Radiation detector

Abstract

To provide a radiation detector which has flexibility and is capable of obtaining a very sharp radiation transmission image.SOLUTION: A radiation detector includes: a scintillator which has a first surface to which radiation is made incident and a second surface opposite the first surface and converts the radiation into fluorescence; a sensor which is provided on the second surface side in the scintillator, and has a light receiving surface for receiving the fluorescence converted by the scintillator; and a plurality of members reflecting or absorbing the fluorescence converted by the scintillator. The scintillator and the sensor are variable in a curved state in a first direction, each of the plurality of members is parallel to the light receiving surface, has a slender shape with a second direction crossing the first direction as a longitudinal direction, and is provided at a part nearer the second surface than the first surface in the scintillator.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to radiation detectors. [Background technology]

[0002] Generally, a radiographic image capturing device is known that captures a radiographic image of a subject by detecting radiation emitted from a radiation source and transmitted through the subject with a radiation detector. Also, a technology for capturing a highly sharp image as a radiographic image is known. For example, Patent Document 1 discloses a technology in which a partition is provided on a sensor substrate on which a sensor for receiving fluorescence is provided as a scintillator for converting radiation into fluorescence, and a scintillator panel in which a phosphor is filled in cells partitioned by the partition is used in a radiation detector. According to the technology described in Patent Document 1, the partition prevents the fluorescence converted from radiation by the scintillator from scattering, and the fluorescence can be guided to the sensor, so that a highly sharp radiographic image can be obtained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 021540 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, non-destructive testing using radiation is performed. As a technique related to this non-destructive testing, a radiation detector is wrapped around the outer periphery of the welded part of the steel pipe to be tested, and a radiation source is arranged on the central axis of the steel pipe, and radiation is irradiated from the radiation source, and a radiological image generated by the radiation detector is obtained. In this non-destructive testing, the radiation detector needs to be curved in order to be wrapped around the outer periphery of the steel pipe. Therefore, a flexible radiation detector is desired.

[0005] However, with the technique described in Patent Document 1, the partition wall gets in the way and the radiation detector cannot be curved sufficiently, so that a flexible radiation detector may not be obtained.

[0006] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a radiation detector that is flexible and capable of obtaining a highly sharp radiotransmitted image. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a radiation detector of a first aspect of the present disclosure comprises a scintillator having a first surface onto which radiation is incident and a second surface opposite the first surface and converting radiation into fluorescence, a sensor provided on the side of the second surface of the scintillator and having a light receiving surface for receiving the fluorescence converted by the scintillator, and a plurality of members that reflect or absorb the fluorescence converted by the scintillator, wherein the curvature state of the scintillator and the sensor is variable in a predetermined direction, and each of the plurality of members has an elongated shape whose longitudinal direction is a direction intersecting with the light receiving surface of the sensor, and is provided at a position within the scintillator closer to the second surface than the first surface.

[0008] Furthermore, in order to achieve the above object, a radiation detector of a second aspect of the present disclosure is the radiation detector of the first aspect, further comprising: a scintillator having a first surface into which radiation is incident and a second surface opposite the first surface, and converting radiation into fluorescence; a sensor provided on the side of the second surface of the scintillator and having a light-receiving surface for receiving the fluorescence converted by the scintillator; and a plurality of members that reflect or absorb the fluorescence converted by the scintillator, wherein the curvature state of the scintillator and the sensor is variable in a first direction, and each of the plurality of members is parallel to the light-receiving surface and has an elongated shape with a second direction intersecting the first direction as its longitudinal direction, and is provided at a position within the scintillator closer to the second surface than the first surface.

[0009] Furthermore, a radiation detector of a third aspect of the present disclosure is the radiation detector of the first or second aspect, wherein the sensor has a sensor portion provided for each of the plurality of pixels, and the plurality of components are arranged at intervals shorter than the pitch of the pixels.

[0010] Furthermore, a radiation detector of a fourth aspect of the present disclosure is a radiation detector of any one of the first to third aspects, wherein the sensor has a sensor portion provided for each of the plurality of pixels, and the plurality of components are arranged at intervals shorter than the pitch of the pixels.

[0011] Furthermore, a radiation detector according to a fifth aspect of the present disclosure is a radiation detector according to any one of the first to fourth aspects, wherein the length of the multiple components in a direction intersecting the light receiving surface is equal to or greater than the distance between the multiple components.

[0012] A radiation detector according to a sixth aspect of the present disclosure is a radiation detector according to any one of the first to fifth aspects, wherein the length of the plurality of components in a direction intersecting the light receiving surface is equal to or less than the length of the light receiving surface for each pixel.

[0013] Furthermore, a radiation detector of a seventh aspect of the present disclosure is a radiation detector of any one of the first to sixth aspects, in which a plurality of granular fluorescent filter materials that emit secondary electrons when irradiated with radiation are provided on the first surface side of the scintillator.

[0014] A radiation detector according to an eighth aspect of the present disclosure is a radiation detector according to any one of the first to seventh aspects, wherein the curved state is variable so as to conform to the outer shape of the object to be inspected.

[0015] A radiation detector according to a ninth aspect of the present disclosure is the radiation detector according to any one of the first to seventh aspects, wherein the curved state is variable so as to conform to the outer shape of the object to be inspected. Effect of the Invention

[0016] According to the present disclosure, it is possible to obtain a flexible and highly sharp radiographic image. [Brief description of the drawings]

[0017] [Figure 1] 1 is a side cross-sectional view showing an example of a configuration of a radiographic image capturing apparatus according to an embodiment; [Diagram 2] 2 is a block diagram showing an example of a main configuration of an electrical system of the radiographic image capturing apparatus according to the embodiment; FIG. [Diagram 3] 1 is a side cross-sectional view showing an example of the configuration of a radiation detector according to a first embodiment. [Figure 4] 4 is a cross-sectional view of the radiation detector shown in FIG. 3 taken along line AA as viewed from the side irradiated with radiation. [Figure 5A] 11 is a diagram for explaining the maximum length of a member in the longitudinal direction and the maximum spacing between the members. FIG. [Figure 5B] 11A and 11B are diagrams for explaining the minimum length of a member in the longitudinal direction and the minimum spacing between members. [Figure 6A] 1A and 1B are diagrams for explaining an inspection object and an inspection target part according to an embodiment; [Figure 6B] 1 is a diagram showing an example of a state in which a radiographic image capturing apparatus according to an embodiment is provided on an object to be inspected. [Figure 7] 13 is a diagram for explaining an example of the length in the longitudinal direction of a member when the radiation detector is curved along an inspection object. FIG. [Figure 8] FIG. 11 is a side cross-sectional view showing an example of the configuration of a radiation detector according to a second embodiment. [Figure 9] 9 is a cross-sectional view of the radiation detector shown in FIG. 8 taken along line AA as viewed from the side irradiated with radiation. [Figure 10] 10 is a side cross-sectional view showing an example of the configuration of a radiation detector according to Modification 1. FIG. [Figure 11] 11 is a side cross-sectional view showing an example of the configuration of a radiation detector according to Modification 2. FIG. [Figure 12] 13 is a side cross-sectional view showing an example of the configuration of a radiation detector according to Modification 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, examples of embodiments for carrying out the technology of the present disclosure will be described in detail with reference to the drawings.

[0019] [First embodiment] First, the configuration of a radiographic image capturing device 10 of this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the radiographic image capturing device 10 includes a housing 21 that transmits radiation, and a radiation detector 20 that detects radiation that has transmitted through an object to be inspected is provided within the housing 21. The radiation detector 20, details of which will be described later, includes a scintillator 22 that converts incident radiation R into fluorescence, and a sensor board 30 on which a plurality of sensor units 32A that receive the fluorescence converted by the scintillator 22 are provided. Also provided within the housing 21 are a control board 26, a case 28, a gate wiring driver 52, and a signal processing unit 54.

[0020] The case 28 and the gate wiring driver 52, and the control board 26 and the signal processing unit 54 are provided on opposite sides of the radiation detector 20, with the radiation detector 20 in between. Note that the case 28 and the gate wiring driver 52, and the control board 26 and the signal processing unit 54 may be provided on the same side of the radiation detector 20.

[0021] The control board 26 has electronic circuits formed thereon, such as an image memory 56, a control unit 58, and a communication unit 66, which will be described later. The case 28 houses a power supply unit 70, which will be described later, and the like.

[0022] Next, the main configuration of the electrical system of the radiographic imaging device 10 of this embodiment will be described with reference to Fig. 2. As shown in Fig. 2, a plurality of pixels 32 are two-dimensionally arranged on the sensor substrate 30 in one direction (row direction in Fig. 2) and an intersecting direction (column direction in Fig. 2) intersecting the one direction. The pixels 32 include the above-mentioned sensor unit 32A and a field effect thin film transistor (TFT (Thin Film Transistor), hereinafter simply referred to as "thin film transistor") 32B. The sensor unit 32A of this embodiment is an example of a sensor of the present disclosure.

[0023] The sensor unit 32A includes an upper electrode, a lower electrode, a photoelectric conversion film, etc. (not shown), absorbs light emitted by the scintillator 22 to generate charges, and accumulates the generated charges. The thin film transistor 32B converts the charges accumulated in the sensor unit 32A into an electric signal and outputs it.

[0024] The sensor substrate 30 is also provided with a plurality of gate wirings 34 extending in the one direction for turning on and off each thin film transistor 32B. The sensor substrate 30 is also provided with a plurality of data wirings 36 extending in the intersecting direction for reading out charges via the thin film transistors 32B in the ON state. Each of the gate wirings 34 of the sensor substrate 30 is connected to a gate wiring driver 52, and each of the data wirings 36 of the sensor substrate 30 is connected to a signal processing unit 54.

[0025] The thin film transistors 32B of the sensor substrate 30 are turned on in sequence row by row by an electrical signal supplied from the gate line driver 52 via the gate line 34. Then, the charges read out by the thin film transistors 32B turned on are transmitted as electrical signals through the data line 36 and input to the signal processing unit 54. As a result, the charges are read out in sequence row by row, and image data representing a two-dimensional radiographic image is obtained.

[0026] The signal processing unit 54 includes an amplifier circuit and a sample-and-hold circuit (both not shown) for amplifying the input electrical signal for each data wiring 36, and the electrical signal transmitted through each data wiring 36 is amplified by the amplifier circuit and then held in the sample-and-hold circuit. A multiplexer and an AD (Analog-to-Digital) converter are connected in sequence to the output side of the sample-and-hold circuit. The electrical signals held in each sample-and-hold circuit are input in sequence (serial) to the multiplexer, and the electrical signals selected in sequence by the multiplexer are converted into digital image data by the AD converter.

[0027] A control unit 58, which will be described later, is connected to the signal processing unit 54, and image data output from the AD converter of the signal processing unit 54 is sequentially output to the control unit 58. An image memory 56 is connected to the control unit 58, and the image data sequentially output from the signal processing unit 54 is sequentially stored in the image memory 56 under the control of the control unit 58. The image memory 56 has a storage capacity capable of storing a predetermined number of pieces of image data, and each time a radiographic image is captured, the image data obtained by the capture is sequentially stored in the image memory 56.

[0028] The control unit 58 includes a CPU (Central Processing Unit) 60, a memory 62 including a ROM (Read Only Memory) and a RAM (Random Access Memory), and a non-volatile storage unit 64 such as a flash memory. An example of the control unit 58 is a microcomputer.

[0029] The communication unit 66 is connected to the control unit 58, and transmits and receives various information to and from external devices via communication means such as wireless communication and wired communication. The power supply unit 70 supplies power to the various circuits and elements such as the gate line driver 52, the signal processing unit 54, the image memory 56, the control unit 58, and the communication unit 66. Note that in Fig. 2, in order to avoid confusion, the wiring connecting the power supply unit 70 to the various circuits and elements is omitted.

[0030] Next, the configuration of the radiation detector 20 of this embodiment will be described in detail with reference to Fig. 3 and Fig. 4. Fig. 3 is a side cross-sectional view showing an example of the configuration of the radiation detector 20 of this embodiment. Fig. 4 is a cross-sectional view taken along line AA of the radiation detector 20 shown in Fig. 3, viewed from the side irradiated with radiation R. For ease of explanation, Fig. 3 also shows the sensor substrate 30 and sensor unit 32A below the scintillator 22.

[0031] As described above, the radiation detector 20 of this embodiment includes the scintillator 22 and the sensor substrate 30. The scintillator 22 and the sensor substrate 30 are laminated in this order from the incident side of radiation R. That is, the radiation detector 20 is a PSS (Penetration Side Sampling) type radiation detector in which radiation R is irradiated from the scintillator 22 side (see also FIG. 1).

[0032] The scintillator 22 has a first surface 22A on which the radiation R is incident and a second surface 22B opposite to the first surface 22A, and converts the radiation R into fluorescence. In this embodiment, when the "upper" and "lower" of the radiation detector 20 are used, the scintillator 22 is used as a reference. For example, the first surface 22A of the scintillator 22 is the "upper" surface of the scintillator 22, and the second surface 22B is the "lower" surface of the scintillator 22. The scintillator 22 is provided on the sensor substrate 30. The scintillator 22 in this embodiment is composed of phosphors 22G (see Figs. 5A and 5B) dispersed in a binder such as a resin. In this embodiment, GOS (Gd2O2S:Tb, gadolinium sulfate) 22G (see Figs. 5A and 5B) is used as an example of the phosphor 22G.

[0033] As described above, the sensor substrate 30 has a plurality of sensor units 32A corresponding to the pixels 32 provided on the base material 31. Each of the plurality of sensor units 32A is provided on the second surface 22B side of the scintillator 22, and has a light receiving surface 32P that receives the fluorescence converted by the scintillator 22. On the other hand, the base material 31 has flexibility, and is, for example, a resin sheet containing plastic such as PI (PolyImide). The thickness of the base material 31 of the sensor substrate 30 may be a thickness that provides a desired flexibility depending on the hardness of the material, the size of the sensor substrate 30, and the like. The thickness of the base material 31 may be, for example, 5 μm to 125 μm, and more preferably 20 μm to 50 μm. A specific example of the base material 31 is XENOMAX (registered trademark).

[0034] Moreover, the radiation detector 20 of this embodiment includes a plurality of members 40 that reflect or absorb the fluorescence converted by the scintillator 22 .

[0035] Each of the multiple members 40 is provided at a position closer to the second surface 22B than to the first surface 22A within the scintillator 22. In other words, each of the multiple members 40 is provided on the second surface 22B side within the scintillator 22. As shown in Fig. 3 as an example, each of the multiple members 40 in this embodiment is provided in contact with the light receiving surface 32P of the sensor unit 32A.

[0036] As described above, the scintillator 22 converts radiation R into fluorescence. In the scintillator 22, the lower the energy of the radiation R, the closer the position of the radiation R to the first surface 22A on which the radiation R is incident is to be converted into fluorescence. In other words, in the scintillator 22, the higher the energy of the radiation R, the closer the position of the radiation R to the second surface 22B is to be converted into fluorescence. The fluorescence converted from the radiation R is emitted in any direction of 360 degrees and is attenuated in the process of reaching the sensor unit 32A. In the radiation detector 20 of this embodiment, a member 40 that reflects or absorbs fluorescence is provided in a position close to the sensor unit 32A in the scintillator 22, thereby suppressing scattering of the fluorescence converted in a position close to the sensor unit 32A and guiding the fluorescence to the sensor unit 32A.

[0037] 3 and 4, each of the members 40 has an elongated shape with its longitudinal direction being the Z direction, which is a direction intersecting with the light receiving surface 32P of the sensor unit 32A. As an example, the member 40 in this embodiment has a rectangular prism shape. In this case, the length L in the Z axis direction, which is the longitudinal length of the member 40, is Z corresponds to the height of the rectangular prism. The longitudinal length L of the member 40 Z The longer the length L of the member 40 in the longitudinal direction, the sharper the radiographic image obtained by the radiation detector 20 will be. Z However, if the thickness of the member 40 is equal to the thickness H of the scintillator 22, the radiation detector 20 cannot be bent sufficiently, or the member 40 may be broken by bending the member 40. Z is shorter than the thickness H of the scintillator 22 and has a length L in the X-axis direction. X and the length in the Y-axis direction L Y longer than each of (L Z <H、L Z >L X , and L Z >LY).

[0038] The longitudinal length L of the member 40 in this embodiment Z The following provides further explanation. From the viewpoint of reflecting the fluorescence converted from the radiation R by the scintillator 22 by the member 40, the length L of the member 40 in the longitudinal direction is Z First, referring to FIG. 5A, the length L of the member 40 in the longitudinal direction can be determined as follows. Z The maximum value of the length L of the member 40 in the longitudinal direction and the maximum value of the interval W of the member 40 will be described. Z and the maximum value of the interval W of the members 40 are preferably determined in accordance with the specular reflection of the fluorescence F by the members 40. In order for the fluorescence F converted from the radiation R in the radiation detector 20 to be reflected by the member 40 and guided to the sensor unit 32A, the fluorescence F is specularly reflected by the member 40. In order for the fluorescence F to be specularly reflected, the incident angle θ α and reflection angle θ βTherefore, in the radiation detector 20 of this embodiment, the length L of the member 40 in the longitudinal direction is smaller than 45°. Z The length L of the sensor part 32A PX Below (L Z ≦L PX In the radiation detector 20 of this embodiment, the length L of the member 40 in the longitudinal direction is Z The spacing between the members 40 is W or more (L Z Since the plurality of members 40 are disposed at intervals shorter than the pitch of the pixels 32, the interval W between the members 40 is set to be equal to or larger than the length L of the sensor unit 32A. PX (W≦L PX ).

[0039] Next, referring to FIG. 5B, the longitudinal length L Z The minimum value of the length L of the member 40 in the longitudinal direction and the minimum value of the interval W of the member 40 will be described. Z It is preferable that the minimum value of and the minimum value of the interval W of the member 40 are determined according to the Fresnel reflection between the phosphor 22G and the member 40. Total reflection in Fresnel reflection depends on the Brewster angle β, which is determined by the refractive index of the phosphor 22G and the binder (hereinafter referred to as the "first refractive index") and the refractive index of the member 40 (hereinafter referred to as the "second refractive index"). Therefore, the longitudinal length L of the member 40 Z and the minimum value of the interval W of the members 40 are determined by the incidence angle θ α and reflection angle θ β It is preferable that the following formula (1) is satisfied, where is the Brewster angle β. Note that, in the member 40 of the present embodiment, the Brewster angle β is 60° to 70° when the first refractive index is relatively smaller than the second refractive index (first refractive index<<second refractive index). W≧L Z ×1 / tanβ (1)

[0040] In addition, from the viewpoint of bending the radiation detector 20, the length L of the member 40 in the longitudinal direction Zis determined as follows. As an example, as shown in FIG. 6A, when the object 18 to be inspected in non-destructive inspection is a cylindrical object such as a pipe of a natural gas pipeline, and the part 19 to be inspected is a welded part of two pipes, as shown in FIG. 6B, the radiographic image capturing device 10 is wrapped around the object 18 in a curved state along the outer shape of the object 18. In other words, the radiographic image capturing device 10 of this embodiment captures a radiographic image of the part 19 to be inspected while wrapped around the object 18. As shown in FIG. 7, as the radiographic image capturing device 10 curves, the radiation detector 20 also curves. Therefore, the longitudinal length L of the member 40 Z , and the interval W of the members 40 are set to values ​​that allow the radiation detector 20 to bend in accordance with the inspection object 18. Z is shorter than the thickness H of the scintillator 22. In addition, for example, the length L of the member 40 in the longitudinal direction is set to 100 mm so that the tips of the members 40 do not come into contact with each other when the radiation detector 20 is curved. Z , and a spacing W between the members 40 is preferably determined.

[0041] In this way, it is preferable to determine the longitudinal length LZ of the members 40 and the interval W between the members 40 by taking into consideration both the reflection of the fluorescence F by the members 40 and the curvature of the radiation detector 20.

[0042] As described above, a plurality of members 40 are present within the sensor section 32A. Since the region of the sensor section 32A where the member 40 and the light receiving surface 32P are in contact does not receive the fluorescent light F, the aperture ratio of the sensor section 32A, in other words, the region of the sensor section 32A that receives the light, depends on the area of ​​the sensor section 32A covered by the member 40. Therefore, it is preferable that the number of members 40 present within the sensor section 32A, that is, the density of the members 40, is determined according to the desired sensitivity of the sensor section 32A. For example, when the inspection target 18 is a steel pipe, it is preferable that the area of ​​the sensor section 32A covered by the member 40 is 50% or less of the area of ​​the light receiving surface 32P of the sensor section 32A. Specifically, the length L of the member 40 is X and length L YThe product of these and the number n of members 40 present in the sensor unit 32A is the area (L PX ×L PY ) or less (L X ×L Y ×n≦L PX ×L PY ×½). Note that the aperture ratio of the sensor unit 32A in each of the plurality of pixels 32 may differ depending on the arrangement of the member 40. That is, a difference in sensitivity may occur between the pixels 32. In such a case, the control unit 58 or the like may carry out a correction process on the radiographic image obtained by the radiation detector 20 to correct the difference in sensitivity.

[0043] As described above, the material for forming the member 40 may be any material having a second refractive index that can cause Fresnel reflection in the member 40, and examples of such materials include siloxane resin, silica particles, and surfactants. Note that in the Fresnel reflection in the member 40, components that travel in directions other than toward the sensor substrate 30 are scattered light, and can be ignored because they do not directly enter the sensor substrate 30. In addition, with regard to the surface roughness of the member 40, it is considered that Fresnel reflection occurs when the surface is smooth, and scattering occurs when the surface is rough. When scattering occurs, the scattered light does not directly enter the sensor substrate 30 as described above, and can be ignored.

[0044] The method of manufacturing the radiation detector 20 of this embodiment is not particularly limited. For example, a sensor substrate 30 provided with the sensor portion 32A, a sheet material provided with a plurality of members 40, and a sheet material of the scintillator 22 coated with the phosphor 22G are prepared. Furthermore, the radiation detector 20 may be manufactured by sequentially stacking the sheet material provided with the members 40 and the sheet material of the scintillator 22 coated with the phosphor 22G on the sensor substrate 30. Also, for example, the plurality of members 40 are formed by coating on the sensor substrate 30 provided with the sensor portion 32A. Then, the phosphor 22G is applied on the sensor substrate 30 on which the plurality of members 40 are formed to form the scintillator 22, thereby manufacturing the radiation detector 20.

[0045] As described above, the radiation detector 20 of the present embodiment includes a scintillator 22 having a first surface 22A onto which radiation R is incident and a second surface 22B opposite to the first surface 22A, and converting radiation R into fluorescence F, a sensor unit 32A provided on the second surface 22A side of the scintillator 22 and having a light receiving surface 32P that receives the fluorescence F converted by the scintillator 22, and a plurality of members 40 that reflect or absorb the fluorescence F converted by the scintillator 22. Each of the plurality of members 40 has an elongated shape whose longitudinal direction is the Z-axis direction intersecting with the light receiving surface 32P of the sensor unit 32A, and is provided at a position within the scintillator 22 closer to the second surface 22B than to the first surface 22A.

[0046] In the radiation detector 20 of this embodiment, a plurality of members 40 that reflect or absorb the fluorescence F are provided in the scintillator 22, and the fluorescence F can be reflected by the members 40 and guided to the light receiving surface 32P of the sensor unit 32A, so that a highly sharp radiographic image can be obtained. In addition, each of the plurality of members 40 has an elongated shape with the Z-axis direction intersecting with the light receiving surface 32P of the sensor unit 32A as the longitudinal direction, and is provided at a position closer to the second surface 22B than the first surface 22A in the scintillator 22, so that the radiation detector 20 can have flexibility. Specifically, the radiation detector 20 of this embodiment can be curved in both the X-axis direction and the Y-axis direction. Furthermore, even when the radiation detector 20 is curved, the members 40 can be prevented from being broken. Therefore, the radiation detector 20 of this embodiment can have flexibility and can have a highly sharp radiographic image.

[0047] In the radiation detector 20 of this embodiment, the length L of the sensor unit 32A in the X-axis direction is PX Compared to the length L of the member 40 in the X-axis direction X is sufficiently short, and the length L PY Compared to the length L of the member 40 in the Y-axis direction Yis sufficiently short, the radiation detector 20 can be easily bent in both the X-axis direction and the Y-axis direction. That is, the radiation detector 20 of this embodiment is not limited in the direction in which the radiation detector 20 can be bent. In order to increase the degree of freedom in the direction in which the radiation detector 20 can be bent, the length L of the member 40 in the X-axis direction is X and the length in the Y-axis direction L Y It is preferable that the difference between is relatively small.

[0048] In the radiation detector 20 of this embodiment, the multiple members 40 are arranged at intervals shorter than the pitch of the pixels 32. Specifically, the interval W between the members 40 is set to be equal to or smaller than the length L of the sensor unit 32A. PX Therefore, alignment between the pixel 32 and the member 40 is not necessary.

[0049] In this embodiment, the shape of the member 40 is a quadrangular prism whose cross section in the XY plane is rectangular, but the shape of the member 40 is not limited to this embodiment. For example, the shape of the member 40 may be a quadrangular prism whose cross section is square, or a cylinder whose cross section is circular.

[0050] [Second embodiment] In this embodiment, another embodiment of the radiation detector 20 will be described. Fig. 8 is a side cross-sectional view showing an example of the configuration of the radiation detector 20 of this embodiment. Fig. 9 is a cross-sectional view of the radiation detector 20 shown in Fig. 8 taken along line AA as viewed from the side where radiation R is irradiated. For ease of explanation, Fig. 9 also shows the sensor substrate 30 and sensor unit 32A below the radiation detector 20.

[0051] 8 and 9, in this embodiment, the radiation detector 20 can be bent in the X-axis direction, and each of the multiple members 40 is parallel to the light receiving surface 32P and has an elongated shape with the Y-axis direction intersecting the X-axis direction as its longitudinal direction. That is, while the member 40 in the first embodiment has an elongated shape with the Z-axis direction as its longitudinal direction, the member 40 in this embodiment has an elongated shape with the Y-axis direction intersecting the X-axis direction as its longitudinal direction. The X-axis direction in this embodiment is an example of a first direction in the present disclosure, and the Y-axis direction in this embodiment is an example of a second direction in the present disclosure.

[0052] Specifically, as shown in FIG. 8, the side cross section of each of the multiple members 40 of this embodiment, i.e., the shape in the XZ plane, is similar to the side cross section of each of the multiple members 40 of the first embodiment (see FIG. 3).

[0053] On the other hand, as shown in Fig. 9, each of the members 40 of this embodiment has a different shape from the member 40 of the first embodiment (see Fig. 4). Y is the length L of pixel 32 in the Y-axis direction PY longer than (L Y >L PY As an example, in this embodiment, the length L of each of the members 40 in the Y-axis direction is Y is set to be equal to the length in the Y-axis direction of the scintillator 22. However, the length in the Y-axis direction of each of the members 40 is not limited to this.

[0054] Thus, in this embodiment, each of the multiple members 40 has an elongated shape with the Y-axis direction as the longitudinal direction. In other words, in this embodiment, each of the multiple members 40 is arranged approximately parallel to one another while extending in the Y-axis direction. Therefore, in the radiation detector 20 of this embodiment, regardless of the length LY of the members 40 in the Y-axis direction, the radiation detector 20 can be bent in the X-axis direction. In other words, by setting the above-mentioned Y-axis direction of the radiation detector 20 to a direction along the axial direction of the steel pipe, which is the inspection object 18, the radiation detector 20 can be bent and wrapped around the inspection object 18.

[0055] In this embodiment, each of the members 40 has a length L Z , and the interval W between the members 40 are the length L in the Z-axis direction of each of the multiple members 40 in the first embodiment. Z , and the interval W between the members 40, etc. may be set in the same manner.

[0056] As described above, the radiation detector 20 of this embodiment includes a scintillator 22 having a first surface 22A on which radiation R is incident and a second surface 22B opposite to the first surface 22A, and converting radiation R into fluorescence F, a sensor unit 32A provided on the second surface 22A side of the scintillator 22 and having a light receiving surface 32P that receives the fluorescence F converted by the scintillator 22, and a plurality of members 40 that reflect or absorb the fluorescence F converted by the scintillator 22. The scintillator 22 and the sensor unit 32A are curved in the X-axis direction. Each of the plurality of members 40 is parallel to the light receiving surface 32P, has an elongated shape with the Y-axis direction intersecting the X-axis direction as its longitudinal direction, and is provided at a position closer to the second surface 22B than to the first surface 22A in the scintillator 22.

[0057] In the radiation detector 20 of this embodiment, a plurality of members 40 that reflect or absorb the fluorescence F are provided in the scintillator 22, and the fluorescence F can be reflected by the members 40 and guided to the light receiving surface 32P of the sensor unit 32A, so that a highly sharp radiographic image can be obtained. In addition, each of the plurality of members 40 has an elongated shape with the Z-axis direction intersecting with the light receiving surface 32P of the sensor unit 32A as the longitudinal direction, and is provided at a position closer to the second surface 22B than the first surface 22A in the scintillator 22, so that the members 40 can be flexible and bendable in the X-axis direction. In addition, even when the radiation detector 20 is bent, the members 40 can be prevented from being broken. Therefore, according to the radiation detector 20 of this embodiment, a highly sharp radiographic image can be obtained that is flexible.

[0058] According to the member 40 of the radiation detector 20 of this embodiment, the length L YSince the length of the curved portion can be made sufficiently long, the direction in which the radiation detector 20 can be curved is limited, but the sharpness of the radiographic image can be increased.

[0059] The radiation detector 20 and the member 40 may be, for example, in the form of any of the following modified examples 1 to 3.

[0060] (Variation 1) Fig. 10 is a side cross-sectional view showing an example of the configuration of a radiation detector 20 of this modified example. In the radiation detector 20 of this modified example shown in Fig. 10, a plurality of granular fluorescent filter materials 42 that emit secondary electrons when irradiated with radiation R are provided on the first surface 22A side of the scintillator 22.

[0061] When the fluorescent filter material 42 is irradiated with radiation R, it emits secondary electrons (recoil electrons) from the surface of the fluorescent filter material 42 due to Compton scattering. In the scintillator 22, the sensitivity is improved by the sensitization effect of the secondary electrons emitted by the fluorescent filter material 42. In other words, the fluorescent filter material 42 functions as an activator material in the scintillator 22. In this modification, the fluorescent filter material 42 is provided on the first surface 22A side of the scintillator 22, so that the sensitivity of the portion of the scintillator 22 on the first surface 22 side can be improved. Therefore, the radiation transmission image obtained by the radiation detector 20 can be made into a sharper image. In addition, the fluorescent filter material 42 can suppress scattering of the fluorescence F converted by the scintillator 22, so that the radiation transmission image obtained by the radiation detector 20 can be made into a sharper image.

[0062] Examples of such fluorescent filter materials 42 are preferably terbium (Tb), dysprosium (Dy), cesium (Ce), etc., and other metals and metal compounds such as lead (Pb), copper (Cu), tungsten (Tg), tantalum (Tn), steel, stainless steel, brass, aluminum (Al), nickel (Ni), cobalt (Co), silver (Ag), gold (Au), and platinum (Pt).

[0063] In this manner, in the radiation detector 20 of this embodiment, the scintillator 22 may be, for example, a GOS phosphor (Gd2O2S:Tb, gadolinium sulfate) containing a fluorescent filter material 42 that functions as an activator.

[0064] (Variation 2) FIG. 11 is a side cross-sectional view showing an example of the configuration of the radiation detector 20 of this modified example. As shown in FIG. 11, in this modified example, the position in the Z-axis direction at which each of the multiple members 40 is provided is different from each of the above-mentioned embodiments. In each of the above-mentioned embodiments, each of the multiple members 40 is provided in contact with the light receiving surface 32P of the sensor section 32A. In contrast, each of the multiple members 40 in this modified example is not in contact with the light receiving surface 32P of the sensor section 32A. Note that, also in this modified example, each of the multiple members 40 is provided at a position closer to the second surface 22B than to the first surface 22A in the scintillator 22. Specifically, the length L of the member 40 in the Z-axis direction is Z The center position of the thickness H of the scintillator 22 is closer to the sensor portion 32A than the center position of the thickness H of the scintillator 22.

[0065] In this way, even if each of the multiple members 40 is provided in a state where it is not in contact with the light receiving surface 32P of the sensor section 32A, by providing them at a position closer to the second surface 22B than to the first surface 22A in the scintillator 22, it is possible to obtain a highly sharp image with the radiation detector 20 of this modified example, as in the above-described embodiments. Furthermore, by giving each of the multiple members 40 the shape of the member 40 of the first embodiment or the member 40 of the second embodiment, it is possible to make the radiation detector 20 flexible.

[0066] When the radiation detector 20 is curved, distortion may occur at the interface between the member 40 and the sensor unit 32A (sensor substrate 32), i.e., the light receiving surface 32P. In such a case, by providing the member 40 in a state where it is not in contact with the light receiving surface 32P of the sensor unit 32A, it is possible to prevent the member 40 from being damaged by the generated distortion.

[0067] (Variation 3) Fig. 12 is a side cross-sectional view showing an example of the configuration of radiation detector 20 of this modified example. In radiation detector 20 of this modified example, multiple members 40 are arranged side by side in the X-axis direction in scintillator 22. In other words, two stages of members 40 are included in scintillator 22. In radiation detector 20 shown in Fig. 12, members 40 are provided that include multiple members 401 provided closer to first surface 22A of scintillator 22 and multiple members 402 provided closer to second surface 22B.

[0068] In this embodiment, each of the multiple members 401 is also provided at a position closer to the second surface 22B than to the first surface 22A in the scintillator 22. Specifically, the length L Z1 The center position of the thickness H of the scintillator 22 is closer to the sensor portion 32A than the center position of the thickness H of the scintillator 22.

[0069] Length L of member 401 in the Z-axis direction Z1 and the length L of the member 402 in the Z-axis direction Z2 In this modification, the length L of the member 401 in the Z-axis direction is Z1 and the length L of the member 402 in the Z-axis direction Z2 The sum of these lengths is the length L in the Z-axis direction of the member 40 in each of the above embodiments. Z can be considered to be equivalent to

[0070] In this way, even if each of the multiple members 40 is provided in multiple stages within the scintillator 22, by providing them at a position closer to the second surface 22B than to the first surface 22A within the scintillator 22, a highly sharp image can be obtained with the radiation detector 20 of this modification, as in the above embodiments. Furthermore, by giving each of the multiple members 40 the shape of the member 40 of the first embodiment or the member 40 of the second embodiment, a flexible radiation detector 20 can be obtained.

[0071] As described above, the radiation detector 20 of the present disclosure is flexible and capable of obtaining a highly sharp radiographic image.

[0072] The radiation detector 20 and the members 40 are not limited to the above-mentioned first and second embodiments and modified examples 1 to 3. For example, the above-mentioned first and second embodiments and the following modified examples 1 to 3 may be appropriately combined. In the first embodiment, the multiple members 40 are arranged in an aligned state in the X-axis direction and the Y-axis direction, but the multiple members 40 may be arranged randomly.

[0073] In the present embodiment, a case has been described in which a PSS type radiation detector in which radiation is irradiated from the scintillator 22 side has been applied to the radiation detector 20, but the present invention is not limited to this. For example, a radiation detector in which an ISS (Irradiation Side Sampling) type radiation detector in which radiation is irradiated from the sensor substrate 30 side may be applied to the radiation detector 20.

[0074] In addition, in the present embodiment, a case has been described in which an indirect conversion type radiation detector that converts radiation into light and then converts the converted light into electric charges is applied to the radiation detector 20, but the present invention is not limited to this. For example, a direct conversion type radiation detector that directly converts radiation into electric charges may also be applied to the radiation detector 20. [Explanation of symbols]

[0075] 10, 101-103 Radiographic imaging device 18 Inspection subject 19 Parts to be inspected 20, 201-203 Radiation detectors 21 Case 22 scintillator, 22A first surface, 22B second surface, 22G phosphor (GOS) 26 Control Board 28 cases 30 Sensor board 31 Base material 32 pixels 32A sensor section, 32B thin film transistor, 32P light receiving surface 34 Gate wiring 36 Data Wiring 40, 401, 402 parts 42 Fluorescent filter material 52 Gate wiring driver 54 Signal Processing Section 56 Image Memory 58 Control Unit 60 CPU 62 Memory 64 Storage section 66 Communications Department 70 Power supply section F fluorescence H Thickness L X , L Y , L Z , L Z1 , L Z2 , L PX , L PY length R Radiation W Spacing β Brewster angle θ α angle of incidence, θ β reflection angle

Claims

1. a scintillator having a first surface onto which radiation is incident and a second surface opposite to the first surface, the scintillator converting the radiation into fluorescence; a sensor provided on the second surface side of the scintillator and having a light receiving surface that receives the fluorescence converted by the scintillator; A plurality of members that reflect or absorb the fluorescence converted by the scintillator; Equipped with the scintillator and the sensor are variable in curvature in a predetermined direction; Each of the plurality of members has an elongated shape with a longitudinal direction intersecting with the light receiving surface of the sensor, and is provided at a position within the scintillator closer to the second surface than to the first surface. Radiation detector.

2. a scintillator having a first surface onto which radiation is incident and a second surface opposite to the first surface, the scintillator converting the radiation into fluorescence; a sensor provided on the second surface side of the scintillator and having a light receiving surface that receives the fluorescence converted by the scintillator; A plurality of members that reflect or absorb the fluorescence converted by the scintillator; Equipped with the scintillator and the sensor are variable in curvature in a first direction; Each of the plurality of members is parallel to the light receiving surface, has an elongated shape with a second direction intersecting with the first direction as a longitudinal direction, and is provided at a position within the scintillator closer to the second surface than to the first surface. Radiation detector.

3. the sensor has a sensor portion provided for each of a plurality of pixels, The plurality of members are arranged at intervals shorter than the pitch of the pixels. The radiation detector according to claim 1 or 2.

4. Each of the plurality of members is provided in contact with the light receiving surface of the sensor. The radiation detector according to claim 1 .

5. The length of the plurality of members in a direction intersecting the light receiving surface is equal to or greater than the interval between the plurality of members. The radiation detector according to claim 1 .

6. The length of the plurality of members in a direction intersecting the light receiving surface is equal to or less than the length of the light receiving surface for each pixel. The radiation detector according to claim 1 .

7. a plurality of granular fluorescent filter materials that emit secondary electrons when irradiated with the radiation are provided on the first surface side within the scintillator; The radiation detector according to claim 1 .

8. The curved state is variable according to the outer shape of the object to be inspected. The radiation detector according to claim 1 .

9. The curved state is variable according to the outer shape of the object to be inspected. The radiation detector according to claim 1 .

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