Radiation detector, and method for designing radiation detector

Abstract

Provided is a method for designing a radiation detector that has a plurality of pixels provided with a gap between adjacent pixels, and has a polyhedral structure bent at at least one location along one direction, wherein a minimum number of bending operations required to avoid overlapping incidence in which radiation emitted from a radiation source is incident on both of two adjacent pixels is derived as an optimal value of the number of bending operations.

Description

Radiation detector and design method for radiation detector

[0001] The disclosed technology relates to radiation detectors and methods for designing radiation detectors.

[0002] The following technologies are known regarding radiation detectors. For example, Japanese Patent Publication No. 8-243098 describes an X-ray CT apparatus comprising an X-ray source that emits X-rays and a detector container arranged in an arc shape with respect to the X-ray source.

[0003] Japanese Patent Publication No. 06-214036 describes a multi-element X-ray detector configured by arranging a plurality of X-ray detection element arrays, each array comprising a scintillator that emits visible light of an intensity corresponding to the intensity of X-rays from an incident X-ray tube and a photoelectric conversion element that converts visible light incident on a light-receiving surface into an electrical signal, wherein the X-ray detection element arrays are arranged linearly on the same plane, and each X-ray detection element is oriented in the direction of the focal point of the X-ray tube.

[0004] Computed Tomography (CT) scanners are increasingly using larger-area radiation detectors. CT scanners with large-area radiation detectors are called Wide Detector (WD) CT scanners. In WDCT scanners, overlapping radiation incidence can occur due to the large area (length) of the radiation detector. The incidence angle θ of radiation emitted from the source increases towards the edges of the radiation detector. This increase in incidence angle θ is more pronounced at the edges of large-area (length) radiation detectors. At the edges of large-area (length) radiation detectors, the incidence angle θ of radiation becomes large enough that overlapping radiation incidence can occur, where radiation hits both of two adjacent pixels. Overlapping radiation incidence leads to a deterioration in the image quality of the radiation images taken using that radiation detector.

[0005] To avoid overlapping radiation incidence, it is conceivable to change the orientation of the detection surface of the radiation detector depending on the radiation incidence location. In other words, by forming a multifaceted structure in the radiation detector that is bent at least once along one direction, it is possible to avoid overlapping radiation incidence. However, the more times the radiation detector is bent (the number of bends), the higher the assembly cost becomes.

[0006] The disclosed technology aims to achieve high image quality in radiation detectors with minimal assembly costs.

[0007] The design method for a radiation detector relating to the disclosed technology is a design method for a radiation detector having a polyhedral structure having a plurality of pixels separated by gaps between adjacent pixels and folded at at least one point along one direction, wherein the minimum number of folds required to avoid overlapping incidence, where radiation emitted from a radiation source is incident on both of two adjacent pixels, is derived as the optimal number of folds.

[0008] The optimal value may be derived by restricting the gap dimensions such that the radiation utilization efficiency, which is determined by the ratio of the pixel dimensions to the sum of the gap dimensions and the pixel dimensions, is above a threshold.

[0009] The process may involve deriving the change in radiation utilization efficiency, which is determined by the ratio of the gap dimensions to the pixel dimensions when the gap dimensions are changed, deriving the change in the minimum number of folds when the gap dimensions are changed, deriving the change in the evaluation value, which is determined by the ratio of the utilization efficiency to the minimum number of folds when the gap dimensions are changed, and deriving the minimum number of folds as the optimal value when the gap dimensions that result in utilization efficiency being above a threshold and the evaluation value being maximized are applied.

[0010] The conditions under which overlapping incidence does not occur may be defined based on the distance between the radiation detector and the radiation source, the pixel dimensions, and the gap dimensions.

[0011] For multiple pixels aligned in one direction, it may be determined based on conditions whether overlapping incidence occurs, and the boundary between pixels where overlapping incidence does not occur and pixels where it does occur may be determined as the folding position. The optimal number of folding cycles may be 2.

[0012] The radiation detector is installed on the CT scanner, and one direction of rotation may be intersecting with the rotation direction of the radiation detector during the operation of the CT scanner.

[0013] The radiation detector relating to the disclosed technology has a plurality of pixels with gaps between adjacent pixels, and has a three-sided structure that is bent at two points along one direction.

[0014] The radiation detector is installed in the CT scanner, and one direction of rotation may be intersecting with the rotation direction of the radiation detector during the operation of the CT scanner. The radiation detector may be composed of a combination of multiple units having the same structure and shape.

[0015] This makes it possible to achieve high image quality with minimal assembly costs in radiation detectors.

[0016] This is a schematic cross-sectional view showing an example of the configuration of a typical CT scanner. This is a schematic cross-sectional view showing an example of the configuration of a WDCT scanner. This is a cross-sectional view showing an example of the configuration of a radiation detector. This is a cross-sectional view showing overlapping radiation incidence. This is a cross-sectional view showing an example of the configuration of a radiation detector to avoid overlapping radiation incidence. This is a model diagram for deriving the optimal number of folds for a radiation detector. This is a model diagram for deriving the optimal number of folds for a radiation detector. This is a diagram showing an example of the procedure for deriving the optimal number of folds for a radiation detector. This is a graph showing an example of the change in radiation utilization efficiency when the dimensions of the gap between pixels are changed. This is a graph showing an example of the change in the minimum number of folds required to avoid overlapping incidence when the dimensions of the gap between pixels are changed. This is a graph showing an example of the change in evaluation value when the dimensions of the gap between pixels are changed. This is a flowchart showing an example of the procedure for setting the folding position of a radiation detector. This is a combination of the graphs shown in Figures 7A, 7B, and 7C. This is a schematic cross-sectional view showing an example of the configuration of a radiation detector having a three-sided structure. This is a schematic cross-sectional view showing an example of the configuration of a radiation detector having a three-sided structure. This is a cross-sectional view showing an example of the configuration of a unit that constitutes part of a radiation detector. This is a perspective view showing an example of the configuration of a radiation detector with a three-sided structure. This is a perspective view showing an example of the application of the configuration of a radiation detector with a three-sided structure to a WDCT device.

[0017] Hereinafter, an example of an embodiment of the disclosed technology will be described with reference to the drawings. In each drawing, the same or equivalent components and parts will be given the same reference numerals, and redundant descriptions will be omitted.

[0018] Figure 1A is a schematic cross-sectional view showing an example of the configuration of a typical CT scanner 100A having a radiation detector 10 of normal area. Figure 1B is a schematic cross-sectional view showing an example of the configuration of a WDCT scanner 100B having a large-area radiation detector 10.

[0019] A typical CT scanner 100A and a WDCT scanner 100B each have a radiation detector 10, a patient table 102, and a radiation source (radiation tube) 103, respectively. The radiation source 103 and radiation detector 10 are housed inside an annular gantry 101. The patient table 102 can slide toward the inside of the gantry 101. The radiation source 103 and radiation detector 10 can continuously acquire radiation images (projection images) while rotating along the circumferential surface of the gantry 101. A tomographic image is obtained by reconstructing multiple radiation images taken in different directions. Imaging width W in a typical CT scanner 100A Ａ For example, the imaging width W in the WDCT apparatus 100B is 4 cm. Ｂ For example, it is 16 cm. With the WDCT device 100B, moving organs such as the heart can be imaged in just one rotation, thus providing clear radiographic images.

[0020] In this specification and the drawings, the sliding direction of the bed 102 (the depth direction of the gantry 101, the axis direction of the patient's body) is the Y direction, the rotation direction of the radiation detector 10 (the circumferential direction of the gantry 101) is the X direction, and the height direction of the CT devices 100A and 100B is the Z direction.

[0021] Figure 2 is a cross-sectional view showing an example of the configuration of a radiation detector 10. The radiation detector 10 has a plurality of pixels 23, each containing a scintillator 21 and a photodetector 22. The scintillator 21 is stacked on top of the photodetector 22. Radiation (X-rays) is incident from the scintillator 21 side. That is, in the radiation detector 10, the surface of the scintillator 21 is the radiation detection surface (incident surface) 26. The photodetector 22 is, for example, a photodiode.

[0022] Radiation incident on the detection surface 26 is converted into visible light by the scintillator 21. The visible light is converted into an electrical signal by the photodetector 22. Multiple pixels 23 are separated from each other by separation regions 24A and 23B, and an electrical signal (pixel value) is generated for each pixel. The separation region 24A provided in the layer of the scintillator 21 is made of a light-reflective material such as titanium oxide. This makes it possible to confine the visible light generated in a certain pixel within that pixel. The separation region 24B provided in the layer of the photodetector 22 is made of a semiconductor or an insulator. The electrical signals for each pixel are insulated and separated by the separation region 24B.

[0023] In the WDCT apparatus 100B (see Figure 1B), due to the large area (long length) of the radiation detector 10, overlapping incidence of radiation, where radiation strikes both adjacent pixels 23, can occur. The angle θ of incidence of radiation emitted from the radiation source to the radiation detector 10 increases towards the edges of the radiation detector 10. This increase in the incidence angle θ is more pronounced at the edges of the large-area (long length) radiation detector 10. At the edges of the large-area (long length) radiation detector 10, as shown in Figure 3, the incidence angle θ of the radiation becomes large enough that overlapping incidence of radiation, where radiation strikes both adjacent pixels 23, can occur. Overlapping incidence of radiation leads to a deterioration in the image quality of the radiation image taken using the radiation detector 10.

[0024] To avoid overlapping radiation incidence, as shown in Figure 4, the orientation of the detection surface 26 of the radiation detector 10 can be changed according to the radiation incidence position. That is, by forming a multifaceted structure in the radiation detector 10 that is bent at least once along one direction (the Y direction), it is possible to avoid overlapping radiation incidence. However, the more times the radiation detector 10 is bent (the number of bends), the higher the assembly cost becomes. The disclosed technology aims to optimize the number of bends in a radiation detector 10 having a multifaceted structure. The details are described below.

[0025] Figures 5A and 5B are model diagrams for deriving the optimal number of folds for the radiation detector 10. Let f be the distance (focal length) between the radiation source 103 and the radiation detector 10. Let d be the Y-direction dimension of the pixel 23 in the radiation detector 10, and h be the Z-direction dimension. Let s be the Y-direction dimension of the gap 25 provided between the pixels. The gap 25 corresponds to the width of the separation regions 24A and 23B. Assume that the radiation source 23 is located directly above the center in the Y-direction of the radiation detector 10.

[0026] The incident angle θ of radiation at the nth pixel 23 located from the center in the Y direction of the radiation detector 10. ｎ θ is expressed by equation (1) below. ｎ = tan －１ [{d×n+s×(n-0.5)} / f] ...(1)

[0027] The maximum incidence angle φ at which no overlapping radiation incidence occurs is determined by the dimensions of the gap 25 and is expressed by equation (2) below. In equation (2), m is the margin (tolerance) of the gap 25. φ = tan －１ {(s-m) / h} ...(2)

[0028] The condition under which overlapping incidence does not occur in the radiation detector 10 is expressed by the following equation (3): θ ｎ <φ ... (3)

[0029] By increasing the dimension s of the gap 25, the maximum incidence angle φ at which overlapping radiation incidence does not occur increases, thus reducing the minimum number of folds M required to avoid overlapping incidence. However, increasing the dimension s of the gap 25 increases the area of ​​the dead zone in which radiation cannot be detected by the radiation detector 10. In other words, increasing the dimension s of the gap 25 reduces the radiation utilization efficiency E of the radiation detector 10. Therefore, when deriving the optimal number of folds for the radiation detector 10, it is preferable to set a threshold for the radiation utilization efficiency E and restrict the dimension s of the gap 25 so that the radiation utilization efficiency is equal to or greater than the threshold. Based on the above, the procedure for deriving the optimal number of folds for the radiation detector 10 is described below.

[0030] Furthermore, a collimator (e.g., 301 of Japanese Patent Publication No. 2023-39071) is a structure that has an effect equivalent to dimension s. The collimator is a component placed on the radiation incident side of the detection surface 26 of the radiation detector 10, and has multiple walls that form multiple through holes through which radiation passes. When optimizing including this collimator, the larger of the collimator width projected from the focal position to the detection surface and dimension s can be considered as the new s. When dimension s is managed as the width of the collimator rather than the gap between pixels, the following advantages are available. Since the scintillator 21 and photodiode 22 are expensive components, it is desirable to make them common components for multiple devices. On the other hand, since the collimator is a component that is later placed on the detection surface 26 of the radiation detector 10, it is relatively easy to manufacture different versions for each device. Therefore, by making the scintillator 21, photodiode 22 and the dimension s determined from them common to multiple CT devices, and changing the width of the collimator placed on the detection surface 26 of the radiation detector 10, it is possible to obtain optimal image quality for each CT device.

[0031] Figure 6 shows an example of a procedure for deriving the optimal number of folds for the radiation detector 10. In the following, the distance f between the radiation source 103 and the radiation detector 10 is assumed to be 1000 mm as an example. The sum of the Y-direction dimension d of the pixel 23 and the Y-direction dimension s of the gap 25 (d+s) is assumed to be 1 mm as an example. The Z-direction dimension h of the pixel 23 is assumed to be 1.5 mm as an example. The margin (tolerance) m of the gap 25 is assumed to be 0.05 mm as an example. The Y-direction dimension s of the gap 25 is treated as a variable parameter.

[0032] In step S1, the change in the radiation utilization efficiency E when the Y-direction dimension s of the gap 25 is changed is derived. The radiation utilization efficiency E is defined by the following equation (4). That is, the radiation utilization efficiency E is the ratio of the Y-direction dimension d of the pixel 23 to the sum of the Y-direction dimension s of the gap 25 and the Y-direction dimension d of the pixel 23 (d+s). E = d / (d+s) ... (4)

[0033] FIG. 7A is a graph showing an example of the transition of the radiation utilization efficiency E when the dimension s in the Y direction of the gap 25 is changed. Since d + s is fixed at 1 mm as described above, the radiation utilization efficiency E decreases as the dimension s in the Y direction of the gap 25 increases.

[0034] In step S2, the transition of the minimum number of bending times M required to avoid double incidence is derived when the dimension s in the Y direction of the gap 25 is changed. First, the bending positions of the radiation detector 10 are set using the above equations (1) to (3). FIG. 8 is a flowchart showing an example of the procedure for setting the bending positions of the radiation detector 10.

[0035] A value n for identifying the pixel position is assigned to each of the pixels 23 arranged along the Y direction of the radiation detector 10. n increases by 1 from the center in the Y direction toward the end.

[0036] In step S11, 1 is substituted for n. In step S12, it is determined whether double incidence occurs in the n-th pixel 23 using the equations (1) to (3). If it is determined that double incidence occurs, the process proceeds to step S13, and if it is determined that double incidence does not occur, the process proceeds to step S16.

[0037] In step S13, the boundary between the n-th pixel 23 where double incidence occurs and the (n - 1)-th pixel 23 adjacent thereto where double incidence does not occur is set as the bending position.

[0038] In step S14, the radiation detector 10 is bent at the bending position set in step S13. For example, the bending angle may be set so that the incident angle θ of the radiation in the n-th pixel 23 becomes 0°.

[0039] In step S15, it is determined whether n is n ｅ or not. n ｅ is the value corresponding to the pixel 23 located at the end in the Y direction of the radiation detector 10. If it is determined that n is n ｅ this routine ends. If n is n ｅIf it is determined that it is not, the process proceeds to step S16. In step S16, n is incremented and the process returns to step S12.

[0040] According to the above process, the boundary between the pixel 23 where no overlapping incidence occurs and the pixel 23 where overlapping incidence occurs is set as the bending position. By setting the bending position in this way, it is possible to minimize the number of bending times required to avoid overlapping incidence. Therefore, the total number of bending positions set by the above process becomes the minimum number of bending times M required to avoid overlapping incidence.

[0041] The minimum number of bending times M changes according to the dimension s in the Y direction of the gap 25. By changing the value of s in the equations (1) to (3) used in step S11, it is possible to derive the transition of the minimum number of bending times M required to avoid overlapping incidence when the dimension s in the Y direction of the gap 25 is changed.

[0042] FIG. 7B is a graph showing an example of the transition of the minimum number of bending times M required to avoid overlapping incidence when the dimension s in the Y direction of the gap 25 is changed. As the dimension s in the Y direction of the gap 25 increases, the minimum number of bending times M required to avoid overlapping incidence decreases.

[0043] In step S3, the transition of the evaluation value V when the dimension s of the gap 25 is changed is derived. The evaluation value V is a value determined according to the ratio of the utilization efficiency E of radiation and the minimum number of bending times M required to avoid overlapping incidence, and is represented by the following equation (5). As the utilization efficiency E of radiation increases and as the minimum number of bending times M required to avoid overlapping incidence decreases, the evaluation value V increases. Note that the evaluation value V may be derived by adding a weighting factor to each of E and M. V = E / M... (5)

[0044] FIG. 7C is a graph showing an example of the transition of the evaluation value V when the dimension s of the gap 25 is changed. The transition of the evaluation value V can be derived based on the transition of the utilization efficiency E of radiation derived in step S1 and the transition of the minimum number of bending times M required to avoid overlapping incidence derived in step S2.

[0045] In step S4, the dimension s in the Y direction of the gap 25 is identified such that the radiation utilization efficiency E is above a threshold and the evaluation value V is maximized. Then, the minimum number of bends M required to avoid overlapping incidence when the identified gap dimension s is applied is derived as the optimal number of bends.

[0046] The optimal number of folds can be easily derived by combining the graphs shown in Figures 7A to 7C, as shown in Figure 9. For example, if the threshold for the radiation utilization efficiency E is set to 80%, then "0.15 mm" is identified as the Y-direction dimension s of the gap 25 where the radiation utilization efficiency E is 80% or higher and the evaluation value V is maximized. When the gap dimension s is 0.15 mm, "2" is derived as the minimum number of folds M required to avoid overlapping incidence. The "2" derived as the minimum number of folds M becomes the optimal number of folds.

[0047] In other words, assuming f = 1000 mm, d + s = 1 mm, h = 1.5 mm, and m = 0.05 mm, the radiation detector 10 can achieve high image quality with minimal assembly cost by having a three-sided structure that is bent at two points along the Y direction, as shown in Figure 10.

[0048] Assuming that the radiation detector 10 has 256 pixels in the Y direction, for example, as shown in Figure 11A, it is possible to have a three-sided structure with 64 pixels on the first surface 27A, 128 pixels on the second surface 27B, and 64 pixels on the third surface 27C. Figure 11A illustrates a configuration in which a component 30 including a collimator is placed on the detection surface 26 of the radiation detector 10 having a three-sided structure. The component 30 is tapered so as not to interfere with the bent portion of the radiation detector 10. Therefore, it is possible to create an asymmetrical unit 40 as shown in Figure 11B by cutting out 64 pixels from the structure shown in Figure 11A, and to form the structure shown in Figure 11A by appropriately inverting and combining four units 40 that have the same structure and shape. In this way, by forming a radiation detector 10 having a three-sided structure by combining multiple units 40 that have the same structure and shape, it is possible to reduce assembly man-hours and parts management man-hours.

[0049] The "64 pixels x 4" configuration offers further advantages. It is desirable that the number of data points to be processed in a CT scanner be a power of two. By using a "64 pixels x 4" configuration, the total number of pixels in the Y direction of the radiation detector can be a power of two (256 pixels), and each of the four units 40 can also have a number of pixels in the Y direction that is a power of two (64 pixels). By configuring the three-sided radiation detector with a "64 pixels x 4" configuration in this way, data processing becomes easier.

[0050] Figure 12 is a perspective view of a radiation detector 10A having a three-sided structure according to an embodiment of the disclosed technology. The radiation detector 10A is composed of a plurality of detection elements 20. Each detection element 20 has a plurality of pixels, each containing a scintillator and a light-receiving element. The plurality of pixels have gaps between adjacent pixels. In the detection element 20, the surface of the scintillator serves as the radiation detection surface (light-receiving surface) 26. The light-receiving element is, for example, a photodiode.

[0051] The radiation detector 10A has a first surface 27A, a second surface 27B, and a third surface 27C, the orientations of which are different from each other. The first surface 27A and the third surface 27C, located at one end and the other end in the Y direction, are each composed of 2x2 detection surfaces 26 of four detection elements 20. The second surface 27B, located in the center in the Y direction, is composed of 2x4 detection surfaces 26 of eight detection elements 20.

[0052] When a three-sided radiation detector 10A is applied to a WDCT apparatus 100B (see Figure 1B), the direction in which the first surface 27A, the second surface 27B, and the third surface 27C are aligned is oriented in the Y direction (the sliding direction of the bed 102). That is, the two bent parts of the radiation detector 10A are positioned along the Y direction. As shown in Figure 13, multiple radiation detectors 10A having a three-sided structure may be arranged within the gantry 101 along the X direction (the rotation direction of the radiation detector).

[0053] As described above, the design method according to the embodiment of the disclosed technology relates to a radiation detector 10 having a polyhedral structure having a plurality of pixels 23 with gaps between adjacent pixels and being bent at at least one point along one direction. The design method according to this embodiment includes deriving the minimum number of bends M required to avoid overlapping incidence, where radiation emitted from a radiation source 103 is incident on both of two adjacent pixels 23, as the optimal value for the number of bends.

[0054] The more times a radiation detector is folded, the higher the assembly cost. According to the design method of this embodiment, the minimum number of folds M required to avoid overlapping incidence is set as the optimal value for the number of folds, making it possible to achieve high image quality with minimal assembly cost.

[0055] Furthermore, the design method according to this embodiment includes deriving an optimal value by limiting the dimension s of the gap 25 so that the radiation utilization efficiency E is equal to or greater than a threshold. This makes it possible to derive an optimal value for the number of folds while taking into account the radiation utilization efficiency E.

[0056] Furthermore, the design method according to this embodiment includes deriving the change in radiation utilization efficiency E when the dimension s of the gap 25 provided between pixels is changed, deriving the change in the minimum number of folds M required to avoid overlapping incidence when the dimension s of the gap 25 is changed, deriving the change in an evaluation value V determined according to the ratio of the radiation utilization efficiency E to the minimum number of folds M when the dimension s of the gap 25 is changed, and deriving the minimum number of folds M as the optimal value when the dimension s of the gap 25 is applied such that the utilization efficiency E is above a threshold and the evaluation value V is maximized.

[0057] The minimum number of bends M required to avoid overlapping radiation exposure varies depending on the dimension s of the gap 25. By determining the dimension s of the gap 25 based on the radiation utilization efficiency E and the evaluation value V, it becomes possible to balance the radiation utilization efficiency E with the assembly cost.

[0058] Furthermore, the design method according to this embodiment includes defining conditions under which overlapping incidence does not occur based on the distance f between the radiation detector 10 and the radiation source 103, the dimension d of the pixel 23, and the dimension s of the gap 25. It also includes determining whether or not overlapping incidence occurs for a plurality of pixels 23 arranged along the Y direction based on the above conditions, and determining the boundary between pixels where overlapping incidence does not occur and pixels where overlapping incidence occurs as the folding position. This prevents the folding position from being set excessively, making it possible to minimize the number of folds required to avoid overlapping incidence.

[0059] The following additional information is disclosed regarding the above embodiments. (Addendum 1) A design method for a radiation detector having a polyhedral structure having a plurality of pixels separated by gaps between adjacent pixels and folded at at least one point along one direction, the design method for deriving the minimum number of folds required to avoid overlapping incidence, in which radiation emitted from a radiation source is incident on both of two adjacent pixels, as the optimal number of folds.

[0060] (Note 2) The design method according to Note 1, wherein the dimensions of the gap are limited to derive the optimal value, wherein the radiation utilization efficiency, which is determined according to the ratio of the pixel dimensions to the sum of the dimensions of the gap and the dimensions of the pixels, is greater than or equal to a threshold.

[0061] (Note 3) The design method according to Note 1 or Note 2, wherein the following steps are taken: the transition of the radiation utilization efficiency determined according to the ratio of the dimensions of the gap to the dimensions of the pixels when the dimensions of the gap are changed; the transition of the minimum number of folds when the dimensions of the gap are changed; the transition of the evaluation value determined according to the ratio of the utilization efficiency to the minimum number of folds when the dimensions of the gap are changed; and the minimum number of folds when the dimensions of the gap are applied such that the utilization efficiency is above a threshold and the evaluation value is maximized is derived as the optimal value.

[0062] (Note 4) A design method according to any one of Notes 1 to 3, which defines the conditions under which overlapping incidence does not occur based on the distance between the radiation detector and the radiation source, the dimensions of the pixel, and the dimensions of the gap.

[0063] (Note 5) The design method described in any one of Notes 1 to 4, wherein it is determined whether or not overlapping incidence occurs for multiple pixels aligned in one direction based on the above conditions, and the boundary between pixels where overlapping incidence does not occur and pixels where overlapping incidence occurs is determined as the folding position.

[0064] (Note 6) The design method described in any one of Notes 1 to 5, wherein the optimal value is 2.

[0065] (Note 7) The design method according to any one of Notes 1 to 6, wherein the radiation detector is provided on a CT apparatus, and the one direction is a direction that intersects with the rotation direction of the radiation detector when the CT apparatus is in operation.

[0066] (Note 8) A radiation detector having a three-sided structure with multiple pixels separated by gaps between adjacent pixels, and bent at two points along one direction.

[0067] (Note 9) The radiation detector described in Note 8, provided on a CT apparatus, wherein the one direction is a direction that intersects with the rotation direction of the radiation detector during operation of the CT apparatus.

[0068] (Note 10) The radiation detector described in Note 9, which is composed of multiple units having the same structure and shape.

[0069] Furthermore, the disclosure of Japanese Patent Application No. 2024-190919, filed on 30 October 2024, is incorporated herein by reference in its entirety. In addition, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A design method for a radiation detector having a polyhedral structure with multiple pixels separated by gaps between adjacent pixels and folded at at least one point along one direction, wherein the design method derives the minimum number of folds required to avoid overlapping incidence, where radiation emitted from a radiation source is incident on both adjacent pixels, as the optimal number of folds.

2. The design method according to claim 1, wherein the optimal value is derived by limiting the dimensions of the gap such that the radiation utilization efficiency, which is determined according to the ratio of the pixel dimensions to the sum of the dimensions of the gap and the dimensions of the pixels, is greater than or equal to a threshold.

3. The design method according to claim 1, comprising: deriving the change in radiation utilization efficiency determined according to the ratio of the dimensions of the gap to the dimensions of the pixel when the dimensions of the gap are changed; deriving the change in the minimum number of folds when the dimensions of the gap are changed; deriving the change in an evaluation value determined according to the ratio of the utilization efficiency to the minimum number of folds when the dimensions of the gap are changed; and deriving the minimum number of folds as the optimal value when the dimensions of the gap are applied such that the utilization efficiency is above a threshold and the evaluation value is maximized.

4. The design method according to claim 1, which defines the conditions under which overlapping incidence does not occur based on the distance between the radiation detector and the radiation source, the dimensions of the pixel, and the dimensions of the gap.

5. The design method according to claim 4, wherein it is determined whether or not overlapping incidence occurs for a plurality of pixels aligned in one direction based on the above conditions, and the boundary between pixels where overlapping incidence does not occur and pixels where overlapping incidence occurs is determined as the folding position.

6. The design method according to claim 1, wherein the optimal value is 2.

7. The design method according to claim 1, wherein the radiation detector is provided on a CT apparatus, and the one direction is a direction that intersects with the rotation direction of the radiation detector during operation of the CT apparatus.

8. A radiation detector having multiple pixels separated by gaps between adjacent pixels, and having a three-sided structure that is bent at two points along one direction.

9. The radiation detector according to claim 8, provided on a CT apparatus, wherein the one direction is a direction that intersects with the rotation direction of the radiation detector during operation of the CT apparatus.

10. The radiation detector according to claim 9, which is composed of a combination of multiple units having the same structure and shape.

Images