JP6704737B2 - Radiation detector - Google Patents

Description

The present invention relates to a radiation detector.

A radiation detector including a scintillator unit having a plurality of segments and a photodetection unit that detects scintillation light in a plurality of portions of the scintillator unit is known (for example, refer to Patent Documents 1 to 7). In such a radiation detector, the segment in which the radiation is absorbed is identified 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 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 reduce the number of outputs taken out from the radiation detector in order to reduce the cost and the size. It is also required to secure good discrimination characteristics between the segments based on the extracted output.

Therefore, an object of the present invention is to provide a radiation detector capable of ensuring good discrimination characteristics between segments while reducing the number of outputs.

The radiation detector of the present invention includes a plurality of radiation detection units that detect scintillation light, and an output extraction unit that is electrically connected to the plurality of radiation detection units, and each of the plurality of radiation detection units has a first A first scintillator part having one segment, a second scintillator part having a second segment, and a first photodetector part optically coupled to a first end face of the first scintillator part on one side in a predetermined direction. , A second photodetector section optically coupled to the second end surface of the second scintillator section on one side in the predetermined direction, and the first scintillator section and the second scintillator section are arranged in the predetermined direction. Is optically coupled in the region on the other side, and the output extraction unit includes a first resistance chain to which first photodetection units of the plurality of radiation detection units are connected, and a plurality of radiation detection units, respectively. A second resistance chain to which the second photodetector of is connected.

If the photodetection units are connected to a resistance chain between multiple radiation detection units and the outputs are taken out from both ends of the resistance chain, the number of outputs will be greater than in the case where the outputs are taken out separately from each photodetection unit. Can be reduced. However, for example, if all the photodetection units are connected to one resistance chain among a plurality of radiation detection units, the number of segments to be discriminated based on the output taken out may increase and the discrimination characteristic between the segments may deteriorate. is there. On the other hand, in the above-mentioned radiation detector, the first photodetection sections are connected to the first resistance chain and the second photodetection sections are connected to the second resistance chain among the plurality of radiation detection units. ing. Accordingly, the scintillation is performed by the calculation based on the both-end output of the first resistance chain and/or the both-end output of the second resistance chain and the calculation based on the sum of both-end outputs of the first resistance chain and the two-end output of the second resistance chain. It is possible to independently specify the radiation detection unit in which the light is generated and the segment in which the scintillation light is generated. Therefore, it is possible to secure good discrimination characteristics between the segments while reducing the number of outputs.

In the radiation detector of the present invention, the first scintillator portion has a plurality of first segments arranged along a predetermined direction and a first optical discontinuity portion provided between adjacent first segments. The second scintillator portion has a plurality of second segments arranged along a predetermined direction and a second optical discontinuity portion provided between adjacent second segments, and the first photodetector portion is , The second photo-detector is optically coupled to the first end surface of the first segment located on the most one side in the predetermined direction, and the second photodetector part of the second segment located on the most one side in the predetermined direction. The first segment, which is optically coupled to the second end face and is located on the most other side in the predetermined direction, and the second segment, which is most 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 optically separated. It may have been done. As described above, even when each scintillator unit has a plurality of segments and there are many segments to be discriminated, it is possible to secure good discrimination characteristics between the segments.

In the radiation detector of the present invention, the plurality of radiation detection units are arranged such that the first scintillator portion and the second scintillator portion are arranged side by side along a direction intersecting with the predetermined direction, and intersect with the predetermined direction. In the radiation detection units that are adjacent in the direction, the first light detection unit of one radiation detection unit and the second light detection unit of the other radiation detection unit may be adjacent to each other. According to this, since the positional relationship between the first photodetection section and the second photodetection section is the same among the plurality of radiation detection units, and the photodetection sections having the same positional relationship are connected to the resistance chain. Good discrimination between the segments can be performed by a relatively simple process.

Further, in the radiation detector of the present invention, the plurality of radiation detection units are arranged such that the first scintillator portion and the second scintillator portion are arranged side by side along a direction intersecting the predetermined direction, and In the radiation detection units that are adjacent to each other in the intersecting direction, the first photodetection units or the second photodetection units may be adjacent to each other. According to this, even when the scintillation light leaks between the adjacent radiation detection units, it is possible to reduce the error occurring at the detection position in the depth direction of the scintillation light.

Moreover, in the radiation detector of the present invention, the plurality of radiation detection units may be arranged two-dimensionally. According to this, since the plurality of radiation detection units are two-dimensionally arranged, the radiation detection range can be expanded. Even when the plurality of radiation detection units are two-dimensionally arranged in this way, it is possible to secure good discrimination characteristics between the segments while reducing the number of outputs.

Further, in the radiation detector of the present invention, the first optical discontinuity portion and the second optical discontinuity portion may be light scattering portions formed by irradiation with laser light. In this case, the first scintillator portion is obtained by forming the light scattering portion between the adjacent first segments by the irradiation of the laser light. Similarly, the second scintillator portion is obtained by forming the light scattering portion between the adjacent second segments by the irradiation of the laser light. Therefore, for example, the first scintillator portion and the second scintillator portion can be easily and highly dimensionally compared with a case where a plurality of scintillator blocks are joined while interposing a light scattering member (optically discontinuous member). Can be obtained at

Further, the radiation detector of the present invention further comprises an arithmetic unit electrically connected to the output extraction unit, and the arithmetic unit is based on at least one of the output from the first resistance chain and the output from the second resistance chain. The scintillation light is generated, the scintillation light is generated from the first segment and the second segment of the radiation detection unit based on the output from the first resistance chain and the output from the second resistance chain. The segment may be identified. By such a calculation, the radiation detection unit in which the scintillation light is generated and the segment in which the scintillation light is generated can be independently specified, and excellent discrimination characteristics can be obtained.

According to the present invention, it is possible to provide a radiation detector capable of ensuring good discrimination characteristics between segments while reducing the number of outputs.

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 scintillation light generated. FIG. 2 is a schematic diagram of a PET device in which the radiation detector of FIG. 1 is mounted. It is sectional drawing of the 1st modification of the radiation detection unit of FIG. (A) is sectional drawing of the 2nd modification of the radiation detection unit of FIG. 2, (b) is sectional drawing of the 3rd modification of the radiation detection unit of FIG. It is sectional drawing of the 4th modification of the radiation detection unit of FIG. It is sectional drawing of the 5th modification of the radiation detector of FIG. (A) And (b) is a perspective view of the 6th modification of the radiation detector of FIG. (A) is sectional drawing of the 7th modification of the radiation detection unit of FIG. 2, (b) is sectional drawing of the 8th modification of the radiation detection unit of FIG. (A) is a graph showing the histogram of Example 1, and (b) is a graph showing the histogram of Example 2. (A) is a graph showing a histogram of Example 3, and (b) is a graph showing a histogram of Example 4. (A) is a graph showing a histogram of Example 5, and (b) is a graph showing a histogram of Example 6. (A) is a cross-sectional view of a radiation detection unit of Example 7, and (b) is a graph showing a histogram of Example 7. It is sectional drawing of the 9th modification of the radiation detection unit of FIG. It is a figure for demonstrating the radiation detector of FIG. It is a figure for explaining the 5th modification. It is a figure for explaining the 5th modification. It is sectional drawing of the 10th modification of the radiation detection unit of FIG. (A) And (b) is sectional drawing of the 11th modification and the 12th modification of the radiation detection unit of FIG. (A) is sectional drawing of the 13th modification of the radiation detection unit of FIG. 2, (b) is BB sectional drawing of (a). (A) is a graph showing the histogram of Example 8, and (b) is a graph showing the histogram of Example 9. (A) is a graph showing the histogram of Example 10, and (b) is a graph showing the histogram of Example 11. (A) is a graph showing a histogram of Example 12, and (b) is a graph showing a histogram of Example 13. 16 is a graph showing a histogram of Example 14.

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

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

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

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

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

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

The second light scattering unit 32 scatters a part of the scintillation light that has entered the second light scattering unit 32, and attenuates the intensity of the scintillation light that passes through the second light scattering unit 32. The second light scattering section 32 has, for example, a planar shape orthogonal to the direction D. More specifically, the second light scattering part 32 has, for example, the same shape (in this example, a square shape) as the second end surface 33 of the second segment 31A (the surface on the one side S1 in the direction D). ing. The plurality of first light-scattering units 22 are arranged, for example, so as to have equal intervals 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, amorphizing) a part of the crystal mass forming each of the scintillator portions 20 and 30. This modification is performed by irradiation with laser light. More specifically, laser light having optical transparency is condensed to the crystal masses forming the scintillator portions 20 and 30, and the condensing point of the laser light is relatively set along a predetermined surface of the crystal mass. Move to. As a result, light absorption is caused at a portion where the condensing points of the laser light are aligned in the crystal mass, and a modified region is formed along a predetermined surface of the crystal mass. When this laser light is a pulsed laser light, one modified spot is formed by irradiation with one pulse of laser light, and a plurality of modified spots are arranged along a predetermined surface of the crystal mass. A quality region is formed. The modified regions thus formed serve as the light scattering parts 22 and 32. That is, each of the light scattering portions 22 and 32 is formed by irradiation with laser light.

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

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

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

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

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

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

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

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

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

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

The light detection unit 80 has a first light detection unit 82 and a second light detection unit 84. The 1st photon detection part 82 is optically combined with the 1st end surface 23 of the 1st segment 21A, for example via an adhesive agent for optics. The second photodetecting section 84 is optically coupled to the second end surface 33 of the second segment 31A, for example, via an optical adhesive. The first light detection unit 82 detects the intensity of the scintillation light that has entered the first end face 23, and outputs an electric signal having a magnitude corresponding to the detected value. The second light detection unit 84 detects the intensity of the scintillation light that has entered the second end face 33, and outputs an electric signal having a magnitude corresponding to the detected value. Each of the photodetectors 82 and 84 is, for example, a semiconductor photodetector using a photomultiplier tube, an avalanche photo diode (APD), an MPPC (Multi-Pixel Photon Counter), or the like. The MPPC is a photon counting device including a plurality of Geiger mode APD pixels.

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

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

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

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

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

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

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

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

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

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

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

Subsequently, the calculation unit obtains a ratio R4 between the sum AS (or the difference between the sum AS and BS) and the sum of the sum AS and the sum BS by the following equation (5), and the relationship between the ratio R4 and the count number. The segment 121 in which the scintillation light is generated is identified from 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 radiation detection unit 110 in which the scintillation light is generated and the segment 121 in which the scintillation light is generated are independently identified by the calculation based on the outputs A1 and A2 and the outputs B1 and B2. Can be done by That is, the generation position of the scintillation light can be independently specified for each of the first direction d1 and the second direction d2. As a result, the segment 121 in which the scintillation light is generated can be identified.

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

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

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

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

Further, in the radiation detector 1, each scintillator unit 20, 30 has a plurality of segments 21, 31, and even if there are many segments to be discriminated, it is possible to secure good discrimination characteristics between the segments. it can.

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

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

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

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

Further, in the radiation detector 1, the light detection unit 80 is optically connected to the first end surface 23 of the first segment 21A and the second end surface 33 of the second segment 31A. Therefore, the electrical connection to the light detection unit 80 can be performed from one side in the direction D (the lower side in FIG. 2 ). As described above, the radiation detector 1 facilitates mounting on a device such as a PET device.

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

Further, in the radiation detector 1, the flow amount of scintillation light between the first segment 21E and the second segment 31E is increased by the light guide unit 70. That is, the light guide unit 70 functions as a light guide. Therefore, the discrimination characteristic between the segments can be improved.

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

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

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

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

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and is modified within a range not changing the gist described in each claim or applied to other things. May be.

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

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

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

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

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

Further, the configuration of the output extraction unit 90 may be changed as in the radiation detector 1N of the fifth modified example shown in FIG. In the fifth modified example, the positional relationship between the first light detection unit 82 and the second light detection unit 84 is not the same among the plurality of radiation detection units 10. Even in such a case, if the arrangement of the first photodetector 82 and the second photodetector 84 is known, the segment in which the scintillation light is generated can be identified by the same process as the above process. Therefore, also in the fifth modified example, as in the above-described embodiment, it is possible to reduce the number of outputs and ensure good discrimination characteristics between the segments. Furthermore, according to the fifth modified example, even if the scintillation light leaks between the adjacent radiation detection units 10, the error generated at the scintillation light detection position can be reduced.

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

Further, unlike the radiation detection unit 10F of the seventh modified example shown in FIG. 12A, the first light scattering section 22 and the second light scattering section 32 may not be formed. In the radiation detection unit 10F, the first scintillator unit 20 has only one first segment 21, and the second scintillator unit 30 has only one second segment 31. According to such a seventh modified example as well, similar to the above-described embodiment, it is possible to reduce the number of outputs and secure good discrimination characteristics between the segments.

Further, the radiation detection unit 10G may be configured as in the eighth modified example shown in FIG. In the radiation detection unit 10G, the first scintillator section 20 and the second scintillator section 30 are formed by joining a plurality of scintillator blocks while interposing a light scattering member (optically discontinuous member) between each other. .. The joined scintillator blocks are the first segment 21 and the second segment 31, and the first optical discontinuity portion 22B and the second optical discontinuity portion 32B are formed by the light scattering member interposed therebetween. It is configured. In this way, the first optical discontinuity and the second optical discontinuity do not have to be formed by irradiation with laser light. In addition, in the radiation detection unit 10G, the number of the first segments 21 and the second segments 31 is three. According to the eighth modified example as well, similar to the above-described embodiment, it is possible to reduce the number of outputs and secure good discrimination characteristics between the segments. Further, in the radiation detection unit 10G, the connecting portion 40 optically couples the first segment 21C and the second segment 31C located on the othermost side S2 in the direction D and is adjacent to one of these sides S1. The first segment 21B and the second segment 31B are optically coupled. In this way, the first scintillator unit 20 and the second scintillator unit 30 may be optically coupled in the region on the other side S2 in the predetermined direction D.

Further, unlike the radiation detection unit 10M of the ninth modified example shown in FIG. 17, the light guide section 70 may not be provided. In the ninth modification, the one side portion 62 of the light reflecting portion 60 is provided so as to come into contact with the surfaces 25 and 35 which are specular reflecting surfaces. According to such a ninth modified example as well, similar to the above-described embodiment, it is possible to reduce the number of outputs and secure good discrimination characteristics between the segments. Further, unlike the radiation detection unit 10M of the ninth modified example, the first region 26 and the second region 36 which are diffuse reflection regions may not be formed. In the ninth modification, the entire surface of the first segment 21A and the surface of the second segment 31A are specular reflection regions.

Further, the radiation detection unit 10P may be configured as in the tenth modification shown in FIG. In the tenth modification, a planar light scattering surface 27 is provided in the first segment 21A. The light scattering surface 27 is arranged along the direction D, and extends between the first end surface 23 and the first light scattering portion 22 between the first segments 21A and 21B. The light scattering surface 27 is arranged so as to pass through the center of the first segment 21A. Further, a planar light scattering surface 37 is provided in the second segment 31A. The light scattering surface 37 is arranged along the direction D and extends between the second end surface 33 and the second light scattering portion 32 between the second segments 31A and 31B. The light scattering surface 37 is arranged so as to pass through the center of the second segment 31A. Each of the light scattering surfaces 27 and 37 is formed by laser light irradiation, similarly to each of the light scattering portions 22 and 32.

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

The radiation detection unit 10Q of the eleventh modification shown in FIG. 22A and the radiation detection unit 10R of the twelfth modification shown in FIG. 22B may be configured. In the eleventh modified example, the hemispherical optical binder 73 is provided on the surface 25 of the first segment 21E, and the hemispherical optical binder 74 is provided on the surface 35 of the second segment 31E. In the twelfth modified example, the hemispherical optical binder 75 is provided over the surface 25 of the first segment 21E and the surface 35 of the second segment 31E. The refractive index of the optical coupling agents 73 to 75 is smaller than the refractive index of each of the first scintillator section 20 and the second scintillator section 30. As the optical binders 73 to 75, for example, the same material as the optical binder 42 can be used. The surfaces 25 and 35 are specular reflection surfaces. With the eleventh modification and the twelfth modification as described above, as in the above embodiment, it is possible to reduce the number of outputs and ensure good discrimination characteristics between the segments. Furthermore, the distribution amount of scintillation light between the first segment 21E and the second segment 31E can be further increased. That is, when the difference between the refractive index of each scintillator portion 20 and 30 and the refractive index of the outside thereof (air layer 72) (approximately 1) is large, the scintillation light that has proceeded through each scintillator portion 20 and 30 has each surface 25. , 35, the total reflection is likely to occur, and the scintillation light is less likely to escape from the scintillator portions 20, 30. On the other hand, by providing the optical coupling agents 73 to 75 having the refractive index between the scintillator portions 20 and 30 and the air layer 72 on the surfaces 25 and 35, the scintillator portions 20 and 30 to the air layer 72 are provided. Therefore, the scintillation light can easily escape, and the amount of the scintillation light flowing between the first segment 21E and the second segment 31E can be further increased. In particular, in the twelfth modified example, since the optical binder 75 functions as a light guide, the flow rate of scintillation light between the first segment 21E and the second segment 31E can be further increased. The optical binders 73 to 75 may have any shape, for example, a rectangular parallelepiped shape. The surface 25 and the surface 35 may be rough-polished surfaces.

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

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

The optical discontinuity may use refraction or reflection instead of using the above scattering. Such an optical discontinuity is formed, for example, by interposing a medium (optical discontinuity member) 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, the discrimination characteristics between the segments were examined for one radiation detection unit. FIG. 13A is a graph showing the histogram of the first embodiment. In the first embodiment, each of the first segment 21 and the second segment 31 is three. Further, similarly to the ninth modified example, in the connection portion 40, the surfaces 24 and 34 are not rough polishing surfaces but specular reflection surfaces, and the entire surfaces of the first segment 21 and the second segment 31 are specular reflection areas. The light guide portion 70 was not provided. The other points are the same as in the above embodiment.

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

In Example 1, the value of the index V1 was 0.373 and the value of the index V2 was 675. It can be seen from FIG. 13A that the distances between the distributions are large and the separation characteristics are good.

FIG. 13B is a graph showing the histogram of the second embodiment. In Example 2, the surface 24 and the surface 34 were rough-polished surfaces as in the above embodiment. The other points were the same as in Example 1. In Example 2, the value of the index V1 was 0.265 and the value of the index V2 was 688. Both the index V1 and the index V2 were improved as compared with Example 1. When the two central peaks B and C approach each other, the outer peaks are also pulled inward, the distance between the outermost peaks A and D is increased, and the peak-to-valley ratio of the separation characteristics is improved. ..

FIG. 14A is a graph showing a histogram of the third embodiment. In the third embodiment, each of the first segment 21 and the second segment is five. Further, similarly to the ninth modified example, the entire surfaces of the first segment 21 and the second segment 31 are specular reflection regions, and the light guide section 70 is not provided. The other points are the same as in the above embodiment. In Example 3, the value of the index V1 was 0.306 and the value of the index V2 was 530.

FIG. 14B is a graph showing a histogram of the fourth embodiment. In the fourth embodiment, the light guide section 70 is provided. The other points were the same as in Example 3. In Example 4, the value of the index V1 was 0.255 and the value of the index V2 was 534. As described above, in both the index V1 and the index V2, the example 4 is improved over the example 3. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between the segments.

14A and 14B, in the fourth embodiment, as compared with the third embodiment, the distribution of the first segment 21 located on the othermost side in the direction D and the largest distribution in the direction D. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between these segments.

FIG. 15A is a graph showing the histogram of Example 5. In the fifth embodiment, as in the fourth modification, the first region 26 and the second region 36 are set as the diffuse reflection regions by providing the diffuse reflection portion 68 using the diffuse reflection material. The other points were the same as in Example 4. In Example 5, the value of the index V1 was 0.243 and the value of the index V2 was 577. As described above, both the index V1 and the index V2 are improved as compared with the fourth embodiment. From this, it can be seen that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region.

Further, from FIGS. 14B and 15A, in the fifth embodiment, compared with the fourth embodiment, the distribution of the first segment 21 located on the most one side in the direction D and the first segment It can be seen that the distance between 21 and the distribution of the first segments 21 adjacent to each other on the other side in the direction D is large. From this, it is understood that the discrimination characteristic between the first segments 21 can be improved by making the first region 26 a diffuse reflection region. Similarly, in the fifth embodiment, as compared with the fourth embodiment, the distribution of the second segment 31 located on the most one side in the direction D and the distribution on the other side in the direction D with respect to the second segment 31 are adjacent. It can be seen that the distance between the distributions of the matching second segments 31 is large. From this, it can be seen that the discrimination characteristic between the second segments 31 can be improved by making the second region 36 a diffuse reflection region.

FIG. 15B is a graph showing the histogram of Example 6. In Example 6, similarly to the above-described embodiment, the first region 26 and the second region 36 were roughened to be diffuse reflection surfaces, and thus the first region 26 and the second region 36 were made diffuse reflection regions. The other points were the same as in Example 4. In Example 6, the value of the index V1 was 0.228 and the value of the index V2 was 641. As described above, both the index V1 and the index V2 are improved as compared with the fourth embodiment. From this, it can be seen that the discrimination characteristic between the segments can be improved by providing the diffuse reflection region. Also, from FIGS. 14B and 15B, also in the sixth embodiment, as compared with the fourth embodiment, the distribution of the first segment 21 located on the most one side in the direction D and the first It can be seen that the distance between the distribution of the first segments 21 adjacent to the other side in the direction D with respect to the segment 21 is large. Further, the same can be seen for the second segment 31.

FIG. 16A is a sectional view of the radiation detection unit 10L according to the seventh embodiment. In the seventh embodiment, similarly to the first modification, the radiation including the first scintillator unit 20, the second scintillator unit 30, and the two scintillator units 20L that optically connect these by cutting out from one scintillator block. The detection unit 10L was formed. The first scintillator unit 20, the second scintillator unit 30, and each scintillator unit 20L are divided by a light scattering unit 44 formed by irradiation with laser light. In the seventh embodiment, each of the first segment 21, the second segment 31, and the segment 21L of the scintillator portion 20L is set to four. Further, the light guide section 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 photodetection unit 82 to the second photodetection unit 84 will be referred to as the first segment 21 ₁ and the first segment 21 _{2 respectively.} , First segment 21 ₃ , first segment 21 ₄ , segment 21L ₅ , segment 21L ₆ , segment 21L ₇ , segment 21L ₈ , segment 21L ₉ , segment 21L ₁₀ , segment 21L ₁₁ , segment 21L ₁₂ , second segment 31 ₁₃ the second segment _{31 14,} second segment _{31 15,} that the second segment _{31 16.}

In the seventh embodiment, the first light scattering portion 22 between the first segments 21 ₂ and 21 ₃ and the light between the first segment 21 ₄ and the segment 21L ₅ formed at a position where the amount of scintillation light flowing is relatively large. Scattering section 44, light scattering section 22L between segments 21L ₆ and 21L ₇ , light scattering section 22L between segments 21L ₁₀ and 21L ₁₁ , light scattering section 44 between segment 21L ₁₂ and second segment 31 ₁₃ , and second segment 31 _14, 31 between ₁₅ second light scattering portion 32, of in each, by narrowing the area of the modified region than the light scattering portion other than the above, to restrict the flow rate of the scintillation light between segments. In FIG. 16A, the light scattering portion in which the area of the modified region is narrow is shown by a thick line. Instead of reducing the area of the modified region, the density of formation of the modified region may be reduced to limit the amount of scintillation light flowing between the segments.

FIG. 16B is a graph showing the histogram of Example 7. 1-16 of 16 in (b), 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. 16B, it can be seen that the distances between the distributions are large and the separation characteristics are good. From this, it is understood that the discrimination characteristic between the segments can be improved by limiting the distribution amount between the segments in which the distribution amount of the scintillation light is relatively large.

FIG. 24A is a graph showing the histogram of Example 8. In Example 8, each of the first segment 21 and the second segment 31 was seven. Further, similarly to the ninth modified example, the entire surfaces of the first segment 21 and the second segment 31 are specular reflection regions, and the light guide section 70 is not provided. The other points are the same as in the above embodiment.

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

As shown in FIG. 24A, in Example 8, the value of the index V1 is 0.245, the value of the index V2 is 753, and the value of the index V(L)/P(L) is 0.204. And the value of the index V(R)/P(R) was 0.212.

FIG. 24B is a graph showing a histogram of Example 9. In the ninth embodiment, the light guide section 70 is provided. The other points were the same as in Example 8. In Example 9, 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 The value of) was 0.167. As described above, in both the index V1 and the index V2, the example 9 is improved over the example 8. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between the segments.

Further, from FIGS. 24A and 24B, in the ninth embodiment, compared with the eighth embodiment, the distribution of the first segment 21 located on the most other side in the direction D and the most distribution in the direction D. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it is understood that the provision of the light guide portion 70 can improve the discrimination characteristic between these segments.

FIG. 25A is a graph showing the histogram of Example 10. In the tenth embodiment, similarly to the eleventh modification, on the surface of the first segment 21 located on the othermost side in the direction D and on the surface of the second segment 31 located on the othermost side in the direction D. A hemispherical optical binder 73 was provided. The other points were the same as in Example 9. In Example 10, the value of the index V1 is 0.130, the value of the index V2 is 794, the value of the index V(L)/P(L) is 0.179, and the index V(R)/P(R The value of) was 0.215. As described above, in both the index V1 and the index V2, the example 10 is improved over the example 9. From this, it can be understood that the provision of the optical binder 73 can improve the discrimination characteristic between the segments.

Further, from FIG. 24B and FIG. 25A, in the tenth embodiment, as compared with the ninth embodiment, the distribution of the first segment 21 located closest to the other side in the direction D and the most distribution in the direction D. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it can be understood that the provision of the optical binder 73 can improve the discrimination characteristic between these segments.

FIG. 25B is a graph showing the histogram of Example 11. In the eleventh embodiment, as in the thirteenth modification, the light scattering surface 28 is provided in the first segment 21 located on the othermost side in the direction D, and the second segment 31 located on the othermost side in the direction D. A light scattering surface 38 is provided inside. The other points were the same as in Example 8. In Example 11, the value of the index V1 was 0.153, the value of the index V2 was 777, the value of the index V(L)/P(L) was 0.174, and the index V(R)/P(R ) Was 0.474. As described above, in both the index V1 and the index V2, the example 11 is improved over the example 8. From this, it is understood that the provision of the light scattering surfaces 28 and 38 can improve the discrimination characteristic between the segments.

24A and 25B, in the eleventh embodiment, compared with the eighth embodiment, the distribution of the first segment 21 located on the othermost side in the direction D and the most distribution in the direction D. It can be seen that the distance to the distribution of the second segment 31 located on the other side is approaching. From this, it is understood that the provision of the light scattering surfaces 28 and 38 can improve the discrimination characteristic between these segments.

FIG. 26A is a graph showing the histogram of Example 12. In the twelfth embodiment, similarly to the fourth modified example, the first region 26 and the second region 36 are set as the diffuse reflection regions by providing the diffuse reflection portion 68 using the diffuse reflection material. In Example 12, the value of the index V1 is 0.145, the value of the index V2 is 792, the value of the index V(L)/P(L) is 0.079, and the index V(R)/P(R The value of) was 0.100. As described above, both the index V1 and the index V2 are improved as compared with the ninth embodiment. 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(L)/P(L) was improved as compared with Example 9. From this, by providing the diffuse reflection region, the first segment 21 located on the most one side in the direction D and the first segment 21 adjacent to the other side in the direction D with respect to the first segment 21. It can be seen that the discrimination characteristic between the two can be improved. Further, the index V(R)/P(R) was improved as compared with Example 9. From this, by providing the diffuse reflection region, the second segment 31 located on the most one side in the direction D and the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31 are provided. It can be seen that the discrimination characteristic between the two can be improved.

FIG. 26B is a graph showing the histogram of Example 13. In Example 13, similarly to the above-described embodiment, the first region 26 and the second region 36 were roughened to be diffuse reflection surfaces, so that the first region 26 and the second region 36 were made diffuse reflection regions. The other points were the same as in Example 9. In Example 13, the value of the index V1 is 0.136, the value of the index V2 is 771, the value of the index V(L)/P(L) is 0.115, and the index V(R)/P(R The value of) was 0.139. As described above, both the index V1 and the index V2 are improved as compared with the ninth embodiment. 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 as compared with Example 9. From this, by providing the diffuse reflection region, the second segment 31 located on the most one side in the direction D and the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31 are provided. It can be seen that the discrimination characteristic between the two can be improved.

FIG. 27 is a graph showing a histogram of Example 14. In the fourteenth embodiment, similarly to the tenth modification, the light scattering surface 27 is provided in the first segment 21 located on the most one side in the direction D, and the second segment 31 located on the most one side in the direction D. A light scattering surface 38 is provided inside. The other points were the same as in Example 9. In Example 14, the value of the index V1 is 0.144, the value of the index V2 is 811, the value of the index V(L)/P(L) is 0.097, and the index V(R)/P(R The value of) was 0.112. As described above, both the index V1 and the index V2 are improved as compared with the ninth embodiment. From this, it is understood that the provision of the light scattering surfaces 27 and 37 can improve the discrimination characteristic between the segments. Furthermore, the index V(L)/P(L) was improved as compared with Example 9. From this, by providing the light scattering surface 27, the first segment 21 located on the most one side in the direction D and the first segment 21 adjacent to the other side in the direction D with respect to the first segment 21. It can be seen that the discrimination characteristic between and can be improved. Further, the index V(R)/P(R) was improved as compared with Example 9. From this, by providing the light scattering surface 37, the second segment 31 located on the most one side in the direction D and the second segment 31 adjacent to the other side in the direction D with respect to the second segment 31. It can be seen that the discrimination characteristic between and can be improved.

18A is a sectional view of the radiation detector 1 of the embodiment, and FIG. 18B is a conceptual diagram showing the radiation detector 1 similarly to FIG. FIG. 19A is a cross-sectional view of the radiation detector 1N of the fifth modified example, and FIG. 19B is a conceptual diagram showing the radiation detector 1N as in FIG. FIG. 20 is a conceptual diagram showing a connection state of the output extraction unit 90 of the radiation detector 1N. As shown in FIG. 18, in the radiation detector 1, in the plurality of radiation detection units 10, the first scintillator unit 20 and the second scintillator unit 30 are arranged along the direction L orthogonal to (intersecting) the direction D. Are arranged as follows. In the radiation detection units 10 and 10 that are adjacent to each other in the direction L, the first light detection unit 82 of one radiation detection unit 10 and the second light detection unit 84 of the other radiation detection unit 10 are adjacent to each other. That is, as described above, 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.

As shown in FIG. 19, also in the radiation detector 1N, the plurality of radiation detection units 10 are arranged so that the first scintillator unit 20 and the second scintillator unit 30 are arranged along the direction L. In the radiation detector 1N, in the radiation detection units 10 and 10 that are adjacent to each other in the direction L, the first photodetection sections 82 or the second photodetection sections 84 are adjacent to each other. That is, as described above, 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.

As shown in FIG. 20, also in the radiation detector 1N, the plurality of radiation detection units 10 are two-dimensionally arrayed, similarly to the radiation detector 1 of the embodiment. More specifically, similar to the case of the radiation detector 1 of the embodiment, in the plurality of radiation detection units 10, the first photodetection units 82 are arranged along the direction orthogonal to the direction D and the direction L, and the direction The second photodetectors 84 are arranged so as to be aligned along a direction orthogonal to the D and the direction L.

By the way, in the radiation detector 1, scintillation light may leak between the adjacent radiation detection units 10. One of the reasons for this is, for example, that the scintillation light is transmitted through the light reflecting portion 60 that shields the radiation detecting units 10 from each other. Another reason is that, for example, a part of the scintillation light that should be incident on the first photodetector 82 leaks and is incident on the adjacent second photodetector 84.

When the scintillation light leaks between the adjacent radiation detection units 10 as described above, an error occurs in the detection position of the scintillation light. For example, when the scintillation light is transmitted through the light reflection section 60 in the radiation detector 1, the light originally to be detected on the second light detection section 184 side is on the opposite side as shown by an arrow AR1 in FIG. It will be detected by the first light detection unit 182. As a result, a large error occurs in the detection direction of the scintillation light in the first direction d1, and an error also occurs in the second direction d2.

On the other hand, in the radiation detector 1N, when the scintillation light is transmitted through the light reflecting portion 60 as in the above case, as shown by an arrow AR2 in FIG. 19, in the second segment 31A of the adjacent radiation detection unit 10. It is specified that scintillation light is generated. In this case, an error in the second direction d2 occurs at the detection position of the scintillation light, but an error in the first direction d1 is suppressed. As described above, according to the radiation detector 1N, even if the scintillation light leaks between the adjacent radiation detection units 10, the error occurring at the detection position in the depth direction (first direction d1) of the scintillation light is reduced. can do.

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

Claims (6)

A plurality of radiation detection units for detecting scintillation light,
An output extraction unit electrically connected to the plurality of radiation detection units,
Each of the plurality of radiation detection units,
A first scintillator portion having a first segment;
A second scintillator portion having a second segment;
A first photodetecting section optically coupled to a first end surface of the first scintillator section on one side in a predetermined direction;
A second photodetector that is optically coupled to a second end surface of the second scintillator portion on one side in the predetermined direction,
The first scintillator section and the second scintillator section are optically coupled in a region on the other side in the predetermined direction,
The output extraction unit is
A first resistance chain to which the first photodetector of each of the plurality of radiation detection units is connected;
A second resistance chain to which the second photodetector of each of the plurality of radiation detection units is connected, and a radiation detector. The first scintillator portion has a plurality of first segments arranged along the predetermined direction, and a first optical discontinuity portion provided between the adjacent first segments,
The second scintillator portion has a plurality of second segments arranged along the predetermined direction, and a second optical discontinuity portion provided between the adjacent second segments,
The first photodetector is optically coupled to the first end surface of the first segment located on the most one side in the predetermined direction,
The second photodetector is optically coupled to the second end surface of the second segment located on the most one side in the predetermined direction,
The first segment located on the other side 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. The radiation detector according to claim 1, wherein the radiation detectors are separated. The plurality of radiation detection units are arranged such that the first scintillator section and the second scintillator section are arranged along a direction intersecting the predetermined direction,
In the radiation detection unit adjacent to each other in the direction intersecting with the predetermined direction, the first photodetection unit of one radiation detection unit and the second photodetection unit of the other radiation detection unit are adjacent to each other. The radiation detector according to claim 1 or 2. The plurality of radiation detection units are arranged such that the first scintillator section and the second scintillator section are arranged along a direction intersecting the predetermined direction,
The radiation detector according to claim 1, wherein in the radiation detection units that are adjacent to each other in the direction intersecting with the predetermined direction, the first photodetection units are adjacent to each other or the second photodetection units are adjacent to each other. The radiation detector according to claim 1, wherein the plurality of radiation detection units are arranged two-dimensionally. Further comprising an arithmetic unit electrically connected to the output extraction unit,
The arithmetic unit is
Based on at least one of the output from the first resistance chain and the output from the second resistance chain, the radiation detection unit in which scintillation light is generated is specified,
The segment in which the scintillation light is generated among the first segment and the second segment of the radiation detection unit is specified based on the output from the first resistance chain and the output from the second resistance chain. The radiation detector according to claim 5 .

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