Configuration of a modular computed tomography detector

Abstract

The present invention relates to a detection system for a computed tomography system. The detection system comprises a first detector and a second detector, each detector configured to detect X-ray radiation from the computed tomography system impacting its respective detector. The detection system further includes a repositioning mechanism configured to reposition at least one of the first detector and the second detector relative to the other of the first detector and the second detector.

Description

Technical Field

[0001] The present invention relates to a detection system for a computed tomography system, a computed tomography system including the detection system, and a method for imaging a subject with a computed tomography system.

Background Art

[0002] Today, computer tomography (CT) imaging systems are very expensive because the detector area is large for the coverage required in both the direction of the longitudinal extension of the patient to be imaged and the direction of the rotational scanning motion of the CT system. However, a large detector is not required in all cases, and depending on the application, a smaller field of view of the detection system, that is, an extension of the detector in the rotational direction may be allowed. At the same time, since the coverage in the longitudinal direction of the scanning operation of the CT scanner in the patient direction is large, the scanning for avoiding motion artifacts is speeded up, the total scan time is shortened, and the scanning of dynamic events becomes possible.

[0003] CN 104 983 439 A describes a computed tomography scanner including a rotating disk equipped with a plurality of flat panel detectors.

[0004] US 2020 / 323500 A1 describes a medical imaging system including a detector configured to detect radiation that has passed through a collimator, the detector including a plurality of detector tiles, and at least one detector tile moving relative to other detector tiles.

[0005] JP H03 279887 A describes a nuclear medicine device including a plurality of radiation detectors arranged obliquely adjacent to a detection surface.

[0006] Therefore, the inventors of the present invention have found it advantageous to have an improved detection system for computed tomography systems that at least partially solves these problems and allows for adjustment of the detection area of ​​the computed tomography system to adapt to the needs of a particular image processing procedure. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide an improved detection system for computed tomography systems that allows for the flexible adaptation of the detection area to the needs of specific image processing procedures. [Means for solving the problem]

[0008] The object of the present invention is solved by the subject matter of the independent claim, and further embodiments are incorporated into the dependent claims.

[0009] The embodiments described relate similarly to detection systems for computed tomography systems, computed tomography systems including detection systems, and methods for imaging subjects using computed tomography systems. The embodiments described further may be combined in any possible manner. Synergistic effects may arise from different combinations of embodiments, but these do not need to be described in detail.

[0010] Furthermore, while all embodiments of the present invention relating to a method may be performed in the order of steps described, it should be noted that this is not the only and essential order of steps in the method. The methods described herein may be performed in a different order of steps disclosed without departing from the embodiments of each method, unless otherwise specifically stated below.

[0011] According to a first aspect of the present invention, a detection system for a computed tomography system is provided. The detection system includes a first detector configured to detect X-ray radiation from a computed tomography system impacting a first detector, and a second detector configured to detect X-ray radiation from a computed tomography system impacting a second detector. The detection system further includes a repositioning mechanism configured to reposition at least one of the first detector and the second detector relative to the other of the first detector and the second detector.

[0012] Therefore, a modular concept of reconfigurable detector subregions that can be moved to different positions is provided. Thus, because the detector subregions can be moved to different positions, the detection system can be adapted to various required area coverages. Various morphological setups of the detection system can be used for imaging, providing flexibility in positioning detection systems of various configurations. Different morphological settings of the detection region of a computed tomography system may be preferred depending on the application. For example, in brain scans, pediatric imaging, or limb imaging, the size of the object being imaged may be smaller than the maximum field of view of the detection system, so a full field of view of the detection system in the rotational direction of the computed tomography scanner may not be necessary. However, expanding the coverage of the detection system in the patient direction is very interesting because it can halve the acquisition time by doubling the detector coverage in this direction, which can be very important for non-compliant patients such as children or stroke patients. In other imaging setups, for example, a wider field of view in the rotational direction may be required due to the patient's size or the required imaging area, but wider coverage of the detection system along the patient's longitudinal axis may not be necessary, which can be compensated for by longer acquisition times due to additional rotational scanning motions around the z-axis of the computed tomography scanner.

[0013] Therefore, while large detectors can solve many of the aforementioned problems, they can be expensive. The modular, reconfigurable detector according to the present invention can be adapted to different required area coverage and aspect ratios for the detection region, enabling a good trade-off between price and required area coverage.

[0014] In addition to the sheer size of the detection area, the type of detector is also an attractive factor for trade-off configurations. Therefore, various movable detector modules can represent various types of detectors. This could be, for example, a spectral detector that can be used in the central region of the detection area and / or moved to the lateral regions, or a spectral detector that covers the entire field of view in the rotational direction but may be smaller in size in the longitudinal direction towards the patient.

[0015] In one embodiment of the present invention, the first detector and the second detector are configured to form a detection area of ​​a computed tomography system.

[0016] In embodiments of the present invention, the repositioning mechanism is configured to adjust the aspect ratio of the detection area of ​​the computed tomography system.

[0017] In one embodiment of the present invention, the first detector and the second detector are configured to form a detection region with essentially no gap between the first detector and the second detector.

[0018] In one embodiment of the present invention, the repositioning mechanism comprises a guide mechanism configured to guide at least one of the first detector and the second detector along a predetermined trajectory from a first position to a second position, and / or the repositioning mechanism comprises a rotation mechanism configured to rotate at least one of the first detector and the second detector with respect to a rotation axis essentially parallel to the direction of X-ray radiation.

[0019] In one embodiment of the present invention, the repositioning mechanism includes a locking mechanism configured to lock at least one of the first detector and the second detector in a predetermined position at least one of the first position and the second position.

[0020] In one embodiment of the present invention, the repositioning mechanism is configured to adjust the angular tilt of the first detector and / or the second detector with respect to the direction of X-ray radiation from the computed tomography system.

[0021] In one embodiment of the present invention, a first detector and / or a second detector include a scattering prevention grid configured to suppress scattered X-ray radiation reaching each detector, and the scattering prevention grid is configured to align the focus of the scattering prevention grid with respect to the X-ray source of a computed tomography system.

[0022] In one embodiment of the present invention, the anti-scattering grid is a one-dimensional anti-scattering grid, and the anti-scattering grid is configured to adjust the direction of the grid lines of the one-dimensional anti-scattering grid with respect to the aspect ratio of the detection area of ​​the computed tomography system.

[0023] In one embodiment of the present invention, the second detector differs from the first detector in terms of its spectral response to X-ray radiation.

[0024] In one embodiment of the present invention, the detection system comprises at least one third detector configured to detect X-ray radiation from the computed tomography system that strikes the third detector, and the repositioning mechanism is configured to reposition the at least one third detector relative to the first detector and the second detector.

[0025] According to another aspect of the present invention, a computed tomography system is provided. The computed tomography system comprises a detection system according to any of the above embodiments, an X-ray source configured to emit X-ray radiation, and a collimator configured to collimate the X-ray radiation into a detection area formed by a first detector and a second detector.

[0026] According to another aspect of the present invention, a method of imaging a subject by means of the computed tomography system according to the above-described embodiments is provided. The method includes providing the computed tomography system according to the above-described embodiments, determining a detection area for imaging the subject, and repositioning at least one of the first detector and the second detector relative to the other of the first detector and the second detector to form the determined detection area.

[0027] In one embodiment of the present invention, the method includes, following the step of repositioning at least one of the first detector and the second detector, locking at least one of the first detector and the second detector in a predetermined position.

[0028] In one embodiment of the present invention, the method includes adjusting the angular tilt of the first detector and / or the second detector with respect to the direction of the X-ray radiation of the computed tomography system.

[0029] In an embodiment of the present invention, the method is automatically executed based on an imaging protocol and / or the shape of the patient. Thus, the workflow can be improved. Therefore, the advantages provided by any of the above aspects are equally applicable to all other aspects, and vice versa.

[0030] In summary, the present invention relates to a detection system for computed tomography systems. The detection system comprises a first detector and a second detector, each detector configured to detect X-ray radiation from a computed tomography system impacting its respective detector. The detection system further includes a repositioning mechanism configured to reposition at least one of the first detector and the second detector relative to the other of the first detector and the second detector.

[0031] One advantage of the embodiments of the present invention for a detection system for computed tomography systems is that the modular, reconfigurable detector can be adapted to different required area coverages of the detector, thus enabling a good trade-off between price and coverage. Another advantage is that the field of view of the detection system can be broadened. Another advantage is that, in addition to the pure size and aspect ratio of the detector, the type of detector and the configuration of the anti-scatter grid can be adjusted according to the needs of a particular imaging procedure.

[0032] These advantages are not limited to those mentioned above, and other advantages may be conceivable within the context of this application.

[0033] The above aspects and embodiments will become apparent from and will be described with reference to the exemplary embodiments described below. Exemplary embodiments of the present invention will be described below with reference to the following drawings. [Brief explanation of the drawing]

[0034] [Figure 1] This is a schematic diagram of a standard detection system for fixed aspect ratio in computed tomography systems. [Figure 2] This diagram shows a schematic setting of a detection system for a computed tomography system according to an embodiment of the present invention. [Figure 3] A schematic diagram of a detection system for a computed tomography system according to another embodiment of the present invention is shown. [Figure 4A]A schematic diagram of a detection system for a computed tomography system including a one-dimensional scattering prevention grid, according to another embodiment of the present invention, is shown. [Figure 4B] A schematic diagram of a detection system for a computed tomography system including a one-dimensional scattering prevention grid, according to another embodiment of the present invention, is shown. [Figure 5] A schematic diagram of a computed tomography system including a detection system according to another embodiment of the present invention is shown. [Figure 6] This shows a block diagram of a method for imaging a subject using a computed tomography system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0035] Figure 1 is a schematic diagram of a standard detection system with a fixed aspect ratio for computed tomography (CT) imaging. In a general-purpose system, the fan angle may be large enough to support an object with a diameter of approximately 500 mm. However, this fixed shape setting cannot be adapted to the needs of specific imaging procedures where different aspect ratios for the detection area are desired.

[0036] Figure 2 shows a schematic configuration of the detection system 100 for a computed tomography system 200 according to an embodiment of the present invention. It illustrates a modular concept of detector sub-regions that can be moved to different positions. Various geometric settings allow for flexible positioning in multiple configurations. Therefore, it is preferable to provide different geometric settings for different applications. For example, in brain scans, pediatric imaging, and limb imaging, a complete field of view may not be necessary because objects may be smaller than the field of view. However, with regard to extending the detection system 100 toward the patient, doubling the detector coverage can halve the acquisition time, which can be very important, for example, for non-compliant patients.

[0037] Therefore, referring to Figure 2, different shapes of the same type of detector are shown. The detection system 100 includes a first detector 110 and a second detector 120, each detector configured to detect X-ray radiation from the computed tomography system 200 that strikes its respective detector. In this embodiment, two second detectors 120 are shown. The first detector 110 and the second detector 120 together form a detection area 140, which in this case is wide in the rotational direction from left to right but small in the patient direction from top to bottom. On the opposite side of the scanning path of the computed tomography scanner 200 is the X-ray source 210 of the computed tomography scanner 200. The second detectors 120 can be repositioned by a repositioning mechanism 130, which is not shown in Figure 2.

[0038] After the second detector 120 is repositioned, it, together with the first detector 110, forms a detection region 140 with a different aspect ratio than conventional detectors. The new detection region 140 in this exemplary embodiment has approximately a second-order aspect ratio, as shown in the lower part of Figure 2.

[0039] The repositioning mechanism 130 allows the second detector 120 to be repositioned relative to the first detector 110, thereby adjusting the aspect ratio of the detection region 140. The repositioning mechanism 130 may include a guiding mechanism for guiding at least one of the first detector 110 and the second detector 120 along a predetermined trajectory from a first position to a second position. Furthermore, or optionally, the repositioning mechanism 130 may include a rotation mechanism for rotating at least one of the first detector 110 and the second detector 120 with respect to a rotation axis essentially parallel to the direction of X-ray radiation. Space for the rotation of one of the first or second detectors can be provided, for example, by temporarily raising each detector element toward the isocenter for rotation of the computed tomography system.

[0040] The repositioning mechanism may include a locking mechanism that locks at least one of the first detector 110 and the second detector 120 in place at at least one of the first and second positions. Thus, each detector can be securely and stably fixed between the required end position and a robust moving mechanism, which may be a rail-like system that is hydraulic, with defined end positions, each equipped with a fixture and its respective moving actuator element. A stable and precise position can be obtained at both end positions by using special alignment features on the various interface sides of the module. Small alignment pins that fit into a cone hole or stepped interface ensure that the detector height and z / phi position are the same.

[0041] The repositioning mechanism 130 is preferably configured to adjust the angular tilt of the first detector 110 and / or the second detector 120 with respect to the direction of X-ray radiation from the computed tomography system 200. The tilt can be performed with respect to the optical axis of the system, which can be defined as the line from the X-ray source to the axis of rotation of the computed tomography system in the plane of rotation. Hardware and software adaptations to the detection system 100 and the computed tomography apparatus 200 may be required for module tiling, including adaptation of X-ray beam collimation. For each possible positioning of the detector, detailed detector position calibration can be performed, and data can be taken into consideration for image processing and reconstruction.

[0042] Preferably, the second detector 120 may differ from the first detector 110 with respect to its spectral response to X-ray radiation. The sub-detector module may be a different type of detector. This could be a standard integration of a computed tomography detector, a dual-spectrum computed tomography detector, or a spectral photon counting detector. Such a setup allows for the placement of more expensive spectral detectors depending on the region of interest.

[0043] Referring to Figure 3, a schematic configuration of the detection system 100 for a computed tomography system 200 according to another embodiment of the present invention is shown. In this embodiment, four second detectors 120 are shown, which are repositionable and together with the first detectors 110 form a detection region 140. Depending on the size of the sub-detectors, additional options for geometric configuration are possible. The small size of the sub-detector modules allows for more flexible distribution and eliminates the need to move the central portion along the Z-axis after changing the position of the detectors. The aspect ratio of the detection region 140 can be adjusted by repositioning at least one of the first detectors 110 or the second detectors 120 relative to the other detectors. The top of Figure 3 shows a small, elongated detection region 140, and the bottom of Figure 2 shows detection regions with different aspect ratios. Various trajectories of actuator movement are indicated by arrows. Preferably, the first detector 110 and the second detector 120 form the detection region 140 without leaving any gaps between them in order to avoid dead space within the detection region 140.

[0044] Figures 4A and 4B show schematic diagrams of a detection system 100 for a computed tomography system 200, including a one-dimensional anti-scatter grid 160 according to another embodiment of the present invention. At least one of the first detector 110 and the second detector 120 includes an anti-scatter grid 160 configured to suppress scattered X-ray radiation reaching each detector. The adjustable anti-scatter grid 160 allows adjustment of the focus of the anti-scatter grid 160 relative to the X-ray source 210 of the computed tomography system 200.

[0045] Preferably, the adaptation of the focal alignment to the anti-scattering grid (ASG) and the collimation of the X-ray beam matched to the detection region 140 are provided. Before and after repositioning, it may be advantageous to provide the correct angular tilt of each detector with ASGs at both ends of the detector trajectory. This may be the direction of focusing from the focal position of the X-ray source 210 to the ASG and the channel of the detection element. Alternatively, the focal alignment of individual submodules of the anti-scattering grid may be an alternative method compared to the angular tilt of the entire detector module including the anti-scattering grid.

[0046] The anti-scatter grid 160 may be a one-dimensional anti-scatter grid, and the anti-scatter grid may be configured to adjust the direction of the grid lines of the one-dimensional anti-scatter grid with respect to the aspect ratio of the detection area 140 of the computed tomography system 200. However, it should be noted that computed tomography systems with moderate collimation are usually equipped with a one-dimensional anti-scatter grid, i.e., only unidirectional lamellae. Focusing with this type of collimator is simpler because it does not require tilting. Therefore, in preferred embodiments, a one-dimensional anti-scatter grid is used. A one-dimensional anti-scatter grid is usually used with detectors up to, for example, 64 lines, and for larger patient coverage, scattering becomes greater, and a two-dimensional anti-scatter grid is preferred, for example, in the case of a 128-line scanner. In detector configurations where the size of the detector is large in the direction of the patient, good scattering removal may be required, for example, by rotating the one-dimensional anti-scatter grid in each direction.

[0047] If a detector module, such as the first detector 110 or the second detector 120, is equipped with a one-dimensional anti-scatter grid, it is preferably proposed to rotate these grids or detector modules so that the grid lines are parallel to either the patient direction or the angular direction. To scan a long, narrow body portion extending along the patient direction, the X-ray beam of the X-ray source 210 may be collimated by the collimator 220 of the computed tomography system 200, which is narrow in the angular direction and wide in the patient direction, to cover this body portion. In this case, the grid lines must be oriented in the angular direction to minimize scattered signals. When scanning a wide patient, but the field of view in the patient direction is limited, the beam may be collimated narrow in that direction and wide in the angular direction. In this case, the grid lines must be oriented towards the patient to minimize scattered signals. For all module positions and rotations, to optimally position the grid toward the focal point, modules located further away from the patient direction than the center at z=0 may need to be tilted toward the focal point of the X-ray source, for example, by shaping a base structure to which the detector module is fixed in a repositionable manner. The basic structure can form a sphere made of tiles, with each tile acting as a detector module. The angular alignment relative to the focal point can be adjusted for each detector position.

[0048] Preferably, a single detection system may combine detector modules with one-dimensional anti-scattering grids and detector modules with two-dimensional anti-scattering grids. While one-dimensional anti-scattering grids may be less expensive, two-dimensional anti-scattering grids can suppress scattering and improve image quality. By combining these, a trade-off between cost and image quality can be established. In particular, for modular side modules, two-dimensional anti-scattering grids are beneficial because they can be placed at z-positions where most cross-scattering is likely to affect image degradation.

[0049] Figure 5 shows a schematic diagram of a computed tomography system 200 including a detection system 100 according to another embodiment of the present invention. The computed tomography system 200 consists of an X-ray source 210 and a collimator 220. A subject 150 is irradiated and radiation is detected in a detection region 140 formed by a first detector 110 and a second detector 120. A repositioning mechanism 130 is provided to reposition at least one of the first detector 110 and the second detector 120 relative to the other of the first detector 110 and the second detector 120.

[0050] Figure 6 shows a block diagram of a method for imaging a subject 150 using a computed tomography system 200 according to an embodiment of the present invention. This method comprises the steps of: providing a computed tomography system according to any of the embodiments described above; and determining a detection region 140 for imaging a subject. This method further includes the steps of: rearranging at least one of the first detector 110 and the second detector 120 relative to the other of the first detector 110 and the second detector 120 to form the determined detection region 140; and imaging the subject.

[0051] Preferably, the procedure includes the steps of repositioning at least one of the first detector 110 and the second detector 120, fixing at least one of the first detector 110 and the second detector 120 in a predetermined position, and / or adjusting the angular tilt of the first detector 110 and / or the second detector 120 with respect to the direction of the X-ray radiation of the computed tomography system 200.

[0052] Although the present invention has been illustrated and described in detail in the drawings and the foregoing description, such illustrations and descriptions should be considered illustrative or descriptive and not limiting. The present invention is not limited to the disclosed embodiments. Other variations of the disclosed embodiments can be understood and achieved by those skilled in the art in carrying out the claimed invention, based on an examination of the drawings, disclosure and dependent claims.

[0053] In the claims, the word “having” does not preclude other elements or steps, and the indefinite article “a” or “an” does not preclude plurality. The mere fact that certain means are described in different dependent claims does not imply that combinations of these means cannot be used advantageously. No reference numeral in the claims should be construed as limiting in scope. [Explanation of Symbols]

[0054] 100 detection systems 110 First detector 120 Second detector 130 Relocation mechanism 140 detection area 150 subjects 160 Scatter Prevention Grid 200 Computed Tomography Imaging System 210 X-ray source 220 Collimator

Claims

1. A detection system for computed tomography systems, A first detector, configured to detect X-ray radiation from a computed tomography system that strikes the first detector, A second detector, configured to detect X-ray radiation from a computed tomography system that strikes the second detector, A repositioning mechanism configured to reposition at least one of the first detector and the second detector relative to the other of the first detector and the second detector. It has, The repositioning mechanism includes a guide mechanism configured to guide at least one of the first detector and the second detector along a predetermined trajectory from a first position to a second position, and / or the repositioning mechanism includes a rotation mechanism configured to rotate at least one of the first detector and the second detector with respect to a rotation axis that is essentially parallel to the direction of the X-ray radiation. The first detector and / or the second detector have a scattering prevention grid configured to suppress scattered X-ray radiation reaching each of the detectors. The scattering prevention grid is configured to align its focus with respect to the X-ray source of the computed tomography system. The anti-scatter grid is a one-dimensional anti-scatter grid, and the anti-scatter grid is configured to adjust the direction of the grid lines of the one-dimensional anti-scatter grid with respect to the aspect ratio of the detection area of ​​the computed tomography system. Computed tomography system.

2. The detection system according to claim 1, wherein the first detector and the second detector are configured to form a detection area of ​​the computed tomography system.

3. The detection system according to claim 2, wherein the repositioning mechanism is configured to adjust the aspect ratio of the detection area of ​​the computed tomography system.

4. The detection system according to any one of claims 2 to 3, configured to form the detection region between the first detector and the second detector with essentially no gap.

5. The detection system according to claim 1, wherein the repositioning mechanism has a locking mechanism configured to lock at least one of the first detector and the second detector in place at least one of the first and second positions.

6. The detection system according to any one of claims 1 to 5, wherein the repositioning mechanism is configured to adjust the angular inclination of the first detector and / or the second detector with respect to the direction of the X-ray radiation of the computed tomography system.

7. The detection system according to any one of claims 1 to 6, wherein the second detector differs from the first detector in terms of its spectral response to the X-ray radiation.

8. The detection system according to any one of claims 1 to 7, comprising a third detector, at least one third detector configured to detect X-ray radiation from the computed tomography system that strikes the third detector, wherein the repositioning mechanism is configured to reposition the at least first third detector relative to the first detector and the second detector.

9. A computed tomography system, The aforementioned computed tomography system is A detection system according to any one of claims 1 to 8, An X-ray source configured to emit X-ray radiation, A collimator configured to collimate the X-ray radiation in the detection region formed by the first detector and the second detector, A computed tomography system.

10. A method for imaging a subject using the computed tomography system described in claim 9, wherein the method is: The steps of providing the computed tomography system described in claim 9, The steps include determining a detection region for imaging the subject, The steps include: rearranging at least one of the first detector and the second detector relative to the other of the first detector and the second detector to form the determined detection area; The steps of imaging the subject and A method having

11. The method according to claim 10, further comprising the step of repositioning at least one of the first detector and the second detector, and then locking at least one of the first detector and the second detector in place.

12. The method according to claim 10 or 11, further comprising the step of adjusting the angular tilt of the first detector and / or the second detector with respect to the direction of X-ray radiation from the computed tomography system.

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