Radiation detectors and methods for manufacturing radiation detectors

Abstract

When a radiation detector is constructed by linking together multiple detection elements, each containing multiple pixels that detect radiation, the height positions of the detection surfaces to which the radiation enters may become uneven, potentially degrading the image quality of the radiation image. [Solution] With the detection surface 26 of each of the multiple detection elements 20, which is irradiated by the radiation, in contact with the first reference surface, the back surface of each of the multiple detection elements 26, opposite to the detection surface 26, is joined to the fixing plate 12 via adhesive 11.

Description

Technical Field

[0001] The disclosed technology relates to a radiation detector and a method for manufacturing a radiation detector.

Background Art

[0002] [[ID=]12]As technologies related to radiation detectors, the following technologies are known. For example, in Patent Document 1, a planar detector is described that includes a plurality of rectangular photoelectric conversion element substrates on which a plurality of photoelectric conversion elements are arranged, a base that supports the plurality of photoelectric conversion element substrates on a first surface, and a scintillator that is provided on a surface of the photoelectric conversion element substrate opposite to the base side and converts radiation into light that can be sensed by the photoelectric conversion elements.

[0003] [[ID=]16]In Patent Document 2, an element block having a phosphor element, a photoelectric conversion element provided corresponding to the phosphor element, and a separator provided between the phosphor elements, a substrate on which the element block is mounted, and a fixing frame for fixing the substrate are described, and a multi-element radiation detector in which the substrate is fixed to the fixing frame with reference to the upper surface of the substrate is described.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] For medical radiation detectors such as those used in CT scanners, it is conceivable to connect multiple detection elements to widen the imaging range. Each detection element consists of multiple pixels arranged in a grid to detect radiation (X-ray photons). Simply arranging the detection elements may lead to the accumulation of dimensional errors, potentially degrading the image quality of the radiation images taken using the detector. Furthermore, uneven height positions of the detection surface into which the radiation enters may also degrade the image quality of the radiation images.

[0006] The disclosed technology was developed in view of the above points, and aims to align the height of the detection surface to which radiation is incident when a radiation detector is constructed by combining multiple detection elements. [Means for solving the problem]

[0007] The method for manufacturing a radiation detector relating to the disclosed technology is a method for manufacturing a radiation detector comprising a plurality of detection elements, each comprising a plurality of pixels that detect radiation, wherein the detection surface of each of the plurality of detection elements to which radiation is incident is in contact with a first reference surface, and the back surface of each of the plurality of detection elements opposite to the detection surface is joined to a fixing plate via an adhesive.

[0008] The adhesive may have a thickness profile that corresponds to the thickness variations of the multiple detection elements.

[0009] A laminate containing multiple detection elements, adhesive, and a fixing plate may be sandwiched between a second reference surface, whose distance from the first reference surface is fixed, and the first reference surface.

[0010] A first reference plane may be brought into contact with the detection surfaces of multiple detection elements, with the detection surface facing downward in the vertical direction.

[0011] Each of the multiple detection elements may have a first edge and a second edge that intersects the first edge, and the multiple detection elements arranged along the direction of the first edge and the direction of the second edge, respectively, may be joined to a fixing plate.

[0012] The ratio C / T of the thermal conductivity C of the adhesive to the thickness T of the adhesive may be greater than or equal to a threshold value.

[0013] Multiple detection elements may be used to form a unit, and multiple units may be combined. The orientation of the detection surface may differ for each unit.

[0014] It is preferable to determine the material of the fixing plate considering its rigidity. It is also preferable to determine the material of the fixing plate considering its thermal conductivity.

[0015] The radiation detector relating to the disclosed technology includes a plurality of detection elements, each comprising a plurality of pixels that detect radiation, and a fixing plate bonded to the back surface of the plurality of detection elements via adhesive on the side opposite to the detection surface into which the radiation is incident, wherein the detection surfaces of each of the plurality of detection elements extend within the same plane.

[0016] The adhesive may have a thickness profile that corresponds to the thickness variations of the multiple detection elements. [Effects of the Invention]

[0017] According to the disclosed technology, when configuring a radiation detector by combining multiple detection elements, it becomes possible to align the height of the detection surface to which the radiation is incident. [Brief explanation of the drawing]

[0018] [Figure 1] This is a plan view showing an example of the configuration of a radiation detector according to an embodiment of the disclosed technology. [Figure 2] This is a cross-sectional view along line 2-2 in Figure 1. [Figure 3] This is a cross-sectional view showing an example of the configuration of a detection element constituting a radiation detector according to an embodiment of the disclosed technology. [Figure 4A] This is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 4B] This is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 4C] It is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 4D] It is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 5A] It is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 5B] It is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 5C] It is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 5D] It is a plan view showing an example of a method for manufacturing a radiation detector according to an embodiment of the disclosed technology. [Figure 6A] It is a view showing an example of a step of joining a plurality of detection elements and a fixing plate according to an embodiment of the disclosed technology. [Figure 6B] It is a view showing an example of a step of joining a plurality of detection elements and a fixing plate according to an embodiment of the disclosed technology. [Figure 6C] It is a view showing an example of a step of joining a plurality of detection elements and a fixing plate according to an embodiment of the disclosed technology. [Figure 7] It is a cross-sectional view showing a heat dissipation path of a radiation detector according to an embodiment of the disclosed technology. [Figure 8] It is a perspective view showing an example of an array form of a plurality of detection elements. [Figure 9] It is a cross-sectional view showing an example of the configuration of a radiation detector according to a comparative example. [Figure 10A] It is a cross-sectional view schematically showing an example of the configuration of a normal CT apparatus. [Figure 10B] It is a cross-sectional view schematically showing an example of the configuration of a WDCT apparatus. [Figure 11] It is a cross-sectional view showing overlapping incidence of radiation in a detection element. [Figure 12] It is a perspective view of a radiation detector having a three-sided structure according to an embodiment of the disclosed technology. [Figure 13]This is a perspective view showing an example of the configuration of a unit consisting of multiple detection elements. [Figure 14] This is a perspective view of a radiation detector having a three-sided structure according to an embodiment of the disclosed technology. [Modes for carrying out the invention]

[0019] Hereinafter, an example of an embodiment of the disclosed technology will be described with reference to the drawings. In each drawing, identical or equivalent components and parts will be given the same reference numerals, and redundant descriptions will be omitted.

[0020] Figure 1 is a plan view showing an example of the configuration of a radiation detector 10 according to an embodiment of the disclosed technology. Figure 2 is a cross-sectional view along line 2-2 in Figure 1. Figure 3 is a cross-sectional view showing an example of the configuration of a detection element 20 constituting the radiation detector 10.

[0021] The radiation detector 10 has a plurality of detection elements 20. The detection element 20 has a plurality of pixels 23 arranged in a grid pattern for detecting radiation (X-ray photons). As shown in Figure 3, the plurality of pixels 23 are composed of a scintillator 21 and a light-receiving element 22. The scintillator 21 is stacked on the light-receiving element 22. Radiation (X-rays) is incident from the side of the scintillator 21. That is, in the detection element 20, the surface of the scintillator 21 is the radiation detection surface (light-receiving surface) 26. The light-receiving element 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 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] As shown in Figure 1, the detection element 20 has a rectangular shape in plan view, including sides E1 and E2. The radiation detector 10 is constructed by arranging multiple detection elements 20 along sides E1 and E2. In this specification and drawings, the direction along side E1 is the X direction, the direction along side E2 is the Y direction, and the thickness direction of the detection element 20 is the Z direction. The dimensions of sides E1 and E2 are, for example, 10 to 50 mm.

[0024] Figure 1 illustrates a configuration in which two detection elements 20 are arranged side by side along the direction of side E1 (X direction), and four detection elements 20 are arranged side by side along the direction of side E2 (Y direction). Note that the number of detection elements 20 in each direction is not limited to the example shown in Figure 1 and can be determined as appropriate.

[0025] A gap 25 is provided between detection elements 20 that are arranged along the direction of side E2 (Y direction), which is the direction in which the number of detection elements 20 is relatively large. The dimensions of the gap 25 are adjusted so that the distance between sides E1 of detection elements 20 arranged along the direction of side E2 (Y direction) is a predetermined distance d1. The detection elements 20 are manufactured with tolerances in the dimensions of sides E1 and E2. By adjusting the dimensions of the gap 25 as described above, it is possible to absorb the dimensional error of side E2 with the gap 25. This makes it possible to avoid the accumulation of dimensional errors of side E2 even when multiple detection elements 20 are arranged along the direction of side E2 (Y direction). The dimensions of the gap 25 provided at each connection point of the detection elements 20 change according to the dimensional error of side E2 of the detection element 20. That is, the dimensions of the gap 25 may differ for each connection point of the detection elements 20.

[0026] On the other hand, since the number of detection elements 20 arranged in the direction of side E1 (X direction) is small, the accumulation of dimensional errors in side E1 can be tolerated. Therefore, it is not necessary to provide gaps between the detection elements 20 that are arranged along the direction of side E1 (X direction).

[0027] As shown in Figure 2, the multiple detection elements 20 are joined to the fixing plate 12 while maintaining the above-described arrangement. The back surface of the detection element 20 opposite to the detection surface 26 is joined to the fixing plate 12 via adhesive 11. The multiple detection elements 20 are mounted on the fixing plate 12 such that their respective detection surfaces 26 extend within the same plane (i.e., the height positions of the detection surfaces 26 are aligned). The thickness variations of the multiple detection elements 20 are absorbed by the adhesive 11. Therefore, the adhesive 11 has a thickness profile that corresponds to the thickness variations of the multiple detection elements 20.

[0028] The manufacturing method of the radiation detector 10 will be described below. Figures 4A, 4B, 4C, and 4D are plan views showing an example of the manufacturing method of the radiation detector 10.

[0029] Multiple detection elements are arranged using a surface plate 30A and a reference plate 40A (Figure 4A). The surface plate 30A has a flat surface that serves as the reference plane. The reference plate 40A is placed on the surface of the surface plate 30A. The reference plate 40A is a T-shaped or L-shaped ruler and has a side surface 41 that defines a straight line extending in the X direction and a side surface 42 that defines a straight line extending in the Y direction. The straight line defined by side surface 41 will be called the first reference line L1, and the straight line defined by side surface 42 will be called the second reference line L2.

[0030] As shown in Figure 4B, on the surface plate 30A, each side E1 of the detection elements 20A and 20B is brought into contact with the side surface 41 of the reference plate 40A. That is, each side E1 of the detection elements 20A and 20B is positioned on the first reference line L1. Also, the side E2 of the detection element 20A is brought into contact with the side surface 42 of the reference plate 40A. That is, the side E2 of the detection element 20A is positioned on the second reference line L2. Also, the side E2 of the detection element 20B is brought into contact with the detection element 20A. As a result, the detection elements 20A and 20B are aligned along the direction of side E1 (X direction) with their sides E1 aligned. The detection elements 20A and 20B are arranged on the surface plate 30A with the detection surface to which radiation is incident in contact with the surface of the surface plate 30A (i.e., downward).

[0031] Next, as shown in Figure 4C, with the detection elements 20A and 20B stationary on the base plate 30A, the reference plate 40A is moved by a distance d1 in the direction of side E2 (Y direction). The straight line defined by the side surface 41 of the reference plate 40A after the move will be called the third reference line L3. The third reference line L3 is positioned at a distance d1 from the first reference line L1.

[0032] Next, as shown in Figure 4D, each side E1 of detection elements 20C and 20D is brought into contact with the side surface 41 of the reference plate 40A after movement. That is, each side E1 of detection elements 20C and 20D is positioned on the third reference line L3. Also, side E2 of detection element 20C is brought into contact with the side surface 42 of the reference plate 40A. That is, side E2 of detection element 20C is positioned on the second reference line L2. Also, side E2 of detection element 20D is brought into contact with detection element 20C. As a result, detection elements 20C and 20D are aligned along the direction of side E1 (X direction) with their sides E1 aligned. Also, detection elements 20A and 20C are aligned along the direction of side E2 (Y direction) with their sides E2 aligned. The detection elements 20C and 20D are arranged on the surface plate 30A with the detection surface onto which the radiation is incident in contact with the surface of the surface plate 30A (i.e., facing downwards).

[0033] The distance between the sides E1 of detection elements 20A and 20B and the sides E1 of detection elements 20C and 20D is d1, and a gap 25 is formed between detection elements 20A and 20B and detection elements 20C and 20D. The dimensions of the gap 25 are adjusted so that the distance between sides E1 is d1. Dimensional errors of the sides E2 of each detection element are absorbed by the gap 25.

[0034] Subsequently, by moving the reference plate 40A by a distance d1 in the direction of side E2 (Y direction) and repeating the process of arranging two other detection elements in the same manner as above, a 2x4 array configuration as shown in Figure 1 can be formed.

[0035] Here, when the reference plate 40A is moved in the direction of side E2 (Y direction), there is a risk that the already arranged detection elements may move due to friction and disrupt their arrangement. Figures 5A, 5B, 5C, and 5D are plan views showing an example of a manufacturing method that can avoid the movement of the already arranged detection elements.

[0036] Multiple detection elements are arranged using a base plate 30A and a reference plate 40A, as well as a reference plate 40B and a spacer 51 (Figure 5A). The reference plate 40B is a rectangular ruler, with its long side in contact with the side surface 41 of the reference plate 40A with the spacer 51 in between, and its short side in contact with the side surface 42 of the reference plate 40A. The reference plate 40B has a side surface 43 that defines a straight line extending in the X direction. In this example, the straight line defined by the side surface 43 of the reference plate 40B is defined as the first reference line L1, the straight line defined by the side surface 42 of the reference plate 40A is defined as the second reference line L2, and the straight line defined by the side surface 41 of the reference plate 40A is defined as the third reference line L3. The dimensions in the Y direction of the reference plate 40B and the spacer 51 are determined such that the distance between the first reference line L1 and the third reference line L3 is d1. The surface of the base plate 30A is provided with multiple suction ports 50 for fixing pre-arranged detection elements onto the base plate 30A by vacuum suction. The vacuum suction can be switched on and off for each suction port.

[0037] As shown in Figure 5B, on the base plate 30A, each side E1 of the detection elements 20A and 20B is brought into contact with the side surface 43 of the reference plate 40B. That is, each side E1 of the detection elements 20A and 20B is positioned on the first reference line L1. Also, the side E2 of the detection element 20A is brought into contact with the side surface 42 of the reference plate 40A. That is, the side E2 of the detection element 20A is positioned on the second reference line L2. Also, the side E2 of the detection element 20B is brought into contact with the detection element 20A. As a result, the detection elements 20A and 20B are aligned along the direction of side E1 (X direction) with their sides E1 aligned. The detection elements 20A and 20B are arranged on the base plate 30A with the detection surface to which radiation is incident in contact with the surface of the base plate 30A (i.e., downward). After that, vacuum suction is activated by the suction port 50 located directly below the detection elements 20A and 20B. This fixes the detection elements 20A and 20B on the base plate 30A, reducing the risk of their arrangement becoming distorted.

[0038] Next, as shown in Figure 5C, the spacer 51 and the reference plate 40B are removed from the base plate 30A in that order. The reference plate 40A is not moved and remains stationary on the base plate 30A.

[0039] Next, as shown in Figure 5D, each side E1 of the detection elements 20C and 20D is brought into contact with the side surface 41 of the reference plate 40A. That is, each side E1 of the detection elements 20C and 20D is positioned on the third reference line L3. Also, the side E2 of the detection element 20C is brought into contact with the side surface 42 of the reference plate 40A. That is, the side E2 of the detection element 20C is positioned on the second reference line L2. Also, the side E2 of the detection element 20D is brought into contact with the detection element 20C. As a result, the detection elements 20C and 20D are aligned along the direction of side E1 (X direction) with their sides E1 aligned. Also, the detection elements 20A and 20C are aligned along the direction of side E2 (Y direction) with their sides E2 aligned. The detection elements 20C and 20D are arranged on the base plate 30A with their radiation-inducing detection surfaces facing the surface of the base plate 30A (i.e., downwards). Subsequently, vacuum suction is activated by the suction port 50 located directly below the detection elements 20C and 20D. This fixes the detection elements 20C and 20D on the base plate 30A, reducing the risk of their arrangement becoming distorted.

[0040] The distance between the sides E1 of detection elements 20A and 20B and the sides E1 of detection elements 20C and 20D is d1, and a gap 25 is formed between detection elements 20A and 20B and detection elements 20C and 20D. The dimensions of the gap 25 are adjusted so that the distance between sides E1 is d1. Dimensional errors of the sides E2 of each detection element are absorbed by the gap 25.

[0041] As described above, by using a reference plate 40B and spacers 51 in addition to the base plate 30A and reference plate 40A to arrange multiple detection elements, movement of the reference plate 40A becomes unnecessary. This makes it possible to avoid moving the already arranged detection elements. The above effect can be further enhanced by using vacuum suction in combination.

[0042] After the arrangement of the multiple detection elements 20 on the base plate 30A is completed, the multiple detection elements 20 are joined to the fixing plate 12 while maintaining their relative positions. Figures 6A, 6B, and 6C show an example of the process of joining the multiple detection elements 20 to the fixing plate 12.

[0043] As shown in Figure 6A, the base plate 30A is positioned vertically below the plurality of detection elements 20. The plurality of detection elements 20 are arranged on the base plate 30A with the detection surface 26 into contact with the surface of the base plate 30A (i.e., downward). The surface of the base plate 30A is the first reference surface S1. The plurality of detection elements 20 have thickness variations due to dimensional errors in the thickness direction. Therefore, the plurality of detection elements 20 may be arranged on the base plate 30A with uneven height positions on the back surface opposite to the detection surface 26.

[0044] Next, as shown in Figure 6B, adhesive 11 is applied to the back surface of each of the multiple detection elements 20, on the side opposite to the detection surface 26. The adhesive 11 may be made of epoxy resin, for example. Due to its fluidity, the adhesive 11 spreads to fill in the steps caused by variations in the height positions of the back surfaces of the multiple detection elements 20.

[0045] Next, as shown in Figure 6C, a fixing plate 12 is placed on the surface of the adhesive 11. It is preferable that the fixing plate 12 has a certain level of rigidity. Therefore, it is preferable to determine the material of the fixing plate 12 taking rigidity into consideration. Also, it is preferable that the fixing plate 12 has high thermal conductivity in order to promote the diffusion of heat generated by the absorption of radiation by each detection element 20. Therefore, it is preferable to determine the material of the fixing plate 12 taking thermal conductivity into consideration. For example, metal or synthetic resin can be used as the material of the fixing plate 12. Subsequently, a surface plate 30B is placed on the surface of the fixing plate 12 opposite to the surface in contact with the adhesive 11. The contact surface of the surface plate 30B with the fixing plate 12 is designated as the second reference surface S2. The spacer 31 provided between the reference plate 40A and the reference plate 40B maintains the first reference surface S1 and the second reference surface S2 in parallel, and fixes the distance between these surfaces to a predetermined distance d2. The laminate, which includes multiple detection elements 20, adhesive 11, and a fixing plate 12, is sandwiched between a first reference surface S1 defined by a surface plate 30A and a second reference surface S2 defined by a surface plate 30B. The adhesive 11 is then cured by leaving it at room temperature while maintaining the relative positions of the multiple detection elements 20 and the fixing plate 12. The radiation detector 10 is completed by going through the above steps.

[0046] Each of the multiple detection elements 20 is joined to the fixing plate 12 with its detection surface 26 in contact with a first reference surface S1 defined by the base plate 30A. This makes it possible to extend the detection surfaces 26 of each of the multiple detection elements 20 within the same plane (i.e., to align the height positions of the detection surfaces 26). The thickness variations of the multiple detection elements 20 are absorbed by the adhesive 11. Therefore, the adhesive 11 has a thickness profile that corresponds to the thickness variations of the multiple detection elements 20.

[0047] As shown in Figure 7, the fixing plate 12 may be joined to a base plate 13 with a large heat capacity. The heat generated by each detection element 20 absorbing radiation is diffused to the base plate 13 via the adhesive 11 and the fixing plate 12. The greater the thickness of the adhesive 11, the greater the absorption range of thickness variations of the detection element 20, but the lower the thermal conductivity. Therefore, it is preferable to determine the thickness of the adhesive 11 considering both the absorption of thickness variations of the detection element 20 and the thermal conductivity. For example, the type and thickness of the adhesive 11 may be determined such that the ratio C / T of the thermal conductivity C of the adhesive 11 to the thickness T of the adhesive 11 is greater than or equal to a preset threshold. This makes it possible to avoid a significant decrease in either the absorption of thickness variations of the detection element 20 or the thermal conductivity. As the thickness T of the adhesive 11, for example, the thickness of the thickest part, the thickness of the thinnest part, or an intermediate thickness may be applied.

[0048] As described above, the detection element 20 is manufactured with errors in its dimensions in the planar and thickness directions. Therefore, as shown in Figure 8, simply arranging multiple detection elements 20 in a row may result in the accumulation of dimensional errors, potentially degrading the image quality of radiation images captured using the radiation detector. In addition, the height positions of the detection surface 26 to which the radiation enters may become uneven, potentially degrading the image quality of the radiation images.

[0049] In the manufacturing method of the radiation detector 10 according to this embodiment, a plurality of detection elements 20 are arranged so that they are aligned along the direction of side E1 (X direction) and the direction of side E2 (Y direction), respectively, and a gap 25 is formed between the detection elements 20 aligned along the direction of side E2 (Y direction). The dimensions of the gap 25 are adjusted so that the distance between the sides E1 of the detection elements 20 aligned along the direction of side E2 (Y direction) is a predetermined distance d1.

[0050] According to the manufacturing method of this embodiment, the dimensional error of side E2 is absorbed by the gap 25. This makes it possible to avoid the accumulation of dimensional errors of the detection element 20 in the direction of side E2 (Y direction). Since the number of detection elements 20 arranged in the direction of side E1 (X direction) is small, the accumulation of dimensional errors of side E1 can be tolerated.

[0051] Furthermore, the manufacturing method of the radiation detector 10 according to this embodiment includes joining the back surface of each of the plurality of detection elements 20, opposite to the detection surface 26, to the fixing plate 12 via adhesive 11, while the detection surface 26 of each of the plurality of detection elements 20 to which radiation is incident is in contact with the first reference surface S1. The adhesive 11 has a thickness profile corresponding to the thickness variation of the plurality of detection elements 20.

[0052] Here, Figure 9 is a cross-sectional view showing an example of the configuration of a radiation detector 10X according to a comparative example. The radiation detector 10X according to the comparative example is manufactured by applying adhesive 11 to the surface of a fixing plate 12 and placing a plurality of detection elements 20 on the surface of the adhesive 11 with the detection surface 26 facing upward. According to this manufacturing method, due to variations in the thickness of the plurality of detection elements 20, the height positions of the detection surface 26 become uneven, which may degrade the image quality of the radiation images taken using the radiation detector 10X.

[0053] On the other hand, according to the manufacturing method of the radiation detector 10 according to the embodiment of the disclosed technology, each of the plurality of detection elements 20 is joined to the fixing plate 12 with its detection surface 26 in contact with a first reference surface S1 defined by the base plate 30A, so that the detection surfaces 26 of each of the plurality of detection elements 20 can be extended in the same plane (i.e., the height positions of the detection surfaces 26 can be aligned).

[0054] The radiation detector 10 according to the embodiment of the disclosed technology can be applied, for example, to a CT (Computed Tomography) device. In CT devices, there is a trend towards increasing the area of ​​radiation detectors. Figure 10A is a schematic cross-sectional view showing an example of the configuration of a normal CT device 100A having a radiation detector 10 of normal area. Figure 10B is a schematic cross-sectional view showing an example of the configuration of a WD (Wide Detector) CT device 100B having a large-area radiation detector 10.

[0055] A standard 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 a ring-shaped gantry 101. The patient table 102 can slide inward towards 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 standard CT scanner 100A A For example, the imaging width W in the WDCT device 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 enabling the acquisition of clear radiographic images. The radiation detector 10 according to the embodiment of the disclosed technology is composed of a combination of multiple detection elements 20, so it is possible to accommodate a large area of ​​the radiation detector 10 and can be applied to the WDCT device 100B.

[0056] In the WDCT device 100B, overlapping radiation incidence can occur due to the large area (long length) of the radiation detector 10. The incidence angle θ of the radiation emitted from the radiation source to the radiation detector 10 increases towards the edges of the radiation detector 10. This increase in incidence angle θ is more pronounced at the edges of the large area (long length) radiation detector 10. As shown in Figure 11, at the edges of the large area (long length) radiation detector 10, the incidence angle θ of the radiation becomes large enough that overlapping radiation incidence can occur, where the radiation is incident on both of two adjacent pixels 23. Overlapping radiation incidence leads to a deterioration in the image quality of the radiation image taken using the radiation detector 10.

[0057] 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 position. In other words, by forming a multifaceted structure in the radiation detector that is bent at least at one point along one direction, it is possible to avoid overlapping radiation incidence.

[0058] 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 has a first surface 27A, a second surface 27B, and a third surface 27C whose detection surfaces 26 are oriented differently 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 detection surfaces 26 of 2×2 four detection elements 20. The second surface 27B, located in the center in the Y direction, is composed of detection surfaces 26 of 2×4 eight detection elements 20.

[0059] When a three-sided radiation detector 10A is applied to a WDCT device 100B, the direction of side E1 of the detection element 20 (X direction) corresponds to the rotation direction of the radiation detector, and the direction of side E2 of the detection element 20 (Y direction) corresponds to the sliding direction of the examination table 102 (the axis direction of the patient's body).

[0060] The three-sided radiation detector 10A may be manufactured by combining units 60 formed by four 2x2 detection elements 20, for example, as shown in Figure 13. That is, four units 60 are prepared in advance and then connected to complete the three-sided radiation detector 10A. The detection surfaces 26 are oriented in different directions for each unit. As shown in Figure 14, the first surface 27A is formed by the first unit 60A, the second surface 27B is formed by the second unit 60B and the third unit 60C, and the third surface 27C is formed by the fourth unit 60D. The unit 60, consisting of four 2x2 detection elements 20, can be manufactured by the methods shown in Figures 4A to 4D, 5A to 5D, and 6A to 6C.

[0061] The following additional information is disclosed regarding the embodiments described above. (Note 1) A method for manufacturing a radiation detector comprising a plurality of detection elements, each of which includes a plurality of pixels that detect radiation, With the detection surface of each of the plurality of detection elements, onto which radiation is incident, in contact with the first reference surface, the back surface of each of the plurality of detection elements, opposite to the detection surface, is joined to the fixing plate via adhesive. Manufacturing method.

[0062] (Note 2) The adhesive has a thickness profile that corresponds to the thickness variation of the plurality of detection elements. The manufacturing method described in Appendix 1.

[0063] (Note 3) A laminate including the plurality of detection elements, the adhesive, and the fixing plate is sandwiched between a second reference surface, whose distance from the first reference surface is fixed, and the first reference surface. The manufacturing method described in Appendix 1 or Appendix 2.

[0064] (Note 4) The first reference surface is brought into contact with the detection surface of the plurality of detection elements, which is oriented downward in the vertical direction. The manufacturing method described in any one of the appendices 1 to 3.

[0065] (Note 5) Each of the multiple detection elements has a first edge and a second edge that intersects the first edge. The plurality of detection elements, which are arranged along the direction of the first side and the direction of the second side, are joined to the fixing plate. The manufacturing method described in any one of the appendices 1 to 4.

[0066] (Note 6) The ratio C / T of the thermal conductivity C of the adhesive to the thickness T of the adhesive is greater than or equal to a threshold value. The manufacturing method described in any one of the appendices 1 to 5.

[0067] (Note 7) A unit is formed by the multiple detection elements, and multiple units are combined The manufacturing method described in any one of the appendices 1 through 6.

[0068] (Note 8) The orientation of the detection surface differs for each unit. The manufacturing method described in Appendix 7.

[0069] (Note 9) The material of the fixing plate is determined considering rigidity. The manufacturing method described in any one of the appendices 1 through 8.

[0070] (Note 10) The material of the fixing plate is determined considering its thermal conductivity. The manufacturing method described in any one of the appendices 1 through 9.

[0071] (Note 11) Multiple detection elements, each composed of multiple pixels that detect radiation, A fixing plate is bonded to the back surface of the plurality of detection elements, on the side opposite to the detection surface from which radiation is incident, via adhesive. Includes, The detection surfaces of each of the plurality of detection elements extend within the same plane. Radiation detector.

[0072] (Note 12) The adhesive has a thickness profile that corresponds to the thickness variation of the plurality of detection elements. The radiation detector described in Appendix 11. [Explanation of Symbols]

[0073] 10, 10A, 10X radiation detectors 11 Adhesives 12 Fixed plate 13 Base plate 20, 20A, 20B, 20C, 20D detection elements 21 Scintillator 22 Photodetector 23 pixels 25 gaps 26 Detection surface 30A, 30B Surface Plate 31 Spacers 40A, 40B reference plate 51 Spacer 60, 60A, 60B, 60C units 100A CT device 100B WDCT device 101 Gantry 102 berths 103 Source L1 First reference line L2 Second reference line L3 Third reference line S1 First reference plane S2 Second reference plane

Claims

1. A method for manufacturing a radiation detector comprising a plurality of detection elements, each of which includes a plurality of pixels that detect radiation, With the detection surface of each of the plurality of detection elements, onto which radiation is incident, in contact with the first reference surface, the back surface of each of the plurality of detection elements, opposite to the detection surface, is joined to the fixing plate via adhesive. Manufacturing method.

2. The adhesive has a thickness profile that corresponds to the thickness variation of the plurality of detection elements. The manufacturing method according to claim 1.

3. A laminate including the plurality of detection elements, the adhesive, and the fixing plate is sandwiched between a second reference surface, whose distance from the first reference surface is fixed, and the first reference surface. The manufacturing method according to claim 1.

4. The first reference surface is brought into contact with the detection surface of the plurality of detection elements, which is oriented downward in the vertical direction. The manufacturing method according to claim 1.

5. Each of the multiple detection elements has a first edge and a second edge that intersects the first edge. The plurality of detection elements, which are arranged along the direction of the first side and the direction of the second side, are joined to the fixing plate. The manufacturing method according to claim 1.

6. The ratio C / T of the thermal conductivity C of the adhesive to the thickness T of the adhesive is greater than or equal to a threshold. The manufacturing method according to claim 1.

7. A unit is formed by the multiple detection elements, and multiple units are combined The manufacturing method according to claim 1.

8. The orientation of the detection surface differs for each unit. The manufacturing method according to claim 7.

9. The material of the fixing plate is determined considering rigidity. The manufacturing method according to claim 1.

10. The material of the fixing plate is determined considering its thermal conductivity. The manufacturing method according to claim 1.

11. Multiple detection elements, each composed of multiple pixels that detect radiation, A fixing plate is bonded to the back surface of the plurality of detection elements, on the side opposite to the detection surface from which radiation is incident, via adhesive. Includes, The detection surfaces of each of the plurality of detection elements extend within the same plane. Radiation detector.

12. The adhesive has a thickness profile that corresponds to the thickness variation of the plurality of detection elements. The radiation detector according to claim 11.

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