JP6726969B2 - Radiation detector - Google Patents

Description

The present invention relates to a radiation detector.

A radiation detector including a scintillator unit having a plurality of segments and a photodetection unit that detects scintillation light in a plurality of portions of the scintillator unit is known (see, for example, Patent Documents 1 to 7). In such a radiation detector, the segment in which the radiation is absorbed is specified based on the detection values of the scintillation light in the plurality of portions of the scintillator section.

JP, 2007-93376, A Japanese Patent No. 4332613 Japanese Patent No. 4338177 Japanese Patent No. 3597979 Japanese Patent No. 3697340 Japanese Patent No. 5013864 International Publication No. 2012/105292

The radiation detector as described above is required to be easily mounted on a device such as a PET device (Positron Emission Tomography). It is also required to improve the discrimination characteristics between the segments.

Therefore, it is an object of the present invention to provide a radiation detector that can be easily mounted on an apparatus and that has an improved discrimination characteristic between segments.

A radiation detector of the present invention includes a plurality of first segments arranged along a predetermined direction, and a first scintillator unit having a first optical discontinuity portion provided between adjacent first segments, and a predetermined scintillator unit. A second scintillator portion having a plurality of second segments arranged along the direction of, and a second optical discontinuity portion provided between adjacent second segments, and the second scintillator portion located on the most one side in the predetermined direction. And a photodetection unit optically connected to the first end surface of the first segment and the second end surface of the second segment located on the most one side in the predetermined direction, and located on the most other side in the predetermined direction. A first segment and a light guide section that optically connects the second segment located on the other side in the predetermined direction, and the first segment located on the other side in the predetermined direction. , The second segment located on the other side in the predetermined direction is optically coupled, and the first segment other than the first segment located on the other side in the predetermined direction and the predetermined direction The second segment other than the second segment located on the othermost side in is optically separated.

In the above radiation detector, the light detection unit is optically provided on the first end face of the first segment located on the most one side in the predetermined direction and on the second end face of the second segment located on the one most side in the predetermined direction. Connected to each other. Therefore, electrical connection to the light detection unit can be performed from one side in the predetermined direction, and mounting on the device is facilitated. In addition, the first segment located on the other side in the predetermined direction and the second segment located on the other side in the predetermined direction are optically covered with air layers or optical binders on their surfaces. When the light is coupled to, the flow rate of scintillation light is limited by the reflection at the coupling part, so the separation in the discrimination characteristics between these segments is widened, and the separation between other segments is reduced. The characteristics may deteriorate. On the other hand, according to the radiation detector, the amount of scintillation light passing between these segments can be increased by the light guide portion. Therefore, the discrimination characteristic between the segments is improved.

In the radiation detector of the present invention, the light guide section is between the surface of the first segment located on the other side in the predetermined direction and the surface of the second segment located on the other side in the predetermined direction. The light reflecting portion may cover the surface of the first segment and the surface of the second segment so that a space is formed therein. According to this, the light guide part is constituted by the space and the light reflection part, and the first segment located on the other side in the predetermined direction and the second segment located on the other side in the predetermined direction. It is possible to increase the flow rate of scintillation light during the period.

Further, in the radiation detector of the present invention, it is provided on the surface of the first segment located on the other side in the predetermined direction and on the surface of the second segment located on the other side in the predetermined direction. An optical coupling agent may be further provided, and the refractive index of the optical coupling agent may be lower than the refractive index of the first scintillator portion and the refractive index of the second scintillator portion. According to this, it is possible to further increase the flow rate of the scintillation light between the first segment located on the other side in the predetermined direction and the second segment located on the other side in the predetermined direction. You can

In the radiation detector of the present invention, the first segment located on the other side in the predetermined direction and the second segment located on the other side in the predetermined direction are irradiated with laser light. The formed light scattering surface may be provided. According to this, it is possible to further increase the flow rate of the scintillation light between the first segment located on the other side in the predetermined direction and the second segment located on the other side in the predetermined direction. You can

Further, in the radiation detector of the present invention, the first region including at least a part of the surface other than the first end face of the first segment located on the most one side in the predetermined direction, and the most one side in the predetermined direction. The second region including at least a part of the surface other than the second end face of the second segment located at is a diffuse reflection region, and the surface other than the first end face of the plurality of first segments and the surface other than the first region, The surface other than the second end faces of the plurality of second segments and other than the second region may be a specular reflection region. The characteristics of the output (the ratio of the outputs at both ends) extracted when scintillation light is generated are similar between the first segment located on the most one side in the predetermined direction and the first segment adjacent to the first segment. Therefore, discrimination is relatively difficult. On the other hand, in this radiation detector, since the diffuse reflection area is provided on the surface of the first segment located on the most one side in the predetermined direction, it is adjacent to the first segment and the first segment. It is possible to cause a difference in the characteristics of the output (the ratio of the outputs at both ends) extracted when scintillation light is generated between the first segment and the matching first segment. Therefore, the discrimination characteristic between these first segments can be improved. Similarly, since the diffuse reflection area is provided on the surface of the second segment located on the most one side in the predetermined direction, the second segment and the second segment adjacent to the second segment are adjacent to each other. Discrimination characteristics can be improved.

Moreover, in the radiation detector of the present invention, the first region is formed on one of a pair of surfaces facing each other in the first segment located on the most one side in the predetermined direction, and the second region is formed by the predetermined region. It may be formed on one of a pair of surfaces facing each other in the second segment located on the most one side in the direction. In this case, since the plurality of first regions are formed so as to extend in mutually different directions, scintillation light is favorably diffused within the first segment located on the most one side in the predetermined direction. Further, as compared with the configuration in which the first regions are formed on both of the facing surfaces, the processing can be facilitated. Similarly, scintillation light is satisfactorily diffused in the second segment located on the most one side in the predetermined direction, and processing is facilitated as compared with a configuration in which the second region is formed on both of the facing surfaces. Is planned.

Further, in the radiation detector of the present invention, the first region is a diffuse reflection region due to the light reflecting portion covering the surface of the roughened first segment, and the second region is roughened. The surface of the formed second segment may be covered with a light reflecting portion to form a diffuse reflection region. Further, the first region is a diffuse reflection region when the surface of the first segment is covered by the diffuse reflection part, and the second region is diffuse reflection when the surface of the second segment is covered by the diffuse reflection part. It may be an area. According to this, the first region and the second region are diffuse reflection regions, and the discrimination characteristic between the first segment located on the most one side in the predetermined direction and the first segment adjacent to the first segment. Can be improved.

Further, in the radiation detector of the present invention, the first segment located on the one side in the predetermined direction and the second segment located on the one side in the predetermined direction are irradiated with laser light. A formed light scattering surface may be provided. According to this, since the light scattering surface is provided in the first segment located on the most one side in the predetermined direction, between the first segment and the first segment adjacent to the first segment. In the above, it is possible to cause a difference in the characteristics (the ratio of the outputs at both ends) of the output that is taken out when scintillation light is generated. Therefore, the discrimination characteristic between these first segments can be improved. Similarly, since the light scattering surface is provided in the second segment located on the most one side in the predetermined direction, the discrimination between the second segment and the second segment adjacent to the second segment is performed. The characteristics can be improved.

Moreover, the radiation detector of the present invention includes a plurality of first segments arranged along a predetermined direction, and a first scintillator portion having a first optical discontinuity portion provided between adjacent first segments. A second scintillator portion having a plurality of second segments arranged along a predetermined direction and a second optical discontinuity portion provided between the adjacent second segments, and the one side closest to the predetermined direction. A first end surface of the first segment located in the first direction, and a photodetection unit optically connected to the second end surface of the second segment located on the most one side in the predetermined direction. The first segment located on the other side and the second segment located on the most other side in the predetermined direction are optically connected, and the first segment located on the most other side in the predetermined direction. Other than the first segment and the second segment located on the othermost side in the predetermined direction other than the second segment are optically separated, and the first segment located on the most one side in the predetermined direction. The first region including at least a part of the surface other than the first end face of the segment, and the second region including at least a part of the surface other than the second end face of the second segment located on the most one side in the predetermined direction are , A surface other than the first end surface of the plurality of first segments and other than the first area, and a surface other than the second end surfaces of the plurality of second segments and other than the second area are specular reflection areas. Has become.

The characteristics of the output (the ratio of the outputs at both ends) extracted when scintillation light is generated are similar between the first segment located on the most one side in the predetermined direction and the first segment adjacent to the first segment. Therefore, discrimination is relatively difficult. On the other hand, in this radiation detector, since the diffuse reflection area is provided on the surface of the first segment located on the most one side in the predetermined direction, it is adjacent to the first segment and the first segment. It is possible to cause a difference in the characteristics of the output (the ratio of the outputs at both ends) extracted when scintillation light is generated between the first segment and the matching first segment. Therefore, the discrimination characteristic between these first segments can be improved. Similarly, since the diffuse reflection area is provided on the surface of the second segment located on the most one side in the predetermined direction, the second segment and the second segment adjacent to the second segment are adjacent to each other. Discrimination characteristics can be improved.

According to the present invention, it is possible to provide a radiation detector that is easily mounted on a device and has improved discrimination characteristics between segments.

It is a perspective view of the radiation detector of one embodiment of the present invention. It is sectional drawing of the radiation detection unit of the radiation detector of FIG. It is sectional drawing of the radiation detector of FIG. It is a conceptual diagram which shows the connection state of the output extraction part of FIG. It is a conceptual diagram for demonstrating the identification method of the segment which the scintillation light generate|occur|produced. FIG. 2 is a schematic diagram of a PET device in which the radiation detector of FIG. 1 is mounted. It is sectional drawing of the 1st modification of the radiation detection unit of FIG. (A) is sectional drawing of the 2nd modification of the radiation detection unit of FIG. 2, (b) is sectional drawing of the 3rd modification of the radiation detection unit of FIG. It is sectional drawing of the 4th modification of the radiation detection unit of FIG. It is sectional drawing of the 5th modification of the radiation detector of FIG. (A) And (b) is a perspective view of the 6th modification of the radiation detector of FIG. (A) And (b) is sectional drawing of the 7th modification and the 8th modification of the radiation detector of FIG. (A) And (b) is sectional drawing of the 9th modification of the radiation detector of FIG. 1, and a 10th modification. (A) is sectional drawing of the 11th modification of the radiation detector of FIG. 1, (b) is a graph which illustrates the histogram of an 11th modification. (A) is sectional drawing of the 12th modification of the radiation detector of FIG. 1, (b) is a graph which illustrates the histogram of the 12th modification. (A) is a graph showing a histogram of Comparative Example 1, and (b) is a graph showing a histogram of Example 1. (A) is a graph showing the histogram of Example 2, and (b) is a graph showing the histogram of Example 3. (A) is a sectional view of a radiation detection unit of a reference example, and (b) is a graph showing a histogram of the reference example. (A) is sectional drawing of the 13th modification of the radiation detection unit of FIG. 2, (b) is sectional drawing of the 14th modification of the radiation detection unit of FIG. It is sectional drawing of the 15th modification of the radiation detection unit of FIG. (A) And (b) is sectional drawing of the 16th modification and the 17th modification of the radiation detection unit of FIG. (A) is sectional drawing of the 18th modification of the radiation detection unit of FIG. 2, (b) is BB sectional drawing of (a). (A) is a graph showing a histogram of Comparative Example 2, and (b) is a graph showing a histogram of Example 4. (A) is a graph showing a histogram of Example 5, and (b) is a graph showing a histogram of Example 6. (A) is a graph showing a histogram of Example 7, and (b) is a graph showing a histogram of Example 8. 16 is a graph showing a histogram of Example 9.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements will be denoted by the same reference symbols, without redundant description.

As shown in FIG. 1, the radiation detector 1 includes a plurality of radiation detection units 10. The plurality of radiation detection units 10 are two-dimensionally arranged. In this example, the plurality of radiation detection units 10 are arranged in a matrix of 4 rows and 4 columns. The radiation detection units 10 adjacent to each other are integrated by being fixed by, for example, adhesion or the like.

As shown in FIG. 2, the radiation detection unit 10 includes a first scintillator unit 20, a second scintillator unit 30, light reflecting units 50 and 60, and a light detection unit 80. Each of the scintillator portions 20 and 30 is composed of a crystal mass that generates scintillation light by absorbing radiation such as gamma rays incident from the outside. Each of the scintillator units 20 and 30 generates scintillation light having an intensity corresponding to the absorbed dose of the radiation at the position where the radiation is absorbed. The crystal lumps are, for example, Bi ₄ Ge ₃ O ₁₂ (BGO), Ce-doped Lu ₂ SiO ₅ (LSO), Lu _2(1-X) Y _2X SiO ₅ (LYSO), and Gd ₂ SiO ₅ (GSO). ), Pr-doped LuAG (Lu ₃ Al ₅ O ₁₂ ), Ce-doped LaBr ₃ (LaBr ₃ ), Ce-doped LaCl ₃ (LaCl ₃ ), or Ce-doped Lu _0.7 Y. _{It is} composed of crystals such as _0.3 AlO ₃ (LuYAP) and Lutetium Fine Silicate (LFS).

The first scintillator portion 20 has, for example, a regular prismatic shape. The first scintillator unit 20 has a plurality of first segments 21 arranged along a predetermined direction D, and a first light scattering unit (first optical discontinuity unit) provided between adjacent first segments 21. 22 and. That is, the first scintillator unit 20 is divided into a plurality (five in this example) of the first segments 21 by a plurality (four in this example) of the first light scattering units 22. The first segment 21 has, for example, a cubic shape. Hereinafter, the five first segments 21 arranged from one side S1 to the other side S2 in the direction D are respectively referred to as a first segment 21A, a first segment 21B, a first segment 21C, a first segment 21D, and a first segment 21D. It is called segment 21E.

The first light scattering unit 22 scatters a part of the scintillation light that has entered the first light scattering unit 22, and attenuates the intensity of the scintillation light that passes through the first light scattering unit 22. The first light scattering portion 22 has, for example, a planar shape orthogonal to the direction D. More specifically, the first light scattering portion 22 has, for example, the same shape (in this example, a square shape) as the first end surface 23 of the first segment 21A (the surface on one side S1 in the direction D). ing. The plurality of first light-scattering units 22 are arranged, for example, so that the first light-scattering units 22 have equal intervals in the direction D and overlap each other when viewed from the direction D.

The second scintillator section 30 has, for example, a regular prismatic shape. The second scintillator unit 30 includes a plurality of second segments 31 arranged along the direction D, and second light scattering units (second optical discontinuities) 32 provided between the adjacent second segments 31. ,have. That is, the second scintillator unit 30 is divided into a plurality (five in this example) of the second segments 31 by a plurality (four in this example) of the second light scattering units 32. The second segment 31 has, for example, a cubic shape. Hereinafter, the five second segments 31 arranged from one side S1 to the other side S2 in the direction D are respectively referred to as a second segment 31A, a second segment 31B, a second segment 31C, a second segment 31D, and a second segment 31D. It is called segment 31E.

The second light scattering unit 32 scatters part of the scintillation light that has entered the second light scattering unit 32, and attenuates the intensity of the scintillation light that passes through the second light scattering unit 32. The second light scattering section 32 has, for example, a planar shape orthogonal to the direction D. More specifically, the second light scattering portion 32 has, for example, the same shape (in this example, a square shape) as the second end surface 33 (the surface on the one side S1 in the direction D) of the second segment 31A. ing. The plurality of first light-scattering units 22 are arranged, for example, so that the first light-scattering units 22 have equal intervals in the direction D and overlap each other when viewed from the direction D.

Each of the light scattering portions 22 and 32 is formed by modifying (for example, amorphizing) a part of the crystal mass forming each of the scintillator portions 20 and 30. This modification is performed by irradiation with laser light. More specifically, laser light having optical transparency is condensed to the crystal masses forming the scintillator portions 20 and 30, and the condensing point of the laser light is relatively set along a predetermined surface of the crystal mass. Move to. As a result, light absorption is caused in the portion where the condensing points of the laser light are aligned in the crystal mass, and a modified region is formed along a predetermined surface of the crystal mass. When this laser light is pulsed laser light, one modified spot is formed by irradiation with one pulse of laser light, and a plurality of modified spots are arranged along a predetermined surface of the crystal mass, thereby A quality region is formed. The modified regions formed in this way become the light scattering parts 22 and 32. That is, each of the light scattering portions 22 and 32 is formed by irradiation with laser light.

Since the modified spot does not block or absorb the scintillation light, even if the modified spot is formed on the entire surface of the first light scattering portion 22, a part of the incident scintillation light is transmitted. Each of the light scattering portions 22 and 32 formed in this way has a property that the scintillation light transmittance differs depending on the incident angle of the scintillation light. For example, when the scintillation light is vertically incident on each of the light scattering portions 22 and 32, most of the incident scintillation light is transmitted. On the other hand, when the incident angle of the scintillation light becomes large, the transmittance decreases as compared with the case where the scintillation light enters vertically.

In the first scintillator section 20 and the second scintillator section 30 configured as described above, the first segments 21A to 21E and the second segments 31A to 31E are adjacent to each other in the direction orthogonal to the direction D, and The first light scattering portions 22 and the second light scattering portions 32 are arranged adjacent to each other. In this state, the first segment 21E and the second segment 31E located on the othermost side S2 in the direction D are optically connected via the connecting portion 40. In this example, the surface 24 of the first segment 21E on the second scintillator section 30 side and the surface 34 of the second segment 31E on the first scintillator section 20 side are rough-polished surfaces, and the surface 24 and the surface 34 By filling and solidifying the optical coupling agent 42 in between, the 1st segment 21E and the 2nd segment 31E are joined and optically joined. That is, the first segment 21E and the second segment 31E are optically connected between the adjacent boundary surfaces (that is, the surfaces 24 and 34 facing each other).

The connection portion 40 is composed of the surface 24 and the surface 34, which are rough-polished surfaces, and the optical binder 42. The connection portion 40 allows scintillation light to flow between the first segment 21E and the second segment 31E. Also in this connection part 40, since the surface 24 and the surface 34 are rough-polished surfaces, the reflection of scintillation light passing through the connection part 40 is suppressed as compared with the case where it is a mirror surface, and the amount of circulation. Will increase. As the optical binder 42, for example, RTV (Room Temperature Vulcanizing) rubber, optical grease, silicone oil or the like can be used.

In the first scintillator unit 20 and the second scintillator unit 30, the first segments 21A to 21D other than the first segment 21E and the second segments 31A to 31D other than the second segment 31E are optically reflected by the light reflecting unit 50. It is separated. The light reflector 50 is arranged between the first segments 21A to 21D and the second segments 31A to 31D. The light reflection part 50 is a film-shaped reflection member, and is in contact with the first segments 21A to 21D and the second segments 31A to 31D. The surface of the light reflecting section 50 is a specular reflection surface, and specularly reflects the scintillation light incident on the surface. As a result, the surfaces (smooth surfaces) of the first segments 21A to 21D and the second segments 31A to 31D that are in contact with the light reflecting section 50 are specular reflection areas. The light reflecting portion 50 is made of, for example, a material such as Teflon tape (Teflon is a registered trademark), barium sulfate, aluminum oxide, titanium oxide, an ESR (Enhanced Specular Reflector) film, or a polyester film.

The outer surfaces of the first scintillator section 20 and the second scintillator section 30 are covered with the light reflecting section 60. The light reflecting section 60 covers the outer surface of the first scintillator section 20 and the second scintillator section 30 except the first end surface 23 of the first segment 21A and the second end surface 33 of the second segment 31A. .. The light reflection part 60 is a film-shaped reflection member, and is the surface 25 of the first segment 21E (the surface of the other side S2 in the direction D) and the surface 35 of the second segment 31E (the surface of the other side S2 in the direction D). ) And is in contact with the outer surface other than the surfaces 25 and 35. The surface of the light reflection unit 60 is a specular reflection surface, and specularly reflects the scintillation light incident on the surface. As a result, the surfaces of the first segments 21A to 21E and the second segments 31A to 31E that are in contact with the light reflecting portion 60 are specular reflection regions except for the first region 26 and the second region 36 described later. The light reflecting section 60 is made of, for example, the same material as the light reflecting section 50.

A part of the surface of the first segment 21A other than the first end surface 23 and a part of the surface of the second segment 31A other than the second end surface 33 are rough-polished surfaces. As a result, the first region 26, which is the rough polishing surface in the first segment 21A, and the second region 36, which is the rough polishing surface in the second segment 31A, become the diffuse reflection region due to the contact with the light reflecting portion 60. Has become. That is, the first region 26 and the second region 36 diffusely reflect the incident scintillation light. In other words, the first region 26 is a diffuse reflection region due to the light reflecting portion 60 covering the surface of the roughened first segment 21A, and the second region 36 is roughened. The surface of the second segment 31A is covered with the light reflecting portion 60, thereby forming a diffuse reflection region.

The first region 26 is formed on one of a pair of opposing faces in the first segment 21A, and the second region 36 is formed on one of a pair of opposing faces in the second segment 31A. Specifically, in this example, the first segment 21 has two pairs of opposing surfaces on the surface other than the first end surface 23. By forming the first region 26 on one of the pair of surfaces, the first region 26 is formed on the entire surfaces of two adjacent surfaces of the surfaces other than the first end surface 23 of the first segment 21A. ing. Similarly, the second region 36 is formed on the entire surfaces of two adjacent surfaces of the surfaces other than the second end surface 33 of the second segment 31A.

The radiation detection unit 10 further includes a light guide unit 70 that optically connects the first segment 21E and the second segment 31E. In the radiation detection unit 10, the one side portion 62 of the light reflecting portion 60 extends in the direction orthogonal to the direction D, and the one side portion 62 has a space between the surface 25 and the surface 35 which are rough polishing surfaces. The light guide section 70 is configured by being provided so as to be vacant. As a result, a rectangular parallelepiped air layer 72 is formed between the one side portion 62 and the surfaces 25 and 35. In other words, the light guide unit 70 is configured by covering the surface 25 and the surface 35 with the light reflection unit 60 so that a space (air layer 72) is formed between the surface 25 and the surface 35. There is. The light guide portion 70 also allows scintillation light to flow between the first segment 21E and the second segment 31E. As a result, the flow rate of scintillation light between the first segment 21E and the second segment 31E is increased as compared with the case where only the connecting portion 40 is provided. Further, the surface 25 and the surface 35 may be specular reflection surfaces instead of rough polishing surfaces.

In the radiation detection unit 10, when scintillation light is generated in any of the first segments 21A to 21E and the second segments 31A to 31E due to incidence of radiation, the scintillation light is generated while repeating reflection in the specular reflection region and the diffuse reflection region. Part of the scintillation light thus reached reaches the first end face 23, and the rest reaches the second end face 33. At this time, since the scintillation light is attenuated in the first light scattering section 22, the second light scattering section 32, and the connection section 40, the scintillation light is detected in any of the first segments 21A to 21E and the second segments 31A to 31E. The ratio of the amount of light reaching the first end face 23 and the second end face 33 changes stepwise depending on whether or not occurs.

Therefore, for example, by calculating the ratio of the amount of light reaching the first end face 23 and the amount of light reaching the second end face 33, that is, by performing the center of gravity calculation, the first segment 21 or the second segment 21 where the scintillation light is generated. 31 (that is, the first segment 21 or the second segment 31 in which the radiation is absorbed) can be identified. In the radiation detector 1, by utilizing this calculation of the center of gravity, the first segment 21 or the second segment 21A or 21E in which the radiation is absorbed is selected from the first segments 21A to 21E and the second segments 31A to 31E of the plurality of radiation detection units 10. Identify the segment 31. The first segment 21 or the second segment 31 in which the scintillation light is generated may be specified using a method other than the calculation of the center of gravity, and for example, the maximum likelihood method may be used.

The light detection unit 80 has a first light detection unit 82 and a second light detection unit 84. The first photodetection section 82 is optically coupled to the first end face 23 of the first segment 21A, for example, via an optical adhesive. The second photodetection section 84 is optically coupled to the second end surface 33 of the second segment 31A, for example, via an optical adhesive. The first light detection unit 82 detects the intensity of the scintillation light that has entered the first end face 23, and outputs an electric signal having a magnitude corresponding to the detected value. The second light detection unit 84 detects the intensity of the scintillation light incident on the second end face 33 and outputs an electric signal having a magnitude corresponding to the detected value. Each of the photodetectors 82 and 84 is a semiconductor photodetector using, for example, a photomultiplier tube, an avalanche photo diode (APD), an MPPC (Multi-Pixel Photon Counter), or the like. The MPPC is a photon counting device including a plurality of Geiger mode APD pixels.

As shown in FIG. 3, the radiation detector 1 generates scintillation light based on an output extraction unit 90 that extracts an output from the light detection unit 80 of each radiation detection unit 10 and an output that is extracted from the output extraction unit 90. The arithmetic unit 100 for specifying the position is further provided. The output extraction unit 90 is electrically connected to each radiation detection unit 10. The calculation unit 100 is electrically connected to the output extraction unit 90.

The output extraction unit 90 has a first resistance chain 92 and a second resistance chain 96. The first photodetection section 82 of each radiation detection unit 10 is electrically connected to the first resistance chain 92. The second light detection unit 84 of each radiation detection unit 10 is electrically connected to the second resistance chain 96.

As shown in FIG. 4, the positional relationship between the first light detection unit 82 and the second light detection unit 84 is the same among the plurality of radiation detection units 10. That is, in any of the radiation detecting units 10, the first photodetecting section 82 is located on one side (left side in FIG. 4) in the row direction (direction in which the first scintillator section 20 and the second scintillator section 30 are arranged). However, the second photodetector 84 is located on the other side (right side in FIG. 4) in the row direction.

In the first resistor chain 92, the first photodetector units 82 that are adjacent to each other in the row direction are connected to each other via a resistor. Further, in the first resistor chain 92, the first photodetector units 82 located on one side in the row direction are connected via a resistor, and the first photodetector units 82 located on the other side in the row direction are connected. They are connected to each other via a resistor. That is, in the first resistance chain 92, the first photodetection units 82 adjacent to each other in the column direction (direction orthogonal to the row direction on the plane where the first scintillator unit 20 and the second scintillator unit 30 are arranged) have resistances. Connected through. In the second resistance chain 96, the second photodetection units 84 adjacent to each other in the row direction are connected via a resistor. Further, in the second resistor chain 96, the second photodetector units 84 located on one side in the row direction are connected via a resistor, and the second photodetector units 84 located on the other side in the row direction are connected. They are connected to each other via a resistor. That is, in the second resistance chain 96, the second photodetection units 84 adjacent to each other in the column direction are connected to each other via the resistance.

The values of electric signals at the four vertices of the first resistance chain 92 are input to the arithmetic unit 100 as outputs A1 to A4, and the values of the electric signals at the four vertices of the second resistance chain 96 are input as outputs B1 to B4. To be done.

The calculation unit 100 identifies the radiation detection unit 10 in which the scintillation light is generated based on the outputs A1 to A4 and/or the outputs B1 to B4. Further, the calculation unit 100 identifies the segment in which the scintillation light is generated, among the first segment 21 and the second segment 31 of the identified radiation detection unit 10, based on the outputs A1 to A4 and the outputs B1 to B4. Hereinafter, a method of identifying the segment in which the scintillation light is generated will be described.

First, the radiation detector 101 shown in FIG. 5 will be described. As shown in FIG. 5, the radiation detector 101 includes four radiation detection units 110. Each radiation detection unit 110 has six segments 121 (segments 121A to 121F) arranged along the first direction d1. These radiation detection units 110 are arranged along a second direction d2 that is orthogonal to the first direction d1. The radiation detection units 110 adjacent to each other in the second direction d2 are optically separated by a reflecting member (not shown). Further, the light scattering portion 122 is formed between the segments 121 adjacent to each other in the first direction d1. A first photodetector 182 is optically connected to each segment 121A, and a second photodetector 184 is optically connected to each segment 121F. The first photo detectors 182 are connected to the first resistance chain 192, and the second photo detectors 184 are connected to the second resistance chain 196.

In the radiation detector 101, the calculation unit calculates the sum AS of the outputs A1 and A2 at both ends of the first resistance chain 192 and the output A1 (or the difference between the outputs A1 and A2) according to the following equations (1) and (2). ) And the sum AS, the ratio R1 is obtained, and the radiation detection unit 110 in which the scintillation light is generated is specified with reference to the histogram G1 representing the relationship between the ratio R1 and the count number.
AS=A1+A2 (1)
R1=A1/AS, or R1=(A1-A2)/AS (2)

Instead of or in addition to this, the sum BS of the outputs B1 and B2 at both ends of the second resistance chain 196 and the output B1 (or the output B1, by the following equations (3) and (4) The radiation detection unit 110 in which the scintillation light is generated may be specified by obtaining the ratio R2 between the difference B2) and the sum BS, and referring to the histogram G2 representing the relationship between the ratio R2 and the count number.
BS=B1+B2 (3)
R2=B1/BS, or R2=(B1-B2)/BS (4)

Instead of or in addition to this, the sum C1 of the outputs A1 and B1, the sum C2 of the outputs A2 and B2, and the sum CS of the sum C1 and the sum C2 are obtained, and the sum C1 (or sums C1 and C2) is obtained. Difference) and the sum CS, and the radiation detection unit 110 in which the scintillation light is generated may be specified with reference to a histogram (not shown) representing the relationship between the ratio R3 and the count number.

That is, the arithmetic unit calculates the ratio of one of the outputs A1 and A2 from the first resistance chain 192 and the outputs B1 and B2 from the second resistance chain 196, or the ratio of the signals (A1+B1, A2+B2) obtained by adding both signals. Based on (that is, at least one ratio), the radiation detection unit 110 in which the scintillation light is generated is specified.

Subsequently, the calculation unit obtains a ratio R4 between the sum AS (or the difference between the sum AS and BS) and the sum of the sum AS and the sum BS by the following equation (5), and the relationship between the ratio R4 and the count number. The segment 121 in which the scintillation light is generated is specified from among the plurality of segments 121 of the specified radiation detection unit 110 with reference to the histogram G3 representing
R4=AS/(AS+BS) or R4=(AS-BS)/(AS+BS) (5)

As described above, in the radiation detector 101, the radiation detection unit 110 in which the scintillation light is generated and the segment 121 in which the scintillation light is generated are independently identified by the calculation based on the outputs A1 and A2 and the outputs B1 and B2. Can be done by That is, the generation position of scintillation light can be independently specified for each of the first direction d1 and the second direction d2. As a result, the segment 121 in which the scintillation light is generated can be identified.

By the same processing as in the case of the radiation detector 101, also in the radiation detector 1, the calculation unit 100 identifies the radiation detection unit 10 in which the scintillation light is generated based on the outputs A1 to A4 and/or the outputs B1 to B4. Based on the outputs A1 to A4 and the outputs B1 to B4, it is possible to specify the segment in which the scintillation light is generated among the first segment 21 and the second segment 31 of the specified radiation detection unit 10. In contrast to the above-described processing procedure, the calculation unit 100 generates scintillation light in the first segment 21 and the second segment 31 of the radiation detection unit 10 based on the outputs A1 to A4 and the outputs B1 to B4. The segment may be specified, and then the radiation detection unit 10 having the specified segment (that is, the radiation detection unit 10 in which the scintillation light is generated) may be specified.

Next, an example in which the radiation detector 1 is mounted on the apparatus will be described with reference to FIG. FIG. 6 is a schematic diagram of a PET device in which a plurality of radiation detectors 1 are mounted. The plurality of radiation detectors 1 are arranged along the circumference of a circle centered on the center C so that the side surface 1A opposite to the side on which the output extraction unit 90 is provided faces the center C side of the measurement target. It is arranged. As a result, the output extraction part 90 of each radiation detector 1 is located on the outer side in the radial direction of the circle centered on the center C. Therefore, it is possible to electrically connect the calculation unit 100 to the radiation detector 1 from the outside in the radial direction. As described above, in the radiation detector 1, the wiring can be easily routed. The plurality of radiation detectors 1 may be arranged along the circumference of a circle centered on the center C such that the side surface orthogonal to the direction D faces the center C side.

Next, the function and effect of the radiation detector 1 will be described.

In the radiation detector 1, the light detection unit 80 is optically connected to the first end surface 23 of the first segment 21A and the second end surface 33 of the second segment 31A. Therefore, the electrical connection to the light detection unit 80 can be performed from one side in the direction D (the lower side in FIG. 2), and the mounting on the device is facilitated. Further, according to the radiation detector 1, the amount of scintillation light that flows between the first segment 21E and the second segment 31E is increased by the light guide unit 70. That is, the light guide unit 70 functions as a light guide. Therefore, the discrimination characteristic between the segments is improved.

Further, in the radiation detector 1, the light guide section 70 covers the front surface 25 and the front surface 35 with the light reflection section 60 so that a space (air layer 72) is formed between the front surface 25 and the front surface 35, It is configured. According to this, the distribution amount of the scintillation light between the first segment 21 and the second segment 31E can be increased.

Further, in the radiation detector 1, since the diffuse reflection area is provided on the surface of the first segment 21A, the output extracted when scintillation light is generated between the first segment 21A and the first segment 21B. It is possible to make a difference in characteristics. Therefore, the discrimination characteristic between the first segments 21A and 21B can be improved. Similarly, since the diffuse reflection area is provided on the surface of the second segment 31A, it is possible to improve the discrimination characteristic between the second segments 31A and 31B.

Further, in the radiation detector 1, the first region 26 is formed on one of the pair of surfaces facing each other in the first segment 21A, and the second region 36 is one of the pair of surfaces facing each other in the second segment 31A. Is formed in. In this case, since the plurality of first regions 26 are formed so as to extend in mutually different directions, the scintillation light is favorably diffused within the first segment 21A. Further, as compared with the configuration in which the first regions 26 are formed on both of the facing surfaces, the processing can be facilitated. Similarly, scintillation light is satisfactorily diffused in the second segment 31A, and the processing is facilitated as compared with the configuration in which the second regions 36 are formed on both of the facing surfaces.

In the radiation detector 1, the first scintillator section 20 is obtained by forming the first light scattering section 22 between the adjacent first segments 21 by the irradiation of the laser light. Similarly, the second scintillator section 30 is obtained by forming the second light scattering section 32 between the adjacent second segments 31 by the irradiation of the laser light. Therefore, for example, the first scintillator portion 20 and the second scintillator portion 30 can be obtained easily and with high dimensional accuracy as compared with a case where a plurality of scintillator blocks are joined while interposing a light scattering member. .. As described above, in the radiation detector 1, the manufacturing is facilitated and the accuracy is improved. The structure or characteristics relating to the difference between the light-scattering portion formed by the irradiation of the laser light and the light-scattering portion formed by joining a plurality of scintillator blocks while interposing the light-scattering member is generally described in a wording. It seems impossible to specify. It is also considered impossible or impractical to analyze and identify such structures or characteristics based on measurement.

Further, in the radiation detector 1, by arranging the light reflecting portion 50 between the first segments 21A to 21D and the second segments 31A to 31D, it is possible to easily and surely achieve predetermined optical separation. it can.

Further, in the radiation detector 1, the first photodetection units 82 are connected to the first resistance chain 92 between the plurality of radiation detection units 10, and the second photodetection units 84 are connected to the second resistance chain 96. It is connected. Therefore, it is possible to reduce the number of outputs as compared with, for example, the case where the outputs are separately extracted from each of the plurality of light detection units. Further, by the calculation based on the outputs A1 to A4 and the outputs B1 to B4 extracted from the first resistance chain 92 and the second resistance chain 96, respectively, the radiation detection unit 10 that has generated the scintillation light is identified and the scintillation light is generated. The identification of the first segment 21 or the second segment 31 described above can be performed independently. Therefore, it is possible to secure good discrimination characteristics between the segments while reducing the number of outputs.

In the radiation detector 1, the first scintillator unit 20 and the second scintillator unit 30 are arranged so that the first light scattering units 22 and the second light scattering units 32 are adjacent to each other in the direction orthogonal to the direction D. It is arranged. Therefore, when the light scattering portions 22 and 32 are formed, the laser light irradiation can be efficiently performed.

Further, in the radiation detector 1, the first photodetection units 82 having the same positional relationship are connected to the first resistance chain 92, and the second photodetection units 84 having the same positional relationship are the second resistance chain 96. Therefore, it is possible to perform good discrimination between the segments by a relatively simple process.

Further, in the radiation detector 1, the calculation unit 100 detects radiation generated by scintillation light based on at least one of outputs A1 to A4 from the first resistance chain 92 and outputs B1 to B4 from the second resistance chain 96. The unit 10 is specified, and the segment in which the scintillation light is generated among the first segment 21 and the second segment 31 is specified based on the outputs A1 to A4 and the outputs B1 to B4. By such a calculation, the radiation detection unit 10 in which the scintillation light has been generated and the segment in which the scintillation light has been generated can be independently specified, and excellent discrimination characteristics can be obtained.

Further, in the radiation detector 1, since the plurality of radiation detection units 10 are two-dimensionally arranged, the radiation detection range can be widened. Further, even when the plurality of radiation detection units 10 are two-dimensionally arranged in this way, it is possible to secure good discrimination characteristics between the segments while reducing the number of outputs.

Further, in the radiation detector 1, since the first light-scattering portion 22 and the second light-scattering portion 32 are formed by the irradiation of the laser light, the area and formation density of the modified region of each light-scattering portion can be adjusted. Thus, the flow rate of scintillation light in each light scattering portion can be easily adjusted. Therefore, it is possible to increase the flow rate of the light scattering section formed in the position where the flow rate of the scintillation light is relatively small, or to decrease the flow rate of the light scattering section which is formed in the position where the flow rate of scintillation light is relatively high. By doing so, the discrimination characteristic between the segments can be improved.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and is modified without departing from the scope of the claims and applied to other things. May be.

For example, the first scintillator unit 20 and the second scintillator unit 30 may be integrally formed as in the radiation detection unit 10A of the first modified example shown in FIG. 7. In this case, the first scintillator unit 20 and the second scintillator unit 30 are formed by being cut out from one scintillator block, for example. In the manufacturing process, for example, the first segments 21A to 21D and the second segments 31A to 31D are cut with a dicing saw. Then, the light reflecting section 50 is inserted between the first segments 21A to 21D and the second segments 31A to 31D. Further, in the radiation detection unit 10A, a light scattering portion 44 formed by irradiation of laser light is provided in place of the connection portion 40, whereby the first segment 21E and the second segment 31E are separated. ..

According to the first modified example as described above, the mounting on the device can be facilitated as in the above-described embodiment. Further, according to the first modified example, the step of joining the first scintillator unit 20 and the second scintillator unit 30 is omitted, so that the manufacturing can be facilitated and the accuracy can be further improved. Further, since the first segment 21E and the second segment 31E are divided by the light scattering portion 44 formed by the irradiation of the laser light, the amount of scintillation light flowing between the first segment 21E and the second segment 31E. Can be easily adjusted.

Further, the configuration of the light guide unit 70 is changed as in the radiation detection unit 10B of the second modification shown in FIG. 8A and the radiation detection unit 10C of the third modification shown in FIG. 8B. You may. In the radiation detection unit 10B, the one side portion 62B of the light reflecting portion 60 has a first portion 65 and a second portion 66 that extend to intersect the direction D. In this example, the extending direction of the first portion 65 and the extending direction of the second portion 66 are orthogonal to each other. The 1st part 65 and the 2nd part 66 are continuing in each other's tip part (end part on the side opposite to surface 25 and surface 35), and the tip part concerned is the 1st scintillator part 20 and the 2nd scintillator part 30. It is located on the border line of. In this example, an air layer 72B having a triangular prism shape is formed between the one side portion 62B and the surfaces 25 and 35. Further, in the radiation detection unit 10C, the one side portion 62C of the light reflecting portion 60 has a curved shape so as to be convex on the side opposite to the surface 25 and the surface 35. In this example, a semicylindrical air layer 72C is formed between the one side portion 62C and the surfaces 25 and 35.

Also in the second modified example and the third modified example as described above, it is possible to secure good discrimination characteristics between the segments, as in the above embodiment. A light guide member (for example, a member made of acrylic resin) formed of a material capable of guiding light may be arranged in a region (space) corresponding to the air layers 72, 72B, 72C.

Further, the configuration of the diffuse reflection region may be changed as in the radiation detection unit 10D of the fourth modified example shown in FIG. In the radiation detection unit 10D, the light reflection section 60 has a diffuse reflection section 68 that covers the first region 26 and the second region 36. The surface of the diffuse reflection part 68 is a diffuse reflection surface. In this case, the surfaces of the first scintillator unit 20 and the second scintillator unit 30 corresponding to the first region 26 and the second region 36 do not have to be rough-polished surfaces, and the surfaces may be smooth surfaces. With such a configuration, the first region 26 and the second region 36 also serve as diffuse reflection regions. That is, in this example, the first region 26 is a diffuse reflection region by the surface of the first segment 21A being covered by the diffuse reflection part 68, and the second region 36 is diffused on the surface of the second segment 31A. The reflective portion 68 covers the area to form a diffuse reflection area. Therefore, the discrimination property between the second segments 31A and 31B can also be improved by the fourth modification. The first region 26 can be any region as long as it includes at least a part of the surface of the first segment 21A other than the first end face 23. For example, the first region 26 may include a surface that is in contact with the light reflecting section 50. Further, the first region 26 may include a part of the surface of the first segment 21B. Even in these cases, the discrimination characteristic between the first segments 21A and 21B can be improved. These points also apply to the second region 36.

Further, the configuration of the output extraction unit 90 may be changed as in the fifth modified example shown in FIG. In the fifth modified example, the positional relationship between the first light detection unit 82 and the second light detection unit 84 is not the same among the plurality of radiation detection units 10. Even in such a case, if the arrangement of the first photodetector 82 and the second photodetector 84 is known, the segment in which the scintillation light is generated can be identified by the same process as the above process. Therefore, according to the fifth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved. Further, according to the fifth modified example, even if the scintillation light leaks between the adjacent radiation detection units 10, it is possible to reduce the error generated at the scintillation light detection position.

Further, the radiation detector 1E and the radiation detection unit 10E may be configured as in the sixth modified example shown in FIG. In FIG. 11A, the light reflection part 60 is omitted. As shown in FIG. 11B, the radiation detector 1E includes a plurality of radiation detection units 10E arranged in a matrix of 4 rows and 4 columns. In each of the plurality of radiation detection units 10E, as shown in FIG. 11A, scintillator units 20E having the same configuration as the first scintillator unit 20 and the second scintillator unit 30 are arranged in a matrix of 2 rows and 2 columns. It is composed by arranging. The adjacent scintillator portions 20E are optically coupled by the connection portion 40 and are optically separated by the light reflection portion 50. Each radiation detection unit 10E has four photodetection sections 86A to 86D optically coupled to the scintillator section 20E. In FIG. 11B, the arrangement of the photodetectors 86A to 86D is virtually shown by a chain double-dashed line below the radiation detector 1E. Between the plurality of radiation detection units 10E, the photodetection units 86A are connected to the first resistance chain, the photodetection units 86B are connected to the second resistance chain, and the photodetection units 86C are connected to the third resistance chain. The photodetectors 86D are connected to each other in the fourth resistance chain. According to the sixth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved.

Further, the radiation detector 1 may be configured as in the seventh modified example shown in FIG. In the seventh modified example, outputs are taken out from each of the first light detection unit 82 and the second light detection unit 84 of the plurality of radiation detection units 10 without using the first resistance chain 92 and the second resistance chain 96. There is. Also in this case, the segment in which the scintillation light is generated can be specified by the importance calculation. Therefore, also in the seventh modified example, similar to the above-described embodiment, mounting on the device is facilitated and the discrimination characteristic between the segments is improved. However, the above-described embodiment is preferable in that the number of outputs can be reduced.

Further, the radiation detector 1 may be configured as in the eighth modified example shown in FIG. In the eighth modified example, the light detection unit 88 includes the first end surface 23 of the first segment 21A of one radiation detection unit 10 of the adjacent radiation detection units 10 and the other radiation detection unit 10 of the adjacent radiation detection units 10. Is optically connected to both of the second end faces 33 of the second segment 31A. The photodetector 88 disposed at the end is optically connected only to the first end face 23 or the second end face 33. The point that the first resistance chain 92 and the second resistance chain 96 of the radiation detection unit 10 are not used is similar to the seventh modification. According to the eighth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved. Furthermore, according to the eighth modification, the number of photodetectors 88 can be reduced and the number of outputs can be reduced.

Further, the radiation detector 1 may be configured as in the ninth modified example shown in FIG. The radiation detection unit 10H of the ninth modified example is configured by the first scintillator unit 20 and the second scintillator unit 30 being optically connected via the two scintillator units 20H. The two scintillator units 20H have the same configuration as the first scintillator unit 20 and the second scintillator unit 30, and are optically connected to each other via the connection unit 40 in the segment on the most one side S1 in the direction D. Are combined. Further, the scintillator portion 20H adjacent to the first scintillator portion 20 is optically coupled to the first segment 21E of the first scintillator portion 20 via the connection portion 40 in the segment located on the other side S2 in the direction D. Has been done. On the other hand, the scintillator portion 20H adjacent to the second scintillator portion 30 is optically coupled to the second segment 31E of the second scintillator portion 30 via the connection portion 40 in the segment located on the other side S2 in the direction D. Has been done. That is, the segments on the most one side S1 in the direction D of the two scintillator portions 20H are optically coupled between the adjacent boundary surfaces (that is, the surfaces facing each other). Further, these segments and the first segment 21E or the second segment 31E are optically coupled between the adjacent boundary surfaces (that is, the surfaces facing each other). In this way, the first scintillator unit 20 and the second scintillator unit 30 may be optically connected via the plurality of scintillator units 20H. The point that the first resistance chain 92 and the second resistance chain 96 are not used is similar to the seventh modification. According to the ninth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved. Furthermore, according to the ninth modification, the number of photodetectors 88 can be reduced, and the number of outputs can be reduced.

Further, the configuration of the light detection unit 80 may be changed as in the tenth modification shown in FIG. The light detection unit 80I of the tenth modified example is configured by a position detection type photodetector capable of detecting the position where the scintillation light is detected. As such a detector, for example, a position detection type photomultiplier tube or a position detection type avalanche photodiode can be used. According to the tenth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved.

Further, the radiation detector 1 may be configured as in the eleventh modified example shown in FIG. In the eleventh modified example, the first photodetector section 82 and the second photodetector section 84 of the plurality of radiation detection units 10 are connected to one resistance chain 99. Even in this case, the segment in which the scintillation light is generated can be specified by the gravity center calculation. Therefore, according to the eleventh modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved. In the eleventh modification, the structure is simplified and the number of the first segments 21 and the second segments 31 is three. This point also applies to the twelfth modified example described below.

Further, the radiation detector 1 may be configured as in the twelfth modified example shown in FIG. In the twelfth modified example, similarly to the eighth modified example, the light detection unit 88 includes the first end surface 23 of the first segment 21A of the one radiation detection unit 10K of the adjacent radiation detection units 10K and the adjacent radiation detection unit. It is optically connected to both of the second end faces 33 of the second segments 31A of the other radiation detection unit 10K of 10K, and these photodetection portions 88 are connected to one resistance chain 99. In addition, the adjacent radiation detection units 10K are optically coupled to each other via the connection portion 40 in the segment on the one side S1 in the direction D. Moreover, the light reflection part 60 is shared by the adjacent radiation detection units 10K. According to the twelfth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved. Furthermore, according to the twelfth modified example, it is possible to reduce the number of light detection units 88 and reduce the number of outputs. In addition, as shown in FIGS. 14B and 15B, the difference in the distribution on the separation characteristic that occurs between the radiation detection units 10 of the eleventh modification is small in the twelfth modification. It can be seen that the separation characteristics are good. As described above, the twelfth modified example is also preferable in that the discrimination characteristic between the segments can be improved.

Further, unlike the radiation detection unit 10M of the thirteenth modification shown in FIG. 19A, the light guide section 70 may not be provided. In the thirteenth modified example, the one side portion 62 of the light reflecting portion 60 is provided so as to contact the surface 25 and the surface 35 which are specular reflecting surfaces. According to such a thirteenth modification as well, as in the above-described embodiment, since the diffuse reflection region is provided on the surface of the first segment 21A, the scintillation light is provided between the first segment 21A and the first segment 21B. It is possible to cause a difference in the characteristics of the output that is taken out in the case of occurrence of. Therefore, the discrimination characteristic between the first segments 21A and 21B can be improved. Similarly, since the diffuse reflection area is provided on the surface of the second segment 31A, it is possible to improve the discrimination characteristic between the second segments 31A and 31B.

Further, unlike the radiation detection unit 10N of the fourteenth modification shown in FIG. 19B, the first region 26 and the second region 36 which are diffuse reflection regions may not be formed. In the fourteenth modification, the entire surface of the first segment 21A and the surface of the second segment 31A are specular reflection regions. According to the fourteenth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved.

Moreover, you may comprise the radiation detection unit 10P like the 15th modification shown in FIG. In the fifteenth modified example, a planar light scattering surface 27 is provided in the first segment 21A. The light scattering surface 27 is arranged along the direction D, and extends between the first end surface 23 and the first light scattering portion 22 between the first segments 21A and 21B. The light scattering surface 27 is arranged so as to pass through the center of the first segment 21A. Further, a planar light scattering surface 37 is provided in the second segment 31A. The light scattering surface 37 is arranged along the direction D, and extends between the second end surface 33 and the second light scattering portion 32 between the second segments 31A and 31B. The light scattering surface 37 is arranged so as to pass through the center of the second segment 31A. Each of the light scattering surfaces 27 and 37 is formed by irradiating the laser light, like the light scattering portions 22 and 32.

According to such a fifteenth modified example as well, similar to the above-described embodiment, it is possible to facilitate manufacturing, improve accuracy, and facilitate mounting on a device. Further, since the light scattering surface 27 is provided in the first segment 21A, the characteristics of the output extracted when scintillation light is generated between the first segment 21A and the first segment 21B (the output of both ends is Ratio) can be made. Therefore, the discrimination characteristic between the first segments 21A and 21B can be improved. Similarly, since the light scattering surface 37 is provided in the second segment 31A, the discrimination characteristic between the second segments 31A and 31B can be improved. In the fifteenth modified example, the light scattering surface 27 does not have to be arranged so as to pass through the center of the first segment 21A, and may be arranged at any position. Further, the light scattering surface 27 may not be arranged along the direction D. A plurality of light scattering surfaces 27 may be provided in the first segment 21A. The entire light scattering surface 27 may be a formation area in which the modified region is formed, or the light scattering surface 27 may have a non-formed area in which the modified region is not formed. The non-formation region may have, for example, a rectangular shape. On the light scattering surface 27, the formation region and the non-formation region may be arranged in a checkered pattern. That is, each of the formation region and the non-formation region may have a rectangular shape and are alternately arranged. Alternatively, the formation region and the non-formation region may be arranged in a stripe shape. That is, each of the formation region and the non-formation region may have a band shape and are alternately arranged. These points also apply to the light scattering surface 37.

Further, the radiation detection unit 10Q of the sixteenth modification shown in FIG. 21A and the radiation detection unit 10R of the seventeenth modification shown in FIG. 21B may be configured. In the sixteenth modification example, the hemispherical optical binder 73 is provided on the surface 25 of the first segment 21E, and the hemispherical optical binder 74 is provided on the surface 35 of the second segment 31E. In the seventeenth modification example, the hemispherical optical binder 75 is provided over the surface 25 of the first segment 21E and the surface 35 of the second segment 31E. The refractive index of the optical coupling agents 73 to 75 is smaller than the refractive index of each of the first scintillator section 20 and the second scintillator section 30. As the optical binders 73 to 75, for example, the same material as the optical binder 42 can be used. The surfaces 25 and 35 are specular reflection surfaces. According to the sixteenth modification and the seventeenth modification, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved as in the above embodiment. Furthermore, the distribution amount of scintillation light between the first segment 21E and the second segment 31E can be further increased. That is, when the difference between the refractive index of each of the scintillator portions 20 and 30 and the refractive index of the outside (air layer 72) (approximately 1) is large, the scintillation light that has traveled through each of the scintillator portions 20 and 30 has a surface 25. , 35, the total reflection is likely to occur, and it becomes difficult for scintillation light to escape from the scintillator portions 20, 30. On the other hand, by providing the optical coupling agents 73 to 75 having the refractive index between the scintillator portions 20 and 30 and the air layer 72 on the surfaces 25 and 35, the scintillator portions 20 and 30 to the air layer 72 are provided. Therefore, the scintillation light can easily escape, and the flow rate of the scintillation light between the first segment 21E and the second segment 31E can be further increased. In particular, in the seventeenth modified example, since the optical binder 75 functions as a light guide, the flow rate of scintillation light between the first segment 21E and the second segment 31E can be further increased. The optical binders 73 to 75 may have any shape, for example, a rectangular parallelepiped shape. Further, the surface 25 and the surface 35 may be rough-polished surfaces.

The radiation detection unit 10S may be configured as in the eighteenth modification shown in FIG. In the eighteenth modification, a planar light scattering surface 28 is provided in the first segment 21E. The light scattering surface 28 is arranged along the direction D so as to be orthogonal to the surface 24 of the first segment 21E. The light scattering surface 28 is arranged so as to pass through the center of the first segment 21E. Further, a planar light scattering surface 38 is provided in the second segment 31E. The light scattering surface 38 is arranged along the direction D so as to be orthogonal to the surface 34 of the second segment 31E. The light scattering surface 38 is arranged so as to pass through the center of the second segment 31E. Each of the light scattering surfaces 28, 38 is formed by irradiating a laser beam, like the light scattering portions 22, 32.

According to the eighteenth modified example as well, similar to the above-described embodiment, the mounting on the device is facilitated and the discrimination characteristic between the segments is improved. Furthermore, the distribution amount of scintillation light between the first segment 21E and the second segment 31E can be further increased. In the eighteenth modification, the light scattering surface 28 does not have to be arranged so as to pass through the center of the first segment 21E, and may be arranged at any position. Further, the light scattering surface 28 may not be arranged along the direction D. A plurality of light scattering surfaces 28 may be provided in the first segment 21E. The entire light scattering surface 28 may be a formation area in which the modified region is formed, and the light scattering surface 27 may have a non-formed area in which the modified region is not formed. The non-formation region may have, for example, a rectangular shape. On the light scattering surface 28, the formation region and the non-formation region may be arranged in a checkered pattern. That is, each of the formation region and the non-formation region may have a rectangular shape and are alternately arranged. Alternatively, the formation region and the non-formation region may be arranged in a stripe shape. That is, each of the formation region and the non-formation region may have a band shape and are alternately arranged. These points also apply to the light scattering surface 38. Further, the light guide unit 70 may be further provided.

In addition, the first light scattering portion 22 and the second light scattering portion 32 do not have to be formed by irradiation with laser light. For example, the first light-scattering portion 22 and the second light-scattering portion 32 may be formed by joining a plurality of scintillator blocks while interposing a light-scattering member (optically discontinuous member) between each other. .. In this case, each scintillator block becomes the first segment 21 and the second segment 31. Further, the optical discontinuity may use refraction or reflection instead of using the above scattering. Such an optical discontinuity is formed, for example, by interposing a medium (optical discontinuity member) such as air or an optical binder having a refractive index different from that of the scintillator between a plurality of scintillator blocks.

[Example]
As an example and a comparative example, the discrimination characteristics between the segments were examined for one radiation detection unit. FIG. 16A is a graph showing the histogram of Comparative Example 1. In the comparative example, each of the first segment 21 and the second segment 31 is five. Further, as in the fourteenth modification, the entire surfaces of the first segment 21 and the second segment 31 are specular reflection regions. In addition, the light guide portion 70 was not provided as in the thirteenth modification. The other points are the same as those of the above embodiment.

As the evaluation index of the discrimination characteristic, the index V1 and the index V2 were calculated by the following equations (6) and (7).
V1=(CB)/(DA) (6)
V2=D-A (7)
Here, A is the position of the apex in the distribution of the first segment 21 located on the one side S1 in the direction D, and B is the distribution of the first segment 21 located on the other side S2 in the direction D. The position of the apex, C is the position of the apex in the distribution of the second segment 31 located on the other side S2 in the direction D, and D is the position of the second segment 31 located on the one side S1 in the direction D. The positions of the vertices in the distribution are shown. In order to increase the distance between the distributions and improve the separation characteristics, it is desirable that the index V1 be small and the index V2 be large.

As shown in FIG. 16A, in Comparative Example 1, the value of the index V1 was 0.306 and the value of the index V2 was 530.

FIG. 16B is a graph showing the histogram of the first embodiment. In the first embodiment, the light guide section 70 is provided. The other points were the same as in Comparative Example 1. In Example 1, the value of the index V1 was 0.255 and the value of the index V2 was 534. As described above, in both the index V1 and the index V2, the example 1 is improved over the comparative example 1. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between the segments.

16A and 16B, in Example 1, as compared with Comparative Example 1, the distribution of the first segment 21 located on the othermost side in the direction D and the distribution in the direction D are the largest. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between these segments.

FIG. 17A is a graph showing a histogram of the second embodiment. In the second embodiment, as in the fourth modified example, the first region 26 and the second region 36 are made into the diffuse reflection regions by providing the diffuse reflection portion 68 using the diffuse reflection material. The other points were the same as in Example 1. In Example 2, the value of the index V1 was 0.243 and the value of the index V2 was 577. As described above, both the index V1 and the index V2 are improved as compared with the first embodiment. From this, it can be understood that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region.

16B and FIG. 17A, in the second embodiment, as compared with the first embodiment, the distribution of the first segment 21 located on the most one side in the direction D and the first segment It can be seen that the distance between the distribution of the first segments 21 adjacent to the other side in the direction D with respect to 21 is large. From this, it can be understood that the discrimination characteristic between the first segments 21 can be improved by making the first region 26 a diffuse reflection region. Similarly, in the second embodiment, as compared with the first embodiment, the distribution of the second segment 31 located on the most one side in the direction D and the distribution of the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31. It can be seen that the distance between the distributions of the matching second segments 31 is large. From this, it is understood that the discrimination characteristic between the second segments 31 can be improved by making the second region 36 a diffuse reflection region.

FIG. 17B is a graph showing the histogram of the third embodiment. In Example 3, similarly to the above-described embodiment, the first region 26 and the second region 36 were roughened to be diffuse reflection surfaces, and thus the first region 26 and the second region 36 were made diffuse reflection regions. The other points were the same as in Example 1. In Example 3, the value of the index V1 was 0.228 and the value of the index V2 was 641. As described above, both the index V1 and the index V2 are improved as compared with the first embodiment. From this, it can be understood that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region. Also, from FIGS. 16B and 17B, also in the third embodiment, as compared with the first embodiment, the distribution of the first segment 21 positioned on the most one side in the direction D and the first It can be seen that the distance between the distribution of the first segments 21 adjacent to the other side in the direction D with respect to the segment 21 is large. Also, the same applies to the second segment 31.

FIG. 18A is a cross-sectional view of the radiation detection unit 10L of the reference example. In this reference example, similarly to the first modification, the radiation provided with the first scintillator unit 20, the second scintillator unit 30, and the two scintillator units 20L that optically connect these by cutting out from one scintillator block. The detection unit 10L was formed. The first scintillator unit 20, the second scintillator unit 30, and each scintillator unit 20L are divided by a light scattering unit 44 formed by irradiation with laser light. In this reference example, each of the first segment 21, the second segment 31, and the segment 21L of the scintillator portion 20L is four. Further, the light guide section 70 was not provided. The other points are the same as those of the above embodiment. Hereinafter, the first segment 21, the segment 21L, and the second segment 31 arranged on the optical path from the first photodetection unit 82 to the second photodetection unit 84 will be referred to as the first segment 21 ₁ and the first segment 21 _{2 respectively.} , First segment 21 ₃ , first segment 21 ₄ , segment 21L ₅ , segment 21L ₆ , segment 21L ₇ , segment 21L ₈ , segment 21L ₉ , segment 21L ₁₀ , segment 21L ₁₁ , segment 21L ₁₂ , second segment 31 ₁₃ the second segment _{31 14,} second segment _{31 15,} that the second segment _{31 16.}

In this reference example, the first light scattering portion 22 between the first segments 21 ₂ and 21 ₃ and the light between the first segment 21 ₄ and the segment 21L ₅ , which are formed at a position where the flow rate of scintillation light is relatively large. Scattering section 44, light scattering section 22L between segments 21L ₆ and 21L ₇ , light scattering section 22L between segments 21L ₁₀ and 21L ₁₁ , light scattering section 44 between segment 21L ₁₂ and second segment 31 ₁₃ , and second segment 31 _14, 31 between ₁₅ second light scattering portion 32, of in each, by narrowing the area of the modified region than the light scattering portion other than the above, to restrict the flow rate of the scintillation light between segments. In FIG. 18A, a light scattering portion having a narrowed area of the modified region is shown by a thick line. Instead of reducing the area of the modified region, the density of formation of the modified region may be reduced to limit the flow rate of scintillation light between the segments.

FIG. 18B is a graph showing a histogram of the reference example. 1-16 of Figure 18 (b) in the first segment ₂₁ 1 to 21 _4, the segment _21L 5 _{~21L 12,} the position of the vertex of each distribution of the second segment _{31 13-31 16} represents respectively. From FIG. 18B, it can be seen that the distances between the distributions are large and the separation characteristics are good. From this, it is understood that the discrimination characteristic between the segments can be improved by limiting the distribution amount between the segments in which the distribution amount of the scintillation light is relatively large.

FIG. 23A is a graph showing a histogram of Comparative Example 2. In Comparative Example 2, each of the first segment 21 and the second segment 31 was seven. Further, as in the 14th modification, the entire surfaces of the first segment 21 and the second segment 31 are specular reflection regions. In addition, the light guide portion 70 was not provided as in the thirteenth modification. The other points are the same as those of the above embodiment.

In addition to the indexes V1 and V2 described above, indexes V(L)/P(L) and indexes V(R)/P(R) were calculated as the evaluation indexes of the discrimination characteristics. Here, V(L) is the count number in the distribution of the first segment 21 adjacent to the other side with respect to the first segment 21 located on the most one side in the direction D, and P(L) is the direction. The count number in the distribution of the first segment 21 located closest to one side in D is V(R) is the second number adjacent to the second segment 31 located closest to one side in the direction D on the other side. P(R) represents the count number in the distribution of the two segments 31, and P(R) represents the count number in the distribution of the second segment 31 located on the most one side in the direction D, respectively. The distance between the distribution of the first segment 21 located on the most one side in the direction D and the distribution of the first segment 21 adjacent to the other side in the direction D with respect to the first segment 21 is separated and separated. In order to improve the characteristics, it is desired to reduce V(L)/P(L). The distance between the distribution of the second segment 31 located on the most one side in the direction D and the distribution of the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31 is separated and separated. In order to improve the characteristics, it is desired to reduce the index V(R)/P(R).

As shown in FIG. 23A, in Comparative Example 2, the value of the index V1 is 0.245, the value of the index V2 is 753, and the value of the index V(L)/P(L) is 0.204. And the value of the index V(R)/P(R) was 0.212.

FIG. 23B is a graph showing a histogram of the fourth embodiment. In the fourth embodiment, the light guide section 70 is provided. The other points were the same as in Comparative Example 2. In Example 4, the value of the index V1 is 0.152, the value of the index V2 is 755, the value of the index V(L)/P(L) is 0.101, and the value of the index V(R)/P(R The value of) was 0.167. As described above, in both the index V1 and the index V2, the example 4 is improved over the comparative example 2. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between the segments.

23A and 23B, in Example 4, as compared with Comparative Example 2, the distribution of the first segment 21 located on the othermost side in the direction D and the distribution in the direction D are the largest. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between these segments.

FIG. 24A is a graph showing a histogram of Example 5. In the fifth embodiment, similarly to the seventeenth modification, on the surface of the first segment 21 located on the othermost side in the direction D and on the surface of the second segment 31 located on the othermost side in the direction D. A hemispherical optical binder 73 was provided. The other points were the same as in Example 4. In Example 5, the value of the index V1 is 0.130, the value of the index V2 is 794, the value of the index V(L)/P(L) is 0.179, and the index V(R)/P(R The value of) was 0.215. As described above, in both the index V1 and the index V2, the example 5 is improved over the example 4. From this, it can be understood that the provision of the optical binder 73 can improve the discrimination characteristic between the segments.

23B and FIG. 24A, in the fifth embodiment, compared with the fourth embodiment, the distribution of the first segment 21 located on the most other side in the direction D and the largest distribution in the direction D. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it can be seen that the provision of the optical binder 73 can improve the discrimination characteristic between these segments.

FIG. 24B is a graph showing a histogram of the sixth embodiment. In the sixth embodiment, similarly to the eighteenth modification, the light scattering surface 28 is provided in the first segment 21 located on the most other side in the direction D, and the second segment 31 located on the most other side in the direction D. A light scattering surface 38 is provided inside. The other points were the same as in Comparative Example 2. In Example 6, the value of the index V1 is 0.153, the value of the index V2 is 777, the value of the index V(L)/P(L) is 0.174, and the index V(R)/P(R). The value of) was 0.474. As described above, in both the index V1 and the index V2, the example 6 is improved as compared with the comparative example 2. From this, it is understood that the provision of the light scattering surfaces 28 and 38 can improve the discrimination characteristic between the segments.

23A and 24B, in Example 6, as compared with Comparative Example 2, the distribution of the first segment 21 located on the other side in the direction D and the direction D is the largest. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it is understood that the provision of the light scattering surfaces 28 and 38 can improve the discrimination characteristic between these segments.

FIG. 25A is a graph showing the histogram of Example 7. In Example 7, similarly to the fourth modified example, the first region 26 and the second region 36 were set as the diffuse reflection regions by providing the diffuse reflection section 68 using the diffuse reflection material. In Example 7, the value of the index V1 is 0.145, the value of the index V2 is 792, the value of the index V(L)/P(L) is 0.079, and the index V(R)/P(R The value of) was 0.100. As described above, both the index V1 and the index V2 are improved as compared with the fourth embodiment. From this, it can be understood that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region. Further, the index V(L)/P(L) was improved as compared with Example 4. From this, by providing the diffuse reflection region, the first segment 21 located on the most one side in the direction D and the first segment 21 adjacent to the other side in the direction D with respect to the first segment 21 are provided. It can be seen that the discrimination characteristic between the two can be improved. Further, the index V(R)/P(R) was improved as compared with Example 4. From this, by providing the diffuse reflection region, the second segment 31 located on the most one side in the direction D and the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31 are provided. It can be seen that the discrimination characteristic between the two can be improved.

FIG. 25B is a graph showing a histogram of the eighth embodiment. In Example 8, similarly to the above-described embodiment, the first region 26 and the second region 36 were roughened to be diffuse reflection surfaces, and thus the first region 26 and the second region 36 were made diffuse reflection regions. The other points were the same as in Example 4. In Example 8, the value of the index V1 is 0.136, the value of the index V2 is 771, the value of the index V(L)/P(L) is 0.115, and the index V(R)/P(R). The value of) was 0.139. As described above, both the index V1 and the index V2 are improved as compared with the fourth embodiment. From this, it can be understood that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region. Further, the index V(R)/P(R) was improved as compared with Example 4. From this, by providing the diffuse reflection region, the second segment 31 located on the most one side in the direction D and the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31 are provided. It can be seen that the discrimination characteristic between the two can be improved.

FIG. 26 is a graph showing a histogram of Example 9. In the ninth embodiment, as in the fifteenth modification, the light scattering surface 27 is provided in the first segment 21 located on the most one side in the direction D, and the second segment 31 located on the most one side in the direction D. A light scattering surface 38 is provided inside. The other points were the same as in Example 4. In Example 9, the value of the index V1 is 0.144, the value of the index V2 is 811, the value of the index V(L)/P(L) is 0.097, and the index V(R)/P(R The value of) was 0.112. As described above, both the index V1 and the index V2 are improved as compared with the fourth embodiment. From this, it can be understood that the discrimination characteristics between the segments can be improved by providing the light scattering surfaces 27 and 37. Further, the index V(L)/P(L) was improved as compared with Example 4. From this, by providing the light scattering surface 27, the first segment 21 located on the most one side in the direction D and the first segment 21 adjacent to the other side in the direction D with respect to the first segment 21. It can be seen that the discrimination characteristic between and can be improved. Further, the index V(R)/P(R) was improved as compared with Example 4. From this, by providing the light scattering surface 37, the second segment 31 located on the most one side in the direction D and the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31. It can be seen that the discrimination characteristic between and can be improved.

DESCRIPTION OF SYMBOLS 1... Radiation detector, 10... Radiation detection unit, 20... 1st scintillator part, 21, 21A-21E... 1st segment, 22... 1st light-scattering part (1st optical discontinuity part), 23... 1st End surface, 26... 1st area|region, 30... 2nd scintillator part, 31, 31A-31E... 2nd segment, 32... 2nd light-scattering part (2nd optical discontinuity part), 33... 2nd end surface, 36... 2nd area|region, 40... Connection part, 50... Light reflection part, 60... Light reflection part, 70... Light guide part, 80... Photodetection unit, 82... 1st photodetection part, 84... 2nd photodetection part, 90 ... output extraction part, 92... first resistance chain, 96... second resistance chain, D... predetermined direction.

Claims (10)

A plurality of first segments arranged along a predetermined direction, and a first scintillator portion having a first optical discontinuity portion provided between the adjacent first segments,
A plurality of second segments arranged along the predetermined direction, and a second scintillator portion having a second optical discontinuity portion provided between the adjacent second segments;
Light optically connected to the first end surface of the first segment located on the most one side in the predetermined direction and the second end surface of the second segment located on the most one side in the predetermined direction. A detection unit,
In the predetermined direction of the second segment located on the other side in the predetermined direction, and the surface of the other side of the first segment in the predetermined direction located on the other side in the predetermined direction. A surface of the other side, so that the scintillation light can flow between each other, a light guide section that is optically connected,
The first segment located on the othermost side in the predetermined direction and the second segment located on the othermost side in the predetermined direction are optically coupled,
The first segment other than the first segment located on the other side in the predetermined direction and the second segment other than the second segment located on the other side in the predetermined direction are optical. Radiation detectors that are physically separated. The light guide portion, between the first segment the surface of, and the second segment wherein the surface of which is positioned most on the other side in the predetermined direction to be positioned closest to the other side of the predetermined direction The radiation detector according to claim 1, wherein the radiation detector covers the surface of the first segment and the surface of the second segment so that a space is formed. On the said surface of the first segment located most other side in the predetermined direction, and an optical coupling agent provided on the surface of the second segment located most other side in the predetermined direction Further equipped with,
The radiation detector according to claim 2, wherein a refractive index of the optical coupling agent is smaller than a refractive index of the first scintillator portion and a refractive index of each of the second scintillator portion. A light scattering surface formed by irradiation of laser light is provided in the first segment located on the most other side in the predetermined direction and in the second segment located on the other most side in the predetermined direction. The radiation detector according to claim 1, wherein the radiation detector is provided. A first region including at least a part of a surface other than the first end face of the first segment located on the most one side in the predetermined direction, and the second region located on the most one side in the predetermined direction. The second region including at least a part of the surface other than the second end face of the segment is a diffuse reflection region,
Surfaces other than the first end surfaces of the plurality of first segments and other than the first area, and surfaces other than the second end surfaces of the plurality of second segments and other than the second area are specular reflection areas. The radiation detector according to any one of claims 1 to 4. The first region is formed on one of a pair of surfaces facing each other in the first segment located on the most one side in the predetermined direction,
The radiation detector according to claim 5, wherein the second region is formed on one of a pair of surfaces facing each other in the second segment located on the most one side in the predetermined direction. The first region serves as the diffuse reflection region by the light reflecting portion covering the surface of the roughened first segment,
7. The radiation detector according to claim 5, wherein the second region serves as the diffuse reflection region when the light reflecting portion covers the surface of the roughened second segment. The first region serves as the diffuse reflection region by covering the surface of the first segment with the diffuse reflection portion,
7. The radiation detector according to claim 5, wherein the second region serves as the diffuse reflection region by covering the surface of the second segment with a diffuse reflection portion. A light scattering surface formed by irradiation with laser light is provided in the first segment located on the most one side in the predetermined direction and in the second segment located on the most one side in the predetermined direction. The radiation detector according to claim 1, wherein the radiation detector is provided. A plurality of first segments arranged along a predetermined direction, and a first scintillator portion having a first optical discontinuity portion provided between the adjacent first segments,
A plurality of second segments arranged along the predetermined direction, and a second scintillator portion having a second optical discontinuity portion provided between the adjacent second segments;
Light optically connected to the first end surface of the first segment located on the most one side in the predetermined direction and the second end surface of the second segment located on the most one side in the predetermined direction. And a detection unit,
The first segment located on the other side in the predetermined direction and the second segment located on the other side in the predetermined direction are optically connected,
The first segment other than the first segment located on the other side in the predetermined direction and the second segment other than the second segment located on the other side in the predetermined direction are optical. Are separated,
A first region including at least a part of a surface other than the first end face of the first segment located on the most one side in the predetermined direction, and the second region located on the most one side in the predetermined direction. The second region including at least a part of the surface other than the second end face of the segment is a diffuse reflection region,
Surfaces other than the first end faces of the plurality of first segments and other than the first region, and surfaces other than the second end faces of the plurality of second segments and other than the second region are specular reflection regions. There is a radiation detector.

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