JP2016145819A - Radiation detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detector which achieves ease of mounting on an apparatus and has an enhanced characteristic of discrimination between segments.SOLUTION: A radiation detector includes: a first scintillator part 20 having a first segment 21 and a first light scattering part 22; a second scintillator part 30 having a second segment 31 and a second light scattering part 32; a light detection unit 80 optically connected to a first end face 23 of a first segment 21A positioned on the side of far one side S1 in the direction D and a second end face 33 of a second segment 31A positioned on the side of far end side S1 in the direction D; and a light guide part 70 optically connecting a first segment 21E and a second segment 31E positioned on the side of far end side S2 in the direction D. The first segment 21A and the second segment 31E are optically connected each other. The first segments 21A to 21D and the second segments 31A to 31D are optically separated from each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radiation detector.

  A radiation detector including a scintillator section having a plurality of segments and a light detection unit that detects scintillation light at a plurality of portions of the scintillator section 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). There is also a need to improve the discrimination characteristics between segments.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation detector that can be easily mounted on an apparatus and has improved discrimination characteristics between segments.

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

  In the radiation detector, the light detection unit is optically provided on the first end surface of the first segment located on the most one side in the predetermined direction and on the second end surface of the second segment located on the most one side in the predetermined direction. Connected. Therefore, electrical connection to the light detection unit can be performed from one side in a predetermined direction, and mounting on the apparatus is facilitated. Also, 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 separated from each other by an air layer or an optical binder. When combined, the flow rate of the scintillation light is limited by reflection at the coupling part, so that the separation between these segments is widened and the separation between the other segments is reduced, and the discrimination between the segments as a whole is reduced. There is a risk that the characteristics will deteriorate. On the other hand, according to the said radiation detector, the distribution | circulation amount of the scintillation light between these segments can be increased with a light guide part. Therefore, the discrimination characteristic between 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 in the space. According to this, the light guide part is constituted by the space and the light reflecting part, 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 amount of scintillation light flowing between the two.

  Moreover, in the radiation detector of this invention, it was provided on the surface of the 1st segment located in the other side in the predetermined direction, and on the surface of the 2nd segment located in the other side in the predetermined direction. An optical binder may be further included, and the refractive index of the optical binder may be smaller than the refractive index of the first scintillator portion and the refractive index of the second scintillator portion. According to this, the circulation amount 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 can be further increased. Can do.

  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. A formed light scattering surface may be provided. According to this, the circulation amount 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 can be further increased. Can do.

  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 one side in the predetermined direction, and the first side in the predetermined direction The second region including at least a part of the surface other than the second end surface of the second segment located in the region is a diffuse reflection region, and the surface other than the first end surface and the first region of the plurality of first segments, And the surfaces other than the second end face and the second region of the plurality of second segments may be specular reflection regions. The first segment located on the most side in the predetermined direction and the first segment adjacent to the first segment have similar output characteristics (ratio of output at both ends) when scintillation light is generated. Therefore, discrimination is relatively difficult. On the other hand, in this radiation detector, since the diffuse reflection region is provided on the surface of the first segment located on the most side in the predetermined direction, the first segment is adjacent to the first segment. A difference can be caused in the characteristics (output ratio at both ends) of the output extracted when scintillation light is generated between the matching first segments. Therefore, the discrimination characteristics between these first segments can be improved. Similarly, since the diffuse reflection region is provided on the surface of the second segment located on the most side in the predetermined direction, the second segment and the second segment adjacent to the second segment are provided. The discrimination characteristic can be improved.

  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 side in a predetermined direction, and the second region is a predetermined region You may form in one of a pair of surface which opposes in the 2nd segment located in the one side most in a direction. In this case, since the plurality of first regions are formed so as to extend in different directions, scintillation light is favorably diffused in the first segment located on the most side in the predetermined direction. Further, the processing can be facilitated as compared with the configuration in which the first regions are formed on both of the opposing surfaces. Similarly, the scintillation light is satisfactorily diffused in the second segment located on the most side in the predetermined direction, and the processing is facilitated as compared with the configuration in which the second regions are formed on both opposing surfaces. Is planned.

  In the radiation detector of the present invention, the first region is a diffuse reflection region by covering the surface of the roughened first segment with the light reflecting portion, and the second region is roughened. The light reflecting portion may cover the surface of the second segment thus formed to form a diffuse reflection region. The first region is a diffuse reflection region by covering the surface of the first segment with the diffuse reflection portion, and the second region is diffuse reflection by covering the surface of the second segment with the diffuse reflection portion. It may be an area. According to this, the 1st field and the 2nd field serve as a diffuse reflection field, and the discriminating characteristic between the 1st segment located in the 1st side in the predetermined direction and the 1st segment which adjoins the 1st segment concerned Can be improved.

  In the radiation detector of the present invention, the first segment located on the most side in the predetermined direction and the second segment located on the most 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 side in the predetermined direction, between the first segment and the first segment adjacent to the first segment. In FIG. 5, it is possible to make a difference in the characteristics (output ratio between both ends) of the output extracted when scintillation light is generated. Therefore, the discrimination characteristics between these first segments can be improved. Similarly, since the light scattering surface is provided in the second segment located on the most side in the predetermined direction, discrimination between the second segment and the second segment adjacent to the second segment is performed. Characteristics can be improved.

  The radiation detector of the present invention includes a first scintillator section having a plurality of first segments arranged along a predetermined direction and a first optical discontinuity section 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 adjacent second segments, and one side in the predetermined direction And a light detection unit optically connected to the second end surface of the second segment located on one side of the first segment in the predetermined direction, and being the most in the predetermined direction The first segment located on the other side and the second segment located on the other side in the predetermined direction are optically connected and located on the other side in the predetermined direction. The first segment other than the first segment and the second segment other than the second segment located on the other side in the predetermined direction are optically separated and located on the one side in the predetermined direction. A first region including at least a part of the surface other than the first end surface of the first segment, and a first region including at least a part of the surface other than the second end surface of the second segment located on the most side in the predetermined direction. The two regions are diffuse reflection regions, the surface other than the first end surface of the plurality of first segments and the surface other than the first region, and the surface other than the second end surface of the plurality of second segments and other than the second region, It is a specular reflection area.

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

  According to the present invention, it is possible to provide a radiation detector that can be easily mounted on an apparatus 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. It is the schematic of the PET apparatus by which the radiation detector of FIG. 1 was 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 of the radiation detector of FIG. 1, and an 8th modification. (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 a 12th modification. (A) is a graph which shows the histogram of the comparative example 1, (b) is a graph which shows the histogram of Example 1. FIG. (A) is a graph which shows the histogram of Example 2, (b) is a graph which shows the histogram of Example 3. FIG. (A) is sectional drawing of the radiation detection unit of a reference example, (b) is a graph which shows the histogram of a 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 of a radiation detection unit of Drawing 2, and a 17th modification. (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 which shows the histogram of the comparative example 2, (b) is a graph which shows the histogram of Example 4. FIG. (A) is a graph which shows the histogram of Example 5, (b) is a graph which shows the histogram of Example 6. FIG. (A) is a graph which shows the histogram of Example 7, (b) is a graph which shows the histogram of Example 8. FIG. 10 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 reference numerals are used for the same or corresponding elements, and duplicate descriptions are omitted.

  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 adjacent radiation detection units 10 are integrated with each other by being fixed, for example, by bonding.

As shown in FIG. 2, the radiation detection unit 10 includes a first scintillator unit 20, a second scintillator unit 30, light reflection units 50 and 60, and a light detection unit 80. Each of the scintillator units 20 and 30 is composed of a crystal lump 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 radiation at a position where the radiation is absorbed. The crystal mass is, for example, Bi ₄ Ge ₃ O ₁₂ (BGO), Ce ₂ doped Lu ₂ SiO ₅ (LSO), Lu _{2 (1-X)} Y _2X SiO ₅ (LYSO), Gd ₂ SiO ₅ (GSO). ), PrAG-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 _0.3 Consists of crystals such as AlO ₃ (LuYAP) and Lutetium Fine Silicate (LFS).

  The first scintillator section 20 has, for example, a regular prismatic shape. The first scintillator unit 20 includes a plurality of first segments 21 arranged along a predetermined direction D, and a first light scattering unit (first optical discontinuous unit) provided between adjacent first segments 21. 22. In other words, the first scintillator unit 20 is divided into a plurality of (in this example, five) first segments 21 by a plurality of (in this example, four) first light scattering units 22. The first segment 21 has, for example, a cubic shape. Hereinafter, 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 21. It is called segment 21E.

  The first light scattering unit 22 scatters a part of the scintillation light incident on 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 unit 22 has, for example, a planar shape orthogonal to the direction D. More specifically, the 1st light-scattering part 22 has the same shape (in this example, square shape) as the 1st end surface 23 (surface of the one side S1 in the direction D) of the 1st segment 21A, for example. ing. The plurality of first light scattering portions 22 are arranged, for example, so as to have an equal interval in the direction D, and to overlap each other when viewed from the direction D.

  The second scintillator section 30 has, for example, a regular prismatic shape. The second scintillator section 30 includes a plurality of second segments 31 arranged along the direction D, and a second light scattering section (second optical discontinuous section) 32 provided between the adjacent second segments 31. ,have. That is, the second scintillator section 30 is divided into a plurality (five in this example) of second segments 31 by a plurality (four in this example) of second light scattering parts 32. The second segment 31 has, for example, a cubic shape. Hereinafter, 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 31. This is called segment 31E.

  The second light scattering unit 32 scatters a part of the scintillation light incident on the second light scattering unit 32 and attenuates the intensity of the scintillation light passing through the second light scattering unit 32. The second light scattering unit 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 face 33 (the surface of one side S1 in the direction D) of the second segment 31A. ing. The plurality of first light scattering portions 22 are arranged, for example, so as to have an equal interval in the direction D, and to overlap each other when viewed from the direction D.

  Each of the light scattering portions 22 and 32 is formed by modifying (for example, making amorphous) a part of a crystal mass constituting each of the scintillator portions 20 and 30. This modification is performed by laser light irradiation. More specifically, a laser beam having optical transparency is condensed with respect to the crystal lumps constituting the scintillator units 20 and 30, and the condensing point of the laser light is relatively set along a predetermined surface of the crystal lumps. Move to. As a result, light absorption is caused at the portion where the condensing point of the laser beam is aligned in the crystal mass, and a modified region is formed along a predetermined surface of the crystal mass. When this laser beam is a pulsed laser beam, one modified spot is formed by irradiation with one pulse of laser beam, and a plurality of modified spots are arranged along a predetermined surface of the crystal lump. A quality region is formed. The modified regions thus formed become the light scattering portions 22 and 32. That is, each light scattering part 22 and 32 is formed by irradiation of 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 thus formed has a property that the transmittance of the scintillation light varies depending on the incident angle of the scintillation light. For example, when the scintillation light is vertically incident on the light scattering units 22 and 32, the incident scintillation light is almost transmitted. On the other hand, when the incident angle of the scintillation light is increased, the transmittance is reduced as compared with the case where the scintillation light is incident 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 a direction orthogonal to the direction D, and Each 1st light-scattering part 22 and each 2nd light-scattering part 32 are arrange | positioned so that it may adjoin. In this state, the first segment 21E and the second segment 31E located on the other 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. The first segment 21E and the second segment 31E are joined and optically coupled by filling the optical binder 42 therebetween and solidifying. That is, the first segment 21E and the second segment 31E are optically connected between their adjacent boundary surfaces (that is, the surfaces 24 and 34 facing each other).

  The connecting portion 40 is constituted by the surface 24 and the surface 34 which are rough polished surfaces, and an optical binder 42. By this connection part 40, the scintillation light can distribute | circulate between the 1st segment 21E and the 2nd 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 can be suppressed and the amount of circulation can be reduced compared to the case where the surface is a mirror surface. Will increase. As the optical binder 42, for example, RTV (Room Temperature Vulcanizing) rubber, optical grease, silicon 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 reflecting portion 50 is disposed between the first segments 21A to 21D and the second segments 31A to 31D. The light reflecting portion 50 is a film-like reflecting member and is in contact with the first segments 21A to 21D and the second segments 31A to 31D. The light reflecting portion 50 has a specular reflection surface, and specularly reflects the scintillation light incident on the surface. Thereby, the surface (smooth surface) which contacts the light reflection part 50 in 1st segment 21A-21D and 2nd segment 31A-31D is a specular reflection area | region. 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 unit 20 and the second scintillator unit 30 are covered with a light reflecting unit 60. The light reflecting section 60 covers the outer surfaces of the first scintillator section 20 and the second scintillator section 30 other than the first end face 23 of the first segment 21A and the second end face 33 of the second segment 31A. . The light reflecting portion 60 is a film-like reflecting member, and 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 surface 25 and the surface 35. The light reflecting section 60 has a specular reflecting surface, and specularly reflects the scintillation light incident on the surface. Thereby, the surface which contacts the light reflection part 60 in 1st segment 21A-21E and 2nd segment 31A-31E becomes a specular reflection area | region except the 1st area | region 26 and 2nd area | region 36 which are mentioned later. The light reflection part 60 is comprised with the material similar to the light reflection part 50, for example.

  A part of the surface of the first segment 21A other than the first end face 23 and a part of the surface of the second segment 31A other than the second end face 33 are rough polished surfaces. As a result, the first region 26 that is the rough polished surface in the first segment 21A and the second region 36 that is the rough polished surface in the second segment 31A are separated from the diffuse reflection region by contact with the light reflecting portion 60. It has become. That is, the first region 26 and the second region 36 diffusely reflect incident scintillation light. In other words, the first region 26 is a diffuse reflection region by covering the surface of the roughened first segment 21 </ b> A with the light reflecting portion 60, and the second region 36 is roughened. The light reflecting portion 60 covers the surface of the second segment 31A to form a diffuse reflection region.

  The first region 26 is formed on one of a pair of surfaces facing each other in the first segment 21A, and the second region 36 is formed on one of a pair of surfaces facing each other in the second segment 31A. Specifically, in this example, the first segment 21 has two pairs of opposed 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 surface of two adjacent surfaces among 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 surface of two adjacent surfaces among the surfaces other than the second end surface 33 of the second segment 31A.

  The radiation detection unit 10 further includes a light guide 70 that optically connects the first segment 21E and the second segment 31E. In the radiation detection unit 10, one side portion 62 of the light reflecting portion 60 extends in a direction orthogonal to the direction D, and the one side portion 62 is spaced from the surface 25 and the surface 35 that are rough polished surfaces. The light guide unit 70 is configured by being provided. Thereby, a rectangular parallelepiped air layer 72 is formed between the one side portion 62 and the surface 25 and the surface 35. In other words, the light guide unit 70 is configured by the light reflecting unit 60 covering the surface 25 and the surface 35 such that a space (air layer 72) is formed between the surface 25 and the surface 35. Yes. The light guide unit 70 also allows scintillation light to flow between the first segment 21E and the second segment 31E. Thereby, compared with the case where only the connection part 40 is provided, the distribution | circulation amount of the scintillation light between the 1st segment 21E and the 2nd segment 31E is increased. Further, the surface 25 and the surface 35 may be mirror reflection surfaces instead of the 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 the incidence of radiation, it is generated while repeating reflection in the specular reflection area and the diffuse reflection area. A part of the scintillation light 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 unit 22, the second light scattering unit 32, and the connection unit 40, the scintillation light in any of the first segments 21A to 21E and the second segments 31A to 31E. The ratio of the amount of light that reaches the first end face 23 and the second end face 33 changes stepwise depending on whether or not this occurs.

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

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

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

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

  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 radiation detection unit 10, the first light detection unit 82 is located on one side (left side in FIG. 4) in the row direction (the direction in which the first scintillator unit 20 and the second scintillator unit 30 are arranged). The second light detection unit 84 is located on the other side in the row direction (the right side in FIG. 4).

  In the first resistance chain 92, the first photodetecting parts 82 adjacent in the row direction are connected to each other via a resistor. Further, in the first resistance chain 92, the first light detection units 82 located on one side in the row direction are connected to each other via a resistor, and the first light detection unit 82 located on the other side in the row direction. The two are connected via a resistor. That is, in the first resistance chain 92, the first light detection units 82 adjacent in the column direction (a direction orthogonal to the row direction on the plane on which the first scintillator unit 20 and the second scintillator unit 30 are arranged) have resistance. Connected through. In the second resistance chain 96, the second light detection units 84 adjacent in the row direction are connected to each other via a resistor. Further, in the second resistance chain 96, the second light detection units 84 located on one side in the row direction are connected to each other via a resistor, and the second light detection unit 84 located on the other side in the row direction. The two are connected via a resistor. That is, in the second resistance chain 96, the second photodetecting portions 84 adjacent in the column direction are connected to each other via a resistor.

  The arithmetic unit 100 receives electric signal values at four vertices of the first resistance chain 92 as outputs A1 to A4, and inputs electric signal values at the four vertices of the second resistance chain 96 as outputs B1 to B4. Is done.

  The computing unit 100 identifies the radiation detection unit 10 in which scintillation light is generated based on the outputs A1 to A4 and / or the outputs B1 to B4. Furthermore, the calculating part 100 specifies the segment in which the scintillation light generate | occur | produced among the 1st segment 21 and the 2nd segment 31 of the specified radiation detection unit 10 based on output A1-A4 and output B1-B4. Hereinafter, a method for identifying a segment in which 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 orthogonal to the first direction d1. The radiation detection units 110 adjacent in the second direction d2 are optically separated by a reflection member (not shown). A light scattering portion 122 is formed between the segments 121 adjacent in the first direction d1. The first light detection unit 182 is optically connected to each segment 121A, and the second light detection unit 184 is optically connected to each segment 121F. The first light detection units 182 are connected to the first resistance chain 192, and the second light detection units 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 and the difference between the outputs A1 (or outputs A1 and A2) at both ends of the first resistance chain 192 by the following equations (1) and (2). ) And the sum AS, 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 number of counts.
AS = A1 + A2 (1)
R1 = A1 / AS or R1 = (A1-A2) / AS (2)

Instead of or in addition to this, the following equation (3), (4), the sum BS of the outputs B1, B2 at both ends of the second resistance chain 196 and the output B1 (or the output B1, The radiation detection unit 110 in which the scintillation light is generated may be specified by obtaining the ratio R2 of the difference between B2) and the sum BS and referring to the histogram G2 representing the relationship between the ratio R2 and the number of counts.
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 sums C1 and C2 are obtained, and the sum C1 (or sums C1, C2) is obtained. 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 number of counts.

  That is, the arithmetic unit calculates one ratio of the outputs A1 and A2 from the first resistor chain 192 and the outputs B1 and B2 from the second resistor chain 196, or a ratio of 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 sums 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 where the scintillation light is generated is identified among the plurality of segments 121 of the identified 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 identification of the radiation detection unit 110 in which the scintillation light is generated and the identification of the segment 121 in which the scintillation light is generated are independently performed by calculation based on the outputs A1 and A2 and the outputs B1 and B2. Can be done. That is, scintillation light generation positions can be specified independently for each of the first direction d1 and the second direction d2. As a result, the segment 121 where the scintillation light is generated can be specified.

  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 by the same processing as that of the radiation detector 101. Based on the outputs A1 to A4 and the outputs B1 to B4, the segment in which the scintillation light is generated can be specified among the first segment 21 and the second segment 31 of the specified radiation detection unit 10. Note that the calculation unit 100 generates scintillation light out of 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, contrary to the processing procedure described above. After specifying the segment, the radiation detection unit 10 (that is, the radiation detection unit 10 in which scintillation light is generated) having the specified segment 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 apparatus 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 where the output extraction unit 90 is provided faces the center C side of the measurement target. It is arranged. Thereby, the output extraction part 90 of each radiation detector 1 is located in the radial direction outer side of the circle centering on the center C. Therefore, the electrical connection of the calculation unit 100 to the radiation detector 1 can be performed from the outside in the radial direction. As described above, the radiation detector 1 can easily handle the wiring. The plurality of radiation detectors 1 may be arranged along the circumference of a circle centered on the center C so 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 face 23 of the first segment 21A and the second end face 33 of the second segment 31A. Therefore, electrical connection to the light detection unit 80 can be performed from one side in the direction D (lower side in FIG. 2), and mounting on the apparatus is facilitated. Further, according to the radiation detector 1, the amount of scintillation light flowing between the first segment 21 </ b> E and the second segment 31 </ b> E 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 segments is improved.

  Further, in the radiation detector 1, the light guide unit 70 is configured such that the light reflecting unit 60 covers the surface 25 and the surface 35 so that a space (air layer 72) is formed between the surface 25 and the surface 35. It is configured. According to this, the distribution | circulation amount of the scintillation light between the 1st segment 21 and the 2nd 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. Differences in characteristics can be made. Therefore, the discrimination characteristics between the first segments 21A and 21B can be improved. Similarly, since the diffuse reflection region is provided on the surface of the second segment 31A, the discrimination characteristics between the second segments 31A and 31B can be improved.

  Moreover, in the radiation detector 1, the 1st area | region 26 is formed in one of a pair of surface which opposes in the 1st segment 21A, and the 2nd area | region 36 is one of a pair of surface which opposes in the 2nd segment 31A. Is formed. In this case, since the plurality of first regions 26 are formed so as to extend in different directions, scintillation light is favorably diffused in the first segment 21A. Further, the processing can be facilitated as compared with the configuration in which the first region 26 is formed on both of the opposing surfaces. Similarly, the scintillation light is favorably 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 opposing surfaces.

  In the radiation detector 1, the 1st scintillator part 20 is obtained by forming the 1st light-scattering part 22 between the adjacent 1st segments 21 by irradiation of a laser beam. Similarly, the 2nd light-scattering part 32 is formed between the adjacent 2nd segments 31 by irradiation of a laser beam, and the 2nd scintillator part 30 is obtained. Therefore, for example, the first scintillator unit 20 and the second scintillator unit 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, manufacturing is facilitated and accuracy is improved. In addition, the structure or characteristics related to the difference between the light scattering portion formed by laser light irradiation and the light scattering portion formed by joining a plurality of scintillator blocks with the light scattering member interposed are generally described in words. It is considered impossible to specify. It is also considered impossible or impractical to analyze and identify such structures or properties based on measurements.

  Moreover, in the radiation detector 1, predetermined | prescribed optical separation is easily and reliably implement | achieved by arrange | positioning the light reflection part 50 between 1st segment 21A-21D and 2nd segment 31A-31D. it can.

  Further, in the radiation detector 1, between the plurality of radiation detection units 10, the first light detection units 82 are connected to the first resistance chain 92, and the second light detection units 84 are connected to the second resistance chain 96. It is connected. Therefore, for example, the number of outputs can be reduced as compared with a case where outputs are separately taken out from each of the plurality of light detection units. Further, the radiation detection unit 10 that generates the scintillation light and the scintillation light are generated by calculation based on the outputs A1 to A4 and the outputs B1 to B4 that are extracted from the first resistance chain 92 and the second resistance chain 96, respectively. The identification of the first segment 21 or the second segment 31 can be performed independently. Therefore, it is possible to ensure good discrimination characteristics between 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 such 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. Has been placed. For this reason, when forming the light-scattering parts 22 and 32, laser beam irradiation can be performed efficiently.

  In the radiation detector 1, the first light detection units 82 having the same positional relationship are connected to the first resistance chain 92, and the second light detection units 84 having the same positional relationship are connected to the second resistance chain 96. Therefore, good discrimination between segments can be performed by a relatively simple process.

  Further, in the radiation detector 1, the calculation unit 100 detects radiation in which scintillation light is generated based on at least one of the outputs A1 to A4 from the first resistor chain 92 and the outputs B1 to B4 from the second resistor chain 96. The unit 10 is specified, and the segment where the scintillation light is generated is specified from the first segment 21 and the second segment 31 based on the outputs A1 to A4 and the outputs B1 to B4. By such calculation, it is possible to independently specify the radiation detection unit 10 in which the scintillation light is generated and the segment in which the scintillation light is generated, and to obtain good discrimination characteristics.

  Moreover, in the radiation detector 1, since the several radiation detection unit 10 is arranged two-dimensionally, the detection range of a radiation can be expanded. In addition, even when the plurality of radiation detection units 10 are two-dimensionally arranged in this way, it is possible to ensure good discrimination characteristics between segments while reducing the number of outputs.

  Moreover, in the radiation detector 1, since the 1st light-scattering part 22 and the 2nd light-scattering part 32 are formed by irradiation of a laser beam, the area and formation density of the modification area | region of each light-scattering part are adjusted. Thus, the amount of scintillation light flowing through each light scattering portion can be easily adjusted. Therefore, increase the circulation amount of the light scattering part formed at a position where the circulation amount of the scintillation light is relatively small, or decrease the circulation amount of the light scattering part formed at a position where the circulation amount of the scintillation light is relatively large. By making it, the discrimination characteristic between segments can be improved.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments. The present invention can be modified without departing from the scope described in the claims or applied to other embodiments. May be.

  For example, the 1st scintillator part 20 and the 2nd scintillator part 30 may be integrally formed like the radiation detection unit 10A of the 1st modification shown by FIG. In this case, the 1st scintillator part 20 and the 2nd scintillator part 30 are formed by cutting 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 by a dicing saw. And the light reflection part 50 is inserted between 1st segment 21A-21D and 2nd segment 31A-31D. In addition, in the radiation detection unit 10A, a light scattering portion 44 formed by laser light irradiation is provided instead of the connection portion 40, whereby the first segment 21E and the second segment 31E are separated. .

  Also according to such a first modified example, it is possible to facilitate mounting on the apparatus as in the above embodiment. In addition, according to the first modification, since the step of joining the first scintillator unit 20 and the second scintillator unit 30 is omitted, it is possible to further facilitate the manufacture and increase the accuracy. Further, since the first segment 21E and the second segment 31E are separated by the light scattering portion 44 formed by the laser light irradiation, the amount of scintillation light flowing between the first segment 21E and the second segment 31E Can be adjusted easily.

  Further, the configuration of the light guide 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. May be. In the radiation detection unit 10 </ b> B, the one side portion 62 </ b> B of the light reflecting portion 60 has a first portion 65 and a second portion 66 extending so as 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 first portion 65 and the second portion 66 are continuous at the tip portions (end portions opposite to the surface 25 and the surface 35), and the tip portions are the first scintillator portion 20 and the second scintillator portion 30. It is located on the boundary line. In this example, a triangular columnar air layer 72 </ b> B is formed between the one side portion 62 </ b> B and the surface 25 and the surface 35. Further, in the radiation detection unit 10 </ b> C, the one side portion 62 </ b> C 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 semi-columnar air layer 72 </ b> C is formed between the one side portion 62 </ b> C and the surface 25 and the surface 35.

  According to the second modification and the third modification, it is possible to ensure 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 light guideable material may be disposed in a region (space) corresponding to the air layers 72, 72B, 72C.

  Moreover, you may change the structure of a diffuse reflection area | region like the radiation detection unit 10D of the 4th modification shown by FIG. In the radiation detection unit 10 </ b> D, the light reflection unit 60 includes a diffuse reflection unit 68 that covers the first region 26 and the second region 36. The surface of the diffuse reflection portion 68 is a diffuse reflection surface. In this case, the surfaces corresponding to the first region 26 and the second region 36 in the first scintillator unit 20 and the second scintillator unit 30 do not need to be rough polished surfaces, and the surfaces may be smooth surfaces. Even with such a configuration, the first region 26 and the second region 36 become diffuse reflection regions. That is, in this example, the first region 26 is a diffuse reflection region by covering the surface of the first segment 21A with the diffuse reflection part 68, and the second region 36 diffuses the surface of the second segment 31A. The reflection part 68 covers the area to form a diffuse reflection area. Therefore, the discrimination characteristic between the second segments 31A and 31B can be improved also by the fourth modification. The first region 26 may be an arbitrary region as long as it includes at least a part of the surface other than the first end face 23 of the first segment 21A. For example, the first region 26 may include a surface in contact with the light reflecting unit 50. The first region 26 may include a part of the surface of the first segment 21B. Even in these cases, the discrimination characteristics between the first segments 21A and 21B can be improved. These points are the same for the second region 36.

  Moreover, you may change the structure of the output extraction part 90 like the 5th modification shown by FIG. In the fifth modification, 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 light detection unit 82 and the second light detection unit 84 is known, the segment in which the scintillation light is generated can be specified by the same process as described above. Therefore, according to the fifth modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. Furthermore, according to the fifth modified example, even when the scintillation light leaks between the adjacent radiation detection units 10, it is possible to reduce an error generated at the scintillation light detection position.

  Moreover, you may comprise the radiation detector 1E and the radiation detection unit 10E like the 6th modification shown by FIG. In FIG. 11A, the light reflecting portion 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. As shown in FIG. 11A, each of the plurality of radiation detection units 10E includes scintillator units 20E having the same configuration as the first scintillator unit 20 and the second scintillator unit 30 in a matrix of 2 rows and 2 columns. It is configured by arranging. Adjacent scintillator portions 20E are optically coupled by the connecting portion 40 and optically separated by the light reflecting portion 50. Each radiation detection unit 10E has four light detection units 86A to 86D optically coupled to the scintillator unit 20E. In FIG.11 (b), arrangement | positioning of light detection part 86A-86D is virtually shown by the dashed-two dotted line below the radiation detector 1E. Among the plurality of radiation detection units 10E, the photodetectors 86A are connected to the first resistor chain, the photodetectors 86B are connected to the second resistor chain, and the photodetectors 86C are connected to the third resistor chain. In addition, the photodetecting portions 86D are connected to the fourth resistance chain. Also according to the sixth modified example, as in the above embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved.

  Moreover, you may comprise the radiation detector 1 like the 7th modification shown by Fig.12 (a). In the seventh modification, outputs are taken out from the first light detection units 82 and the second light detection units 84 of the plurality of radiation detection units 10 without using the first resistance chain 92 and the second resistance chain 96, respectively. Yes. Also in this case, the segment in which the scintillation light is generated can be specified by the importance calculation. Therefore, according to the seventh modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. However, the above embodiment is preferable in that the number of outputs can be reduced.

  Moreover, you may comprise the radiation detector 1 like the 8th modification shown by FIG.12 (b). In the eighth modification, 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 unit 10 and the other radiation detection unit 10 of the adjacent radiation detection unit 10. The second segment 31A is optically connected to both of the second end faces 33 of the second segment 31A. Note that the light detection unit 88 disposed at the end is optically connected only to the first end surface 23 or the second end surface 33. The point which does not use the 1st resistance chain 92 and the 2nd resistance chain 96 of the radiation detection unit 10 is the same as that of the 7th modification. According to the eighth modified example, as in the above embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. Furthermore, according to the eighth modification, the number of light detection units 88 can be reduced to reduce the number of outputs.

  Moreover, you may comprise the radiation detector 1 like the 9th modification shown by Fig.13 (a). The radiation detection unit 10H of the ninth modified example is configured by optically connecting the first scintillator unit 20 and the second scintillator unit 30 via two scintillator units 20H. The two scintillator portions 20H have the same configuration as that of the first scintillator portion 20 and the second scintillator portion 30, and are optically connected to each other via the connection portion 40 in the segment on the 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. On the other hand, the scintillator unit 20H adjacent to the second scintillator unit 30 is optically coupled to the second segment 31E of the second scintillator unit 30 via the connection unit 40 in the segment located on the other side S2 in the direction D. Has been. That is, the segments on the most 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). In addition, these segments and the first segment 21E or the second segment 31E are optically coupled between their adjacent boundary surfaces (that is, surfaces facing each other). Thus, the 1st scintillator part 20 and the 2nd scintillator part 30 may be optically connected via the some scintillator part 20H. The point which does not use the 1st resistance chain 92 and the 2nd resistance chain 96 is the same as that of the 7th modification. Also according to the ninth modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. Furthermore, according to the ninth modification, the number of light detection units 88 can be reduced, and the number of outputs can be reduced.

  Moreover, you may change the structure of the photon detection unit 80 like the 10th modification shown by FIG.13 (b). The light detection unit 80I of the tenth modification is configured by a position detection type photodetector that can detect 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 such a tenth modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved.

  Moreover, you may comprise the radiation detector 1 like the 11th modification shown by Fig.14 (a). In the eleventh modification, the first light detection unit 82 and the second light detection unit 84 of the plurality of radiation detection units 10 are connected to one resistance chain 99. Even in this case, the segment where the scintillation light is generated can be specified by the centroid calculation. Therefore, according to the eleventh modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. In the eleventh modification, the structure is simplified, and the first segment 21 and the second segment 31 are three. This also applies to the twelfth modification described below.

  Moreover, you may comprise the radiation detector 1 like the 12th modification shown by Fig.15 (a). In the twelfth modification, as in the eighth modification, the light detection unit 88 includes the first end surface 23 of the first segment 21A of one radiation detection unit 10K of the adjacent radiation detection unit 10K, and the adjacent radiation detection unit. The second radiation detection unit 10 </ b> K of the second radiation detection unit 10 </ b> K is optically connected to both the second end surfaces 33 of the second segment 31 </ b> A, and these light detection units 88 are connected to one resistance chain 99. Further, the adjacent radiation detection units 10K are optically coupled to each other via the connection portion 40 in the segment on the most side S1 in the direction D. The adjacent radiation detection units 10K share the light reflection unit 60. According to such a twelfth modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. Furthermore, according to the twelfth modification, the number of light detection units 88 can be reduced, and the number of outputs can be reduced. Further, as shown in FIGS. 14 (b) and 15 (b), the spread of the distribution on the separation characteristics generated 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. Thus, the twelfth modification is also preferable in that the discrimination characteristics between segments can be improved.

  Moreover, the light guide part 70 does not need to be provided like the radiation detection unit 10M of the thirteenth modified example shown in FIG. In the thirteenth modification, one side portion 62 of the light reflecting portion 60 is provided so as to contact the surface 25 and the surface 35 that are mirror-reflecting surfaces. Also in the thirteenth modified example, the diffuse reflection region is provided on the surface of the first segment 21A as in the above embodiment, so that the scintillation light is between the first segment 21A and the first segment 21B. It is possible to make a difference in the characteristics of the output that is taken out when this occurs. Therefore, the discrimination characteristics between the first segments 21A and 21B can be improved. Similarly, since the diffuse reflection region is provided on the surface of the second segment 31A, the discrimination characteristics between the second segments 31A and 31B can be improved.

  Further, unlike the radiation detection unit 10N of the fourteenth modified example shown in FIG. 19B, the first region 26 and the second region 36 that become the 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 is a specular reflection region. According to such a fourteenth modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved.

  Moreover, you may comprise the radiation detection unit 10P like the 15th modification shown by FIG. In the fifteenth modification, a planar light scattering surface 27 is provided in the first segment 21A. The light scattering surface 27 is disposed 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 disposed so as to pass through the center of the first segment 21A. A planar light scattering surface 37 is provided in the second segment 31A. The light scattering surface 37 is disposed 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 disposed so as to pass through the center of the second segment 31A. Each of the light scattering surfaces 27 and 37 is formed by laser light irradiation, similarly to each of the light scattering portions 22 and 32.

  According to such a fifteenth modified example, as in the above-described embodiment, it is possible to facilitate manufacture, increase accuracy, and facilitate mounting on the apparatus. Further, since the light scattering surface 27 is provided in the first segment 21A, the characteristics of the output that is extracted when scintillation light is generated between the first segment 21A and the first segment 21B (the output at both ends). A difference in the ratio). Therefore, the discrimination characteristics 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 characteristics between the second segments 31A and 31B can be improved. In the fifteenth modification, the light scattering surface 27 may not be disposed so as to pass through the center of the first segment 21A, and may be disposed at an arbitrary 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 region in which a modified region is formed, and the light scattering surface 27 may have a non-formed region in which the modified region is not formed. The non-forming region may be rectangular, for example. In the light scattering surface 27, the formation region and the non-formation region may be arranged in a checkered pattern. That is, the formation region and the non-formation region may be alternately arranged in a rectangular shape. 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 be alternately arranged in a band shape. The same applies to the light scattering surface 37.

  Moreover, you may comprise like the radiation detection unit 10Q of the 16th modification shown by Fig.21 (a), and the radiation detection unit 10R of the 17th modification shown by FIG.21 (b). In the sixteenth modification, a hemispherical optical binder 73 is provided on the surface 25 of the first segment 21E, and a hemispherical optical binder 74 is provided on the surface 35 of the second segment 31E. In the seventeenth modification, a 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 indexes of the optical binders 73 to 75 are smaller than the refractive indexes of the first scintillator unit 20 and the second scintillator unit 30. As the optical binders 73 to 75, for example, the same material as that of the optical binder 42 can be used. The surfaces 25 and 35 are mirror reflection surfaces. Also according to the sixteenth modification and the seventeenth modification, the mounting on the apparatus is facilitated and the discrimination characteristics between the segments are improved as in the above embodiment. Furthermore, the amount of scintillation light flowing 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 scintillator section 20 and 30 and the refractive index (substantially 1) of the outside (air layer 72) is large, the scintillation light that has traveled through each scintillator section 20 and 30 moves to each surface 25. , 35, it becomes easy to totally reflect, and it becomes difficult for the scintillation light to escape from the scintillator portions 20, 30. On the other hand, by providing optical binders 73 to 75 having a refractive index between the scintillator portions 20 and 30 and the air layer 72 on the respective surfaces 25 and 35, the air layer 72 from the scintillator portions 20 and 30. In addition, the scintillation light can easily escape, and the amount of scintillation light flowing 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 amount of scintillation light flowing between the first segment 21E and the second segment 31E can be further increased. The optical binders 73 to 75 may have an arbitrary shape, for example, a rectangular parallelepiped shape. Further, the surface 25 and the surface 35 may be rough polished surfaces.

  Moreover, you may comprise the radiation detection unit 10S like the 18th modification shown by FIG. In the eighteenth modification, a planar light scattering surface 28 is provided in the first segment 21E. The light scattering surface 28 is disposed along the direction D so as to be orthogonal to the surface 24 of the first segment 21E. The light scattering surface 28 is disposed so as to pass through the center of the first segment 21E. In addition, a planar light scattering surface 38 is provided in the second segment 31E. The light scattering surface 38 is disposed along the direction D so as to be orthogonal to the surface 34 of the second segment 31E. The light scattering surface 38 is disposed so as to pass through the center of the second segment 31E. Each of the light scattering surfaces 28 and 38 is formed by laser light irradiation, similarly to each of the light scattering portions 22 and 32.

  Also according to the eighteenth modified example, as in the above-described embodiment, the mounting on the apparatus is facilitated, and the discrimination characteristics between the segments are improved. Furthermore, the amount of scintillation light flowing between the first segment 21E and the second segment 31E can be further increased. In the eighteenth modification, the light scattering surface 28 may not be disposed so as to pass through the center of the first segment 21E, and may be disposed at an arbitrary 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 region in which a modified region is formed, and the light scattering surface 27 may have a non-formed region in which the modified region is not formed. The non-forming region may be rectangular, for example. In the light scattering surface 28, the formation region and the non-formation region may be arranged in a checkered pattern. That is, the formation region and the non-formation region may be alternately arranged in a rectangular shape. 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 be alternately arranged in a band shape. The same applies to the light scattering surface 38. Moreover, the light guide part 70 may be further provided.

  Moreover, the 1st light-scattering part 22 and the 2nd light-scattering part 32 do not need to be formed by irradiation of a laser beam. 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 with a light scattering member (optical discontinuous member) interposed therebetween. . In this case, each scintillator block becomes the first segment 21 and the second segment 31. Further, the optical discontinuity portion does not use scattering as described above, and may use refraction or reflection. Such an optical discontinuity is formed, for example, by interposing a medium (optical discontinuous member) having a refractive index different from that of a scintillator such as air or an optical binder between a plurality of scintillator blocks.

[Example]
As an example and a comparative example, the discrimination characteristic between segments was investigated about one radiation detection unit. FIG. 16A is a graph showing a histogram of Comparative Example 1. FIG. In the comparative example, each of the first segment 21 and the second segment 31 is five. Moreover, the whole surface of the 1st segment 21 and the 2nd segment 31 was made into the specular reflection area | region similarly to the said 14th modification. Moreover, the light guide part 70 was not provided similarly to the said 13th modification. The other points are the same as in the above embodiment.

As evaluation indices for the discrimination characteristics, the indices V1 and V2 were calculated by the following formulas (6) and (7).
V1 = (CB) / (DA) (6)
V2 = DA (7)
Here, A is the position of the vertex in the distribution of the first segment 21 located on the most 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 vertex, C is the position of the vertex 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 most side S1 Each vertex position in the distribution is represented. In order to increase the distance between the distributions and improve the separation characteristics, it is desirable to reduce the index V1 and increase the index V2.

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

  FIG. 16B is a graph showing a histogram of the first embodiment. In the first embodiment, the light guide unit 70 is provided. The other points were the same as those 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. Thus, Example 1 improved from Comparative Example 1 in both the index V1 and the index V2. From this, it can be seen that the discrimination characteristics between the segments can be improved by providing the light guide unit 70.

  Also, from FIG. 16A and FIG. 16B, in Example 1, compared with Comparative Example 1, the distribution of the first segment 21 located on the other side in the direction D and the most in the direction D It can be seen that the distance between the distribution of the second segments 31 located on the other side is getting closer. From this, it can be seen that the discrimination characteristics between these segments can be improved by providing the light guide 70.

  FIG. 17A is a graph showing a histogram of the second embodiment. In the second embodiment, as in the fourth modification, the first region 26 and the second region 36 are made the diffuse reflection region 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. Thus, it improved from Example 1 in both the parameter | index V1 and the parameter | index V2. From this, it can be seen that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region.

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

  FIG. 17B is a graph showing a histogram of the third embodiment. In Example 3, similarly to the above-described embodiment, the first region 26 and the second region 36 are roughened to form a diffuse reflection surface, whereby the first region 26 and the second region 36 are used as a diffuse reflection region. 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. Thus, it improved from Example 1 in both the parameter | index V1 and the parameter | index V2. From this, it can be seen that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region. Also, from FIG. 16B and FIG. 17B, also in the third embodiment, the distribution of the first segment 21 positioned on the most side in the direction D in the third embodiment and the first It can be seen that the distance between the segment 21 and the distribution of the first segment 21 adjacent on the other side in the direction D is increased. The same is true for 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 modified example, the radiation including the first scintillator unit 20, the second scintillator unit 30, and the two scintillator units 20L that optically connect them by cutting out from one scintillator block. A detection unit 10L was formed. The 1st scintillator part 20, the 2nd scintillator part 30, and each scintillator part 20L are divided in light scattering part 44 formed by irradiation of a laser beam. In this reference example, the number of each of the first segment 21, the second segment 31, and the four segments 21L of the scintillator portion 20L is four. Moreover, the light guide part 70 was not provided. The other points are the same as in the above embodiment. Hereinafter, the first segment 21, the segment 21L, and the second segment 31 arranged on the optical path from the first light detection unit 82 to the second light detection unit 84 are respectively referred to as the first segment 21 ₁ and the first segment 21 _2. , 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 , Second segment 31 ₁₄ , second segment 31 ₁₅ , second segment 31 ₁₆ .

In this reference example, the flow amount of the scintillation light is formed on the relatively large position, the first segment ₂₁ 2, 21 between ₃ first light scattering portion 22, the light between the first segment 21 ₄ and segment 21L ₅ scattering unit 44, segment _21L 6, 21L ₇ between the light scattering portion 22L, the segment _21L 10, _{21L 11} between the light scattering portion 22L, the light scattering portion 44 between the segments _{21L 12} and second segment _{31 13,} and the second In each of the second light scattering portions 32 between the segments 31 ₁₄ and 31 ₁₅ , the flow amount of scintillation light between the segments was limited by making the area of the modified region narrower than the light scattering portions other than these. In FIG. 18A, a light scattering portion in which the area of the modified region is narrowed is indicated by a thick line. Instead of reducing the area of the modified region, the flow rate of scintillation light between the segments may be limited by reducing the formation density of the modified region.

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 distance between the distributions is large and the separation characteristics are good. From this, it can be seen that the discrimination characteristic between segments can be improved by restricting the flow rate between segments where the flow rate of scintillation light is relatively large.

  FIG. 23A is a graph showing a histogram of Comparative Example 2. In Comparative Example 2, seven first segments 21 and two second segments 31 were used. Moreover, the whole surface of the 1st segment 21 and the 2nd segment 31 was made into the specular reflection area | region similarly to the said 14th modification. Moreover, the light guide part 70 was not provided similarly to the said 13th modification. The other points are the same as in the above embodiment.

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

  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. Thus, 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 unit 70 is provided. The other points were the same as those 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 index V (R) / P (R ) Was 0.167. Thus, Example 4 was improved over Comparative Example 2 in both the index V1 and the index V2. From this, it can be seen that the discrimination characteristics between the segments can be improved by providing the light guide unit 70.

  Further, from FIG. 23A and FIG. 23B, in Example 4, compared with Comparative Example 2, the distribution of the first segment 21 located on the other side in the direction D and the most in the direction D It can be seen that the distance between the distribution of the second segments 31 located on the other side is getting closer. From this, it can be seen that the discrimination characteristics between these segments can be improved by providing the light guide 70.

  FIG. 24A is a graph showing a histogram of the fifth embodiment. In the fifth embodiment, as in the seventeenth modification, on the surface of the first segment 21 located on the other side in the direction D and on the surface of the second segment 31 located on the other 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 ) Was 0.215. Thus, Example 5 improved from Example 4 in both index V1 and index V2. From this, it can be seen that the discrimination characteristic between the segments can be improved by providing the optical binder 73.

  Further, from FIG. 23B and FIG. 24A, in the fifth embodiment, compared with the fourth embodiment, the distribution of the first segment 21 located on the other side in the direction D and the most in the direction D It can be seen that the distance between the distribution of the second segments 31 located on the other side is getting closer. From this, it can be seen that the discrimination characteristic between these segments can be improved by providing the optical binder 73.

  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 other side in the direction D, and the second segment 31 located on the other side in the direction D. A light scattering surface 38 was provided inside. The other points were the same as those 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 ) Was 0.474. Thus, Example 6 was improved over Comparative Example 2 in both the index V1 and the index V2. From this, it can be seen that the discrimination characteristics between the segments can be improved by providing the light scattering surfaces 28 and 38.

  Further, from FIG. 23A and FIG. 24B, in Example 6, compared to Comparative Example 2, the distribution of the first segment 21 located on the other side in the direction D and the most in the direction D It can be seen that the distance between the distribution of the second segments 31 located on the other side is getting closer. From this, it can be seen that the discrimination characteristics between these segments can be improved by providing the light scattering surfaces 28 and 38.

  FIG. 25A is a graph showing a histogram of the seventh embodiment. In Example 7, similarly to the fourth modification, the first region 26 and the second region 36 are made the diffuse reflection region by providing the diffuse reflection part 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 ) Value was 0.100. Thus, it improved from Example 4 in both the parameter | index V1 and the parameter | index V2. From this, it can be seen 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 over that of Example 4. From this, by providing the diffuse reflection region, the first segment 21 located on the most 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 discriminating characteristics 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 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 discriminating characteristics 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 are formed as a diffuse reflection region by roughening the first region 26 and the second region 36 to form a diffuse reflection surface. 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 ) Value was 0.139. Thus, it improved from Example 4 in both the parameter | index V1 and the parameter | index V2. From this, it can be seen that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region. Furthermore, the index V (R) / P (R) was improved over that of Example 4. From this, by providing the diffuse reflection region, the second segment 31 located on 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 discriminating characteristics between the two can be improved.

  FIG. 26 is a graph showing a histogram of Example 9. In the ninth embodiment, similarly to the fifteenth modification, the light scattering surface 27 is provided in the first segment 21 located on the most side in the direction D, and the second segment 31 located on the most side in the direction D. A light scattering surface 38 was provided inside. The other points were the same as in Example 4. In the ninth embodiment, the value of the indicator V1 is 0.144, the value of the indicator V2 is 811, the value of the indicator V (L) / P (L) is 0.097, and the indicator V (R) / P (R ) Value was 0.112. Thus, it improved from Example 4 in both the parameter | index V1 and the parameter | index V2. From this, it can be seen 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 over that of Example 4. From this, by providing the light scattering surface 27, the first segment 21 located on the most 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 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 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 discontinuous part), 23 ... 1st End surface, 26 ... 1st area | region, 30 ... 2nd scintillator part, 31 and 31A-31E ... 2nd segment, 32 ... 2nd light-scattering part (2nd optical discontinuous 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 ... light detection unit, 82 ... 1st light detection part, 84 ... 2nd light detection 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 section having a first optical discontinuity provided between the adjacent first segments;
A second scintillator section having a plurality of second segments arranged along the predetermined direction and a second optical discontinuity provided between the adjacent second segments;
Light optically connected to the first end surface of the first segment located on the most side in the predetermined direction and the second end surface of the second segment located on the most side in the predetermined direction A detection unit;
A light guide unit that optically connects 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;
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 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 separated from each other.   The light guide has a space 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 radiation detector according to claim 1, wherein the radiation detector is configured by a light reflecting portion covering the surface of the first segment and the surface of the second segment so as to be formed. An optical binder 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; Prepared,
The radiation detector according to claim 2, wherein a refractive index of the optical binder is smaller than a refractive index of the first scintillator part and a refractive index of the second scintillator part.   A light scattering surface formed by laser light irradiation in the first segment located on the other side in the predetermined direction and in the second segment located on the other side in the predetermined direction. The radiation detector as described in any one of Claims 1-3 with which 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 surface of the segment is a diffuse reflection region,
The surface of the plurality of first segments other than the first end surface and other than the first region, and the surface of the plurality of second segments other than the second end surface and other than the second region are specular reflection regions. The radiation detector according to any one of claims 1 to 4. The first region is formed on one of a pair of faces facing each other in the first segment located on the most 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 side in the predetermined direction. The first region is the diffuse reflection region by the light reflecting portion covering the roughened surface of the first segment,
7. The radiation detector according to claim 5, wherein the second region is the diffuse reflection region when a light reflecting portion covers the roughened surface of the second segment. 8. The first region is the diffuse reflection region by covering the surface of the first segment with a diffuse reflection part,
The radiation detector according to claim 5, wherein the second region is the diffuse reflection region by covering the surface of the second segment with a diffuse reflection part.   A light scattering surface formed by laser light irradiation in the first segment located on the most side in the predetermined direction and in the second segment located on the most side in the predetermined direction. The radiation detector as described in any one of Claims 1-8 by which is provided. A plurality of first segments arranged along a predetermined direction, and a first scintillator section having a first optical discontinuity provided between the adjacent first segments;
A second scintillator section having a plurality of second segments arranged along the predetermined direction and a second optical discontinuity provided between the adjacent second segments;
Light optically connected to the first end surface of the first segment located on the most side in the predetermined direction and the second end surface of the second segment located on the most side in the predetermined direction 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. 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 surface of the segment is a diffuse reflection region,
The surface of the plurality of first segments other than the first end surface and other than the first region, and the surface of the plurality of second segments other than the second end surface and other than the second region are specular reflection regions. A radiation detector.

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