one or more ToF cameras the recorded images may advantageously be in the form of a light structured pattern, such as cloud points generated by respective light portions emitted by the ToF camera towards the target surface region of the subject optionally via the at least one primary mirror and / or via the primary mirror and an intermediate mirror. The ToF camera determine the

[0187] 10 travelled distance of a plurality of light portions emitted from the ToF camera and thereby acquire the depth information.

[0188] The one or more digital cameras may comprise a mono digital camera and / or a stereoscopic camera, wherein a stereoscopic camera is considered to constitute two cameras.

[0189] 15 The digital camera(s) may advantageously comprise an image sensor selected from a charge-coupled device (CDD), an active pixel sensor (CMOS) or an Avalanche photodiode array (APD array), a back-illuminated sensor (BSI), an infrared (IR) sensor and / or a global shutter sensor.

[0190] Where the image sensor is an IR sensor the primary mirror(s) and the optional

[0191] 20 intermediate mirror(s) arranged for reflecting IR light is / are advantageously adapted for reflecting IR light e.g. by being coated with gold and / or a dielectric coating.

[0192] Preferably, the image sensor is selected from a charge-coupled device (CDD), an active pixel sensor (CMOS) or an Avalanche photodiode array (APD array).

[0193] The mirror arrangement may preferably be adapted for redirecting the respective portions of light to provide that two or more of the respective portions of light impinge at least partly at different locations of an image sensor of the at least one imaging device in the form of a digital camera of the imaging arrangement, such as to provide that the two or more of the respective portions of light impinge at separate locations of the image sensor of the at least one imaging device of the

[0194] 30 imaging arrangement. In an embodiment, the separate locations may be non- TRAC-P7 -78499

[0195] 19 overlapping separate locations. Alternatively, the separate locations may be partially overlapping separate locations.

[0196] In an embodiment, the at least one imaging device is a digital camera, wherein the digital camera comprises a camera lens, adapted for ensuring that the two or more

[0197] 5 portions of lights impinge on different locations on the image sensor, wherein the two or more portions of lights are directed to the camera lens from different directions.

[0198] In an embodiment, the imaging arrangement comprises two or more digital cameras each comprising an image sensor wherein the mirror arrangement are configured for redirecting the respective portions of light to provide that at least one of the respective portions of light impinges at the image sensor of one of the cameras and that at least one other of the respective portions of light impinges at image sensor on one other of the cameras, optionally the mirror arrangement are configured for redirecting the respective portions of light to provide that at least two of the

[0199] 15 respective portions of light impinges at the image sensor of a same one of the cameras, preferably at different locations of the same image sensor, e.g. via a camera lens ensuring that the two or more portions coming from different directions are directed to different locations of the image sensor.

[0200] In an embodiment, the imaging arrangement is a single imaging arrangement having

[0201] 20 a single image device, preferably the mirror arrangement are configured for redirecting the respective portions of light to provide that at least two, such as all of the respective portions of light impinges at the single image device, preferably at different locations thereof.

[0202] Beneficially, the consecutive image data sets generated from images of respective portions of light represents respective point of views (POV's) of at least one of the respective surface parts and / or the common part of the at least one target surface region. The respective POV's preferably differs from each other. Thereby, even very small motions may be determined and at the same time, undesired image artifacts may be filtered off.

[0203] 30 The computer system is conveniently configured for being calibrated or is calibrated to generating and / or identifying sub-image data sets of each of the consecutive TRAC-P7 -78499

[0204] 20 image data sets, wherein each sub-image data set represents a point of view (POV) of the at least one of the respective surface parts and / or the common part of the at least one target surface region.

[0205] The imaging arrangement is preferably adapted for recording the consecutive digital

[0206] 5 images of the respective light portions as a function of time. Each of the consecutive image data sets may be associated to a time attribute representing a point of time of recording.

[0207] The computer system may advantageously be configured for processing the respective consecutive image data sets and for performing a 3D reconstruction comprising generating consecutive 3D surface representations of at least a part of target surface region of the subject, such as of the at least one of the respective surface parts and / or the common part of the at least one target surface region, preferably the image data sets are associated to or comprises respective time attributes representing point of time of recording.

[0208] 15 In an embodiment, the computer system is configured for identifying matching light features of respective image sets, such as sub-image data sets and for estimating the perspective and / or homographic transformation between the respective matched features of the respective sub-image data sets and based thereon generating the 3D surface representation of the at least one of the respective surface parts and / or the common part of the at least one target surface region.

[0209] In an embodiment, the consecutive image data sets are applied as stereo views or multi views and the 3D reconstruction may be performed using known software tools facilitating 3D reconstruction from 2D images, such as

[0210] Agisoft Metashape: A professional photogrammetry software for 3D reconstruction.

[0211] 25 Pix4D: A suite of software tools for photogrammetry and drone mapping.

[0212] COLMAP: A general-purpose Structure from Motion (SfM) and Multi-View Stereo (MVS) pipeline.

[0213] OpenMVG and OpenMVS: Open-source libraries for multiple-view geometry and dense 3D reconstruction. TRAC-P7 -78499

[0214] 21

[0215] Meshroom: An open-source 3D reconstruction software based on AliceVision framework.

[0216] The computer system may be configured for generating consecutive 3D surface representations of the target surface region of the subject, such as the at least one

[0217] 5 of the respective surface parts and / or the common part of the at least one target surface region of the subject from the consecutive image data sets and for determining potential differences between the consecutive 3D surface representations. Determined differences may indicate that the subject has performed a motion. Preferably, the computer system is configured for processing the determined differences and determine if the difference is caused by a motion or if the difference may be caused by an error, such as an error caused by a shadow area, changed incidence and / or reflection angle or any other optical phenomena, apparatus error and / or calibration errors.

[0218] The computer system may conveniently be capable of determine if a detected motion

[0219] 15 is a true motion or a false motion. A false motion may for example be a local motion of a skin portion that does not reflect an overall movement of the body part under scanning. Such false motions may e.g. be movements caused by tension of a muscle, blinking, movements of mouth region etc. depending on the body part to be subjected to the motion tracking.

[0220] 20 It has been found that the motion tracker arrangement is very effective in distinguishing between true motions and false motions of a detected motion it is believed that this beneficial effect may be caused by the ability of the motion tracker arrangement to have the primary mirror or primary mirrors arranged to redirect potions of light representing surface parts which is not or only rarely subjected to false motions. Preferably the primary mirror or primary mirrors is / are arranged to redirect potions of light representing surface parts with a low risk of soft tissue motion, thereby reducing the risk of detecting false motions.

[0221] In particular, embodiments where the primary mirror or primary mirrors is / are arranged to redirect potions of light representing distinct surface parts, the primary

[0222] 30 mirrors may be arranged to redirect potions of light representing distinct surface parts with low content of soft tissue, such as distinct surface parts where a bone structure is located immediately below the skin, such as a surface part of the skin TRAC-P7 -78499

[0223] 22 covering a right cheek bone, a surface part of the skin covering a left cheek bone a surface part of the skin covering a lower jawbone of the skin covering ( e.g. right or left side), and / or a surface part of the skin covering the nasal bone.

[0224] The computer system may further determine an extend of a motion, such as

[0225] 5 determine if the motion is within a threshold, where the motion is sufficiently small to not affect an ongoing scanning by the medical scanner or to provide that a correction of the scanning may be sufficient or if the motion exceed a threshold, and the computer system may provide a signal to stop the scanning e.g. for restarting the scanning procedure or a part thereof.

[0226] Advantageously, the imaging arrangement is configured for transmitting the consecutive image data sets representing the respective consecutive acquired digital images to the computer system in real time. The computer system is configured for receiving the consecutive image data sets representing the respective consecutive acquired digital images. In an embodiment, the computer system and the imaging

[0227] 15 arrangement are fully or partly integrated with each other.

[0228] The computer system is configured for generating the consecutive 3D surface representations of target surface region, such as the at least one of the respective surface parts and / or the common part of the at least one target surface region of the subject from the consecutive image data sets as a function of time, preferably in real

[0229] 20 time.

[0230] In an embodiment, the motion tracker arrangement further comprises an optical filter screen located between the at least one primary mirror of the mirror arrangement and a location in the scene adapted for the subject to be scanned, wherein the screen is located with a first side facing the at least one primary mirror and a second opposite side facing the location for the subject. The optical filter screen may for example comprise a filter allowing a fraction of light comprising a wavelength range to pass the filter from the second side of the optical filter screen to the first side of the filter screen, while reflecting, absorbing and / or refracting light having wavelengths outside the fraction of light. The light that are not passing the

[0231] 30 filter, may advantageously be reflected. TRAC-P7 -78499

[0232] 23

[0233] The optical filter screen may serve the purpose of protecting the subject from passing light portions from the mirror arrangement to the imaging arrangement and optional projecting light applied in the tracking process, while simultaneously enabling the subject to see images on the screen intended for being shown to the

[0234] 5 subject.

[0235] In an embodiment, the optical filter screen comprises a one-way filter for at least some wavelengths, such as wavelength from less than 1 nm and up -e.g. 200 nm or more, such as 100 nm or more.

[0236] The fraction of light is a wavelength portion of light comprising the wavelength(s)

[0237] 10 applied by the motion tracker arrangement.

[0238] In an embodiment, the one-way filter is a one-way mirror.

[0239] In an embodiment, the filter of the optical filter screen is a band pass filter. Preferably the fraction of light comprises or consists of a portion of invisible light (to human - excluding 380-750 nm), preferably the band pas filter has a center

[0240] 15 wavelength in the near infrared (NIR) range from larger than 750 to 1100, preferably in the range from 800 nm to 1000 nm.

[0241] The spectral bandwidth (Full Width-Half Maximum) of the fraction of light is advantageously 10-100 nm, such as 25-50 nm.

[0242] In an embodiment, the optical filter screen allows light having wavelength(s) within

[0243] 20 the wavelength range of the fraction of light to pass the filter from the first side of the optical filter screen to the second side of the filter screen. Optionally the filter of the optical filter screen in addition allows visible light to pass from the first side of the optical filter screen to the second side of the filter screen.

[0244] First side of filter screen is the primary mirror side and second side of the filter

[0245] 25 screen is the subject side.

[0246] The filter of the optical filter screen may comprise an absorption filter and / or a dichroic filter

[0247] The motion tracker arrangement may advantageously, further comprise a light projector, such as a spot light pointer or a structured light projector for pointing a TRAC-P7 -78499

[0248] 24 spot marking or a structured light onto the second side of the optical filter screen and / or onto the target surface region.

[0249] Then the marker may for example comprise at least one wavelength within the wavelength range of the fraction of light capable of passing the filter screen.

[0250] 5 In an embodiment, the motion tracker arrangement further comprises a projector adapted for projecting a live and / or a still image onto the second side of the optical filter screen, preferably the live and / or a still image. In an embodiment, where the projected image comprises at least one wavelength within the wavelength range of the fraction of light, the projected image may be applied in the pre-calibration of the motion tracker arrangement and / or in the in-use calibration of the motion tracker arrangement,. In an embodiment, where the projected image comprises at least one wavelength outside the wavelength range of the fraction of light, the projected image may be applied for being viewed by the subject, e.g. for providing the subject with information about the scanning status etc. In the latter embodiment, the project

[0251] 15 image may advantageously be free of wavelengths within the wavelength range of the fraction of light.

[0252] The phrases "portion(s) of light" and "light portion(s)" are used interchangeable.

[0253] In an embodiment, the light projector is adapted for projecting a structured light to a reflective location of one or more of the at least one primary mirror and / or to a

[0254] 20 reflective location to an in-use calibration element, which is in fixed pose relative to a pose of the at least one primary mirror.

[0255] Advantageously, the at least one primary mirror is located in an armature e.g. as described above and the light projector is adapted for projecting a light, such as structured light to a reflective location of the armature. Preferably the armature comprising the at least one primary mirror, wherein the at least one primary mirror is fixed in pose relative to the armature.

[0256] In an embodiment, the light projector is adapted for projecting a structured light to a reflective location of one or more of the at least one primary mirror and / or to a reflective location of a calibration element, which is in fixed pose relative to a pose of

[0257] 30 the at least one primary mirror, such as an armature comprising the at least one TRAC-P7 -78499

[0258] 25 primary mirror and wherein the at least one primary mirror is fixed in pose relative to the armature.

[0259] The at least one primary mirror may preferably comprise a primary mirror surface for redirecting the light reflected from the target surface. In an embodiment the primary

[0260] 5 mirror comprises light absorbing features at the primary mirror surface to provide the redirected light to be a redirected structured light, such as a primary mirror surface comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character, wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths.

[0261] The structured light of the light projector and / or the redirected light may comprise a plurality of light features, which are recognizable by a computer system from a set of pixel data obtained by the imaging arrangement. The light features may comprise an indefinite number of light features. The light features may be optically recognizable

[0262] 15 by comprising an optically recognizable attribute, such as a geometrical attribute (e.g. a local shape), an intensity attribute and / or a wavelength attribute.

[0263] The structured light of the light projector and / or the redirected light may have an image plan and an intensity distribution in image plan comprising high intensity area(s) and dark area(s)adjacent to the high intensity area(s), wherein the high

[0264] 20 intensity area(s) has a higher light intensity per unit area as determined in image plan than the dark area(s), preferably the major part of dark area(s) has no light intensity or has a light intensity per unit area which is less than about 5 % of the light intensity of adjacent high intensity area(s), such as less than about 3 %, such as less than about 1 %.

[0265] The structured light of the light projector and / or the redirected light in image plan may comprise a symmetrical or an asymmetrical intensity light pattern, such as comprising a plurality of light dots and / or points, an arch shape, ring or semi-ring shaped lines, a plurality of angled lines, a coded structured light configuration or any combinations thereof,. In an embodiment, the pattern comprises a grid of lines, a

[0266] 30 crosshatched pattern optionally comprising parallel lines. TRAC-P7 -78499

[0267] 26

[0268] The in-use calibration may be performed by matching light features of the projected structured light or features of the redirected light with corresponding light features of the portion of the structured reflected light recorder by the imaging arrangement e.g. according to principles known from the art of feature matching of stereo images

[0269] 5 for example by applying homographic iterative closest match algorithms.

[0270] The motion tracker arrangement may further comprises a lamp for illuminating at least a portion of the scene, e.g. for avoiding undesired shadow areas of the target surface region of the subject.

[0271] In an embodiment, the motion tracker arrangement comprises a structured light

[0272] 10 projector configured for projecting invisible light, such as for projecting light having one or more wavelength in the ranges from 100 nm to 350 nm and / or from 700 nm to 1.4 pm, preferably in the range from 800-1200 nm. The structured light projector may conveniently is configured for projecting a dot pattern and / or a speckle pattern.

[0273] In an embodiment, the structured light projector is configured for projecting the structured light to at least a portion of the scene, preferably for projecting the structured light to the at least one target surface region of the subject.

[0274] It has been found to be very beneficial that at least a part of the imaging arrangement, such as the entire imaging arrangement may be located outside the scene of the scanner, such as out of the range of a magnetic field generated by the

[0275] 20 medical scanner for example where the scanner is or comprises a MRI scanner.

[0276] In an embodiment the at least one imaging device of the imaging arrangement is adapted for being located outside the scene of the scanner.

[0277] The at least one imaging device and the at least one primary mirror may conveniently be adapted to be located with a distance of at least 0.5 m, such as at

[0278] 25 least 1 m, such as at least 1.2 m, such as at least 1.3 m, such as at least 1.4 m, such as at least 1.5 m. In an embodiment the scanner comprises a scanner bore and the at least one imaging device of the imaging arrangement is adapted to be located outside the scanner bore.

[0279] In an embodiment, at least one of the respective portions of light having different

[0280] 30 travelling paths length than at least one other of the respective portions of light TRAC-P7 -78499

[0281] 27 from being reflected from the mirror arrangement to being recorded by the imaging arrangement.

[0282] In an embodiment, at least two of the respective portions of light have travelling paths that differs in from each other in travelling length from being reflected from

[0283] 5 the mirror arrangement, such as travelling paths that differs at least 5 %. Such as at least 10 %, such as at least 15 from each other in travelling length, based on the longest travelling path of the at least two of the respective portions of light.

[0284] Preferably, at least one of the respective portions of light has a travelling path with a total average length of at least 0.5 m, such as at least 1 m, such as at least 1.1 m, such as at least 1.2 m, such as at least 1.3 m, such as at least 1.4 m, such as at least 1.5 m, such as at least 1.6 m.

[0285] In a desired aspect of the invention the at least two portions of light, each representing at least a surface part of the at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of

[0286] 15 the at least one target surface region of the subject, such as distinct surface parts of the at least one target surface region of the subject with no overlap.

[0287] Preferably the at least one primary mirror of the mirror arrangement and the at least one imaging device of the imaging arrangement are configured for providing that the at least two portions of light, each representing at least a surface part of the at least

[0288] 20 one target surface region comprises at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject, such as distinct surface parts of the at least one target surface region of the subject with no overlap.

[0289] The distinct surface parts may advantageously comprise surface parts where a bone structure is located immediately below the skin, such as a surface part of the skin covering a right cheek bone, a surface part of the skin covering a left cheek bone a surface part of the skin covering a lower jawbone of the skin covering (e.g. right or left side), and / or a surface part of the skin covering the nasal bone.

[0290] Advantageously, the distinct surface part comprises at least two distinct surface

[0291] 30 parts, wherein the at least two distinct surface parts has a minimum distance to each other of at least 1 mm, such as of at least 0.5 cm, such as of at least 1 cm, such as TRAC-P7 -78499

[0292] 28 of at least 2 cm the at least one target surface region of the subject such as of from 0.5 to 15 cm determined in a 3D view of the at least one target surface region of the subject.

[0293] In an embodiment, the at least two distinct portions of light representing distinct

[0294] 5 surface parts comprises N distinct portions of light and wherein the primary mirrors comprises N primary mirrors, wherein N is an integer of from 2 to at least 10, such as from 2 to 8, such as from 2 to 6, such as from 2 to 4.

[0295] In an embodiment, the N primary mirrors are arranged for redirect the N distinct portions of light representing the distinct surface parts. Preferably the distinct surface

[0296] 10 parts comprises N distinct surface parts. In an embodiment, the imaging arrangements comprises at least M imaging devices, and wherein the N primary mirrors are arranged to redirect the N distinct portions of light representing the distinct surface parts to provide that at least a first sub-portion of each of the N distinct portions of light representing the distinct surface parts is received by at least one of the at least M imaging devices and a second sub-portion of each of the N distinct portions of light representing the distinct surface parts is received by at least one other of the at least M imaging devices. Advantageously, the first sub-portion and the second sub-portion of each of the N distinct portions of light representing the distinct surface parts may be equal or different from each other, such as being

[0297] 20 overlapping or non-overlapping first sub-portion and second sub-portion, wherein M is an integer of at least 2.

[0298] In an embodiment, M is three or larger, such as from 3 to 10, such as from 3 to 8, such as from 3 to 4.

[0299] Each of the M imaging devices may beneficially be configured for receiving at least a

[0300] 25 sub-portion of the N distinct portions of light representing the N distinct surface parts. Preferably the M imaging devices and the N primary mirrors are arranged and preferably calibrated, relative to each other and relative to the N distinct surface parts to provide that each of the M imaging devices receives at least a sub-portion of the N distinct portions of light representing the N distinct surface parts.

[0301] 30 Each of the M imaging devices may in an embodiment be configured for receiving at least two sub-portions of the N distinct portions of light representing the N distinct TRAC-P7 -78499

[0302] 29 surface parts. Preferably the M imaging devices and the N primary mirrors are arranged, relative to each other and relative to the N distinct surface parts to provide that each of the M imaging devices receives at least a sub-portion of one of the N distinct portions of light representing the N distinct surface parts and at least a sub¬

[0303] 5 portion of one other of the N distinct portions of light representing the N distinct surface parts.

[0304] It has been found to be very beneficial, where the N primary mirrors and the M imaging devices are organized to operate group-wise. Advantageously, each where each group comprises two primary mirrors and two imaging devices, wherein the two mirrors of a group are arranged for redirect the two distinct portions of light representing the distinct to surface parts and wherein the two imaging devices of the group each is configured for receiving at least a sub-portion of each of the two distinct portions of light representing the two distinct surface parts.

[0305] In a preferred embodiment, the computer system is configured for receiving and

[0306] 15 processing the respective consecutive image data sets and for generating the least one 3D representation of at least a portion of the at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject. Advantageously the computer processing comprises cross correlating data

[0307] 20 representing respective sub-portions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices, to determine a relative pose of the respective at least two distinct surface parts.

[0308] Advantageously the computer processing comprises cross correlating data representing respective sub-portions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices to determine the relative pose of the respective at least two distinct surface parts in a coordinate system, such as in a scanner coordinate system.

[0309] Thereby optional correction of scanner images where miner motions are detected

[0310] 30 may relatively fast and effective way be corrected since the motion tracker arrangement and the scanner are operating in a common coordinate system. TRAC-P7 -78499

[0311] 30

[0312] Advantageously, the computer system comprises data representing a pose of each of the at least one primary mirror and / or the optional armature and / or the at least one imaging device and wherein the computer processing comprises cross correlating data representing respective sub-portions of each of the two distinct portions of light

[0313] 5 representing the at least two distinct surface parts of images of respective imaging devices and data representing the pose of one or more of the at least one primary mirror and / or the optional armature and / or the at least one imaging device, to determine the relative pose of the respective at least two distinct surface parts.

[0314] In a preferred embodiment, the computer system of the motion tracker arrangement is configured for receiving a 3D scan image data set from a scanner, wherein the 3D scan image data set comprises data representing a 3D scan image comprising at least a portion of the at least two distinct surface parts of the at least one target surface region of the subject represented by the at least two distinct portions of light.

[0315] 15 Advantageously, the 3D scan image data set comprises data representing a scanner coordinate system and data representing a pose of the 3D scan image in the scanner coordinate system.

[0316] Preferably the computer system is configured for receiving and processing the respective consecutive image data sets and for generating the least one 3D

[0317] 20 representation of at least a portion of the at least one target surface region comprising at least a portion of each of the at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject. Preferably, the computer processing comprises matching at least a portion of the at least two of, preferably of each of the at least two distinct surface parts of the at least two distinct surface parts to the scan image to determine the relative pose of the respective at least two distinct surface parts, preferably to determine the relative pose of the respective at least two distinct surface parts in a coordinate system, such as in the scanner coordinate system.

[0318] Advantageously the scanner is a 3D scanner, preferably selected from an MRI

[0319] 30 scanner, a CT scanner, a PET scanner, an ultrasound scanner and / or any combinations thereof. TRAC-P7 -78499

[0320] 31

[0321] The invention also comprises a scanner system.

[0322] The scanner system comprising a scanner and a motion tracker arrangement, wherein the scanner comprises a scanning scene and a support for supporting a subject comprising a body part located in the scanning scene for being subjected to

[0323] 5 a scanning procedure.

[0324] The motion tracker arrangement comprises

[0325] • a mirror arrangement comprising at least one primary mirror;

[0326] • an imaging arrangement comprising at least one imaging device; and

[0327] • a computer system.

[0328] 10 The mirror arrangement is adapted for redirecting light reflected from at least one target surface region of the subject, wherein the imaging arrangement is adapted to receive light reflected by the mirror arrangement, wherein the redirected light comprises at least two portions of light, wherein each of the respective portions of light comprises light representing a surface part of the target surface region, wherein the mirror arrangement is adapted for redirecting the portions of light towards the imaging arrangement.

[0329] The imaging arrangement is adapted for recording consecutive digital images of the respective light portions redirected towards the imaging arrangement and for generating and transmitting consecutive image data sets representing the respective

[0330] 20 consecutive recorded digital images to the computer system.

[0331] The respective portions of light have different travelling paths from being reflected from the mirror arrangement to being recorded by the at least one imaging device of the imaging arrangement.

[0332] The computer system is configured for processing the respective consecutive image

[0333] 25 data sets and for generating at least one 3D surface representation of at least a portion of the at least one target surface region of the subject.

[0334] In an embodiment, the computer system is configured for processing the respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of the at least one target surface region for TRAC-P7 -78499

[0335] 32 generating the least one 3D surface representation of at least a portion of the at least one target surface region of the subject, preferably comprising at least one of the respective surface parts of the at least one target surface region.

[0336] In an embodiment, the respective portions of light comprises light representing a

[0337] 5 common part of the target surface region

[0338] The respective portions of light may comprise light representing a common part of the at least one target surface region, and wherein the computer system being configured for processing the respective consecutive image data sets and for generating the at least one 3D surface representation of at least a portion of the at

[0339] 10 least one target surface region comprising the common part of the at least one target surface region.

[0340] The motion tracker arrangement may advantageously be as described above.

[0341] The scanner is conveniently a medical scanner, such as an X-ray scanner a MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner, a Bone densitometry

[0342] 15 (DXA), a Magneto-Encephalo-Graphy (MEG) scanner and / or any combinations thereof.

[0343] In an embodiment, the scanner is a 3D scanner, preferably selected from a MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner and / or any combinations thereof.

[0344] 20

[0345] The support for supporting a subject may for example comprise a bearing, a seat, an armrest, a leg rest, a support rod or any combination comprising one or more of these.

[0346] Advantageously, the at least one primary mirror of the mirror arrangement is located

[0347] 25 in the scene e.g. as described above. Preferably, two or more primary mirrors are located in the scene at respective viewing distances to the at least one target surface region of the subject, such as to at least one of the respective surface parts and / or the common part of the at least one target surface region. The respective viewing distances may be determined from a center point of the respective mirrors to a TRAC-P7 -78499

[0348] 33 center point of the at least one target surface region of the subject, such as to a center point of the at least one of the respective surface parts and / or the common part of the at least one target surface region, wherein the respective viewing distances may be equal or different from each other, such as from 1 cm to 1 m, such

[0349] 5 as from 2 cm to 25 cm, optionally the respective viewing distances differs at most 10 cm from each other, such as at most 5 cm from each other.

[0350] Advantageously, the scanner comprises an RF coil, a scanner bore and / or or a patient table and wherein the at least one primary mirror of the mirror arrangement, comprises at least one primary mirror temporally or permanently mounted to the RF coil and or a patient table.

[0351] The primary mirror of the mirror arrangement may e.g. be mounted to the RF coil as described above.

[0352] In an embodiment, the motion tracker system comprises at least one mirror sensor adapted for detecting the pose of one or more of the at least one primary mirror and

[0353] 15 or the armature comprising the at least one mirror, the at least one mirror sensor may preferably be located at a fixed location relative to the scanner, such as to a fixed location of the scanner, such as to a scanner wall portion of a scanner, such as a scanner bore, a floor and / or a ceiling of the scanner.

[0354] The mirror sensor may be as described above. The mirror sensor may conveniently

[0355] 20 be configured for transmitting an alarm signal if detecting that a primary mirror of the at least one primary mirror is deviating from a valid calibrated pose. In an embodiment of the scanner system, the respective portions of light reflected from the target surface region and redirected by the respective primary mirrors to the imaging arrangement represents different Field of views (FOVs) of the at least one of the respective surface parts and / or the common part of the at least one target surface region.

[0356] In an embodiment of the scanner system, the travelling paths of the respective portions of light travelling from the target surface region via reflection by the respective primary mirrors to the imaging arrangement comprises different center

[0357] 30 travel axes from the at least one of the respective surface parts and / or the common part of the at least one target surface region to the imaging arrangement, e.g. as TRAC-P7 -78499

[0358] 34 described above. Preferably the travelling paths of the respective portions of light travelling from the target surface region via reflection by the respective primary mirrors to the imaging arrangement comprises different center travel axes from the at least one of the respective surface parts and / or the common part of the at least

[0359] 5 one target surface region to the respective primary mirrors, preferably a center travel axis has an angle of at least 5°, such as least 10, such as least 20°, such as least 25° to another center travel axis of the center travel axes.

[0360] The center travelling axis may be as defined above.

[0361] In an embodiment of the scanner system, the imaging arrangement, the mirror arrangement and elements thereof may be as applied above.

[0362] In an embodiment of the scanner system, the consecutive image data sets generated from images of respective portions of light represents respective point of views (POV's) of the at least one of the respective surface parts and / or the common part of the at least one target surface region, wherein the respective POV's preferably differs

[0363] 15 from each other.

[0364] The computer system of the scanner system may be configured for being or is calibrated to generating and / or identifying sub-image data sets of each of the consecutive image data sets, wherein each sub-image data set represents a point of view (POV) of the at least one of the respective surface parts and / or the common

[0365] 20 part of the at least one target surface region.

[0366] In an embodiment of the scanner system, the at least one primary mirror comprises a primary mirror surface for redirecting the light reflected from the target surface. The primary mirror advantageously comprises light absorbing features at the primary mirror surface to provide the redirected light to be a redirected structured light, preferably comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character, wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths.

[0367] In a preferred embodiment, the surface parts represented by the at least two

[0368] 30 portions of light need not to have a common part, i.e. an overlapping common part is not required. This has the additional advantageous that distinct surface parts may be TRAC-P7 -78499

[0369] 35 selected to be distinct surface parts having a relative thin tissue layer covering a bone structure, which thereby ensures that the risk of detection of false motions may be reduced, such as reduced to a minimum.

[0370] Advantageously, the at least two portions of light, each representing at least a

[0371] 5 surface part of the at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject, such as distinct surface parts of the at least one target surface region of the subject with no overlap.

[0372] The distinct surface parts may be as described above and may conveniently comprise one or more surface parts where a bone structure is located immediately below the skin, such as a surface part of the skin covering a right cheek bone, a surface part of the skin covering a left cheek bone a surface part of the skin covering a lower jawbone of the skin covering (e.g. right or left side), and / or a surface part of the skin covering the nasal bone.

[0373] 15 In an embodiment, each of the at least two distinct surface parts comprises a surface area where the tissue layer covering bone is 10 mm or less, such as 5 mm or less, e. g. such that at least 10 %, such as at least 25 %, such as at least 50 %, such as 75 % or preferably more of the each of the at least two distinct surface parts comprises a surface area where the tissue layer covering bone is 10 mm or less,

[0374] 20 such as 5 mm or less.

[0375] The at least two distinct portions of light representing distinct surface parts may e.g. comprise N distinct portions of light and the primary mirrors may comprise N primary mirrors for example as described above.

[0376] The N primary mirrors may be arranged for redirecting the N distinct portions of light representing the distinct surface parts to be received by at least M imaging devices, preferably as described above.

[0377] In an embodiment, each of the M imaging devices is configured for receiving at least a sub-portion of the N distinct portions of light representing the N distinct surface parts, preferably the M imaging devices and the N primary mirrors are arranged

[0378] 30 (calibrated) relative to each other and relative to the N distinct surface parts to TRAC-P7 -78499

[0379] 36 provide that the M imaging devices receives at least a sub-portion of the N distinct portions of light representing the N distinct surface parts.

[0380] Preferably, the N primary mirrors and the M imaging devices are organized to operate group-wise, as described above.

[0381] 5 The computer system of the motion tracker arrangement is preferably configured for receiving and processing the respective consecutive image data sets and for generating the least one 3D representation of at least a portion of the at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject. The computer processing advantageously comprises cross correlating data representing respective sub portions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices, to determine a relative pose of the respective at least two distinct surface parts, preferably to determine the relative pose of the respective

[0382] 15 at least two distinct surface parts, preferably to determine the relative pose of the respective at least two distinct surface parts in a coordinate system, such as in a scanner coordinate system of the scanner.

[0383] In an embodiment, the computer system of the motion tracker arrangement may in an embodiment form part of and / or be integrated with a scanner computer system

[0384] 20 of the scanner.

[0385] In an embodiment the computer system of the motion tracker arrangement comprises data representing a pose of each of the at least one primary mirror and / or the optional armature and / or the at least one imaging device. The computer processing may then conveniently comprise cross correlating data representing respective sub portions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices and data representing a pose of one or more of the at least one primary mirror and / or the optional armature and / or the at least one imaging device, to determine the relative pose of the respective at least two distinct surface parts.

[0386] 30 The invention also comprises a method of motion tracking of a subject having a body part located in a scanning scene. The method comprises TRAC-P7 -78499

[0387] 37

[0388] - providing a motion tracker arrangement comprising

[0389] • a mirror arrangement comprising at least one primary mirror;

[0390] • an imaging arrangement comprising at least one imaging device; and

[0391] • a computer system,

[0392] 5 - arranging the mirror arrangement to redirecting light reflected from at least one target surface region of the subject to provide that the redirected light comprises at least two portions of light, such that each of the at least two respective portions of light comprises light representing a surface part of the at least one target surface region, to provide that the mirror arrangement is arranged for redirecting the portions of light towards the imaging arrangement,

[0393] - arranging the imaging arrangement to receive at least a part of the redirected light,

[0394] - activating the imaging arrangement for recording consecutive digital images

[0395] 15 of the respective light portions redirected towards the imaging arrangement and providing the imaging arrangement for generating and transmitting consecutive image data sets representing the respective consecutive recorded digital images to the computer system.

[0396] The method comprises providing the respective portions of light to have different

[0397] 20 travelling paths from being reflected from the mirror arrangement to being recorded by the imaging arrangement and the computer system is configured for processing the respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of the target surface region.

[0398] Preferably, each of the respective portions of light comprises light representing a surface part of the target surface region. The computer system may then preferably be configured for processing the respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of the at least one of the respective surface parts and / or the common part of the at least one target surface region.

[0399] 30 In an embodiment, the method is performed using a motion tracker arrangement as described above. TRAC-P7 -78499

[0400] 38

[0401] The scanner system applied in the method of motion tracking may comprise a scanner system as described above, preferably comprising a motion tracking system as described above.

[0402] The at least one target surface region comprises or consists of a surface region of

[0403] 5 the body part located in the scanning scene, preferably the at least one target surface region is free of artificial marker element(s).

[0404] In an embodiment, the computer system being configured for processing the respective consecutive image data sets and for generating the at least one 3D surface representation of at least a portion of the at least one target surface region, preferably a 3D data representation of at least a portion of the at least one target surface region comprising at least one of the surface parts of the at least one target surface region.

[0405] In an embodiment, each of the at least two portions of light comprises light represents a common part of the at least one target surface region, preferably

[0406] 15 wherein the computer system being configured for processing the respective consecutive image data sets and for generating the least one 3D surface representation to comprises the common part of the at least one target surface region of the subject.

[0407] The method may advantageously comprise pre-calibrating the motion tracker

[0408] 20 arrangement prior to performing the motion tracking of the body part and / or between tracking sessions. The pre-ca libration is advantageously not performed during a scanning session, however, where the motion tracker arrangement comprises one or more primary mirrors and / or an armature associated to step motor e.g. as described, minor detected deviation from a valid calibration pose of a primary mirror and or the armature, may be corrected at any time even during a scanning session e.g. as described above.

[0409] In an embodiment, a pre-calibration pose, may be performed as a factory precalibration pose, which factory pre-calibration pose is performed prior to installing the motion tracker arrangement and which factory pre-calibration pose may be

[0410] 30 applied as a starting point for the pre-calibration performed after the motion tracker arrangement has been installed. In an embodiment, the method may comprise TRAC-P7 -78499

[0411] 39 performing a pre-calibration for each type of scanning to be performed, such as a pre-calibration for each of a number of different body parts to be scanned, e.g. a head scanning pre-calibration, a knee scanning pre-calibration and etc.

[0412] In an embodiment, a pre-calibration may be performed prior to initiating a scanning

[0413] 5 procedure,

[0414] The terms "calibration" and "pre-calibration" and conjugation forms thereof are used interchangeable unless otherwise stated or clear from the context.

[0415] The phrase "a valid calibration pose" means a pose determined in a pre-calibration process, such as the latest pre-calibration pose and / or a selected pre-calibration

[0416] 10 pose.

[0417] The pre-calibration may comprise providing at least one pre-calibration surface region and arranging the pre-calibration surface region at an estimated location in replacement for the at least one target surface region. The pre-calibration may conveniently comprise arranging the pre-calibration surface region in the scene at a location adapted for the target surface region.

[0418] The at least one pre-calibration surface may comprise a surface of a pre-calibration device and the pre-calibration device may be arranged in the scene of the scanner.

[0419] Once the pre-calibration surface is in place in the scanner scene, the pre-calibration continues by providing the mirror(s) of the mirror arrangement (primary and

[0420] 20 optionally intermediate mirror(s)) to redirecting light reflected from the precalibrating surface region, e.g. comprising adjusting the mirror(s) of the mirror arrangement, such that the redirected light comprises at least two pre-calibration portions of light, wherein each of the respective pre-calibration portions of light comprises light representing a surface part, such as a at least one of the respective

[0421] 25 surface parts and / or the common part of the at least one pre-calibration surface region, to provide that the mirror arrangement is arranged for redirecting the precalibration portions of light towards the imaging arrangement.

[0422] The imaging arrangement is provided to receive at least a part of the light redirected from the pre-calibration surface e.g. by adjusting the primary mirror(s), optional TRAC-P7 -78499

[0423] 40 intermediate mirrors and / or the at least one imaging devices if the imaging arrangement.

[0424] Thereafter the imaging arrangement is activated for recording one or more precalibration digital images of the respective calibration light portions redirected

[0425] 5 towards the imaging arrangement and providing the imaging arrangement for generating and transmitting pre-calibration image data sets representing the respective recorded pre-calibration digital images to the computer system.

[0426] The method comprises providing the respective pre-calibration portions of light to have different travelling paths from being reflected from the mirror arrangement to being recorded by the imaging arrangement.

[0427] The computer system is acquiring and / or receiving pre-calibration data representing the pre-calibration surface region and the computer system is processing the respective pre-calibration image data sets and generating a pre-calibrating algorithm comprising correlating the pre-calibration image data sets with the pre-calibration

[0428] 15 data.

[0429] Preferably, the pre-calibration comprises pre-calibrating the computer system to generate and / or identifying sub-image data sets of each of the consecutive image data sets, wherein each sub-image data set represents a point of view (POV) of at least a portion of the target surface region, such as of the at least one of the

[0430] 20 respective surface parts and / or the common part of the at least one target surface region of the subject.

[0431] The pre-calibration surface region may advantageously comprise a pattern comprising sub regions having different reflection properties and / or a 3D structure, such as one or more curved sub regions, one or more protruding sub regions The pattern may for example comprise a checkerboard pattern a plurality of dots, a plurality of points, an arch shape, ring or semi-ring shaped lines, a plurality of angled lines, a coded structured color configuration, a grid of lines, a crosshatched pattern or any combinations thereof).

[0432] In an embodiment, the pre-calibration surface region any be tunable for modelling

[0433] 30 one or more motions, and wherein the method comprising one or more refining cycles each comprising TRAC-P7 -78499

[0434] 41

[0435] - adjusting the pre-ca libration for modelling one or more of the motions

[0436] - repeating the step of

[0437] • generating and transmitting consecutive pre-calibration image data sets representing the respective consecutive recorded pre-calibration digital

[0438] 5 images to the computer system,

[0439] • acquiring and / or receiving pre-calibration data representing the precalibration surface region and

[0440] • processing the respective pre-calibration image data sets comprising correlating the calibration image data sets with the pre-calibration data and

[0441] - refining the pre-calibrating algorithm.

[0442] In an embodiment, the at least one primary mirror comprises a primary mirror surface for redirecting the light reflected from the calibration surface. The primary mirror may comprise light absorbing features at the primary mirror surface to provide the redirected light to comprise redirected structured calibration light portions,

[0443] 15 preferably comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character, wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths.

[0444] The motion tracker arrangement may comprise a marker, wherein the method

[0445] 20 comprises pointing a marking using the marker onto the target surface region and / or onto the pre-calibration surface region. Thereby the pre-calibration may be further fine-tuned.

[0446] In an embodiment, the pre-calibration comprises calibrating the relative pose of the primary mirror and optionally the intermediate mirrors. Preferably, the pre-calibration comprises calibrating the relative pose of the primary mirror in the armature and optionally fixing the primary mirrors in the armature in their respective pre-calibrated pose.

[0447] In an embodiment, the pre-calibration comprising fixing the pose of the at least one imaging device and calibrating the relative pose of the primary mirror and optionally

[0448] 30 the intermediate mirror(s), preferably the fixed pose of the at least one imaging device is referred to as a valid image device pose. TRAC-P7 -78499

[0449] 42

[0450] In an embodiment, the method comprises arranging the mirror arrangement of the motion tracker arrangement as adapted, providing that the at least one primary mirror is located in the scene of the scanner. Preferably the method comprises arranging two or more primary mirrors in the scene e.g. at respective viewing

[0451] 5 distances to the target surface region e.g. the at least one of the respective surface parts and / or the common part of the at least one the target surface region of the subject. The respective viewing distances are determined from a center point of the respective mirrors to a center point of the target surface region, such as to a center point of the at least one of the respective surface parts and / or the common part of the at least one target surface region of the subject. The respective viewing distances may be equal or different from each other, such as from 1 cm to 1 m, such as from 2 cm to 25 cm, optionally the respective viewing distances differs at most 10 cm from each other, such as at most 5 cm from each other.

[0452] In an embodiment, the method comprises arranging the mirror arrangement to

[0453] 15 provide that the respective portions of light reflected from the target surface region and redirected by the respective primary mirrors to the imaging arrangement, represents different Field of views (FOVs) of the at least one of the respective surface parts and / or the common part of the at least one target surface region.

[0454] In an embodiment, the method comprises arranging the mirror arrangement to

[0455] 20 provide that the travelling paths of the respective portions of light travelling from the target surface region via reflection by the respective primary mirrors to the imaging arrangement comprises different center travel axes determined as described above from the target surface region, such as from the at least one of the respective surface parts and / or the common part of the at least one target surface region of the subject of to the imaging arrangement. Preferably, the travelling paths of the respective portions of light travelling from the target surface region via reflection by the respective primary mirrors to the imaging arrangement comprises different center travel axes from the target surface region to the respective primary mirrors, preferably a center travel axis of the center travel axes has an angle of at least 5°,

[0456] 30 such as least 10, such as least 20°, such as least 25° to another center travel axis of the center travel axes. TRAC-P7 -78499

[0457] 43

[0458] The method preferably comprises arranging the mirror arrangement to provide that two or more of the respective portions of light impinges at least partly at different locations of an image sensor of the at least one imaging device of the imaging arrangement, such as to provide that the two or more of the respective portions of

[0459] 5 light impinges at separate partially overlapping or non-overlapping locations of the image sensor of the at least one imaging device of the imaging arrangement.

[0460] In an embodiment, the method comprises temporally or permanently mounting at least one primary mirror of the mirror arrangement to an RF coil and or a patient table.

[0461] 10 The RF coil may for example comprise one or more through openings into the location in the scene adapted for the body part to be scanned and the method comprises mounting the at least one primary mirror to be located to redirect light portion or portions passing from the at least one target surface region of the subject and through the one or more through openings. In an embodiment the RF coil comprises two or more through openings and the method may comprise mounting at least two primary mirrors to the RF coil to redirect light portions that have passed through respective of the at least two through openings. In an embodiment, the method comprises mounting at least two primary mirrors comprising mounting one primary mirror to redirect one of the light portions and mounting another one of the

[0462] 20 primary mirrors to redirect another one of the light portions, where the respective light portions that have passed through the respective of the two or more through openings represents distinct surface parts of the at least one target surface region of the subject.

[0463] In an embodiment, the motion tracker system comprises at least one mirror sensor

[0464] 25 adapted for detecting the pose of one or more of the at least one primary mirror and or the armature. The method may preferably comprise arranging the at least one mirror sensor to be located at a fixed location relative to the scanner, such as to a fixed location of the scanner, such as to a scanner wall portion of a scanner, such as a scanner bore, a floor and / or a ceiling of the scanner.

[0465] 30 As described above, the armature preferably comprises at least one primary mirror and / or one or more intermediate mirrors. TRAC-P7 -78499

[0466] 44

[0467] The pose, also referred to as the valid calibration pose, of the respective primary mirrors and optionally the armature may be determined by a pre-calibration procedure as described elsewhere herein.

[0468] The at least one mirror sensor be as described above.

[0469] 5 In an embodiment, the at least one mirror sensor is configured for transmitting an alarm signal if detecting that a primary mirror of the at least one primary mirror and / or the armature is deviating from a valid calibration pose, such as a precalibration pose, thereby the motion tracker arrangement may immediately alert a user if one or more of the primary mirrors has been moved to be out of conformation with the valid calibration pose. In an embodiment, where the user receives an alarm the method may comprise stopping the scanning procedure and provide that the pose of the one of more primary mirror and / or of the armature is / are corrected to be in conformation with the valid calibration pose, e.g. based on instructions received from the mirror sensor e.g. via a user screen.

[0470] 15 In an embodiment, each of the at least one primary mirror and / or the armature is associated to a step motor for adjusting pose of the respective primary mirrors and the armature and wherein the at least one mirror sensor is configured for transmitting instruction to the at least one step motor, to modify the pose of the at least one primary mirror and / or armature that has been detected to deviate from a

[0471] 20 valid calibration pose, to provide the at least one primary mirror and / or armature to be in conformation with the valid calibration pose. The method may comprise performing a control test to confirm that the at least one primary mirror and / or armature has been reset to be in conformation with the valid calibration pose prior to reset or continue the scanning procedure.

[0472] In an embodiment, the motion tracker is pre-calibrated e.g. as described below, providing one or more of the at least one primary mirror of the mirror arrangement and / or one or the armature and / or one or more of the at least one imaging device to be in respective valid calibration pose, preferably to provide each of the at least one primary mirror of the mirror arrangement to be in respective valid pose, such as

[0473] 30 providing at least the armature to be in a valid calibration pose. TRAC-P7 -78499

[0474] 45

[0475] Where the imaging arrangement comprises two or more imaging devices each comprising an image sensor, the method may conveniently comprise arranging the mirror arrangement for redirecting the respective portions of light to provide that at least one of the respective portions of light impinges at the image sensor of one of

[0476] 5 the imaging devices and that at least one other of the respective portions of light impinges at image sensor on one other of the imaging devices Optionally, the mirror arrangement is arranged for redirecting the respective portions of light to provide that at least two of the respective portions of light impinges at the image sensor of a same one of the imaging devices, preferably at different locations of the same image sensor.

[0477] In an embodiment, the method comprises arranging the mirror arrangement to provide that the consecutive image data sets generated from images of respective portions of light represent respective point of views (POV's) of the at least one of the respective surface parts and / or the common part of the at least one target surface

[0478] 15 region, wherein the respective POV's preferably differs from each other.

[0479] In an embodiment, the method comprises providing the imaging arrangement for recording the consecutive digital images of the respective light portions as a function of time, wherein each of the consecutive image data sets is associated to or comprises a time attribute representing a point of time of recording, preferably as

[0480] 20 described above.

[0481] The method conveniently comprise providing the computer system for processing the respective consecutive image data sets and for generating consecutive 3D surface representation of the at least one of the respective surface parts and / or the common part of the at least one target surface region, preferably the image data sets comprises respective time attributes representing point of time of recording. The computer system may be as described above.

[0482] In an embodiment, the method comprises providing the computer system for identifying matching light features of respective image sets, such as sub-image data sets and for estimating the perspective transformation between the respective

[0483] 30 matched features of the respective sub-image data sets and based thereon generating the 3D surface representation of at least a portion of the target surface region, such as at least a portion of a part of the at least one of the respective TRAC-P7 -78499

[0484] 46 surface parts and / or the common part of the at least one target surface region of the subject.

[0485] In an embodiment, the method comprises providing the computer system for generating consecutive 3D surface representations of at least one of the respective

[0486] 5 surface parts and / or the common part of the at least one target surface region from the consecutive image data sets and for determining potential differences between the consecutive 3D surface representations. Preferably, the computer system is provided for processing determined differences and determine at least one property of a motion causing the difference, e.g. as described above.

[0487] 10 In an embodiment, the method comprises arranging the at least one imaging device of the imaging arrangement to be located outside the scene of the scanner, preferably such that the at least one imaging device and the at least one primary mirror are located with a distance of at least 1 m, such as at least 1.2 m, such as at least 1.3 m, such as at least 1.4 m, such as at least 1.5 m.

[0488] In an embodiment, the method comprises projecting a structured light projector to at least a portion of the scene such as to the at least one target surface region of the subject. The structured light projector may be as described elsewhere herein.

[0489] In a desired aspect of the method of the invention, the method comprises providing that the at least two portions of light, each representing at least a surface part of the

[0490] 20 at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject, such as distinct surface parts of the at least one target surface region of the subject with no overlap.

[0491] The distinct surface parts may conveniently be as described elsewhere herein.

[0492] 25 Preferably the method comprises arranging the at least one primary mirror of the mirror arrangement and the at least one imaging device of the imaging arrangement such that they are configured for providing that the at least two portions of light, each represents at least a surface part of the at least one target surface region comprising at least two distinct portions of light representing distinct surface parts of

[0493] 30 the at least one target surface region of the subject, such as distinct surface parts of the at least one target surface region of the subject with no overlap. TRAC-P7 -78499

[0494] 47

[0495] In an embodiment, the at least two distinct portions of light representing distinct surface parts comprises N distinct portions of light and wherein the primary mirrors comprises N primary mirrors, wherein N is an integer of from 2 to at least 10, such as from 2 to 8, such as from 2 to 6, such as from 2 to 4.

[0496] 5 In an embodiment, the method comprises providing that the N primary mirrors are arranged for redirect the N distinct portions of light representing the distinct surface parts. Preferably, the method comprises providing that the distinct surface parts comprises N distinct surface parts. In an embodiment, the method comprises providing that the imaging arrangements comprises at least M imaging devices, and wherein the N primary mirrors are arranged to redirect the N distinct portions of light representing the distinct surface parts to provide that at least a first sub-portion of each of the N distinct portions of light representing the distinct surface parts is received by at least one of the at least M imaging devices and a second sub-portion of each of the N distinct portions of light representing the distinct surface parts is

[0497] 15 received by at least one other of the at least M imaging devices. Advantageously, the method comprises providing that the first sub-portion and the second sub-portion of each of the N distinct portions of light representing the distinct surface parts may be equal or different from each other, such as being overlapping or non-overlapping first sub-portion and second sub-portion, wherein M is an integer of at least 2.

[0498] 20 In an embodiment, M is three or larger, such as from 3 to 10, such as from 3 to 8, such as from 3 to 4.

[0499] The method advantageously comprises arranging the M imaging devices to provide that each of the M imaging devices is configured for receiving at least a sub-portion of the N distinct portions of light representing the N distinct surface parts. Preferably the method comprises providing that the M imaging devices and the N primary mirrors are arranged and preferably calibrated, relative to each other and relative to the N distinct surface parts to provide that each of the M imaging devices receives at least a sub-portion of the N distinct portions of light representing the N distinct surface parts.

[0500] 30 The method advantageously comprises arranging the M imaging devices to provide that each of the M imaging devices may in an embodiment be configured for receiving at least two sub-portions of the N distinct portions of light representing the TRAC-P7 -78499

[0501] 48

[0502] N distinct surface parts. Preferably the method comprises providing that the M imaging devices and the N primary mirrors are arranged, relative to each other and relative to the N distinct surface parts to provide that each of the M imaging devices receives at least a sub-portion of one of the N distinct portions of light representing

[0503] 5 the N distinct surface parts and at least a sub-portion of one other of the N distinct portions of light representing the N distinct surface parts.

[0504] As described above, it has been found to be very beneficial, where the N primary mirrors and the M imaging devices are organized to operate group-wise.

[0505] Advantageously, the method comprises providing that the each group comprises two primary mirrors and two imaging devices, wherein the two mirrors of a group are arranged for redirect the two distinct portions of light representing the distinct to surface parts and wherein the two imaging devices of the group each is configured for receiving at least a sub-portion of each of the two distinct portions of light representing the two distinct surface parts.

[0506] 15 In a preferred embodiment, the method comprises programming the computer system for receiving and processing the respective consecutive image data sets and for generating the least one 3D representation of at least a portion of the at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of the at least one target surface

[0507] 20 region of the subject. Advantageously, the method comprises programming the computer system to provide that the computer processing comprises cross correlating data representing respective sub-portions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices, to determine a relative pose of the respective at least two distinct surface parts.

[0508] Advantageously, the method comprises programming the computer system to provide that the computer processing comprises cross correlating data representing respective sub-portions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices to

[0509] 30 determine the relative pose of the respective at least two distinct surface parts in a coordinate system, such as in a scanner coordinate system. TRAC-P7 -78499

[0510] 49

[0511] Thereby optional correction of scanner images where miner motions are detected may relatively fast and effective way be corrected since the motion tracker arrangement and the scanner are operating in a common coordinate system.

[0512] Advantageously, the method comprises programming the computer system for

[0513] 5 receiving data representing a pose of each of the at least one primary mirror and / or the optional armature and / or the at least one imaging device and wherein the computer processing comprises cross correlating data representing respective subportions of each of the two distinct portions of light representing the at least two distinct surface parts of images of respective imaging devices and data representing the pose of one or more of the at least one primary mirror and / or the optional armature and / or the at least one imaging device, to determine the relative pose of the respective at least two distinct surface parts.

[0514] In a preferred embodiment, the method comprises programming the computer system for receiving a 3D scan image data set from a scanner, wherein the 3D scan

[0515] 15 image data set comprises data representing a 3D scan image comprising at least a portion of the at least two distinct surface parts of the at least one target surface region of the subject represented by the at least two distinct portions of light.

[0516] Advantageously, the 3D scan image data set comprises data representing a scanner coordinate system and data representing a pose of the 3D scan image in the scanner

[0517] 20 coordinate system.

[0518] Preferably, the method comprises programming the computer system to provide that the computer system is configured for receiving and processing the respective consecutive image data sets and for generating the least one 3D representation of at least a portion of the at least one target surface region comprising at least a portion of each of the at least two distinct portions of light representing distinct surface parts of the at least one target surface region of the subject. Preferably, the computer processing comprises matching at least a portion of the at least two of, preferably of each of the at least two distinct surface parts of the at least two distinct surface parts to the scan image to determine the relative pose of the respective at least two

[0519] 30 distinct surface parts, preferably to determine the relative pose of the respective at least two distinct surface parts in a coordinate system, such as in the scanner coordinate system. TRAC-P7 -78499

[0520] 50

[0521] Advantageously the scanner is a 3D scanner, preferably selected from an MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner and / or any combinations thereof.

[0522] 5 DECRIPTION OF CERTAIN EMBODIMENT, EXAMPLES AND ELEMENT ILLUSTRATING THE INVENTION

[0523] Brief description of preferred embodiments and elements of the invention.

[0524] The above and / or additional objects, features and advantages of the present invention will be further elucidated by the following illustrative and non-limiting description of embodiments, examples and elements of the present invention, with reference to the appended drawings.

[0525] The figures are schematic, are not drawn to scale, and may be simplified for clarity. Throughout, the same reference numerals are used for identical or corresponding parts.

[0526] 15 Figure 1 schematically illustrates a model for creating 3D depth using two imaging devices, such as two digital cameras.

[0527] Figure 2 schematically illustrates a model of recording digital images of two portions of light comprising light representing respective surface parts optionally comprising a common part of a target surface region, wherein a mirror arrangement are adapted for redirecting the portions towards the imaging arrangement.

[0528] Figure 3 schematically illustrates light portions reflected towards imaging devices from a curved primary mirror.

[0529] Figure 4 schematically illustrates light portions reflected towards imaging devices from a spherically convex shaped primary mirror.

[0530] 25 Figure 5 illustrates an upright scanner with a motion tracker arrangement of an embodiment of the invention. The scanner and the motion tracker arrangement may together form a scanner system of an embodiment of the invention. TRAC-P7 -78499

[0531] 51

[0532] Figure 6 illustrates an MEG scanner with a motion tracker arrangement of an embodiment of the invention. The scanner and the motion tracker arrangement may together form a scanner system of an embodiment of the invention.

[0533] Figure 7 illustrates a cross-sectional side view of a medical scanner with narrow bore

[0534] 5 and a motion tracker arrangement of an embodiment of the invention where the imaging arrangement comprises a ToF camera. The scanner and the motion tracker arrangement may together form a scanner system of an embodiment of the invention.

[0535] Figure 8 illustrates a medical scanner with narrow bore and a motion tracker arrangement of an embodiment of the invention where the imaging arrangement comprises a projector and at least one digital camera. The scanner and the motion tracker arrangement may together form a scanner system of an embodiment of the invention.

[0536] Figure 9a illustrates a medical scanner with narrow bore and a motion tracker

[0537] 15 arrangement of an embodiment of the invention where the imaging arrangement comprises a two primary mirrors. The scanner and the motion tracker arrangement may together form a scanner system of an embodiment of the invention.

[0538] Figure 9b illustrates images of light portions reflected via each of the two primary mirrors.

[0539] Figure 10 illustrates a motion tracker arrangement of an embodiment of the invention comprising a mirror arrangement and at least one imaging device, wherein the mirror arrangement comprises flat primary mirrors.

[0540] Figure 11 illustrates a motion tracker arrangement of an embodiment of the invention comprising a mirror arrangement and at least one imaging device, wherein

[0541] 25 the mirror arrangement comprises curved primary mirrors.

[0542] Figure 12 illustrates a motion tracker arrangement of an embodiment of the invention comprising a mirror arrangement and at least one imaging device, wherein the mirror arrangement comprises curved primary mirrors and wherein a filter screen is located between the primary mirrors of the ma and the imaging arrangement. TRAC-P7 -78499

[0543] 52

[0544] Figure 13 illustrates a motion tracker arrangement of an embodiment of the invention comprising a mirror arrangement and at least one imaging device, wherein the mirror arrangement comprises two flat primary mirrors and an intermediate mirror.

[0545] 5 Figure 14 illustrates a scanner system comprising a not shown motion tracker arrangement of an embodiment of the invention and a monitor projecting device for transmitting feedback to a subject during a scanning procedure.

[0546] Figure 15 illustrates an armature comprising primary mirrors of a mirror arrangement of a motion tracker arrangement of an embodiment of the invention.

[0547] Figures 16a-16c illustrate motion tracker arrangements of embodiments of the invention, where the primary mirrors are adapted for redirecting portions of light representing distinct surface parts.

[0548] Figure 17 illustrates a motion tracker arrangement of an embodiment of the invention, where the primary mirrors are adapted for redirecting portions of light

[0549] 15 representing distinct surface parts.

[0550] Prior art 3D generation usually requires two cameras or a stereo camera representing such two cameras. Figure 1 illustrates the basic parameters for and an example of such a calibration where the left and the right cameras are acquiring respectively a left image and a right image, wherein both of the left image and the right image

[0551] 20 comprises an element P of a scene. In order to calibrate the images to generate a 3D image of the scene, the spatially pose of each of the left camera and the right camera are known or estimated. Each of the left image and the right image are processed by allocating pixel coordinates (UL,VL) and (uR,vR) respectively, wherein a principal point p of the left image is estimated as the center of the left image and is set to (UL,VL= 0,0) and a principal point pRof the right image is estimated as the center of the right image and is set to (uR,vR= 0,0). In the illustration the spatially pose of the left image and the right image are here given by the distance b between the images and their respective coordinates (XA,YA,ZA) and (XB,YB,ZB). The spatially pose of the element P of the scene is referred to a world reference coordinates (X, Y,

[0552] 30 Z). TRAC-P7 -78499

[0553] 53

[0554] Based on the left image coordinates (XA,YA,ZA) the pixel coordinates (UL,VL) and the right image coordinates (XB,YB,ZB) the pixel coordinates (uR,vR) may then be transformed to the world reference coordinates (X, Y, Z).

[0555] The illustration of figure 2 comprises a camera 1 with a camera coordinate system

[0556] 5 (CSYS) with the coordinates (Xc,Yc,Zc), a mirror box with a mirror box coordinate system (CSYS) with the coordinates (Xt>,Yb,Zt>) and a primary mirror 2, with a mirror coordinate system (CSYS) with the coordinates (Xmi,Ymi,Zmi). Also a scanner coordinate system (CSYS) with the coordinates (Xs,Ys,Zs) is illustrated.

[0557] The primary mirror 2 is located to direct a surface part, such as a common part P of a target surface region of a subject towards the camera 1, to be imaged by the camera in the coordinate system (Xc,Yc,Zc).

[0558] The mirror 2 is located in the not shown mirror box. The primary mirror coordinate system (CSYS) with the coordinates (Xmi,Ymi,Zmi) may preferably be calibrated with the mirror box, such that the pose of the mirror in the mirror box is known, whereby

[0559] 15 the coordinates (Xmi,Ymi,Zmi) of the mirror coordinate system may easily be transformed to the mirror box coordinates (Xb,Yt>,Zt>) - here referred to as "in-house" calibration.

[0560] As described the mirror box may comprise two or more primary mirrors or sections of primary mirror(s), each having a mirror coordinate system, which may each be

[0561] 20 transformed to the to the mirror box coordinates (Xb,Yb,Zb) to thereby include 3D data, preferably in the form of a stereo image.

[0562] After the mirror box has been applied to the medical scanner, the pose of the mirror box may be calibrated as described elsewhere herein. The calibration may conveniently be a calibration to a reference coordinate system, such as a world reference coordinate system or a scanner reference coordinate system and / or a calibration to the camera coordinate system (CSYS) with the coordinates (Xc,Yc,Zc) and / or the scanner coordinate system (CSYS) with the coordinates (XS,YS,ZS).

[0563] As illustrated the detection and transformation of the image or images of a reflected light portion redirected from a target surface of the subject may be transformed to

[0564] 30 the scanner coordinate system (CSYS) with the coordinates (XS,YS,ZS), whereby detected motions of the subject may be accounted for by the medical scanner, e.g. TRAC-P7 -78499

[0565] 54 for correction of scanning images or for stopping an ongoing scanning sequence and restarting where required.

[0566] Figure 3 illustrates a curved primary mirror with a center of curvature M and a radius r. The primary mirror is located to redirecting light reflected from a target surface

[0567] 5 region P of a subject and towards a camera. As it can be seen, the angle of reflection R is identical to the angle of incidence, which thereby ensure that a transformation to a reference coordinate system may be performed with a high accuracy.

[0568] Figure 4 is similar to figure 3, but with the difference that the primary mirror here is a spherically convex shaped primary mirror. Light rays parallel to the principal axis reflect outward as if they are diverging from a focal point behind the mirror. The principal axis of a spherical mirror is the line perpendicular to the surface of the mirror and passing through the center of the mirror.

[0569] Light rays directed toward the center of curvature reflect back in the same

[0570] 15 path, as they hit the mirror perpendicularly. In total this mean that mirrors always produce a virtual, upright, and diminished image.

[0571] Figure 5 shows an upright medical scanner 15, such as an upright MRI, CT and / or PET scanner. A subject 16 is located in the scene of the scanner. The subject is standing with a firm grip in a grab bar 14 for support to stand as motionless as

[0572] 20 possible during the scanning procedure. An image arrangement 11 is mounted in a roof part of the scanner 15 above the subject 16, where it is not in the way for the subject 16. A first primary mirror 12a and a second primary mirror 12b are located to redirect respective portions of light reflected from a target surface region of the subject 16 and towards the imaging arrangement 11, wherein the respective at least two portions of light comprises light representing respective surface parts optionally comprising a common part of the target surface region.

[0573] In an embodiment, the respective at least two portions of light comprises light representing distinct surface parts.

[0574] The medical scanner 15 comprises at least one screen to show the images acquired

[0575] 30 from the portions of reflected light, here illustrated by two screens, wherein a first of TRAC-P7 -78499

[0576] 55 the screen displays an acquired image 12a' of the light reflected by the first primary mirror 12a and a second screen 12b' displays an acquired image 12b' of the light reflected by the second primary mirror 12b.

[0577] Figure 6 shows a Magnetoencephalography (MEG) scanner 25 for recording brain

[0578] 5 activity of a subject. The illustrated MEG scanner is an open scanner in which the subject is sitting. It should be understood that the arrangement with an open scanner and the subject sitting in the scene may be provided for any other medical scanner as described elsewhere herein.

[0579] The subject 26 is sitting in the scanner scene on a supporting chair 24 and a helmet 17 of the MEG scanner 25 is applied onto the head of the subject 16.

[0580] An image arrangement 21 is mounted in a roof part of the MEG scanner 25 above the subject 26, where it is not in the way for the subject 26. A first primary mirror 22a and a second primary mirror 22b are located to redirect respective portions of light reflected from a target surface region of the subject 26 and towards the

[0581] 15 imaging arrangement 21, wherein the respective at least two portions of light comprises light representing respective surface parts optionally comprising a common part of the target surface region.

[0582] In an embodiment, the respective at least two portions of light comprises light representing distinct surface parts.

[0583] 20 The medical scanner 25 comprises at least one screen to show the images acquired from the portions of reflected light, here illustrated by two screens, wherein a first of the screen displays an acquired image 22a' of the light reflected by the first primary mirror 22a and a second screen 22b' displays an acquired image 22b' of the light reflected by the second primary mirror 22b.

[0584] The medical scanner shown in figure 7 is an MRI scanner 35 with narrow bore, for example in the order of 40-60 cm in diameter.

[0585] A subject 36 is located in the bore, which in this embodiment is the scene. The subject 36 is supported by the bearing 34, which may also be referred to as a patient table and which may be pulled out of the bore, when the scanning procedure is

[0586] 30 terminated. TRAC-P7 -78499

[0587] 56

[0588] In this embodiment the subject's head is the target for the scanning and the subject 36 is located with the head at a location where the magnetic field is relatively high, such as at a distance D3 from a safety line 30, beyond which an imaging arrangement 31 is located, the safety line may for example be a 5 gauss safety line,

[0589] 5 or a 30 gauss safety line, depending on the equipment to be located outside the safety line 30. The distance D3 may usually be at least 150 cm, such as from 180 to 220 cm. The head to be scanned is advantageously located at at least a distance D2 into the bore, wherein D2 preferably is at least about 75 cm, such as from 80 to 120 cm.

[0590] An RF coil 39, here having an open cage-like structure is located to at least partially surround the head of the subject 36. The RF coil 39 has the function of transmitting radiofrequency pulses to excite atomic nuclei in the scanning area (here a portion of the brain) and detecting the subsequent NMR emitted by the nuclei in the scanning area.

[0591] 15 A primary mirror 32 is located in the bore to redirect light reflected from a target surface region of the subject 36 and towards the imaging arrangement 31. The primary mirror may be located to redirect light portion or portions passing from the at least one target surface region of the subject and through one or more through openings of the RF coil 39, e.g. as described above. The one or more primary mirrors

[0592] 20 may be associated to a not shown step motor as described above.

[0593] In this embodiment, the imaging arrangement 31 comprises at least one ToF camera

[0594] As described above, where the imaging arrangement comprises at least one ToF camera, the ToF camera(s) may generate both depth information and intensity data which are recorded at the consecutive digital images and from which the 3D representation of at least the portion of the target surface region of the subject 36, preferably as a function of time, is generated.

[0595] The images recorded by the ToF camera(s) may advantageously be in the form of a light structured pattern, such as cloud points generated by respective light portions emitted by the ToF camera towards the target surface region of the subject 36 via

[0596] 30 the at least one primary mirror 32 mirror. The ToF camera may determine the TRAC-P7 -78499

[0597] 57 travelled distance of a plurality of light portions emitted from the ToF camera and thereby acquire the depth information.

[0598] A vertical distance DI between a center of the primary mirror and the target surface region of the subject 36 is advantageously from 5 to 35 cm, such as from 25 to 25

[0599] 5 cm.

[0600] In front of the primary mirror 32, an optical filter screen 33 is located. The optical filter screen 33 is located with a first side facing the at least one primary mirror and a second opposite side facing the subject 36. The filter of the optical filter screen 33, may preferably allow a light fraction of the light waves of the ToF camera to pass the

[0601] 10 filter from the second side of the optical filter screen to the first side and optionally from the first side to the second side of the filter screen, while reflecting, absorbing and / or refracting light having wavelengths outside the fraction of light.

[0602] The medical scanner shown in figure 8 is an MRI scanner 35 similar or identical to the medical scanner shown in figure 7.

[0603] 15 As in figure 7, a subject 36 is located in the bore and is supported by the bearing 34. The head of the subject 36 is the target for the scanning and the subject 36 and an, RF coil 39 in the form of an open cage-like structure is located to at least partially surround the head of the subject 36.

[0604] A primary mirror 32 is located in the bore to redirect light reflected from a target

[0605] 20 surface region of the subject 36 and towards the imaging arrangement 41.

[0606] In this embodiment, the imaging arrangement 41 comprises a projector 41b, projecting a light pattern 41c towards the primary mirror 32. The imaging arrangement 41 also comprises a imaging device in the form of a digital camera 41a arranged for receiving and imaging portions of light redirected from a target surface

[0607] 25 region of the subject 36, together with reflected light of the light pattern 41c as indicated with the center axis C of the reflected light to be received and imaged by the digital camera. Since the light pattern is impinging onto the primary mirror as a steady pattern and is reflected from the primary mirror together with reflections of the target surface region, any motions of the target surface region or parts thereof

[0608] 30 may be detected with a surprisingly high accuracy. TRAC-P7 -78499

[0609] 58

[0610] In a variation of the embodiment shown in figure 8, the imaging arrangement 41 further comprises a ToF camera and / or an additional digital camera.

[0611] The medical scanner shown in figure 9a is an MRI scanner 35 similar or identical to the medical scanner shown in figure 7.

[0612] 5 As in figure 7, a subject 36 is located in the bore and is supported by the bearing 34. The head of the subject 36 is the target for the scanning and the subject 36 and an RF coil 39 in the form of an open cage-like structure is located to at least partially surround the head of the subject 36.

[0613] A mirror arrangement 52, e.g. arranged in a not shown armature e.g. as described elsewhere herein is located to redirect light reflected from a target surface region of the subject 36 and towards the imaging arrangement 51. The mirror arrangement 52 comprises a first primary mirror 52a and a second primary mirror 52b, wherein the redirected light comprises a first portion 52a' of redirected light, which is redirected by the first primary mirror 52a and a second portion 52b' of redirected light, which is

[0614] 15 redirected by the second primary mirror 52b, wherein each of the first portion 52a' of redirected light and the second portion 52b' of redirected light comprises light representing respective surface parts optionally comprising at least a common part of the target surface region. The first primary mirror 52a and the second primary mirror 52b are angled relative to each other.

[0615] 20 In an embodiment, the respective at least two portions of light comprises light representing distinct surface parts.

[0616] The imaging arrangement 51 comprises an imaging device in the form of a digital camera 51 and optionally a projector 51b arranged for projecting a light pattern towards at least one of the first primary mirror 52a and the second primary mirror 52b.

[0617] In a variation thereof, the first primary mirror 52a and the second primary mirror 52b are replaced by at convex mirror.

[0618] In figure 9b, the left image 52a" illustrates an image of the light 52a' reflected via the first primary mirror 52a and the right image 52b" illustrates an image of the light

[0619] 30 52b' reflected via the second primary mirror 52b. As it can be seen the left image TRAC-P7 -78499

[0620] 59

[0621] 52a" and the right image 52b" comprises images of light representing respective surface parts optionally comprising a common part of the target surface region with an overlay of images of the reflected pattern. As explained light pattern emitted by the projector 51b is impinging onto the primary mirrors 52a, 52b as a steady pattern

[0622] 5 and is reflected from the primary mirrors 52a, 52b together with reflections of the target surface region. At the same time the left image 52a" and the right image 52b" provides a stereo vision. Thereby, any motions - even very small motions - of the target surface region or parts thereof may be detected with a very high accuracy.

[0623] Figure 10 illustrates a motion tracker arrangement of an embodiment of the invention comprising a mirror arrangement comprising a flat primary mirror I and a flat primary mirror II and at least one imaging device, here in the form of a digital camera 61. As illustrated with the arrows and the dotted lines indicating the propagation of light from a not shown target surface region towards the respective flat primary mirror I and the flat primary mirror II, from where the light is redirected

[0624] 15 towards the digital camera 61 where the received light is imaged e.g. as described above. It can be seen that a common Field of View (cFoV) of the respective flat primary mirror I and the flat primary mirror II is relatively narrow, such as up to 150 % of the extend of a smallest of the flat primary mirror I and the flat primary mirror II.

[0625] 20 Figure 11 illustrates a motion tracker arrangement of an embodiment of the invention comprising a mirror arrangement comprising a convex primary mirror I and a convex primary mirror II and at least one imaging device, here in the form of a digital camera 61. As illustrated with the arrows and the dotted lines indicating the propagation of light from a not shown target surface region towards the respective convex primary mirror I and the convex primary mirror II, from where the light is reflected towards the digital camera 61 where the received light is imaged e.g. as described above. It can be seen that a common Field of View (cFoV) of the respective convex primary mirror I and the convex primary mirror II is much larger than where the primary mirrors are flat as shown in figure 10. The cFOV may be

[0626] 30 several times larger than the extent of a smallest of the convex primary mirror I and the convex primary mirror II. Using convex mirrors may therefore be applied to increase Field of View. TRAC-P7 -78499

[0627] 60

[0628] In a variation thereof, a combination of one or more flat primary mirrors and one or more convex mirrors may be applied.

[0629] The motion tracker arrangement shown in figure 12 is as the motion tracker arrangement of figure 11, with the difference that an optical filter in screen is located

[0630] 5 between a subject 66 to be scanned and the convex primary mirrors I and II.

[0631] The optical filter screen is located with a first side 63a facing the convex primary mirrors I and II and a second opposite side 63b facing the location for the subject 66. The optical filter screen may advantageously be as described above. Advantageously, the optical filter screen is a band pass filter having a center wavelength in the near infrared (NIR) range also referred to as a NIR- passing filter. The optical filter screen is here a flat optical filter screen. The optical filter screen allows the subject viewing images, such a video stream projected to the optical filter screen.

[0632] The motion tracker arrangement shown in figure 12 is as the motion tracker

[0633] 15 arrangement of figure 10, with the difference that, the flat primary mirror I and the flat primary mirror II is redirecting light reflected from the not shown target surface region towards the digital camera via an intermediate mirror. By using intermediate mirror(s), it may be simpler to redirect light from the target surface region towards an imaging arrangement even where the scene of the medical scanner is located in a very narrow space, such as a bore.

[0634] The medical scanner shown in figure 14 is an MRI scanner 35 similar or identical to the medical scanner shown in figure 7.

[0635] As in figure 7, a subject 36 is located in the bore and is supported by the bearing 34. The head of the subject 36 is the target for the scanning and the subject 36 and an,

[0636] 25 RF coil 39 in the form of an open cage-like structure is located to at least partially surround the head of the subject 36.

[0637] A primary mirror 32 is located in the scene, which is here the bore, to redirect light reflected from a target surface region of the subject 36 and towards a not shown imaging arrangement. TRAC-P7 -78499

[0638] 61

[0639] In front of the primary mirror 32, an optical filter screen 33 is located. The optical filter screen 33 is located with a first side facing the at least one primary mirror and a second opposite side facing the subject 36. Advantageously, the optical filter screen 33 is a band pass filter having a center wavelength in the near infrared (NIR) range

[0640] 5 also referred to as a NIR- passing filter. The optical filter screen is here a flat optical filter screen. The optical filter screen allows the subject viewing images, such a video stream projected to the optical filter screen optionally via the screen 67, here illustrated as a flat screen TV.

[0641] The optical filter screen may thereby participate in providing a comfortable environment to the subject, which may ensure that the subject may be relaxing during a scanning procedure. At the same time, the optical filter screen may be applied for providing feedback to the subject during a scanning procedure.

[0642] The armature shown in figure 15 comprises a frame 70 and a calibration pattern 72 located at a selected location of the frame. In the shown example, two primary

[0643] 15 mirrors 71a and 71b are mounted in the armature. By having the at least one primary mirror in an armature, the calibration may be even simpler and further makes it relatively simple to retrofitting the motion tracker arrangement in already existing medical scanners.

[0644] The armature may be applied for pre-calibrating the primary mirrors 71a, 71b as

[0645] 20 described above. The pre-calibration may be performed as a factory pre-calibration. The pre-calibration may comprise calibrating the relative pose of the primary mirrors 71a, 71b in the armature and optionally fixing the primary mirrors in the armature in their respective pre-calibrated pose.

[0646] The final calibration may then be performed when the motion traction arrangement are retrofitted to a medical scanner using the calibration pattern 72.

[0647] The motion tracker arrangement illustrated in figure 16a comprises a mirror arrangement comprising N primary mirrors comprising a first flat primary mirror 89a and a second flat primary mirror 89b and an imaging arrangement comprising M imaging devices comprising a first image device 81a and a second image device 81b.

[0648] 30 The motion tracker arrangement also comprises a computer system 88, here in the form of a computer 88a comprising an associated computer screen 88b. TRAC-P7 -78499

[0649] 62

[0650] A subject 86 is located in a not shown scanner. Only the face of the head of the subject 86 is shown.

[0651] The first flat primary mirror 89a is arranged for redirect a first light portion reflected from a first surface part 87a of a target surface region of the face of the subject 86.

[0652] 5 The first light portion represents the first surface part 87a. The first light portion is redirected towards the imaging arrangement and the first image device 81a and the second image device 81b are arranged such that each of the first image device 81a and the second image device 81b receives a sub-portion of the light portion representing the first surface part 87a.

[0653] The second flat primary mirror 89b is arranged for redirect a second light portion reflected from a second surface part 87b of a target surface region of the face of the subject 86. The second light portion represents the second surface part 87b. The second light portion is redirected towards the imaging arrangement and the first image device 81a and the second image device 81b are arranged such that each of

[0654] 15 the first image device 81a and the second image device 81b receives a sub-portion of the light portion representing the second surface part 87b.

[0655] The first surface part 87a and the second surface part 87b are distinct surface parts.

[0656] The first image device 81a and the second image device 81b of the imaging arrangement are configured for recording consecutive digital images of the

[0657] 20 respective sub-portions of light that they each have received and for transmitting the consecutive recorded images to the computer system 88.

[0658] The computer system is programmed for receiving and processing the respective consecutive image data sets and for generating consecutive 3D representations of at least a portion of the target surface region comprising at a portion of the distinct surface parts 87a, 87b. The computer processing comprises cross correlating data representing respective sub portions of each of said two distinct portions of light representing the two distinct surface parts 87a, 87b, whereby the computer system 88 determines the relative pose of the distinct surface parts 87a, 87b e.g. in a coordinate system as described above.

[0659] 30 The computer system 88 thereby generates consecutive 3D surface representations of at least a portion of the distinct surface parts 87a, 87b as a function of time. The TRAC-P7 -78499

[0660] 63 computer system 88 is further configured for determining potential differences between the consecutive 3D surface representations. Determined differences may indicate that the subject has performed a motion. Preferably, the computer system 88 is configured for processing the determined differences and determine if the

[0661] 5 difference is caused by a motion of the subject or if the difference may be caused by an error, such as an error caused by a shadow area, changed incidence and / or reflection angle or any other optical phenomena, apparatus error and / or calibration errors.

[0662] The motion tracker arrangement illustrated in figure 16b is a variation of the motion tracker arrangement illustrated in figure 16a. The motion tracker arrangement illustrated in figure 16b comprises a mirror arrangement comprising N primary mirrors comprising a first flat primary mirror 89a and a second flat primary mirror 89b and an imaging arrangement comprising M imaging devices comprising a first image device 81a, a second image device 81b and a third image device 81c.

[0663] 15 The motion tracker arrangement also comprises a computer system 88, here in the form of a computer 88a comprising an associated computer screen 88b.

[0664] A subject 86 is located in a not shown scanner. Only the face of the head of the subject 86 is shown.

[0665] The first flat primary mirror 89a is arranged for redirect a first light portion reflected

[0666] 20 from a first surface part 87a of a target surface region of the face of the subject 86. The first light portion represents the first surface part 87a. The first light portion is redirected towards the imaging arrangement and the first image device 81a and the third image device 81b are arranged such that each of the first image device 81a and the third image device 81c receives a sub-portion of the light portion representing the first surface part 87a.

[0667] The second flat primary mirror 89b is arranged for redirect a second light portion reflected from a second surface part 87b of a target surface region of the face of the subject 86. The second light portion represents the second surface part 87b. The second light portion is redirected towards the imaging arrangement and the first

[0668] 30 image device 81a and the second image device 81b are arranged such that each of TRAC-P7 -78499

[0669] 64 the first image device 81a and the second image device 81b receives a sub-portion of the light portion representing the second surface part 87b.

[0670] The first surface part 87a and the second surface part 87b are distinct surface parts.

[0671] The first image device 81a, the second image device 81b and the third image device

[0672] 5 81c of the imaging arrangement are configured for recording consecutive digital images of the respective sub-portions of light that they each have received and for transmitting the consecutive recorded images to the computer system 88.

[0673] The computer system is programmed for receiving and processing the respective consecutive image data sets as described above e.g. in the example illustrated in figure 16a.

[0674] The motion tracker arrangement illustrated in figure 16c is another variation of the motion tracker arrangement illustrated in figure 16a. The motion tracker arrangement illustrated in figure 16b comprises a mirror arrangement comprising N primary mirrors comprising a first flat primary mirror 89a and a second flat primary

[0675] 15 mirror 89b and an imaging arrangement comprising M imaging devices comprising a first image device 81a and a second image device 81b.

[0676] The motion tracker arrangement also comprises a computer system 88, here in the form of a computer 88a comprising an associated computer screen 88b.

[0677] A subject 86 is located in a not shown scanner. Only the face of the head of the subject 86 is shown.

[0678] The first flat primary mirror 89a is arranged for redirect a first light portion reflected from a first surface part 87a of a target surface region of the face of the subject 86. The first light portion represents the first surface part 87a. The first light portion is redirected towards the imaging arrangement and the first image device 81a is

[0679] 25 arranged to receive a sub-portion of the light portion representing the first surface part 87a.

[0680] The second flat primary mirror 89b is arranged for redirect a second light portion reflected from a second surface part 87b of a target surface region of the face of the subject 86. The second light portion represents the second surface part 87b. The TRAC-P7 -78499

[0681] 65 second light portion is redirected towards the imaging arrangement and the first image device 81a and the second image device 81b are arranged such that each of the first image device 81a and the second image device 81b receives a sub-portion of the light portion representing the second surface part 87b.

[0682] 5 The first surface part 87a and the second surface part 87b are distinct surface parts.

[0683] The first image device 81a and the second image device 81b of the imaging arrangement are configured for recording consecutive digital images of the respective sub-portions of light that they each have received and for transmitting the consecutive recorded images to the computer system 88.

[0684] 10 The computer system is programmed for receiving and processing the respective consecutive image data sets as described above e.g. in the example illustrated in figure 16a.

Claims

TRAC-P7 -7849966PATENT CLAIMS1. A motion tracker arrangement adapted for motion tracking of a subject comprising a body part located in a scanning scene of a scanner, wherein the motion tracker arrangement comprises5 • a mirror arrangement comprising at least one primary mirror;• an imaging arrangement comprising at least one imaging device; and• a computer system, wherein said mirror arrangement is adapted for redirecting light reflected from at least one target surface region of the subject, wherein said imaging arrangement is10 adapted to receive light reflected by said mirror arrangement, wherein said redirected light comprises at least two portions of light, wherein each of said at least two portions of light comprises light representing at least a surface part of said at least one target surface region, wherein the mirror arrangement is adapted for redirecting said portions of light towards said imaging arrangement,15 wherein said imaging arrangement is adapted for recording consecutive digital images of said respective light portions redirected towards said imaging arrangement and for generating and transmitting consecutive image data sets representing said respective consecutive recorded digital images to said computer system, wherein said respective portions of light have different travelling paths from being20 reflected from said mirror arrangement to being recorded by said imaging arrangement, and wherein said computer system being configured for processing said respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of said at least one target surface region,25 preferably a 3D surface representation of at least a portion of said at least one target surface region comprises at least one of said surface parts of said at least one target surface region.TRAC-P7 -78499672. The motion tracker arrangement of claim 1, wherein at least, such as each of said at least two portions of light comprises light represents a common part of said at least one target surface region, and preferably wherein said computer system being configured for processing said respective consecutive image data sets and for5 generating at least one 3D surface representation of at least a portion of said at least one target surface region, the at least one 3D surface representation of at least a portion of said at least one target surface region comprising said common part of said at least one target surface region.

3. The motion tracker arrangement of claim 1 and claim 2, wherein said mirror arrangement and said imaging arrangement are configured for providing that said respective surface parts and / or said common part of said at least one target surface region represented by each of said at least two portion of light is adapted to be recorded to form at least 0.05 % of one or more of said recorded image, such as at least 0.1 %, such as at least 1 % of one or more of said recorded image, preferably15 in terms of clout points and / or pixels.4 The motion tracker arrangement of any one of the preceding claims, wherein the at least one target surface region comprises or consists of a surface region of the body part located in the scanning scene, preferably the at least one target surface region is free of artificial marker element(s).20 5. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement comprises at least two primary mirrors and / or the imaging arrangement comprises at least two imaging devices.

6. The motion tracker arrangement of any one of the preceding claims, wherein the primary mirror arrangement comprises N primary mirrors, wherein N is an integer from 1 to 10, such as up to 4.

7. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement comprises at least one flat primary mirror, such as at least two flat primary mirrors or more.

8. The motion tracker arrangement of any one of the preceding claims, wherein30 the mirror arrangement comprises two or more flat primary mirrors each having a mirror plane, wherein two or more of said flat primary mirrors are orientated suchTRAC-P7 -7849968 that their respective mirror planes are intersecting each other, preferably to provide that their respective normal vectors have an angle of from 2° to 50°, such as an angle of from 2° to 30°, such as an angle from 5° to 25°, such as an angle from 10° to 20°.5 9. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement comprises at least one convex primary mirror, such as at least two convex primary mirrors, optionally the one or more convex primary mirrors comprises one or more spherical primary mirrors and / or one or more convex parabolic primary mirrors.

10. The motion tracker arrangement of claim 8 or claim 9, wherein the at least one convex primary mirror comprises a focal length of from 1 mm to 5 m, such as from 0.5 cm to 2 m, such as from 1 cm to 1 m.

11. The motion tracker arrangement of any one of claims 8-10, wherein the at least one convex primary mirror comprises a radius of curvature of from 1 cm to 1015 m, such as from 2 cm to 5 m, such as from 5 cm to 2 m.

12. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement comprises at least two primary mirrors located or adapted to be located with a minimum distance to each other of from 1 mm to 1 m, such as up to 20 cm, optionally the primary mirrors are fixed with said minimum distance.20 13. The motion tracker arrangement of any one of the preceding claims, wherein the at least one primary mirror of the mirror arrangement is located in an armature, preferably the mirror arrangement comprises a plurality of primary mirrors located in said armature, preferably said mirror(s) are adjustable anchored in said common armature, said armature is preferably free of ferromagnetic material.

14. The motion tracker arrangement of any one of the preceding claims, wherein the at least one primary mirror of the mirror arrangement is adapted to be located in said scene of the scanner, preferably, said two or more primary mirrors are adapted to be located in said scene at respective viewing distances to at least one of said respective surface parts and / or said common part of said at least one target surface30 region, wherein the respective viewing distances is determined from a center point of said respective mirrors to a center point of said common part of said at least oneTRAC-P7 -7849969 target surface region and / or to said surface part represented by the portion of light redirected by said respective mirrors, wherein said respective viewing distances may be equal or different from each other, such as from 1 cm to 1 m, such as from 2 cm to 25 cm, optionally the respective viewing distances differs at most 10 cm from each5 other, such as at most 5 cm from each other.

15. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement is configured for transmitting data representing the pose of one or more of the at least one primary mirror to said computer system and / or wherein the imaging arrangement is configured for transmitting data representing the pose of one or more of the at least one imaging device to said computer system.

16. The motion tracker arrangement of any one of the preceding claims, wherein the at least one primary mirror of the mirror arrangement, comprises at least one primary mirror temporally or permanently mounted to an RF coil, a scanner bore and / or or a patient table.15 17. The motion tracker arrangement of any one of the preceding claims, the motion tracker system comprises at least one mirror sensor adapted for detecting the pose of one or more of the at least one primary mirror and or the armature (with at least one primary mirror) comprising the at least one mirror, the at least one mirror sensor may preferably be located at a fixed location relative to the scanner, such as20 to a fixed location of the scanner, such as to a scanner wall portion of a scanner, such as a scanner bore, a floor and / or a ceiling of the scanner.

18. The motion tracker arrangement of claim 17, wherein the at least one mirror sensor comprises at least one of an IR sensor (e.g. IR LED, IR photodiode, IR camera), an ultrasound sensor and / or a time of flight sensor.

19. The motion tracker arrangement of claim 17 or claim 18, wherein the at least one mirror sensor is configured for transmitting an alarm signal if detecting that a primary mirror of the at least one primary mirror and / or the armature is deviating from a valid calibration pose, such as a pre-calibration pose.20 The motion tracker arrangement of any one of claims 17-19, wherein the at30 least one mirror sensor is configured for transmitting instruction to a user and / or to transmitting instructions to at least one step motor, each associated to one of the atTRAC-P7 -7849970 least one primary mirror and / or the armature, which at least one primary mirror and / or armature has been detected to deviate from a valid calibration pose, and to instructing the user and / or the at least one step motor to modify the pose of the at least one primary mirror and / or armature which has / have been detected to deviate5 from a valid calibration pose, to be in in conformation with the valid calibration pose.

21. The motion tracker arrangement of any one of claims 17-20, wherein the motion tracker is pre-calibrated, providing one or more of the at least one primary mirror of the mirror arrangement and / or one or the armature and / or one or more of the at least one imaging device to be in respective valid calibration pose, preferably to provide each of the at least one primary mirror of the mirror arrangement to be in respective valid pose, such as providing at least the armature to be in a valid calibration pose.

22. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement is adapted to be arranged to provide that the respective15 portions of light reflected from said at least one target surface region and redirected by said respective primary mirrors to said imaging arrangement, represents different Field of views (FOVs) of said at least one target surface region, preferably of at least one of said common part and / or of said respective surface parts of said at least one target surface region.20 23. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement is or is adapted to be arranged to provide that the travelling paths of said respective portions of light travelling from said at least one target surface region via reflection by said respective primary mirrors to said imaging arrangement, comprises different center travel axes from the target surface region to the imaging arrangement, such as from at least one of said respective surface parts and / or of said common part of said at least one target surface region via reflection by said respective primary mirrors to said imaging arrangement.

24. The motion tracker arrangement of claim 23, wherein the travelling paths of said respective portions of light travelling from said at least one target surface region30 via reflection by said respective primary mirrors to said imaging arrangement comprises different center travel axes from the at least one target surface region to the respective primary mirrors, wherein the different center axes preferably differsTRAC-P7 -7849971 with at least 5°, such at least 10°, such as at least 20°, such as at least 25°, optionally the travelling paths of said respective portions of light travelling from at at least one of said respective surface parts and / or said common part of the at least one target surface region of the subject to the respective primary mirrors comprises5 different center travel axes, wherein at least one of said different center travel axes from the common target surface region to the respective primary mirrors has an angle of at least 5°, such as of least 10°, such as of at least 20°, such as of at least 25° relative to another one of said different center travel axes from the at least one of said respective surface parts and / or said common part of the at least one target surface region to the respective primary mirrors.

25. The motion tracker arrangement of any one of the preceding claims, wherein the mirror arrangement comprises at least one intermediate mirror adapted for redirecting at least one of the light portions between one of the primary mirror(s) and the imaging arrangement.15 26. The motion tracker arrangement of any one of the preceding claims, wherein the at least one imaging devices of the imaging arrangement comprise one or more imaging devices selected from one or more digital cameras, one or more time-of- flight (ToF) cameras and combinations thereof.

27. The motion tracker arrangement of any one of the preceding claims, wherein20 said mirror arrangement is adapted for redirecting said respective portions of light to provide that two or more of the respective portions of light impinge at least partly at different locations of an image sensor of the at least one imaging device of the imaging arrangement, such as to provide that said two or more of the respective portions of light impinge at separate locations of the image sensor of the at least one imaging device of the imaging arrangement.

28. The motion tracker arrangement of any one of the preceding claims, wherein said imaging arrangement comprises two or more digital cameras each comprising an image sensor wherein said mirror arrangement are configured for redirecting said respective portions of light to provide that at least one of the respective portions of30 light impinges at the image sensor of one of the digital cameras and that at least one other of the respective portions of light impinges at an image sensor on one other of the digital cameras, optionally said mirror arrangement are configured for redirectingTRAC-P7 -7849972 said respective portions of light to provide that at least two of the respective portions of light impinges at the image sensor of a same one of the digital cameras, preferably at different locations of the same image sensor, e.g. via a camera lens ensuring that said two or more portions coming from different directions are5 directed to different locations of the image sensor.

29. The motion tracker arrangement of any one of the preceding claims, wherein said imaging arrangement is a single imaging arrangement having a single image device, preferably said mirror arrangement are configured for redirecting said respective portions of light to provide that at least two, such as all of the respective portions of light impinges at said single image device, preferably at different locations thereof.

30. The motion tracker arrangement of any one of the preceding claims, wherein said consecutive image data sets generated from images of respective portions of light represents respective point of views (POV's) of at least one of said respective15 surface parts and / or said common part of said at least one target surface region, wherein said respective POV's preferably differs from each other.

31. The motion tracker arrangement of any one of the preceding claims, wherein said computer system is configured for being or is calibrated for generating and / or identifying sub-image data sets of each of said consecutive image data sets, wherein20 each sub-image data set represents a point of view (POV) of at least one of said respective surface parts and / or said common part of said at least one target surface region.

32. The motion tracker arrangement of any one of the preceding claims, wherein said imaging arrangement is adapted for recording said consecutive digital images of said respective light portions as a function of time, wherein each of said consecutive image data sets is associated to or comprises a time attribute representing a point of time of recording.

33. The motion tracker arrangement of any one of the preceding claims, wherein said imaging arrangement.30 34. The motion tracker arrangement, of any one of the preceding claims, wherein said computer system being configured for processing said respective consecutiveTRAC-P7 -7849973 image data sets and for performing a 3D reconstruction comprising generating consecutive 3D surface representations of at least a part of the at least one target surface region of the subject, such as comprising at least one of said respective surface parts and / or said common part of said at least one target surface region,5 preferably said image data sets are associated to or comprises respective time attributes representing point of time of recording.

35. The motion tracker arrangement of any one of the preceding claims, wherein said computer system is configured for identifying matching light features of respective image sets, such as sub-image data sets and for estimating the perspective and / or homographic transformation between the respective matched features of said respective sub-image data sets and based thereon generating said 3D surface representation of at least a part of the at least one target surface region of the subject, such as of at least a part of the at least one target surface region of the subject comprising at least one of said respective surface parts and / or said15 common part of said at least one target surface region.

36. The motion tracker arrangement of any one of the preceding claims, wherein said computer system is configured for generating consecutive 3D surface representations of said at least one target surface region of the subject, such as of at least one of said respective surface parts and / or said common part of the at least20 one target surface region from said consecutive image data sets and for determining potential differences between said consecutive 3D surface representations, preferably the computer system is configured for processing determined differences and determine at least one property of a motion causing the difference.

37. The motion tracker arrangement of any one of the preceding claims, wherein said imaging arrangement is configured for transmitting said consecutive image data sets representing said respective consecutive acquired digital images to the computer system in real time and wherein said computer system is configured for generating said consecutive 3D surface representations of at least a part of the at least one target surface region of the subject , optionally comprising at least one of said30 respective surface parts and / or said common part of the at least one target surface region from said consecutive image data sets as a function of time, preferably in real time.TRAC-P7 -784997438. The motion tracker arrangement of any one of the preceding claims, wherein said motion tracker arrangement comprises an optical filter screen located between the at least one primary mirror of the mirror arrangement and a location adapted for the subject to be scanned, wherein the screen is located with a first side facing the5 at least one primary mirror and a second opposite side facing the location for the subject, wherein the optical filter screen comprises a filter allowing a fraction of light comprising a wavelength range to pass the filter from the second side of the optical filter screen to the first side of the filter screen, while reflecting, absorbing and / or refracting light having wavelengths outside said fraction of light.

39. The motion tracker arrangement of claim 38, wherein the filter of the optical filter screen is a band pass filter, preferably said fraction of light comprises or consists of a portion of invisible light (to human - excluding 380-750 nm), preferably the band pas filter has a center wavelength in the near infrared (NIR) range from larger than 750 to 1100, preferably in the range from 800 nm to 1000 nm.15 40. The motion tracker arrangement of claim 38 or claim 39, wherein the optical filter screen allows light having wavelength(s) within the wavelength range of the fraction of light to pass the filter from the first side of the optical filter screen to the second side of the filter screen, optionally the filter of the optical filter screen in addition allows visible light to pass from the first side of the optical filter screen to20 the second side of the filter screen.

41. The motion tracker arrangement of any one of claims 38-40, wherein the filter of the optical filter screen is an absorption filter or a dichroic filter.

42. The motion tracker arrangement of any one of the preceding claims, wherein said motion tracker arrangement further comprises a light projector, such as a light pointer or a structured light projector for pointing a spot marking or a structured light onto the said second side of the optical filter screen and / or onto said at least one target surface region, wherein said marker comprises at least one wavelength within the wavelength range of the fraction of light.

43. The motion tracker arrangement of claim 42, wherein the light projector is30 adapted for projecting a structured light to a reflective location of one or more of the at least one primary mirror and / or to a reflective location of a calibration element,TRAC-P7 -7849975 which is in fixed pose relative to a pose of the at least one primary mirror, preferably an armature comprising the at least one primary mirror and wherein the at least one primary mirror is fixed in pose relative to the armature.

44. The motion tracker arrangement of any one of the preceding claims, wherein5 the at least one primary mirror comprises a primary mirror surface for redirecting the light reflected from the target surface and wherein the primary mirror comprises light absorbing features at said primary mirror surface to provide the redirected light to be a redirected structured light, preferably comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first10 quality of a character and areas of light of a second quality of the character, wherein the character preferably is selected from light intensity, wavelength and / or range of wavelengths, e.g. in the form of cloud points.

45. The motion tracker arrangement of any one of the preceding claims, wherein said motion tracker arrangement further comprises a lamp for illuminating at least a15 portion of the scene.

46. The motion tracker arrangement of any one of the preceding claims, wherein said motion tracker arrangement comprises a structured light projector configured for projecting invisible light, such as for projecting light having one or more wavelength in the ranges from 100 nm to 350 nm and / or from 700 nm to 1.4 pm,20 preferably in the range from 800-1200 nm.

47. The motion tracker arrangement of claim 46, wherein the structured light projector is configured for projecting a dot pattern and / or a speckle pattern.

48. The motion tracker arrangement of claim 46 or claim 47, wherein the structured light projector is configured for projecting the structured light to at least a25 portion of the scene, preferably for projecting the structured light to the at least one target surface region of the subject.

49. The motion tracker arrangement of any one of the preceding claims, wherein the at least one imaging device of the imaging arrangement is adapted for being located outside the scene of the scanner.TRAC-P7 -784997650. The motion tracker arrangement of any one of the preceding claims, wherein the at least one imaging device and the at least one primary mirror is adapted to be located with a distance of at least 0.5 m, such as at least 1 m, such as at least 1.2 m, such as at least 1.3 m, such as at least 1.4 m, such as at least 1.5 m, optionally5 the scanner comprises a scanner bore and the at least one imaging device of the imaging arrangement is adapted to be located outside the scanner bore.

51. The motion tracker arrangement of any one of the preceding claims, wherein at least two of said respective portions of light have travelling paths that differs from each other from being reflected from said mirror arrangement to being recorded by said imaging arrangement, preferably said respective portions of light have a travelling path with a total average length of at least 0.5 m, such as at least 1 m, such as at least 1.1 m, such as at least 1.2 m, such as at least 1.3 m, such as at least 1.4 m, such as at least 1.5 m, such as at least 1.6 m.

52. The motion tracker arrangement of any one of the preceding claims, wherein15 at least two of said respective portions of light have travelling paths that differs in from each other in travelling length from being reflected from said mirror arrangement, such as travelling paths that differs at least 5 %. Such as at least10 %, such as at least 15 from each other in travelling length, based on the longest travelling path of said at least two of said respective portions of light.20 53. The motion tracker arrangement of any one of the preceding claims, wherein the at least two portions of light, each representing at least a surface part of said at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, such as distinct surface parts of said at least one target surface region of the subject with no overlap.

54. The motion tracker arrangement of claim 53, wherein said distinct surface part comprises at least two distinct surface parts, wherein the at least two distinct surface parts has a minimum distance to each other of at least 1 mm, such as of at least 0.5 cm, such as of at least 1 cm, such as of at least 2 cm said at least one30 target surface region of the subject such as of from 0.5 to 15 cm determined in a 3D view of the at least one target surface region of the subject.TRAC-P7 -784997755. The motion tracker arrangement of claim 52 or claim 53, wherein said at least two distinct portions of light representing distinct surface parts comprises N distinct portions of light and wherein said primary mirrors comprises N primary mirrors, wherein N is an integer of from 2 to at least 10, such as from 2 to 8, such as from 25 to 6, such as from 2 to 4.

56. The motion tracker arrangement of claim 55, wherein said N primary mirrors are arranged for redirect said N distinct portions of light representing said distinct surface parts, preferably comprising N distinct surface parts and wherein said imaging arrangements comprises at least M imaging devices, and wherein said N primary mirrors are arranged to redirect said N distinct portions of light representing said distinct surface parts to provide that at least a first sub-portion of each of said N distinct portions of light representing said distinct surface parts is received by at least one of said at least M imaging devices and a second sub-portion of each of said N distinct portions of light representing said distinct surface parts is received by at least15 one other of said at least M imaging devices, wherein the first sub-portion and said second sub-portion of each of said N distinct portions of light representing said distinct surface parts may be equal or different from each other, such as being overlapping or non-overlapping, wherein M is an integer of at least 2.

57. The motion tracker arrangement of claim 56, wherein M is three or larger,20 such as from 3 to 10, such as from 3 to 8, such as from 3 to 4.

58. The motion tracker arrangement of claim 56 or claim 57, wherein each of the M imaging devices is configured for receiving at least a sub-portion of said N distinct portions of light representing said N distinct surface parts, preferably the M imaging devices and the N primary mirrors are arranged (calibrated) relative to each other and relative to the N distinct surface parts to provide that each of the M imaging devices receives at least a sub-portion of said N distinct portions of light representing said N distinct surface parts.

59. The motion tracker arrangement of any one of claims 56 - 58, wherein said N primary mirrors and said M imaging devices are organized to operate group-wise,30 where each group comprises two primary mirrors and two imaging devices, wherein said two mirrors of a group are arranged for redirect said two distinct portions of light representing said distinct to surface parts and wherein said two imaging devicesTRAC-P7 -7849978 of the group each is configured for receiving at least a sub-portion of each of said two distinct portions of light representing said two distinct surface parts.

60. The motion tracker arrangement of any one of claims 53 - 59, wherein said computer system is configured for receiving and processing said respective5 consecutive image data sets and for generating said least one 3D representation of at least a portion of said at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, wherein the computer processing comprises cross correlating data representing respective sub portions of each of said two distinct portions of light representing said at least two distinct surface parts of images of respective imaging devices, to determine a relative pose of said respective at least two distinct surface parts, preferably to determine said relative pose of said respective at least two distinct surface parts preferably to determine said relative pose of said respective at least two distinct surface parts in a15 coordinate system, such as in a scanner coordinate system.61 The motion tracker arrangement of claim 60 wherein the computer system comprises data representing a pose of each of the at least one primary mirror and / or the optional armature and / or the at least one imaging device and wherein the computer processing comprises cross correlating data representing respective sub¬20 portions of each of said two distinct portions of light representing said at least two distinct surface parts of images of respective imaging devices and data representing the pose of one or more of the at least one primary mirror and / or the optional armature and / or the at least one imaging device, to determine the relative pose of said respective at least two distinct surface parts.

62. The motion tracker arrangement of any one of claims 53 - 61, wherein said computer system of said motion tracker arrangement is configured for receiving a 3D scan image data set from a scanner, wherein said 3D scan image data set comprises data representing a 3D scan image comprising at least a portion of said at least two distinct surface parts of said at least one target surface region of the subject30 represented by said at least two distinct portions of light.TRAC-P7 -784997963. The motion tracker arrangement of claim 62, wherein said 3D scan image data set comprises data representing a scanner coordinate system and data representing a pose of the 3D scan image in said scanner coordinate system.

64. The motion tracker arrangement of claim 61 or claim 62, wherein said5 computer system is configured for receiving and processing said respective consecutive image data sets and for generating said least one 3D representation of at least a portion of said at least one target surface region comprising at least a portion of each of the at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, wherein the10 computer processing comprises matching at least a portion of said at least two of, preferably of each of said at least two distinct surface parts of said at least two distinct surface parts to said scan image to determine to determine said relative pose of said respective at least two distinct surface parts preferably to determine said relative pose of said respective at least two distinct surface parts in a coordinate15 system, such as in the scanner coordinate system.

65. The motion tracker arrangement of any one of claims 62 - 64, wherein the scanner is a 3D scanner, preferably selected from an MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner and / or any combinations thereof.

66. A scanner system comprising a scanner and a motion tracker arrangement,20 wherein the scanner comprises a scanning scene and a support for supporting a subject comprising a body part located in the scanning scene, wherein the motion tracker arrangement comprises• a mirror arrangement comprising at least one primary mirror;• an imaging arrangement comprising at least one imaging device; and25 • a computer system, wherein said mirror arrangement is adapted for redirecting light reflected from at least one target surface region of the subject, wherein said imaging arrangement is adapted to receive light reflected by said mirror arrangement, wherein said redirected light comprises at least two portions of light, wherein each of said30 respective portions of light comprises light representing a surface part of said at leastTRAC-P7 -7849980 one target surface region, wherein the mirror arrangement are adapted for redirecting said portions of light towards said imaging arrangement, wherein said imaging arrangement is adapted for recording consecutive digital images of said respective light portions redirected towards said imaging arrangement5 and for generating and transmitting consecutive image data sets representing said respective consecutive recorded digital images to said computer system, wherein said respective portions of light have different travelling paths from being reflected from said mirror arrangement to being recorded by said imaging arrangement, and10 wherein said computer system being configured for processing said respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of said at least one target surface region, such as for generating at least one 3D surface representation of at least a portion of said at least one target surface region of the subject, preferably comprising at least one of said respective surface parts of said at least one target surface region.

67. The scanner system of claim 66, wherein the respective portions of light comprises light representing a common part of the at least one target surface region, and wherein said computer system being configured for processing said respective consecutive image data sets and for generating said at least one 3D surface20 representation of at least a portion of said at least one target surface region comprising the common part of the at least one target surface region.

68. The scanner system of claim 66 or claim 67, wherein the motion tracker arrangement is according to any one of claims 1-65.

69. The scanner system of any one of claims 66-68, wherein the scanner is a25 medical scanner, such as an X-ray scanner a MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner, a Bone densitometry (DXA), a Magneto-Encephalo- Graphy (MEG) scanner and / or any combinations thereof.

70. The scanner system of any one of claims 66-68, wherein the scanner is a 3D scanner, preferably selected from a MRI scanner, a CT scanner, a PET scanner, an30 ultrasound scanner and / or any combinations thereof.TRAC-P7 -784998171. The scanner system of any one of claims 66-70, wherein the support for supporting a subject comprises a bearing, a seat, an armrest, a leg rest, a support rod or any combination comprising one or more of these.

72. The scanner system of any one of claims 66-71, wherein the at least one5 primary mirror of the mirror arrangement is located in said scene, preferably, said two or more primary mirrors are located in said scene at respective viewing distances to said at least one target surface region of the subject, such as to at least one of said respective surface parts and / or said common part of said at least one target surface region, wherein the respective viewing distances is determined from a center point of said respective primary mirrors to a center point of said common part of said at least one target surface region of the subject and / or to a center point of said respective surface parts of said at least one target surface region represented by the respective portions of light redirected by said respective primary mirrors, wherein said respective viewing distances may be equal or different from each other, such as15 from 1 cm to 1 m, such as from 2 cm to 25 cm, optionally the respective viewing distances differs at most 10 cm from each other, such as at most 5 cm from each other.

73. The scanner system of any one of claims 66-72, wherein the scanner comprises an RF coil a scanner bore and / or or a patient table and wherein the at20 least one primary mirror of the mirror arrangement, comprises at least one primary mirror temporally or permanently mounted to the RF coil, a scanner bore and / or or a patient table.

74. The scanner system of any one of claims 66-73, wherein the motion tracker system comprises at least one mirror sensor adapted for detecting the pose of one or more of the at least one primary mirror and or the armature comprising the at least one mirror, the at least one mirror sensor may preferably be located at a fixed location relative to the scanner, such as to a fixed location of the scanner, such as to a scanner wall portion of a scanner, such as a scanner bore, a floor and / or a ceiling of the scanner.30 75. The scanner system of claim 74, wherein the at least one mirror sensor comprises at least one of an IR sensor, an ultrasound sensor and / or a time of flight sensor.TRAC-P7 -784998276. The scanner system of claim 74 or claim 75, wherein the at least one mirror sensor is configured for transmitting an alarm signal if detecting that a primary mirror of the at least one primary mirror is deviating from a valid calibrated pose.

77. The scanner system of any one of claims 66-75, wherein the respective5 portions of light reflected from said target surface region and redirected by said respective primary mirrors to said imaging arrangement represents different Field of views (FOVs) of said at least one target surface region, preferably of at least one of said respective surface parts and / or said common part of said common part of said at least one target surface region.

78. The scanner system of any one of claims 66-77, wherein the travelling paths of said respective portions of light travelling from said at least one target surface region via reflection by said respective primary mirrors to said imaging arrangement comprises different center travel axes from the target surface region to the imaging arrangement, such as from at least one of said respective surface parts and / or said15 common part of said at least one target surface region via reflection by said respective primary mirrors to said imaging arrangement.

79. The scanner system of claim 78, wherein the travelling paths of said respective portions of light travelling from said at least one target surface region via reflection by said respective primary mirrors to said imaging arrangement comprises20 different center travel axes from the at least one target surface region to the respective primary mirrors, wherein the different center axes preferably differs with at least 5°, such at least 10°, such as at least 20°, such as at least 25°, optionally the travelling paths of said respective portions of light travelling from at least one of said respective surface parts and / or said common part of the at least one target surface region of the subject to the respective primary mirrors comprises different center travel axes, wherein at least one of said different center travel axes from the common target surface region to the respective primary mirrors has an angle of at least 5°, such as of least 10°, such as of at least 20°, such as of at least 25° relative to another one of said different center travel axes from at least one of said30 respective surface parts and / or said common part of the at least one target surface region to the respective primary mirrors.TRAC-P7 -784998380. The scanner system of any one of claims 66-79, wherein said consecutive image data sets generated from images of respective portions of light represents respective point of views (POV's) of at least one of said respective surface parts and / or said common part of said at least one target surface region, wherein said5 respective POV's preferably differs from each other.

81. The scanner system of any one of claims 66-80, wherein said computer system is configured for being or is calibrated to generating and / or identifying subimage data sets of each of said consecutive image data sets, wherein each subimage data set represents a point of view (POV) of at least one of said respective surface parts and / or said common part of said at least one target surface region.

82. The scanner system of any one of claims 66-81, wherein the at least one primary mirror comprises a primary mirror surface for redirecting the light reflected from the target surface and wherein the primary mirror comprises light absorbing features at said primary mirror surface to provide the redirected light to be a15 redirected structured light, preferably comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character, wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths.20 83. The scanner system of any one of 66-82, wherein the at least two portions of light, each representing at least a surface part of said at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, such as distinct surface parts of said at least one target surface region of the subject with no overlap.

84. The scanner system of claim 83, wherein said distinct surface part comprises at least two distinct surface parts, wherein the at least two distinct surface parts has a minimum distance to each other of at least 1 mm, such as of at least 0.5 cm, such as of at least 1 cm, such as of at least 2 cm said at least one target surface region of the subject such as of from 0.5 to 15 cm determined in a 3D view of the at least one30 target surface region of the subject.TRAC-P7 -784998485. The scanner system of claim 83 or claim 84, wherein said at least two distinct portions of light representing distinct surface parts comprises N distinct portions of light and wherein said primary mirrors comprises N primary mirrors, wherein N is an integer of from 2 to at least 10, such as from 2 to 8, such as from 2 to 6, such as5 from 2 to 4.

86. The scanner system of claim 85, wherein said N primary mirrors are arranged for redirect said N distinct portions of light representing said distinct surface parts, preferably comprising N distinct surface parts and wherein said imaging arrangements comprises at least M imaging devices, and wherein said N primary mirrors are arranged to redirect said N distinct portions of light representing said distinct surface parts to provide that at least a first sub-portion of each of said N distinct portions of light representing said distinct surface parts is received by at least one of said at least M imaging devices and a second sub-portion of each of said N distinct portions of light representing said distinct surface parts is received by at least15 one other of said at least M imaging devices, wherein the first sub-portion and said second sub-portion of each of said N distinct portions of light representing said distinct surface parts may be equal or different from each other, such as being overlapping or non-overlapping first sub-portion and said second sub-portion, wherein M is an integer of at least 2.20 87. The scanner system of claim 86, wherein M is three or larger, such as from 3 to 10, such as from 3 to 8, such as from 3 to 4.

88. The scanner system of claim 85 or claim 86, wherein each of the M imaging devices is configured for receiving at least a sub-portion of said N distinct portions of light representing said N distinct surface parts, preferably the M imaging devices and the N primary mirrors are arranged (calibrated) relative to each other and relative to the N distinct surface parts to provide that the M imaging devices receives at least a sub-portion of said N distinct portions of light representing said N distinct surface parts.

89. The scanner system of any one of claims 87-88, wherein said N primary30 mirrors and said M imaging devices are organized to operate group-wise, where each group comprises two primary mirrors and two imaging devices, wherein said two mirrors of a group are arranged for redirect said two distinct portions of lightTRAC-P7 -7849985 representing said distinct to surface parts and wherein said two imaging devices of the group each is configured for receiving at least a sub-portion of each of said two distinct portions of light representing said two distinct surface parts.

90. The scanner system of any one of claims 86-89, wherein said computer5 system is configured for receiving and processing said respective consecutive image data sets and for generating said least one 3D representation of at least a portion of said at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, wherein the computer processing comprises cross correlating data representing respective sub portions of each of said two distinct portions of light representing said at least two distinct surface parts of images of respective imaging devices, to determine a relative pose of said respective at least two distinct surface parts, preferably to determine said relative pose of said respective at least two distinct surface parts preferably to determine said relative15 pose of said respective at least two distinct surface parts in a coordinate system, such as in a scanner coordinate system.

91. The scanner system of claim 90 wherein the computer system comprises data representing a pose of each of the at least one primary mirror and / or the optional armature and / or the at least one imaging device and wherein the computer20 processing comprises cross correlating data representing respective sub portions of each of said two distinct portions of light representing said at least two distinct surface parts of images of respective imaging devices and data representing a pose of one or more of the at least one primary mirror and / or the optional armature and / or the at least one imaging device, to determine the relative pose of said respective at least two distinct surface parts.

92. The scanner system of any one of claims 86 - 91, wherein said computer system of said motion tracker arrangement is configured for receiving a 3D scan image data set from the scanner, wherein said 3D scan image data set comprises data representing a 3D scan image comprising at least a portion of at least two30 distinct surface parts of said at least one target surface region of the subject represented by said at least two distinct portions of light.TRAC-P7 -784998693. The scanner system of claim 91, wherein said 3D scan image data set comprises data representing a scanner coordinate system and data representing a pose of the 3D scan image in said scanner coordinate system.

94. The scanner system of claim 91 or claim 92, wherein said computer system is5 configured for receiving and processing said respective consecutive image data sets and for generating said least one 3D representation of at least a portion of said at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, wherein the computer processing comprises matching at least a portion of at least two of, preferably of each of said at least two distinct surface parts of said at least two distinct surface parts to said scan image to determine to determine said relative pose of said respective at least two distinct surface parts preferably to determine said relative pose of said respective at least two distinct surface parts in a coordinate system, such as in the scanner coordinate15 system.

95. The scanner system of any one of claims 92 - 94, wherein the scanner is a 3D scanner, preferably selected from an MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner and / or any combinations thereof.

96. A method of motion tracking of a subject having a body part located in a20 scanning scene, the method comprises- providing a motion tracker arrangement comprising• a mirror arrangement comprising at least one primary mirror;• an imaging arrangement comprising at least one imaging device; and• a computer system,- arranging said mirror arrangement to redirecting light reflected from at least one target surface region of the subject to provide that said redirected light comprises at least two portions of light, such that each of said at least two portions of light comprises light representing at least a surface part of said at least one target surface region and to provide that the mirror arrangement is30 arranged for redirecting said at least two portions of light towards said imaging arrangement,TRAC-P7 -7849987- arranging said imaging arrangement to receive at least a part of said redirected light,- activating the imaging arrangement for recording consecutive digital images of said respective light portions redirected towards said imaging arrangement5 and providing the imaging arrangement for generating and transmitting consecutive image data sets representing said respective consecutive recorded digital images to said computer system, wherein the method comprises providing said respective portions of light to have different travelling paths from being reflected from said mirror arrangement to being recorded by said imaging arrangement, and wherein said computer system being configured for processing said respective consecutive image data sets and for generating at least one 3D surface representation of at least a portion of said at least one target surface region, preferably a 3D data representation of at least a portion of said at least one target15 surface region comprising at least one of said surface parts of said at least one target surface region.

97. The method of claim 96, wherein said portions of light comprises light represents a common part of said at least one target surface region, preferably wherein said computer system being configured for processing said respective20 consecutive image data sets and for generating said least one 3D surface representation to comprises said common part of said at least one target surface region of the subject.

98. The method of claim 96 or claim 97, wherein the scanner system is as defined in anyone of the preceding claims 66-95, preferably the motion tracker arrangement according to any one of claims 1-65, form part of the scanner system comprising a scanner and said motion tracker arrangement.

99. The method of any one of claims 96-98, wherein the at least one target surface region comprises or consists of a surface region of the body part located in the scanning scene, preferably the at least one target surface region is free of30 artificial marker element(s).TRAC-P7 -7849988100. The method of any one of claims 96-99, wherein the method comprises precalibrating the motion tracker arrangement prior to performing the motion tracking of the body part and / or between tracking sessions, wherein the pre-calibrating comprises5 - providing at least one pre-calibration surface region and arranging the at least one pre-calibration surface region in the scene at a location adapted for the target surface region,- providing the mirror arrangement to redirecting light reflected from the at least one pre-calibrating surface region, such that said redirected light comprises at least two pre-calibration portions of light, wherein each of said respective pre-calibration portions of light comprises light representing a precalibrating surface part of, to provide that the mirror arrangement is arranged for redirecting said pre-calibration portions of light towards said imaging arrangement,15 - providing said imaging arrangement to receive at least a part of said light redirected from the pre-calibration surface,- activating the imaging arrangement for recording one or more pre-calibration digital images of said respective calibration light portions redirected towards said imaging arrangement and providing the imaging arrangement for20 generating and transmitting pre-calibration image data sets representing said respective recorded pre-calibration digital images to said computer system, wherein the method comprises providing said respective pre-calibration portions of light to have different travelling paths from being reflected from said mirror arrangement to being recorded by said imaging arrangement, wherein the computer system is acquiring and / or receiving pre-calibration data representing said at least one pre-calibration surface region and wherein the computer system is processing said respective pre-calibration image data sets and generating an pre-calibrating algorithm comprising correlating said pre-calibration image data sets with said pre-calibration data,30 preferably said pre-calibration comprises pre-calibrating the computer system to generate and / or identifying pre-calibrating sub-image data sets of each of said consecutive pre-calibrating image data sets, wherein each pre-calibrating sub-imageTRAC-P7 -7849989 data set represents a point of view (POV) of at least a portion of said at least one pre-calibrating surface region.

101. The method of claim 100, wherein said at least one pre-calibration surface region comprises a pattern (e.g. arranged as a checkerboard pattern) of sub regions5 having different reflection properties and / or a 3D structure, such as one or more curved sub regions, one or more protruding sub regions.

102. The method of claim 100 or claim 101, wherein said pre-calibration at least one pre-calibration surface region is tunable for modelling one or more motions, and wherein the method comprising one or more refining cycles each comprising- adjusting said pre-calibration for modelling one or more of said motions- repeating the step of• generating and transmitting consecutive pre-calibration image data sets representing said respective consecutive recorded pre-calibration digital images to said computer system,15 • acquiring and / or receiving pre-calibration data representing said at least one pre-calibration surface region and• processing said respective pre-calibration image data sets comprising correlating said calibration image data sets with said pre-calibration data and- refining the pre-calibrating algorithm.20 103. The method of any one of claims 100-102, wherein the pose of each of the respective at least one primary mirror is deemed to be a valid calibration pose for said each respective primary mirror.

104. The method of any one of claims 96-103, wherein the at least one primary mirror comprises a primary mirror surface for redirecting the light reflected from the calibration surface and wherein the primary mirror comprises light absorbing features at said primary mirror surface to provide the redirected light to comprise redirected structured calibration light portions, preferably comprising optically distinguished areas, such as a pattern of areas of light and areas of no-light and / or areas of light of a first quality of a character and areas of light of a second quality of the character,30 wherein the character advantageously is selected from light intensity, wavelength and / or range of wavelengths.TRAC-P7 -7849990105. The method of any one of claims 96-104, wherein said motion tracker arrangement further comprises a marker, wherein the method comprises pointing a marking by said marker onto said at least one target surface region and / or onto said at least one pre-calibration surface region.5 106. The method of any one of claims 100-105, wherein the pre-calibration comprising calibrating the relative pose of said primary mirror and optionally said intermediate mirror(s), preferably the pre-calibration comprises calibrating the relative pose of said primary mirror in said armature and wherein the method comprises fixing the primary mirrors in the armature in their respective pre-calibrated pose.

107. The method of any one of claims 100105, wherein the pre-calibration comprising fixing the pose of the at least one imaging device and calibrating the relative pose of said primary mirror and optionally said intermediate mirror(s), preferably the fixed pose of the at least one imaging device is referred to as a valid15 image device pose.

108. The method of any one of claims 96-107, wherein the method comprises arranging the mirror arrangement of the motion tracker arrangement as adapted according to any one of claims 1-37 and providing that the at least one primary mirror is located in the scene of the scanner, preferably the method comprises20 arranging two or more primary mirrors in said scene at respective viewing distances to said at least one target surface region, such as to at least one of said respective surface parts and / or said common part of said at least one target surface region, wherein the respective viewing distances are determined from a center point of said respective mirrors to a center point of at least one of said respective surface parts represented by the portion of light redirected by said respective mirrors and / or said common target surface region, wherein said respective viewing distances may be equal or different from each other, such as from 1 cm to 1 m, such as from 2 cm to 25 cm, optionally the respective viewing distances differs at most 10 cm from each other, such as at most 5 cm from each other.30 109. The method of any one of claims 96-108, wherein the method comprises arranging the mirror arrangement to provide that the respective portions of light reflected from said at least one target surface region and redirected by saidTRAC-P7 -7849991 respective primary mirrors to said imaging arrangement represents different Field of views (FOVs) of said at least one target surface region, preferably of at least one on said respective surface parts and / or said common part of said at least one target surface region.5 110. The method of any one of claims 96-109, wherein the method comprises arranging the mirror arrangement to provide that the travelling paths of said respective portions of light travelling from said at least one target surface region via reflection by said respective primary mirrors to said imaging arrangement comprises different center travel axes from the at least one target surface region to the imaging arrangement, preferably wherein the travelling paths of said respective portions of light travelling from said target surface region via reflection by said respective primary mirrors to said imaging arrangement comprises different center travel axes from the at least one target surface region to the respective primary mirrors, preferably at least one center travel axis of said center travel axes has an15 angle of at least 5°, such as least 10, such as least 20°, such as least 25° to another center travel axis of said center travel axes.

111. The method of any one of claims 96-110, wherein the method comprises arranging the mirror arrangement to provide that two or more of the respective portions of light impinges at least partly at different locations of an image sensor of20 the at least one imaging device of the imaging arrangement, such as to provide that said two or more of the respective portions of light impinges at separate (nonoverlapping) locations of the image sensor of the at least one imaging device of the imaging arrangement.

112. The method of any one of claims 96-111, wherein the method comprises arranging at least one primary mirror of the mirror arrangement to be temporally or permanently mounted to an RF coil, a scanner bore and / or or a patient table.

113. The method of any one of claims 96-112, wherein the method comprises providing the motion tracker system to comprises at least one mirror sensor adapted for detecting the pose of one or more of the at least one primary mirror and or the30 armature comprising the at least one mirror, the at least one mirror sensor may preferably be located at a fixed location relative to the scanner, such as to a fixedTRAC-P7 -7849992 location of the scanner, such as to a scanner wall portion of a scanner, such as a scanner bore, a floor and / or a ceiling of the scanner.

114. The method of claim 113, wherein the at least one mirror sensor comprises at least one of an IR sensor (e.g. IR LED, IR photodiode, IR camera), an ultrasound5 sensor and / or a time of flight sensor.

115. The method of claim 113 or claim 114, wherein the at least one mirror sensor is configured for transmitting an alarm signal if detecting that a primary mirror of the at least one primary mirror and / or the armature is deviating from a valid calibration pose, such as a pre-calibration pose.

116. The method of any one of claims 113-115, wherein the method comprises that at least one mirror sensor is configured for transmitting instruction to a user and / or to transmitting instructions to at least one step motor, each associated to one of the at least one primary mirror and / or the armature, which at least one primary mirror and / or armature has been detected to deviate from a valid calibration pose,15 instructing the user and / or the at least one step motor to modify the pose of the at least one primary mirror and / or armature has been detected to deviate from a valid calibration pose, to be in in conformation with the valid calibration pose.

117. The method of any one of claims 113-116, wherein the method comprises that the motion tracker is pre-calibrated, providing one or more of the at least one20 primary mirror of the mirror arrangement and / or one or the armature and / or one or more of the at least one imaging device to be in respective valid calibration pose, preferably to provide each of the at least one primary mirror of the mirror arrangement to be in respective valid pose, such as providing at least the armature to be in a valid calibration pose.

118. The method of any one of claims 96-117, wherein said imaging arrangement comprises two or more imaging devices each comprising an image sensor and wherein the method comprises arranging said mirror arrangement for redirecting said respective portions of light to provide that at least one of the respective portions of light impinges at the image sensor of one of the imaging devices and that at least30 one other of the respective portions of light impinges at image sensor on one other of the imaging devices, optionally said mirror arrangement is arranged for redirectingTRAC-P7 -7849993 said respective portions of light to provide that at least two of the respective portions of light impinges at the image sensor of a same one of the imaging devices, preferably at different locations of the same image sensor.

119. The method of any one of claims 96-118, wherein the method comprises5 arranging the mirror arrangement to provide that said consecutive image data sets generated from images of respective portions of light represents respective point of views (POV's) of said at least one target surface region of the subject, such as of at least one of said respective surface parts and / or said common part of said at least one target surface region, wherein said respective POV's preferably differs from each other.

120. The method of any one of claims 96-119, wherein the method comprises providing said imaging arrangement for recording said consecutive digital images of said respective light portions as a function of time, wherein each of said consecutive image data sets comprises a time attribute representing a point of time of recording.15 121. The method of any one of claims 96-120, wherein the method comprises providing said computer system for processing said respective consecutive image data sets and for generating consecutive 3D surface representation of said at least one target surface region of the subject, such as of at least one of said respective surface parts and / or said common part of said at least one target surface region,20 preferably said image data sets comprises respective time attributes representing point of time of recording.

122. The method of any one of claims 96-121, wherein the method comprises providing said computer system for identifying matching light features of respective image sets, such as sub-image data sets and for estimating the perspective transformation between the respective matched features of said respective subimage data sets and based thereon generating said 3D surface representation of at least a portion of the at least one target surface region, such as at least a portion of at least one of said respective surface parts and / or said common part of the at least one target surface region of the subject.30 123. The method of any one of claims 96-122 wherein the method comprises providing said computer system for generating consecutive 3D surfaceTRAC-P7 -7849994 representations of said at least one target surface region of the subject, such as of said common target surface region from said consecutive image data sets and for determining potential differences between said consecutive 3D surface representations, preferably the computer system is provided for processing5 determined differences and determine at least one property of a motion causing the difference.

124. The method of any one of claims 96-123, wherein the method comprises arranging the at least one imaging device of the imaging arrangement to be located outside the scene of the scanner, preferably such that the at least one imaging device and the at least one primary mirror are located with a distance of at least 1 m, such as at least 1.2 m, such as at least 1.3 m, such as at least 1.4 m, such as at least 1.5 m.

125. The method of any one of claims 96-124, wherein the motion tracker arrangement comprises a structured light projector configured for projecting invisible15 light, such as for projecting light having one or more wavelength in the ranges from 100 nm to 350 nm and / or from 700 nm to 1.4 pm, preferably in the range from 800- 1200 nm.

126. The method of claim 125, wherein the structured light projector configured for projecting a dot pattern and / or a speckle pattern.20 127. The method of claim 126 or claim 126, wherein the method comprises projecting said structured invisible light to at least a portion of the scene, preferably for projecting the structured light to the at least one target surface region of the subject.

128. The method of any one of claims 96-127, wherein the at least two portions of light, each representing at least a surface part of said at least one target surface region comprises at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, such as distinct surface parts of said at least one target surface region of the subject with no overlap.

129. The method of claim 128, wherein said distinct surface part comprises at30 least two distinct surface parts, wherein the at least two distinct surface parts has a minimum distance to each other of at least 1 mm, such as of at least 0.5 cm, such asTRAC-P7 -7849995 of at least 1 cm, such as of at least 2 cm said at least one target surface region of the subject such as of from 0.5 to 15 cm determined in a 3D view of the at least one target surface region of the subject.

130. The method of claim 128 or claim 129, wherein said at least two distinct5 portions of light representing distinct surface parts comprises N distinct portions of light and wherein said primary mirrors comprises N primary mirrors, wherein N is an integer of from 2 to at least 10, such as from 2 to 8, such as from 2 to 6, such as from 2 to 4.

131. The method of claim 130, wherein said N primary mirrors are arranged for10 redirect said N distinct portions of light representing said distinct surface parts, preferably comprising N distinct surface parts and wherein said imaging arrangements comprises at least M imaging devices, and wherein said N primary mirrors are arranged to redirect said N distinct portions of light representing said distinct surface parts to provide that at least a first sub-portion of each of said N distinct portions of light representing said distinct surface parts is received by at least one of said at least M imaging devices and a second sub-portion of each of said N distinct portions of light representing said distinct surface parts is received by at least one other of said at least M imaging devices, wherein the first sub-portion and said second sub-portion of each of said N distinct portions of light representing said20 distinct surface parts may be equal or different from each other, such as being overlapping or non-overlapping first sub-portion and said second sub-portion, wherein M is an integer of at least 2.

132. The method of claim 131, wherein M is three or larger, such as from 3 to 10, such as from 3 to 8, such as from 3 to 4.25 133. The method of any one of claims 129-132, wherein each of the M imaging devices is configured for receiving at least a sub-portion of said N distinct portions of light representing said N distinct surface parts, preferably the M imaging devices and the N primary mirrors are arranged (calibrated) relative to each other and relative to the N distinct surface parts to provide that the M imaging devices receives at least a30 sub-portion of said N distinct portions of light representing said N distinct surface parts.TRAC-P7 -7849996134. The method of any one of claims 130 - 133, wherein said N primary mirrors and said M imaging devices are organized to operate group-wise, where each group comprises two primary mirrors and two imaging devices, wherein said two mirrors of a group are arranged for redirect said two distinct portions of light representing said5 distinct to surface parts and wherein said two imaging devices of the group each is configured for receiving at least a sub-portion of each of said two distinct portions of light representing said two distinct surface parts.

135. The method of any one of claims 130 - 134, wherein said computer system is configured for receiving and processing said respective consecutive image data sets10 and for generating said least one 3D representation of at least a portion of said at least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, wherein the computer processing comprises cross correlating data representing respective sub portions of each of said two distinct portions of light representing said at least two distinct surface parts of images of respective imaging devices, to determine a relative pose of said respective at least two distinct surface parts, preferably to determine said relative pose of said respective at least two distinct surface parts preferably to determine said relative pose of said respective at least two distinct surface parts in a coordinate system,20 such as in a scanner coordinate system.

136. The method of claim 135, wherein the computer system comprises data representing a pose of each of the at least one primary mirror and / or the optional armature and / or the at least one imaging device and wherein the computer processing comprises cross correlating data representing respective sub portions of25 each of said two distinct portions of light representing said at least two distinct surface parts of images of respective imaging devices and data representing a pose of one or more of the at least one primary mirror and / or the optional armature and / or the at least one imaging device, to determine the relative pose of said respective at least two distinct surface parts.30 137. The method of any one of claims 128 - 136, wherein said computer system of said motion tracker arrangement is configured for receiving a 3D scan image data set from a scanner, wherein said 3D scan image data set comprises data representing aTRAC-P7 -78499973D scan image comprising at least a portion of at least two distinct surface parts of said at least one target surface region of the subject represented by said at least two distinct portions of light.

138. The method of claim 137, wherein said 3D scan image data set comprises5 data representing a scanner coordinate system and data representing a pose of the 3D scan image in said scanner coordinate system.

139. The method of claim 137 or claim 138, wherein said computer system is configured for receiving and processing said respective consecutive image data sets and for generating said least one 3D representation of at least a portion of said at10 least one target surface region comprising at a portion of each of the at least two distinct portions of light representing distinct surface parts of said at least one target surface region of the subject, wherein the computer processing comprises matching at least a portion of at least two of, preferably of each of said at least two distinct surface parts of said at least two distinct surface parts to said scan image to determine to determine said relative pose of said respective at least two distinct surface parts preferably to determine said relative pose of said respective at least two distinct surface parts in a coordinate system, such as in the scanner coordinate system.

140. The method of any one of claims 136 - 139, wherein the scanner is a 3D20 scanner, preferably selected from an MRI scanner, a CT scanner, a PET scanner, an ultrasound scanner and / or any combinations thereof.

Images