Marking system for positioning a patient relative to a medical imaging device

Abstract

Marking system (12) for positioning a patient (6) relative to a medical imaging device (1), the marking system (12) comprising - a real-time acquisition device (13) with a number of image sensors (14, 15) for real-time acquisition of image data (D) relating to a recording area (A), wherein in the recording area (A) there is an area of ​​a scan field plane (B) of the medical imaging device (1) and an area of ​​the patient (6), - a data processing device (16) for calculating the course of a virtual marker line (L1, L1') based on the image data (D) using position information relating to the position of the real-time acquisition device (13) and the scan field plane (B) relative to each other, - an output device (11) for displaying the virtual marking line (L1, L1') and the image data (D) such that a visualization of the position of the area of ​​the scan field plane (B) and the area of ​​the patient (6) relative to each other is provided.

Description

[0001] The invention relates to a marking system for positioning a patient relative to a medical imaging device, a medical imaging device and a use of the marking system.

[0002] Medical imaging equipment includes a patient support, often a patient table or couch, which allows the patient to be positioned relative to other components involved in the imaging process. For example, in a computed tomography (CT) scanner, the patient is typically moved through a tunnel-like opening in the scanner's gantry. Correct patient positioning is essential for the examination or imaging. Correct positioning within the gantry means that the patient's midline (an imaginary line from the patient's nasal bone to their pubic symphysis) is located in the center of the patient support, and the height of the support is adjusted so that the patient's center of gravity of the region being scanned coincides with the center of rotation, or isocenter, of the CT scanner.

[0003] Typically, the patient support, i.e., the patient table or bed, is controllable and motorized, allowing the patient to be moved by an operator of the medical imaging system into a desired starting position. This requires that the horizontal position be set so that the starting position aligns with the position or beginning of the body region being examined. Furthermore, the vertical position must also be adjusted to the body region being examined so that the center point of the volume to be scanned is ideally at the level of an isocenter of the imaging system. To enable this adjustment process by the operator—that is, to align the center plane of the beam or the scan field plane with the patient—a [missing information] is required.To proceed, a display of the actual position of this middle plane of the beam fan or the scan field plane of the imaging device is required.

[0004] The technical problem lies in the display or visualization of the scan field plane.

[0005] Currently, the display is achieved using several laser positioning aids, i.e., line lasers, which must lie in the same plane as the scan field plane itself. These must therefore necessarily be mounted behind a fixed, funnel-shaped housing element on the rotating part of the gantry. Due to the design, specifically the typical tunnel-like gantry configuration, the light beams of these line lasers, as well as the beams from the imaging device (e.g., X-rays), must be able to penetrate this very housing element. This, in turn, results in very specific, sometimes contradictory, requirements for the housing element. On the one hand, it must be as thin as possible to minimize the attenuation of the imaging system's beams, such as the X-rays in a CT system, thus ensuring an efficient imaging chain. Furthermore, it should be mechanically stable to reliably separate the rotating part of the imaging system from the patient, and optically opaque to prevent anxiety or suspicion from visible rotating parts. On the other hand, it must be optically transparent to allow the line lasers to display and visualize the scan field. The cladding element is therefore currently a very complex and expensive component, as these requirements severely restrict material selection and necessitate elaborate manufacturing processes.

[0006] The following documents are considered state of the art: DE 10 232 681 A1, DE 10 2014 218 557 A1, DE 10 2015 216 052 A1, DE 10 2016 210 131 A1 and EP 4 306 054 A1.

[0007] From DE 102 32 681 A1, an alternative method and a corresponding device for positioning a patient are known, in which the patient is recorded by two video cameras. One of the video cameras records the patient coaxially to the rotation axis of the gantry from the head, while the other video camera is positioned laterally to the patient, such that its recording axis is perpendicular to the rotation axis of the gantry. Based on the coaxial camera image, the patient is moved horizontally to the right / left in a direction corresponding to a target marker until the target marker is reached. Based on the lateral camera image, a vertical position of the patient is set. However, the arrangement of the video camera laterally to the patient means that the camera must necessarily be located in a section that lies within the rotating part of the CT system.For this video camera, the same complex requirements apply to the gantry's cladding element, behind which the camera is ultimately hidden, as already described above as disadvantageous, and which are to be avoided by the present invention as explained below.

[0008] It is therefore an object of the present invention to provide an alternative to known marking systems, in particular to reduce the material requirements for the cladding element and / or to be able to position the patient in the best possible way for an examination with a medical imaging device.

[0009] The independent claims relate to solutions to this problem. The dependent claims relate to particular embodiments of these solutions. Regardless of the grammatical gender of a given term, persons of male, female, or other gender identities are included.

[0010] The marking system comprises a real-time acquisition device with a number of image sensors for real-time image data of the position of a patient or object within a recording area. The image data can be multidimensional, for example, in particular two-dimensional or three-dimensional.

[0011] The real-time acquisition device can therefore also be referred to as a sensor system. "Real-time acquisition" here means the continuous acquisition of image data of the patient, at least until the patient is in a designated (initial) patient position or imaging position for an (initial) scan with the medical imaging device. It is also conceivable, however, to monitor the patient position or imaging position during the scan itself. The term "number" here refers to the presence of a single image sensor. Preferably, however, two or more image sensors may be present. "Multidimensional" here means that the image data is at least two-dimensional. Preferably, the image data may also include three-dimensional image data, either alternatively or additionally.The recording area can, for example, include the area recorded during a recording with the medical imaging device, in particular a scan field plane of the medical imaging device, as well as a narrow irradiated area or "strip" around or near the scan field plane.

[0012] In medical imaging equipment, the scan field plane generally refers to the plane that defines the central plane of the radiation field where the actual imaging takes place. For example, in a CT scanner, the scan field plane is the plane in which the scanner's radiation source and detector rotate. Since the radiation between the source and detector should not be obstructed, or at least not obstructed, in the scan field plane to ensure optimal image quality, image sensors and objects with attenuating properties should generally be avoided in this area.

[0013] Furthermore, the marking system includes a data processing device for determining a virtual marking line or a, in particular horizontal and vertical, course of the virtual marking line using the captured image data of the real-time recording device, more precisely the number of image sensors of the real-time recording device, as well as position information.

[0014] The positional information can, for example, consist of relative offset data of the number of image sensors relative to the scan field plane, or of "absolute" spatial coordinates relative to a defined coordinate system, which are then used as boundary conditions or during the calibration of the marking system. In particular, the positional information can include scan field-related sub-information, which relates to the position of the scan field plane relative to a coordinate system, and image sensor-related sub-information, which relates to the position of the real-time acquisition device relative to the coordinate system. The coordinate system can, for example, be a coordinate system of the real-time acquisition device and / or a coordinate system of the medical imaging device.In particular, the positional information and / or at least one of the partial pieces of information can be determined based on a transformation and / or a registration between these two coordinate systems.

[0015] It should be noted here that the position of the recording area can also be specified by a fixed reference point, which is uniquely defined and relative to which a position can then be defined. However, this reference point can be, and is preferred, a point within the recording area.

[0016] Furthermore, the marking system comprises an output device, such as a display or output medium, on which the virtual marking line determined by the data processing unit is displayed in real time within the image data pertaining to the acquisition area, enabling the operator of the medical imaging device to position the patient. A display, in this context, refers specifically to a rasterized display element with a multitude of pixels by means of which an image can be displayed. Preferably, the virtual marking line can be displayed as an overlay within the image data pertaining to the acquisition area.

[0017] Furthermore, the marking system may include a control unit for controlling electrically movable adjustment devices of a patient support, such as a patient table and / or a patient couch, of the medical imaging device for positioning the patient in a intended imaging position relative to the scan field plane for the image acquisition. During positioning, the patient is typically centered or positioned at the isocenter of the medical imaging device.

[0018] Preferably, the real-time acquisition device can be arranged outside the recording area. Particularly preferably, an image sensor can be arranged on a static part of the medical imaging device outside the recording area.

[0019] The marking system is therefore designed to virtually mark the scan field plane of the medical imaging device for the operator on the patient image.

[0020] By using the marking system according to the invention for the virtual marking of a scan field plane of a medical imaging device, preferably a CT system, for positioning a patient relative to the medical imaging device, preferably the CT system, a marking can be appropriately positioned on the patient. This in turn opens up the possibility of remotely positioning the patient without the physical presence of the operator in or an adjacent room of the examination room from which the medical imaging device is normally controlled.

[0021] Furthermore, a method for positioning a patient relative to a medical imaging device, preferably a CT system, is hereby disclosed, comprising the following steps: i) Acquisition of image data relating to a recording area, wherein the recording area contains an area of ​​a scan field plane of the medical imaging device and an area of ​​the patient, in real time using a real-time acquisition device, ii) Calculating the course of a virtual marker line based on the image data using position information relating to the position of the real-time acquisition device and the scan field plane relative to each other, by means of a data processing device, iii) Displaying the virtual marker line and the image data in such a way as to provide a visualization of the position of the scan field plane area and the patient area relative to each other, by means of an output device.

[0022] Furthermore, it may be provided that an electrically movable adjustment device of a patient support in the medical imaging device is controlled by a control unit based on the relative position of the scan field plane and the patient area. This allows, for example, the positioning of the patient in a intended imaging position relative to the scan field plane for the image acquisition with the medical imaging device.

[0023] Furthermore, a method for positioning a patient relative to a medical imaging device, preferably a CT system, is hereby disclosed, comprising the following steps, which are typically performed by a competent operator or, if partially automated, at least supervised: i) First, multidimensional image data of a patient's or object's position in a recording area are captured in real time using a real-time acquisition device. ii) Subsequently, the course of a virtual marker line is determined using the acquired image data from the real-time acquisition device and positional information via a data processing unit. Offset data relating to a geometric offset between the real-time acquisition device and the scan field plane may be incorporated, if necessary. This is because the geometric offset of the coordinate system of the real-time acquisition device and the CT system is known or can be determined during calibration of the marker system with the medical imaging device. iii) The virtual marker line, determined by the data processing device, is then displayed in the image data of the acquisition area for an operator of the medical imaging device via an output device, e.g., a display or output medium, preferably as an inserted overlay, to visualize the scan field plane. This marker line preferably follows the surface contour of a patient (body contour). The display is the visual representation or reproduction of the image data. The image data can therefore be displayed on the output device, preferably superimposed, as images, image sequences, or videos together with the virtual marker line.

[0024] Furthermore, it may be provided that electrically movable adjustment devices of a patient support, for example a patient table and / or a patient couch, of the medical imaging device are controlled by a control unit. This allows, in particular, the patient to be positioned in a designated position within the scan field plane for the image acquisition with the medical imaging device.

[0025] Particularly in torus-shaped imaging devices, a Z-axis extending in the Z-direction is defined as the rotation axis of the torus, and the patient can preferably be positioned in the Z-direction using the patient support. Most preferably, the negative Z-direction corresponds to a cranio-caudal direction of the patient, i.e., a direction extending from top to bottom from the patient's perspective. Furthermore, the patient can preferably also be positioned in the Y-direction, i.e., in a vertical direction (including perpendicular to the rotation axis), using the patient support.

[0026] As previously mentioned, the multidimensional image data contains image sensor information of the patient within the scan area. This information is captured by the real-time acquisition device, such as one or more image sensors, and superimposed on a virtual marker line to visualize the scan field plane on the output device, such as a display. Alternatively or additionally, positioning can also be achieved through patient-controlled movement, for example, by controlling adjustment mechanisms, provided the control is simple and error-free for the patient. The previously described process steps are generally repeated until the patient is in the intended patient or scan position.

[0027] The operator can advantageously use this method to comfortably see and control or adjust the patient position to be set or already set throughout the entire imaging procedure without effort or movement that would hinder the imaging.

[0028] It should be noted here that the marking system described above essentially comprises the device components that can interact, for example, to carry out the process. Therefore, the same definitions, advantages, and the like apply to the same terms.

[0029] A control unit for a medical imaging device, preferably a CT system, can, for example, comprise (in addition to the usual components for controlling such a device) a marking system according to the invention. Alternatively or additionally, the control unit can be designed to carry out the method described above.

[0030] A medical imaging device according to the invention, preferably a CT system, comprises the marking system according to the invention. The medical imaging device is, for example, a computed tomography scanner, a PET scanner, a SPECT scanner, a magnetic resonance imaging scanner, an X-ray scanner, an ultrasound scanner, or the like. However, the invention is particularly advantageous for medical imaging devices that are permanently installed and / or at least immobile or difficult to move. This includes, in particular, medical imaging devices where it is necessary to move or position the patient in relation to the imaging components of the medical imaging device.

[0031] The marking system, i.e., the real-time acquisition device, the data processing device, and the output device, can be provided, for example, during the manufacturing of such a medical imaging device. Alternatively, the marking system, i.e., any hardware and software components, can also be attached, mounted, installed, or implemented on an already manufactured or even installed medical imaging device.

[0032] A large proportion of the aforementioned components of the marking system according to the invention can be implemented wholly or partially as software modules in a processor of a suitable computing system, e.g., a computing unit (or computer) of a control unit of a medical imaging device or a computer used to control such a device. A largely software-based implementation has the advantage that even previously used computing systems can be easily retrofitted by a software update to operate in the manner of the invention. In this respect, the problem is also solved by a corresponding computer program product with a computer program that can be directly loaded into a computing system, containing program sections to execute the steps of the disclosed method when the program is run in the computing system.In addition to the computer program itself, such a computer program product may include additional components such as documentation and / or additional components, including hardware components such as hardware keys (dongles, etc.) for using the software.

[0033] For transport to the computer system of a control unit and / or for storage on or in the computer system, a computer-readable medium, e.g., a memory stick, a hard drive, or other portable or permanently installed data carrier, can be used on which the program sections of the computer program that can be read and executed by a computer system are stored. The computer system may, for example, include one or more cooperating microprocessors or similar components.

[0034] This further discloses a computer program product comprising instructions that, when executed by a computer, cause the computer to perform the steps of the procedure for positioning a patient relative to a medical imaging device. This further discloses a computer-readable storage medium comprising instructions that, when executed by a computer, cause the computer to perform the steps of the procedure for positioning a patient relative to a medical imaging device.

[0035] The marking system according to the invention eliminates the need for an operator to visually check the correct positioning and orientation of the patient relative to a medical imaging device on-site. Instead, checking and, if necessary, correcting the positioning is possible remotely. By using a virtual marker or marking line on the scan field plane, alignment under visual control is no longer dependent on the operator's physical presence at the gantry.

[0036] By using a virtual marker line of the scan field plane, line lasers in the scan field plane can be omitted, thus completely eliminating the optical requirements for the cladding element. This allows for a more robust and safer cladding element design at lower costs and can simultaneously improve imaging quality through a wider selection of materials.

[0037] The dependent claims and the subsequent description each contain particularly advantageous embodiments and further developments of the invention. In particular, the claims of one claim category may also be further developed analogously to the dependent claims of another claim category. Furthermore, within the scope of the invention, the various features of different embodiments and claims may also be combined to form new embodiments.

[0038] There are various ways to determine the virtual marking line, which may also depend on the multidimensional image sensors used.

[0039] Preferably, the real-time acquisition device for real-time acquisition of two-dimensional image data can comprise at least one two-dimensional image sensor, such as a CMOS monochrome sensor or color sensor. This sensor provides two-dimensional live image data of the recording area. This data can be used for visualization and for determining the virtual line, as explained below.

[0040] As previously mentioned, the geometric offset of the coordinate system of the two-dimensional image sensor relative to the coordinate system of the medical imaging device, more precisely to the scan field plane, is known or can be determined through calibration. If the sensor system is integrated as part of the CT system, the geometric offset of the coordinate systems can be determined once during system development through its design within the system. In this case, accuracy is achieved through appropriate mechanical design of the tolerance chains of the components involved.

[0041] Alternatively, the geometric offset can be determined once or individually for each system using a special method. For this purpose, a suitable phantom is placed in the scan plane of the system and captured by the CT system's imaging system. The actual position of the phantom in the coordinate system can be determined based on geometric features or by special spherical markers that are visible in the recorded image data. This recognition is preferably automated using suitable image analysis software. Additionally, the phantom exhibits a geometric pattern with known dimensions and a known relationship to the aforementioned markers. The geometric patterns are captured by the image sensor and transmitted to a computer program, which can determine the image sensor's coordinate system based on the known geometric pattern.This process takes place at at least one spatial position of the phantom and can be performed and repeated at several positions to improve accuracy.

[0042] The data processing device can be particularly preferably configured to determine the course of the virtual marking line by a) transforming the image perspective of the two-dimensional image data from an optical origin of the real-time acquisition device into the scan field plane of the medical imaging device. The optical origin of the real-time acquisition device can, for example, be located on an optical axis of the real-time acquisition device.

[0043] Particularly advantageous is the use of an algorithm to supplement data points that are missing, for example, due to shadowing effects during transformation of the image data. This supplementation can be achieved through simple interpolation or using a neural network trained by machine learning.

[0044] Alternatively, the data processing device can be preferably configured to determine the course of the virtual marking line by (b) estimating three-dimensional image data of the recording area using an algorithm pre-trained based on the two-dimensional image data, wherein the estimated three-dimensional image data are used to represent the virtual marking line according to a surface contour of the patient. This method can increase the imaging accuracy of the virtual marking line without having to use an additional 3D image sensor.

[0045] Preferably, the real-time acquisition device for real-time acquisition of three-dimensional image data can comprise at least one three-dimensional image sensor.

[0046] Preferred methods for real-time data acquisition are optical methods, although ultrasound or radar may also be advantageous. Preferred optical methods include: Time-of-Flight (ToF) technology uses a special sensor in combination with a modulated light source, typically in the infrared range, to determine 3D data over the time of flight of the light signal. The 2D sensor matrix can simultaneously capture the 3D data within the field of view.

[0047] In LIDAR, the 3D data is also determined via the travel time of the light, typically in the infrared range, whereby the field of view is determined sequentially via the deflection of a concentrated light beam.

[0048] Stereography: In this technique, 3D data is determined using two-dimensional image data from at least two 2D image sensors with a known geometric offset (baseline) and thus different perspectives. The calculation is performed using feature matching algorithms and subsequent triangulation of the identified related image points. Structured light: The 3D data is used to reconstruct a projected, known pattern into the field of view of a 2D sensor by means of distortion.

[0049] In particular, it could be one of the following three-dimensional image sensors: For example, the three-dimensional image sensor could be a ToF camera (time-of-flight) or a PMD sensor (photomixed detector sensor). Unlike other 3D camera systems, such as stereo cameras or laser scanners, a ToF camera is more compact and simpler in design. It captures the entire scene with a single image and can achieve high frame rates, making it ideal for real-time applications.

[0050] For example, the three-dimensional image sensor could also be a stereo camera. Stereo cameras are particularly well-suited for capturing spatial information and generating three-dimensional image data because they use two or more lenses to capture a scene from slightly different perspectives, allowing them to record distances and depth information more accurately than single cameras. This precise depth information makes it possible to create excellent 3D models of captured objects, in this case, a patient's surface contour, based on the image data from a stereo camera.

[0051] Another example of a three-dimensional image sensor is a LiDAR system. LiDAR systems can, among other things, measure distances with high accuracy and create detailed 3D models of the environment.

[0052] Another example of a three-dimensional image sensor is a "structured 3D light scanner." Structured light scanners offer high accuracy, are easy to set up, and are safe for the eyes because they do not use focused light like a laser scanner, but rather structured light, i.e., white or blue light.

[0053] The data processing device can be designed to determine the course of a virtual marking line using the image data captured by the real-time recording device and position information.

[0054] Preferably, the position information includes offset data relating to a geometric offset between the real-time acquisition device and the scan field plane of the medical imaging system. This offset data can be information obtained during the calibration or installation of the marking system.

[0055] The output device can be designed to display the virtual marking line determined by the data processing device on a surface contour of the patient reconstructed from the three-dimensional image data if the two-dimensional image data is missing.

[0056] In other words, the real-time acquisition device preferably comprises at least one three-dimensional image sensor for the real-time acquisition of three-dimensional image data of a recording area, in particular the current position of a patient within the recording area, of the medical imaging device. This allows the patient's surface contour to be known or determined, and the virtual marker line can be correctly displayed or superimposed along this surface contour in the image data, thus enabling very precise positioning of the patient within the scan field plane.

[0057] Preferably, the real-time acquisition device can, in addition to the two-dimensional image sensor, include a three-dimensional image sensor for real-time acquisition of three-dimensional image data, or in total at least two two-dimensional image sensors with a known geometric offset from each other and from the scan field plane of the medical imaging device. The latter is a so-called stereographic three-dimensional image data calculation.

[0058] The data processing device can be designed to determine the course of a virtual marking line and to adapt the virtual marking line to a surface contour of the patient based on the three-dimensional image data acquired in this way.

[0059] Preferably, the real-time acquisition device can include two- and three-dimensional image sensors which together acquire two-dimensional (2D) and / or three-dimensional (3D) image data of the patient's current position on the patient support in real time or live.

[0060] Preferably, at least one of the image sensors of the real-time acquisition device can be arranged axially (i.e., parallel to the axis of rotation or perpendicular to the beam fan) offset from a scan field plane on the medical imaging device, e.g., on the gantry at the ring tunnel. The axially offset arrangement has the advantage that the image sensor does not block the beam path and, moreover, no cover element with a viewing window for the image sensor is required, which would conceal the image sensor from the patient's view while still allowing its functionality (which could otherwise trigger suspicion or anxiety in some patients). Furthermore, the requirements for the cover element are reduced. It no longer necessarily needs to be optically transparent, i.e., have a viewing window, which is the case when the image sensor is hidden behind it.

[0061] Preferably, several image sensors of the real-time acquisition device can be arranged axially offset from a scan field plane on the medical imaging device. Multiple image sensors generate image data from different viewpoints, which can be used, for example, to model a 3D model of the patient or simply provide multiple viewpoints from which the operator can observe the patient during positioning.

[0062] It is particularly advantageous for at least one image sensor to be arranged on a static part of the medical imaging device. This has the advantage that the image sensor can also be used when the medical imaging device or its rotor is rotating. Furthermore, this reduces the requirements for the housing element, as a viewing window, which is otherwise required for the line lasers, can be omitted.

[0063] The component or cladding element containing the viewing window must meet several requirements. On the one hand, it must be optically transparent to the line lasers, while on the other hand, it must be visually opaque to the patient in order to conceal potentially disturbing components of the gantry. Simultaneously, it must be transparent to the scanner or the scanner's radiation in the medical imaging system. Due to these numerous requirements, the component or cladding element containing the viewing window is very complex and expensive from both a material and design perspective. Therefore, the present invention makes a significant contribution, particularly from a financial and structural point of view, as it reduces the complex requirements for this component.

[0064] Alternatively or additionally, at least one of the image sensors of the real-time acquisition device can be arranged axially offset to a scan field plane, spatially separated from the medical imaging device, in the immediate vicinity of the medical imaging device, preferably suspended from a ceiling section above the patient support of a recording room or examination room, i.e. ceiling-hung.

[0065] Particularly preferably, several image sensors of the real-time acquisition device can be arranged axially offset to a scan field plane and spatially separated from the medical imaging device.

[0066] It is particularly advantageous to mount at least one image sensor axially offset from a scan field plane on a static part of the medical imaging system and, if the medical imaging system is located in an examination or reception room, spatially separated from the medical imaging system, on a section of the ceiling of the reception room above a patient support. Image sensors spatially separated from the medical imaging system are particularly easy to retrofit or replace in case of a defect, as this requires only minor modifications to the medical imaging system itself.

[0067] "Perspective distortions" here refer to distortions caused by the perspective of the image sensor. Because the image sensor is located axially outside the scan field plane along the axis of rotation, it captures the patient with perspective distortion. Perspective distortion is therefore a deformation or transformation of a viewed object and its surroundings, which, due to the relative size of near and far features, deviates significantly from how the object would appear under normal (essentially perpendicular) viewing conditions. The invention allows a virtual marker line inserted into perspectively distorted image data to be displayed accordingly (or the image data itself), i.e., adjusted by means of a linear or nonlinear mapping or transformation, so that the perspective distortions are completely or at least largely compensated.

[0068] Preferably, the data processing device can be configured to perform parallax correction. Parallax correction is a correction of coordinates in which an apparent displacement of the object being recorded, e.g., the patient within the recording area, due to the observer's position, i.e., the image sensor's position, is corrected. Parallax correction is advantageous for relating the coordinates of the image data to a standardized reference position, e.g., the isocenter of the medical imaging device or another defined reference point. This makes it possible to compare the coordinates of different observations, i.e., different image sensors or different points on the patient, and to create a model without the positional changes caused by parallax distorting the results. For example, in a partially perspective orThe oblique image from an image sensor positioned at an angle above the patient along the axis of rotation means that a virtual marker line inserted into the image, without parallax correction, will not accurately represent the correct contour everywhere in the image. In the portion of the image where the patient's surface contours were captured by the image sensor essentially perpendicularly from above, the parallax effect is negligible, and therefore no parallax correction is required. However, in the portion of the image where the patient's surface contours were captured obliquely by the image sensor, parallax correction is necessary so that an inserted virtual marker line accurately represents the curved surface contours of the patient's body.

[0069] Furthermore, the data processing device can be configured to virtually insert or place the virtual marker line of the scan field plane as a corrected overlay into the image data within the acquisition area. The virtual marker line of the scan field plane can then be displayed as a corrected overlay in the image data by the output device for the operator, enabling them to correctly position the patient.

[0070] Particularly preferably, the data processing device can be configured to perform a parallax correction of the position of the virtual marker line in the image data depicting the patient area, based on geometric offset data (coordinates / position and orientation / viewing angle) of the at least two-dimensional image sensor of the real-time acquisition device relative to the scan field plane. In practice, the position (translation) and orientation (rotation) of the sensor relative to the gantry coordinate system are preferably taken into account during parallax correction. Prior correction of image data distortions caused by an optical lens system can be advantageous.

[0071] Because the patient's position changes during the positioning process, the patient's relative position to the real-time capture device or image sensor and to the recording area also changes, so that the parallax correction is continuously adjusted for the image data.

[0072] Preferably, the width of the virtual marking line of the marking system can be chosen such that it is at most 3 mm, preferably at most 2.5 mm, particularly preferably at most 2 mm, and most preferably at most 1.5 mm, in the center of an opening of a gantry of the medical imaging device.

[0073] Preferably, the parameters of the marking system, such as line thickness, can be selected such that the scan field plane can be set as precisely as possible at the output device with an error of < 2 mm. The relevant standard for medical devices does not yet include a virtual solution, which is why a virtual solution could potentially be a valuable addition to the standard.

[0074] Finally, it should be mentioned once again that the medical imaging equipment is preferably a computed tomography (CT) scanner, a positron emission tomography (PET) scanner, a single-photon emission computed tomography (SPECT) scanner, a magnetic resonance imaging (MRI) scanner, or an X-ray scanner.

[0075] All these devices are known in their basic functionality and in particular use motor-controlled, positionable patient tables. Accordingly, they can be combined particularly advantageously with the present invention.

[0076] The following examples, which may be helpful for understanding the invention and / or the technical problem to be solved, are explained with reference to the accompanying figures. Where relative positional terms such as "top" or "bottom" are used below, these are to be understood as meaning that the normal effect of gravity is downwards and the medical imaging device is oriented accordingly for its intended operation. The figures are generally not to scale. They show: Fig. 1 a schematic side view of an embodiment of a medical imaging device in the form of a CT scanner according to the prior art, Fig. 2 a schematic representation of a laser line for marking the scan field plane on a patient with a CT scanner according to the state of the art, Fig. 3 a schematic perspective view of an embodiment of a medical imaging device according to the invention in the form of a CT system with an embodiment of a marking system according to the invention and a patient in a first patient position after positioning with the marking system according to the invention, Fig. 4 a schematic side view of the CT system Fig. 3 without the patient to demonstrate different image sensor positions, Fig. 5. A perspective view of the patient in the first patient position from the perspective of one of the image sensor positions. Fig. 4, Fig. 6 a schematic flowchart of an embodiment of a method for positioning a patient relative to a medical imaging device.

[0077] First, the following will be used as a starting point Fig. 1 and Fig. 2 a common method is described in which the scan field plane is displayed on the patient itself when positioning a patient with a line laser LL (see arc-shaped line L0 on the patient 6 in Fig. 2) This requires a line laser (LL), which, viewed along the rotation axis of the CT system, is positioned in the radiation plane or scan field plane. Consequently, it must be located within the rotating part of the CT system and therefore rotates with the system during the scan. With this arrangement, the line laser (LL) cannot simply be replaced by an image sensor, as this area is exposed to X-rays during the scan. Since patients may experience discomfort from seeing rotating components, such as the line laser, during the scan, these components are typically covered with apertures or louvers. For the line laser (LL) to optically mark the scan field plane on the patient, the louver must have an optical window that is transparent to the line laser (LL), i.e., it must be laser-transparent.At the same time, it must be optically opaque so that the patient cannot see through it. Most importantly, however, it must be transparent to the X-rays of the CT system itself so that the image is not affected. These very specific requirements for the cladding element severely restrict the possible material selection and, as mentioned at the outset, make the cladding element very expensive and complicated to manufacture. To avoid such costs and such a complicated manufacturing process, the invention provides to replace the line laser LL and the physical marking of the scan field plane on the patient with a virtual marking line L1, L1 in a virtual image of the patient 6, which is displayed to the operator in real time, together with image data D of the patient 6, for positioning the patient 6 on an output device 11 (see figure). Fig. 5).

[0078] Fig. Figure 3 shows a possible embodiment of a medical imaging device 1 according to the invention, here a computed tomography system (CT system 1) with such a marking system 12, which is explained further below, as well as, as usual, with a radiation detector 4 and a radiation source 5, here an X-ray source 5. The X-ray source 5 is configured to expose the radiation detector 4 with X-rays. The radiation detector 4 is configured to detect X-rays. The CT system 1 shown comprises a ring-shaped or torus-shaped gantry 2 (static part) with a rotor 3 (rotatable part relative to it). The rotor 3 comprises the X-ray source 5 and the radiation detector 4 (see Figure 3). Fig. 3).

[0079] During an imaging process, the rotor 3 rotates around the isocenter R, more precisely around the axis of rotation 8. A subject 6, here a patient 6, is positioned on the patient support 7, here a patient bed 7, and can be moved along the axis of rotation 8 through the gantry 2, as will be explained further below. A tunnel-like space is arranged in the center of the gantry 2, and the exact center point of this arrangement is the isocenter R, which is the center of the imaging process. The gantry 2 thus extends essentially rotationally symmetrically around the isocenter R. The plane that extends in the plane of rotation of the radiation source 5 and detector 4 and through the central plane of the beam fan is called the scan field plane B. Adjacent to the scan field plane B on both sides is a so-called irradiated area (in Fig. 4 (represented as a vertical, rectangular strip extending centrally below the theoretically optimal camera position P1 between the two sections of the rotor 3), through which the radiation source 5 sends X-rays to the detector 4. The scan field plane B and the irradiated area are located in the recording area A, which in this example is also captured by the 3D image sensor.

[0080] Perpendicular to the scan field plane B, the CT system has a Z-direction. In the positive Z-direction, extending from the patient table 7 towards the CT system 1, a front and then a back section of the gantry 2 are arranged. For imaging, a patient 6 is moved into the space between the two sections of the rotor 3 using the aforementioned patient table 7, which is controlled and moved by motor, and positioned appropriately. The patient 6 is preferably moved in the opposite direction to the craniocaudal direction with a central body axis passing through the isocenter R. In addition to positioning in the Z-direction, the patient must also be positioned in the vertical Y-direction in relation to the isocenter R.

[0081] The CT system 1 includes a real-time acquisition device 13, which comprises a 2D image sensor 14 and a 3D image sensor 15. The 2D image sensor 14 is located on the front of the gantry 2, above the patient table 7, on a static part of the gantry 2. It can, in principle, be positioned anywhere on the CT system or in the examination room. The 3D image sensor 15 is shown here as an example mounted on the ceiling of the examination room. The essential factor for the positioning of the image sensor 14 and the image sensor 15 is that they can capture the patient 6 in as many patient positions or acquisition positions as possible. If necessary, additional 2D and / or 3D image sensors (not shown in the figure) can be used if this improves the real-time acquisition of the patient 6.

[0082] In addition, a control unit 9 with a computing unit 18 is provided for the aforementioned control of the CT system 1 for positioning the patient and / or for generating an image data set based on signals detected by the radiation detector 4.

[0083] The control unit 9 serves, among other things, to control the CT system 1 and includes the processing unit 18. An input device 10 and an output device 11 are connected to this processing unit 18. The input device 10 and the output device 11 can, for example, enable interaction by a user or the display of a generated image data set. For positioning the patient 6, the control unit 9 has a marking system 12 according to the invention, which is used for subsequent positioning in a first acquisition position or patient position by the operator of the CT system 1 via the adjustment means 7a, which are electrically connected to a control unit 17 (e.g., on the processing unit 18).

[0084] The real-time acquisition unit 13 of the marking system 12 is also connected to the processing unit 9 of the control device 9. This unit is used to acquire multidimensional image data D of an acquisition area A, in which the patient 6 is also located. The real-time acquisition unit 13 comprises a 2D image sensor 14, which is attached to a static part of the CT system 1 axially along the axis of rotation 8, offset from the isocenter R. The offset data O Z(P2) , O Y(P2) in the two CT coordinate directions or axes Y +- , Z +-This image sensor position P2 of the 2D image sensor 14 is fed into the processing unit 18 of the control device 9 as a boundary condition during the calibration of the marking system 12 according to the invention. Translational and rotational deviations along and about all three spatial axes can be determined during calibration. Accordingly, the position of the sensors is not exclusively fixed to the plane along the Z and Y axes. A deviation in the X direction is also possible. Along the third CT coordinate direction or axis X +- The image sensors 14, 15 here have no offset from the rotation axis 8 of the CT system 1 in order to facilitate the calculation. However, the invention is not limited to this. At this point, it should be mentioned that the origin of the CT coordinate system can, in principle, be located anywhere, but it is preferred that it be located at the isocenter R. The in Fig. The coordinate cross shown in Figure 4 does not indicate the origin, but merely symbolizes the orientation of the individual CT coordinate directions or axes Y. +- , Z +- .

[0085] Furthermore, the real-time acquisition unit 13 includes a 3D image sensor 15, which is arranged or attached separately from the CT system 1 to a ceiling section of the examination room in which the CT system 1 is located, above the patient table 7, axially offset from the isocenter R along the axis of rotation 8 at a further image sensor position P3. The 3D image sensor 15 does not necessarily have to be located outside the gantry 2. A 2D sensor, a 3D sensor, or a combination of both can be arranged both inside and outside the gantry 2. The offset data O Z(P3) , O Y(P3)This image sensor position P3 of the 3D image sensor 15 is fed into the processing unit 18 of the control device 9 as a further boundary condition during the calibration of the marking system 12 according to the invention. Additional cameras may also be present. The example shown provides that the optical axis of the image sensor 15 intersects the scan field plane B, specifically in an area of ​​the medical imaging device 1.

[0086] Furthermore, the marking system 12 includes a data processing device 16, which is integrated here into the computing unit 18 of the control unit 9. The data processing device 16 processes the image data D acquired in real time from the patient 6 in the acquisition area A by the real-time acquisition unit 13 and, based on this and on offset data from a calibration of the coordinates of the respective image sensors of the marking system 12 relative to the CT system 1 performed during commissioning, determines or calculates the course of a virtual marking line L1, L1' for visualizing the scan field plane B for the operator. To enable the operator of the CT system 1 to use the marking line L1, L1' to position the patient 6, it is displayed to the operator in real time on the output device 11, preferably as an overlay in the patient 6 image data.Where necessary, virtual marker line L1 is displayed as a virtual marker line with parallax correction L1', i.e., parallax-corrected. Parallax correction is required so that virtual marker line L1' follows the contour of the patient's surface and is not simply a straight marker line L1. Marker line L1 virtually indicates to the operator the current position of the scan field plane B on the patient 6 within the acquisition area A. The operator then only needs to move the patient 6 in the relevant directions Y. +- , Z +- and possibly X +-Position the patient table 7 so that the scan field plane B of the CT system 1 is at the desired first acquisition position, i.e., the patient 6 is in the first patient position. If the patient 6 is already in the correct position, the acquisition(s) can begin immediately. If not, the operator adjusts the patient table 7 with the patient 6 on it using the adjustment means 7a, which can be controlled via the control unit 17, until the patient 6 is positioned as intended, typically with the starting point of the acquisition at the isocenter R of the CT system 1. This allows the scan field plane B and the patient 6 to be positioned correctly relative to each other without the operator actually having to be physically present, because the CT system can be fully remotely controlled using the control unit 9.

[0087] It will now be demonstrated using a roughly schematic flowchart according to Fig. Section 6 describes how a positioning process or a procedure for positioning a patient 6 for an image with the CT system 1 can be carried out by way of example, i.e. which steps are repeated in which order until the patient 6 is appropriately positioned.

[0088] In step i), multidimensional image data D of a patient's position 6 in the recording area A are permanently acquired using the image sensors 14, 15.

[0089] In step ii), a virtual marker line L1, L1' is determined using the captured image data D and position information.

[0090] In step iii), the previously determined virtual marker line L1, L1' is displayed as an overlay in the captured image data D of the recording area A for the operator to visualize the scan field plane B (see Fig. 5).

[0091] In step iv) the patient 6 is moved or positioned electrically, if necessary, by means of the patient bed 7 which can be controlled via the control unit 17 using adjusting means 7a.

[0092] After such a pass, this process starts again from the beginning, with the described steps taking place in real time and the operator continuously moving the patient to a designated first patient or recording position (without having to wait significantly for any of the steps).

[0093] Finally, it should be noted once again that the detailed devices and methods described above are exemplary embodiments and that the basic principle can be varied in many ways by those skilled in the art without departing from the scope of the invention, insofar as it is defined by the claims. For example, the CT scanner or CT system is described merely as an example of other imaging modalities. Although the figures only illustrate a change in the patient's position in the Z and Y directions, the method can easily be applied to a change in the patient's position in the X direction, i.e., in the direction of rotation around the z-axis, if desired. This allows the patient to be positioned in this direction as well. For the sake of completeness, it should also be noted that the use of the indefinite articles "a" or "a" is not intended to be interpreted in this way.The term "one" does not preclude the possibility that the relevant characteristics may be present multiple times. Similarly, the terms "unit" or "facility" and "system" do not preclude the possibility that they consist of several components, which may also be spatially distributed. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 232 681 A1 [0006, 0007] DE 10 2014 218 557 A1

[0006] DE 10 2015 216 052 A1

[0006] DE 10 2016 210 131 A1

[0006] EP 4 306 054 A1

[0006]

Claims

[1] Marking system (12) for positioning a patient (6) relative to a medical imaging device (1), the marking system (12) comprising - a real-time acquisition device (13) with a number of image sensors (14, 15) for real-time acquisition of image data (D) relating to a recording area (A), wherein in the recording area (A) there is an area of ​​a scan field plane (B) of the medical imaging device (1) and an area of ​​the patient (6), - a data processing device (16) for calculating the course of a virtual marker line (L1, L1') based on the image data (D) using position information relating to the position of the real-time acquisition device (13) and the scan field plane (B) relative to each other, - an output device (11) for displaying the virtual marking line (L1, L1') and the image data (D) such that a visualization of the position of the area of ​​the scan field plane (B) and the area of ​​the patient (6) relative to each other is provided. [2] Marking system (12) according to claim 1, - where the image data (D) are two-dimensional, - wherein the data processing device (16) is configured to calculate the course of the virtual marking line (L1, L1') by a) a transformation of an image perspective of the two-dimensional image data (D) from an optical origin of the real-time acquisition device (13) into the scan field plane (B) of the medical imaging device (1), preferably with an algorithmic supplementation of data points that are missing due to shadowing effects during the transformation, and / or b) an estimation of three-dimensional image data (D) relating to the recording area (A) based on the two-dimensional image data (D) using a pre-trained algorithm, wherein the estimated three-dimensional image data (D) are used to represent the virtual marking line (L1, L1') according to a surface contour of the patient (6). [3] Marking system (12) according to any one of the preceding claims, - wherein the image data (D) are three-dimensional and / or are acquired using a ToF camera, a stereo camera, a LIDAR system and / or a structured 3D light scanner, - wherein the output device (11) is set up to display the virtual marking line (L1, L1') on a surface contour of the patient (6) reconstructed from the image data (D). [4] Marking system (12) according to any one of the preceding claims, - wherein the real-time acquisition device (13) comprises, in addition to a two-dimensional image sensor, a three-dimensional image sensor for real-time acquisition of three-dimensional image data (D) or a total of at least two two-dimensional image sensors, each with a known geometric offset from each other and from the scan field plane (B) and / or - wherein the data processing device (16) is configured to determine the course of the virtual marking line (L1, L1') and to adapt the virtual marking line (L1, L1') to a surface contour of the patient (6) based on the acquired three-dimensional image data (D). [5] Marking system (12) according to any one of the preceding claims, - wherein at least one of the image sensors (14) of the real-time acquisition device (13) is arranged axially offset to the scan field plane (B) on, preferably a static part (2), of the medical imaging device (1), wherein preferably several image sensors (14, 15) of the real-time acquisition device (13) are arranged axially offset to the scan field plane (B), and / or - wherein at least one of the image sensors (15) of the real-time acquisition device (13) is arranged axially offset to the scan field plane (B) spatially separated from the medical imaging device (1) in an immediate vicinity of the medical imaging device (1), preferably suspended from a ceiling section above the patient support (7) of an imaging room. [6] Marking system according to one of the preceding claims, - wherein the data processing device (16) is configured to perform a parallax correction, preferably based on geometric offset data of one of the image sensors (14, 15) of the real-time acquisition device (13) relative to the scan field plane (B) and / or with respect to a position of the virtual marker line (L1, L1') in the image data (D), and accordingly insert the virtual marker line (L1, L1') as a parallax-corrected overlay virtually into the image data (D). [7] Marking system according to one of the preceding claims, - wherein the width of the virtual marking line (L1, L1') of the marking system (12) is selected such that it corresponds to at most 3 mm, preferably at most 2.5 mm, particularly preferably at most 2 mm, most preferably at most 1.5 mm, in the center of an opening of a gantry (2) of the medical imaging device (1). [8] Marking system according to one of the preceding claims, - wherein an optical axis of the real-time acquisition device (13), in particular of an image sensor (15) of the real-time acquisition device (13), intersects the scan field plane (B), in particular in an area of ​​the medical imaging device (1). [9] Medical imaging device (1), preferably a CT system, comprising the marking system (12) according to any one of claims 1 to 8. [10] Use of the marking system (12) according to any one of claims 1 to 8 for visualizing the position of the scan field plane (B) and the area of ​​the patient (6) relative to each other for positioning the patient (6) relative to the medical imaging device (1).

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