Marking device

Abstract

The invention relates to a marking device having a marker carrier and radiopaque marker elements which are optically recognizable in visible light fastened thereto. The marker carrier itself is flat, occupies an area of at least 10 cm2 and has a thickness of not more than 5 mm. The marker carrier completely or partially encloses a clear space in such a way that the clear space is open towards one side of the marker carrier and formed by a concave peripheral section of the marker carrier.

Description

[0001] Eisenführ Speiser

[0002] Berlin, September 10, 2025

[0003] Our reference: AB 1479-02WO JVO / adp

[0004] Provider / owner: Atlas medical Technologies GmbH

[0005] Official file number: New registration

[0006] Atlas medical Technologies GmbH Lohrheidestraße 53, 44866 Bochum

[0007] Marking device

[0008] The invention relates to a marking device, in particular a marking device with visually detectable features for application to a body.

[0009] Marker devices are used, for example, in the medical field to mark external body parts of a patient for registration or motion tracking. Specifically, marker devices are used to represent a spatial reference that can be identified in images acquired with various scanning devices. This allows for the mapping of a planned procedure to this spatial reference. For this purpose, the marker devices are applied to the skin of a patient, for example, around the site of a planned procedure. An example is described in Sangkyu Lee et al., "A Skin-Conformal, Stretchable, and Breathable Fiducial Marker Patch for Surgical Navigation Systems," Micromachines 2020, 11, 194.

[0010] For example, in robot-assisted surgery, it is advantageous if the marking device is easily recognizable and clearly identifiable by cameras or modalities such as tomography or X-ray imaging. At the same time, marking devices should not impede a potential procedure, be easy to apply, not be particularly expensive as disposable items, and simultaneously provide reliable marking. According to the invention, a marking device is proposed that comprises a marker carrier and attached marker elements that are radio-opaque and optically detectable in visible light. The marker carrier is flat and occupies an area of ​​at least 10 cm². 2The marker carrier has a maximum thickness of 5 mm. This thickness refers to the thickness of the marker carrier without the attached radio-opaque and visible-light visible marker elements. The marker carrier is designed to completely or partially enclose a free space. If the marker carrier only partially encloses the free space, the free space is open towards a side edge of the marker carrier and is formed by a concave circumferential section of the marker carrier.

[0011] Preferably, the marking device is designed asymmetrically, preferably with respect to any type of symmetry. An asymmetrical design of the marking device is preferably achieved by irregularly arranged marker elements on the marker carrier.

[0012] In one embodiment, the marker carrier itself is designed to be as inconspicuous as possible in visible light images as well as in tomographic or X-ray images. The material of the marker carrier preferably has a higher transparency compared to the marker elements. This simplifies the detection of the marker elements. Because the marker carrier is thinner than the marker elements and preferably has a thickness that is less than a quarter of the thickness of the marker elements, the marker carrier is barely visible in tomographic or X-ray images. For images of the marking device taken with visible or infrared light, it is advantageous if the marker carrier has a matte, diffusely reflective surface so that the processing and evaluation of images taken with light are not disrupted by reflections.One advantage of a flat marker carrier in the form of a cloth is that, in images taken in daylight, the carrier forms a uniform background for the marker elements, independent of the color of the body surface, such as skin tone. An image acquisition unit then always "sees" the marker elements against the same background, for example, green. In contrast to the marker carrier, the preferably spherical or hemispherical marker elements should always be clearly visible in images and reflect diffusely rather than directly, or produce as few artifacts as possible in tomography or X-ray images.

[0013] The free space defined by the marker carrier and wholly or partially enclosed by it preferably has an O-shaped, U-shaped, V-shaped, parabolic, circular, rectangular, elliptical, or semi-elliptical shape. The free space itself can be symmetrical and accordingly have an axis of symmetry. A dimension of the free space extending along the axis of symmetry is preferably larger than the dimensions of the free space in the various directions extending perpendicular to the axis of symmetry.

[0014] In one embodiment, the marker carrier is designed to be flexible enough to drape over a body. For this purpose, the marker carrier can be made, for example, of a cloth or fabric woven from interwoven threads. The fabric can have a twill weave, a cross twill weave, or a plain weave. Such a marker carrier can have an adhesive film on one side, allowing it to be applied to a body surface, which does not need to be flat. This adhesive film prevents the marker carrier from slipping after application. Because the marker carrier is flexible and drapeable, it allows for deformation and movement of the body surface to which it is attached.

[0015] A double-sided adhesive film can be provided for attaching the marker carrier to a body surface; a single-sided self-adhesive film can also form the marker carrier.

[0016] In use, a marking device with a flat, drapable marker carrier can replace an otherwise required sterile covering.

[0017] Such a marking device with a drapable marker carrier can, for example, have a rectangular base shape and a cutout that forms the free space. The cutout preferably extends in a U-shape, V-shape, parabola, or semi-elliptical shape into a rectangle enclosing the marker carrier.

[0018] In an alternative embodiment, the marker carrier of the marking device is designed to be so rigid that it essentially maintains a flat shape in its relaxed state even under the influence of its own weight, bending by less than its thickness under its own weight. According to a preferred embodiment, such a relatively rigid marker carrier is preferably formed in a truss-like structure of struts and openings enclosed by the struts. One of the struts, acting as a clearance-limiting strut, preferably runs along the edge of the clearance defined by the marker carrier. Such a relatively rigid marker carrier can be manufactured in one piece as a plastic part, for example, by injection molding. The struts of the marker carrier preferably have an at least approximately circular cross-section, which also determines the thickness of the marker carrier.

[0019] Both the marking device with a relatively flexible, drapable marker carrier and the marking device with a relatively rigid marker carrier are preferably designed such that at least some of the marker elements are arranged along an edge of the marker carrier enclosing the free space. Here, too, the arrangement of the marker elements is preferably irregular, in particular asymmetrical. This helps in unambiguously identifying the orientation of the marker carrier.For an evaluation of the orientation and - in the case of the drapable marker carrier - any deformation of the marker carrier that may be present, models of the respective marker device in their relaxed, geometrically undistorted form are stored in an automated acquisition device - which is explained in more detail below - so that the marker elements captured by means of an imaging device can be easily and unambiguously assigned to the marker elements of the higher-lying model.

[0020] For the evaluation of images from the marking device, it is generally advantageous if at least some of the marker elements on the marker carrier are spaced far apart. It is also beneficial if the free space enclosed by the marker carrier is as large as possible to minimize interference with the procedure. This allows the marker carrier to be positioned around the site of a planned procedure, enabling particularly precise determination of positions within the intervention area. On the other hand, the marker carrier should not be too large, in order to keep the area of ​​the body to be irradiated, for example with X-rays, as small as possible.

[0021] Furthermore, the marking device, regardless of whether the marker carrier is relatively flexible or relatively rigid, features an optically detectable, machine-readable code, such as a QR code or the like. The machine-readable code can be applied to the marker carrier. For example, the marker carrier can have an application area onto which a sticker with a machine-readable code can be affixed. Preferably, the application area is located on an edge of the marker carrier that does not face free space, so that a sticker with a machine-readable code can extend beyond the application area and serve to attach the marker carrier to a body surface.For this purpose, a marking device is preferably provided which, in addition to the marker carrier, also has a sticker with a machine-readable code, wherein the area of ​​the sticker is larger than the application area on the marker carrier.

[0022] According to a preferred embodiment, the machine-readable code only appears after the sticker is affixed to the marker carrier. For example, the sticker has a transparent backing material printed with a light color, such as white, while the application area on the marker carrier is dark, such as black. This reduces the cost of producing the stickers.

[0023] The marker elements themselves are preferably flat, circular, spherical, or hemispherical. If the marker elements are spherical, they can be composed of two hemispheres. This has the advantage that the hemispheres can be injection molded and thus manufactured cost-effectively. The marker elements preferably consist of a sterilizable material, i.e., a material that is not affected by conventional sterilization methods.

[0024] Instead of a spherical shape, the marker elements can also have the shape of other solid bodies or be designed as "lines," i.e., strut-like. One advantage of a strut-like design for the marker elements is that only 2-3 layers are needed for a tomography scan. In the tomography scanned layers, points then appear, for example, where the struts of a marker element intersect the scanned layer. A clear assignment to a marker element across three or more layers is then possible.

[0025] The marker elements are preferably made of a homogeneous material with high density to ensure good visibility in X-ray images or computed tomography scans and to avoid causing artifacts. The marker elements can, for example, contain a dimethacrylate such as urethane dimethacrylate.

[0026] The marking device is preferably part of a surgical support system comprising at least one optical image acquisition unit, for example, a camera, and an evaluation unit. The evaluation unit is connected to the camera on one side and to a memory in which data describing the geometry of the marking device (geometric models of the marking device) are stored on the other. During operation, the evaluation unit can receive and evaluate images acquired by the image acquisition unit. The evaluation unit is configured to identify a marking device and optically distinctive features of the marking device in the images received from the image acquisition unit. Such optically distinctive features are edges of the marker carrier or struts forming the marker carrier, and in particular the marker elements attached to the marker carrier.

[0027] After identifying the optically distinctive features in the images supplied by the image acquisition unit, the evaluation unit can assign the captured features to corresponding features of the geometric model of the marking device stored in its memory. Following this assignment, the evaluation unit can determine the specific orientation and, if necessary, deformation of the actual marking device captured by the image acquisition unit. This allows, for example, the regular or continuous correction or updating of a registration using preoperatively acquired models of a patient, in order to enable, for instance, the most precise possible robot-assisted surgery.

[0028] Furthermore, the evaluation unit can be designed to uniquely identify individual marking devices using the respective QR code and, for example, to prevent multiple connections of a marking device.

[0029] Preferably, the marking device is used in a process in which the marking device is first applied to a body surface, and the marking device applied to the body surface is then captured using an image acquisition unit and / or a modality such as a tomography device. After the characteristic and optical features of the marking device have been identified, in particular the marker elements, the actual position of the marker elements can be recorded with corresponding positions in a preoperative model based on their identified position. This procedure is generally known from the use of medical navigation systems.

[0030] Registration typically takes place before a potential intervention. During treatment, the position of the marker elements can be continuously or periodically recorded. By evaluating the current position of the marker elements, the initial registration can be corrected or adjusted. Furthermore, movements of the body surface can be tracked in this way. The invention will now be explained in more detail using examples. The description of the examples refers to the following figures:

[0031] FIG. 1: is a schematic representation of a marking device with a drapable marker holder;

[0032] FIG. 2: is a schematic longitudinal section through the marking device from Figure 1;

[0033] FIG. 3: is a schematic representation of a marking device with a comparatively rigid marker carrier;

[0034] FIG. 4: is a schematic representation of a marking device with a flexible, transparent marker carrier and printed marker elements;

[0035] FIG. 5: is a schematic representation of an alternative marking device with a flexible, transparent marker carrier and printed marker elements;

[0036] FIG. 5: is a schematic representation of an alternative marking device with a flexible, transparent marker carrier and printed marker elements; and

[0037] FIG. 7: is a schematic representation of a system comprising a marking device, an image acquisition unit, an evaluation unit and a memory for at least one geometric model of a marking device.

[0038] Figure 1 shows a marking device 10 with a marker carrier 12 and marker elements 14 attached to the marker carrier 12. The marker carrier 12 is flexible and drapeable, allowing it to conform to a non-planar body surface. On its reverse side, facing away from the marker elements 14, the marker carrier 12 is provided with an adhesive film 16. A cutout in the marker carrier defines a clearance 18, which, for example, allows direct access to the body surface for a procedure. The clearance 18 is at least partially enclosed by the marker carrier and allows the marker elements 14 to be positioned very close to the site of the procedure. This enables precise position detection. In the longitudinal section shown in Figure 2, it can be seen that the adhesive film 16 preferably extends over the entire reverse side of the marker carrier 12.

[0039] The adhesive film 16 allows the marker carrier to be adhered to a body surface over its entire area, even if the surface is not flat but concave, convex, or both. The adhesive film 16 is selected such that its adhesion to the body surface is sufficient to prevent the marking device 10 from slipping and, in the case of a flexible marker carrier 12, to ensure that it adheres to the body surface as completely as possible. At the same time, the adhesive forces exerted by the adhesive film 16 between the marker carrier 12 and the body surface are designed to be low enough to allow for easy removal of the marking device 10 from the body surface.

[0040] The marker elements 14 preferably have a hemispherical shape and consist of a homogeneous, radiopaque material. Due to their hemispherical shape, the marker elements are easily identifiable from different directions. Alternative suitable shapes for the marker elements 14 are solid bodies such as truncated cones, cylinders, half octahedra or dodecahedra, or the like. Preferably, the marker elements 14 have a color that contrasts with the color of the marker carrier 12. Furthermore, the marker elements are preferably diffusely reflective.

[0041] The flexible and therefore drapable marker carrier 12 shown in Figures 1 and 2 is formed from an elastic film or a drapable fibrous fabric.

[0042] Instead of a flexible and thus drapable marker carrier 12, the marking device 10 can also have a comparatively rigid marker carrier 12', which essentially retains its flat shape in the relaxed state even under the influence of its own weight, so that it bends under its own weight by less than the amount of its thickness. In the embodiment shown in Figure 3, such a comparatively rigid marker carrier 12' is formed by struts 20 and openings 22 enclosed by the struts. One of the struts, as a clearance-limiting strut 24, preferably runs along the edge of the clearance 18 defined by the marker carrier. Such a comparatively rigid marker carrier 12' can be manufactured in one piece as a plastic part, for example, by injection molding.The struts 20 and 24 of the marker carrier 12' preferably have an at least approximately round cross-section of less than 5 mm in diameter, which also determines the thickness of the marker carrier 12'.

[0043] As can be seen in Figures 1 and 3, the marking device 10 has an optically detectable, machine-readable code, for example a QR code 26, a Data Matrix code, or the like, in the case of both a relatively flexible marker carrier 12 and a relatively rigid marker carrier 12'. The machine-readable code 26 can be applied directly to the marker carrier 12 or 12'. The relatively rigid marker carrier 12' has an application surface 28 onto which a sticker 30, printed with the machine-readable code 26, can be affixed. In the illustrated embodiment, the application surface 28 is arranged on an edge of the comparatively rigid marker carrier 12' that does not point towards the free space, so that the sticker 30 with a machine-readable code 26 can extend beyond the application surface 28 and serve to attach the marker carrier 12' to a body surface.In this case, the marking device 10 therefore includes, in addition to the marker carrier 12', the sticker 30 with the machine-readable code 26, wherein one dimension of the sticker 30 is larger than the corresponding dimension - e.g. the width - of the application area 28 on the marker carrier 12'.

[0044] The marker carrier 10 can also be made of a flexible, transparent material and, for example, be formed by a transparent film 32 onto which optically identifiable marker elements 14.1 and 14.2 are printed with a radiopaque ink. The film 32 can, for example, be an incision film and need not have a cutout to form the free space 18 from the embodiment shown in Figure 1, since it is possible to pierce the film 12 with a needle. In the embodiments shown in Figures 3 and 4, the free space 18 can be formed by an unprinted area of ​​the film 32.

[0045] The pattern printed on slide 12 can include marker elements 14.1, 14.2, 14.3 and / or 14.4 of different shapes, as illustrated in Figures 4 and 5.

[0046] However, even if the marker carrier 12 is formed from a cloth, the differently shaped marker elements 14.1 and 14.2 can be printed with radiopaque ink; that is, hemispherical marker elements are not absolutely necessary. If the marker carrier 12 is formed from a cloth, it preferably has a cutout 18 that forms a free space; see Figure 6. Figure 7 shows exemplary components of a surgical support system 40, namely a camera 42 as an optical image acquisition unit, and an evaluation unit 44, which is connected on one side to the camera 42 and on the other side to a memory 46 in which data describing the geometry of the marking device 10 are stored. The data describing the geometry of the marking device 10 represent geometric models of the marking device 10.

[0047] The camera 42 can be a stereo camera or a 3D camera that can capture images of the marking device according to the time-of-flight principle (i.e., based on the travel time of light pulses), which represent a three-dimensional image of the marking device in a known manner.

[0048] During operation, the evaluation unit 44 can receive and evaluate images captured by the image acquisition unit. The evaluation unit 44 is designed to identify a marking device 10 and optically distinctive features of the marking device 10 in the images received from the image acquisition unit. Such optically distinctive features are edges of the marker carrier 12 or elements forming the marker carrier.

[0049] Struts 20 and in particular the marker elements 14 attached to the marker carrier.

[0050] Reference symbol list

[0051] 10 Marking device

[0052] 12 drapable marker holders

[0053] 12' Rigid marker carrier 14 marker elements

[0054] 14.1, 14.2, 14.3, 14.4 printed marker elements

[0055] 16 adhesive tape

[0056] 18 Free space

[0057] 20 struts 22 (enclosed by struts) opening

[0058] 24 Clearance limiting strut

[0059] 26 QR code / machine-readable code

[0060] 28 application area

[0061] 30 stickers, 32 incision films

[0062] 40 Surgical Support System

[0063] 42 Camera

[0064] 44 evaluation units

[0065] 46 storage

Claims

Claims 1. Marking device (10) with a marker carrier (12) and radio-opaque and optically detectable marker elements (14) attached thereto, wherein the marker carrier (12) itself is flat, with a surface area of ​​at least 10 cm² 2 occupies and has a maximum thickness of 5 mm and wherein the marker carrier (12) completely encloses or partially encloses a free space (18) such that the free space (18) is open to one side of the marker carrier (12) and is formed by a concave circumferential section of the marker carrier (12).

2. Marking device (10) according to claim 1, wherein the free space (18) has an egg-shaped, U-shaped, V-shaped, rectangular, parabolic, elliptical or semi-elliptical shape.

3. Marking device (10) according to claim 1 or 2, wherein the marker carrier (12) is flexible in such a way that it can be draped on a body.

4. Marking device (10) according to at least one of claims 1 to 3, wherein the marker carrier (12) is formed from a fabric or cloth.

5. Marking device (10) according to claim 3 or 4, wherein the marker carrier (12) is provided on its back side facing away from the marker elements (14) with an adhesive film (16) for attaching the marker carrier (12) to a body surface.

6. Marking device (10) according to at least one of claims 1 to 3, wherein the marker carrier (12) is formed in a truss-like manner by struts (20, 24) and openings (22) enclosed by the struts.

7. Marking device (10) according to claim 6, wherein the marker carrier (12) is such that the marker carrier (12) retains its planar shape on its own and is preferably so rigid that it bends under its own weight by less than the amount of its thickness.

8. Marking device (10) according to at least one of claims 1 to 7, wherein several marker elements (14) are preferably arranged unevenly distributed along an edge of the marker carrier (12) enclosing the free space (18).

9. Marking device (10) according to at least one of claims 1 to 8, wherein the marker carrier (12) is provided with an optically detectable, machine-readable code (26) such as a QR code, a data matrix code or the like.

10. Marking device (10) according to at least one of claims 1 to 9, wherein the marker carrier (12) has an application surface (28) onto which a sticker (30) with a machine-readable code (26) can be applied. 1 1. Marking device (10) according to claim 10, wherein the application surface (28) is arranged on an edge of the marker carrier (12) that does not point towards the free space, such that the sticker (30) can extend beyond the application surface (28) and serve to attach the marker carrier (12) to a body.

12. Marking device (10) according to at least one of claims 1 to 11, wherein the markers (14.1 , 14.2, 14.3, 14.4) are printed on the marker carrier (12) with radiopaque ink.

13. Marking device (10) according to at least one of claims 1 to 12, wherein the marker carrier (12) comprises a film.

14. Surgical support system (40), comprising an optical image acquisition unit (42), an evaluation unit (44) which is connected on one side to the optical image acquisition unit (42) and to a memory (46) which is connected to the evaluation unit (44) and in which data describing the geometry of a marking device (10) according to claims 1 to 13 are stored.

Images