JP2022148952A - Radiation detector, scintillator unit, and image generation device - Google Patents

Abstract

To provide a radiation detector and a scintillator unit having high position discrimination capability in a peripheral edge part, and also provide an image generation device having high spatial resolution that can generate high-quality images using the radiation detector.SOLUTION: A radiation detector and a scintillator unit each include a plurality of scintillator elements 2 disposed two-dimensionally and a light-receiving element 3, and scintillator elements 2A disposed on the outermost periphery are provided with light leakage prevention means 4 for optically blocking other scintillator elements 2B and preventing leakage of scintillation light to the side of the other scintillator elements 2B.SELECTED DRAWING: Figure 1

Description

The present invention relates to a radiation detector, a scintillator unit and an image generating device.

Radiation detectors that detect radiation emitted from an object are used not only for inspecting radiation-contaminated articles and living bodies, but also for acquiring images that provide information necessary for patient treatment or diagnosis in the medical field.
In particular, positron emission tomography (hereinafter referred to as "PET apparatus"), which utilizes positron emission tomography (hereinafter referred to as "PET"), is one example of medical diagnostic equipment that uses radiation detectors. be done. A PET device is a device that detects radiation emitted from a patient to whom a radiopharmaceutical is administered and acquires an image of the density distribution of the radiopharmaceutical in the patient's body, and is used in cancer examinations and the like. Therefore, a radiation detector used in a medical diagnostic apparatus such as a PET apparatus is required to accurately detect the position of radiation emitted from an object (patient).

As such a radiation detector, there is known one that includes a scintillator element that absorbs radiation and generates scintillation light, and a photodetector that detects the position and light intensity of the generated scintillation light. More specifically, a plurality of scintillator elements are arranged two-dimensionally or three-dimensionally, and the photodetector detects scintillation light emitted from the scintillator elements and identifies the scintillator element that responds to the incident radiation. There is known a configuration of a radiation detector that detects the incident position of radiation by performing.
In such a radiation detector, the resolution related to the identification of the scintillator element that responded, that is, the radiation detection position discrimination capability related to acquisition of position information of the radiation incident on the radiation detector (hereinafter simply referred to as "position discrimination capability") A study is being conducted on technology related to the improvement of

For example, in Patent Document 1, scintillation light from a scintillator element is diffused in a light guide and made incident on a light detection unit (a plurality of photomultiplier tubes), and the scintillator element that responds to the ratio of the amount of light received at this time. It is described that, based on the difference depending on the position, a plurality of circuits are used to calculate which scintillator element the radiation is incident on, thereby enhancing the position discrimination ability.

Further, for example, Patent Document 2 discloses a group of scintillator elements, a light guide for guiding light from the scintillator elements, and a photomultiplier tube that is optically coupled to the light guide and converts the light into an electrical signal. In a radiation detector with It is described that by allowing the radiation to be incident on the scintillator element at any position, accurate position discrimination is possible.

Japanese Utility Model No. 60-123683 Japanese Unexamined Patent Application Publication No. 2004-354343

As described in Patent Documents 1 and 2, it is known that in a radiation detector, a light guide is provided between a scintillator element and a photomultiplier tube to improve position discrimination performance.
However, when using the light guides as described in Patent Document 1 and Patent Document 2, there arise problems such as attenuation of scintillation light within the light guide and an increase in cost associated with the production of the light guide. In addition, as described in Patent Document 1, when the scintillation light incident on the photodetector is diffused by a light guide, the amount of light received by the photodetector decreases, resulting in a decrease in calculation accuracy. becomes.

In conventional radiation detectors, irrespective of the presence or absence of a light guide, when identifying scintillator elements that have responded, the response from the scintillator element arranged at the end of the radiation detector and the response from the adjacent scintillator element , the light intensity distributions in the photodetectors are similar to each other. As a result, when the position calculation based on the light intensity distribution is performed, the position calculation result of the response from the scintillator element arranged at the end of the radiation detector and the response from the adjacent scintillator element are similar. , the difference disappears. For this reason, it is often difficult to individually identify the responses of the two scintillator elements in the photodetector, and deterioration of the position discrimination ability at the edge (periphery) of the radiation detector becomes a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a radiation detector and a scintillator unit having high position discrimination performance, particularly in the peripheral portion.
Another object of the present invention is to provide an image generating apparatus with high spatial resolution that uses the above radiation detector and is capable of generating high quality images.

As a result of intensive studies on the above problem, the inventors of the present invention have found that, among a plurality of scintillator elements arranged two-dimensionally, the scintillation light from the scintillator element arranged on the outermost periphery is prevented from leaking to the other scintillator elements. By providing the means, when the response of the scintillator element arranged on the outermost circumference (the light emitted from the scintillator element arranged on the outermost circumference) is input to the photodetector, the difference from the response of the other scintillator elements is detected. We have found that it is possible to generate In other words, by changing the light intensity distribution of the scintillation light from the scintillator elements arranged at the outermost periphery (edge) on the photodetector, it is possible to make the position calculation result significantly different from the scintillator elements adjacent to the edge. I found what I can do. Furthermore, thereby, a radiation detector and a scintillator unit with improved position discrimination ability in the peripheral portion, and an image generating device with high spatial resolution capable of generating high-quality images by utilizing this radiation detector are formed. The present invention has been completed based on the knowledge that it is possible.
That is, the present invention is the following radiation detector, scintillator unit, and image generating device.

A radiation detector of the present invention for solving the above problems is a radiation detector comprising a plurality of scintillator elements arranged two-dimensionally and a light receiving element optically coupled to the plurality of scintillator elements, wherein The scintillator element arranged in the second scintillator element is provided with light leakage prevention means for optically blocking other scintillator elements and preventing leakage of scintillation light to the side of the other scintillator elements.
According to this feature, by optically blocking the scintillator element arranged on the outermost circumference from the other scintillator elements and preventing the leakage of light, the response of the scintillator element arranged on the outermost circumference is reduced to that of the light-receiving element. It is possible to make a difference between the light intensity distribution when the response of another scintillator element is input to the light receiving element and the light intensity distribution when the response of another scintillator element is input to the light receiving element. For this reason, a significant difference occurs between the position calculation result related to the response from the scintillator element arranged on the outermost circumference and the position calculation result related to the response from the adjacent scintillator element, and the light receiving element detects the position. It becomes possible to individually identify the responses of the two scintillator elements. This makes it possible to improve the position discrimination performance in the peripheral portion of the radiation detector.
Hereinafter, the light intensity distribution when the response (scintillation light) of the scintillator element arranged on the outermost periphery is input to the light receiving element and the light intensity distribution when the response of the other scintillator elements is input to the light receiving element. , is sometimes simply referred to as a "response difference (of the scintillator element)".

Further, as an embodiment of the radiation detector of the present invention, the light leakage preventing means has a light reflecting surface and is made of a flat plate without slits.
According to this feature, it is possible to realize the response difference of the scintillator element by the light leakage prevention means with a simple structure using a member (flat plate) that does not require fine processing. In addition, since detailed processing of the member related to the light leakage prevention means is not required, the cost of the radiation detector can be reduced, and the response difference of the scintillator element can be generated without depending on the processing accuracy of the member. becomes possible. This makes it possible to further improve the position discrimination performance in the peripheral portion of the radiation detector.

Further, as an embodiment of the radiation detector of the present invention, the light leakage prevention means includes a single flat plate for preventing leakage of scintillation light from a plurality of scintillator elements arranged on the outermost periphery. have.
According to this feature, the number of members related to the light leakage prevention means can be reduced, and the light intensity distribution related to the response of the scintillator element arranged on the outermost periphery and the light intensity distribution related to the response of the other scintillator elements can be separated. It becomes easier to make a difference. This makes it possible to further improve the position discrimination performance in the peripheral portion of the radiation detector.

In one embodiment of the radiation detector of the present invention, light reflecting means for reflecting scintillation light is provided between a plurality of scintillator elements arranged inside the outermost periphery, and the light reflecting means has a light reflecting surface. and a combination of flat plates provided with slits.
According to this feature, by providing the light reflecting means between the scintillator elements other than the scintillator elements arranged on the outermost periphery, the response of the scintillator elements incident on the light receiving element is partitioned, and the scintillator element in the light receiving element It is possible to easily identify the response of the In addition, by combining a flat plate with a slit as a member related to the light reflecting means, it is possible to easily perform positioning and compartmentalization in the arrangement of the scintillator elements, and reduce the work load related to assembly. becomes possible.
Furthermore, according to this feature, between the scintillator elements other than the scintillator elements arranged on the outermost periphery, the scintillation light leaks from the slit as the light reflecting means. At this time, the response of the scintillator element at locations other than the outermost periphery is incident on the light receiving element as a light intensity distribution having a certain spread outside the section. For this reason, a light intensity distribution wider than the originally defined range is input, and it is possible to improve the calculation accuracy in the calculation (especially the barycentric calculation) related to the identification of the response of the scintillator element in the light receiving element. . This makes it possible to improve the position discrimination ability of the radiation detector as a whole.

Further, one embodiment of the radiation detector of the present invention is characterized by forming a scintillator array including a scintillator element and light leakage prevention means, and laminating a plurality of scintillator arrays.
According to this feature, by stacking a plurality of scintillator arrays each composed of a combination of a scintillator element capable of improving position discrimination in the peripheral portion and a light leakage prevention means, the position of the radiation detector particularly related to the end of the scintillator array can be improved. It is possible to improve the discrimination ability and enhance the responsiveness (sensitivity) of the radiation detector.

Further, as one embodiment of the radiation detector of the present invention, a scintillator array comprising a scintillator element, a light leakage prevention means and a light reflection means is formed, a plurality of scintillator arrays are laminated, and each layer has a scintillator array has a structure in which the light reflecting means are arranged in different positions.
When scintillator arrays each including a scintillator element and a light reflecting means are simply stacked, there are places where the light reflecting means are continuously arranged in the stacking direction. At this time, since the division of the scintillator elements in each layer overlaps, the effect of improving the responsiveness (resolution) as a radiation detector by stacking the scintillator arrays cannot be obtained. In addition, at the ends of the scintillator array, the light intensity distribution related to the response from the scintillator element becomes similar to the light intensity distribution related to the response of the adjacent scintillator element, leading to deterioration of the position discrimination ability of the radiation detector. Become.
On the other hand, according to this feature, at the end (outermost circumference) of the scintillator array, the response difference of the scintillator element is caused by the light leakage prevention means, so that the response of the scintillator element at the end of the scintillator array can be properly identified. In addition, inside the outermost periphery of the scintillator array, by making the locations of the light reflecting means different for each layer of the scintillator array, the light reflecting means adjacent to each other in the stacking direction are all continuously arranged. It can be a structure that does not occur. As a result, the response of the scintillator element from each layer can be appropriately divided and made incident on the light receiving element, thereby improving the position discrimination ability of the radiation detector and the responsiveness (sensitivity) of the radiation detector. It is possible to increase both Also, the structural design of the scintillator array as a whole is facilitated.

Further, as an embodiment of the radiation detector of the present invention, the light reflecting means is also provided between the scintillator elements arranged on the outermost circumference, and extends from between the scintillator elements arranged inside the outermost circumference. and a second light reflecting means provided independently of the first light reflecting means.
According to this feature, by providing the light reflecting means respectively on the outermost peripheral side and the inner side of the scintillator array, the scintillator elements on the outermost peripheral side can be easily partitioned and the position calculation accuracy can be improved. planned. In addition, on the outermost periphery of the scintillator array, by enabling the formation of a structure in which the arrangement location is different from that of the light reflecting means provided inside, an optimal structure for enhancing the position discrimination performance at the outermost periphery (edge) can be achieved. It becomes possible to form independently. This makes it possible to further improve the position discrimination performance in the peripheral portion of the radiation detector.

Further, as one embodiment of the radiation detector of the present invention, the light leakage prevention means is characterized by being composed of a member having an integral structure extending in the stacking direction of the scintillator array.
According to this feature, when the scintillator arrays are stacked and used, the light leakage prevention means can be easily manufactured and arranged, and the light leakage prevention means can more reliably cause the response difference of the scintillator elements. Become.

A scintillator unit of the present invention for solving the above problems is a scintillator unit comprising a plurality of scintillator elements arranged two-dimensionally, wherein the scintillator element arranged on the outermost circumference includes other scintillator elements and optical scintillator elements. It is characterized by providing a light leakage preventing means for blocking the scintillation light effectively and preventing the scintillation light from leaking to other scintillator elements.
According to this feature, when combined with the light receiving element, the difference between the light intensity distribution related to the response of the scintillator element arranged on the outermost periphery and the light intensity distribution related to the response of the other scintillator elements input to the light receiving element It is possible to form a scintillator unit that can make a difference in the . As a result, a significant difference is generated between the position calculation result related to the response from the scintillator element arranged on the outermost periphery and the position calculation result related to the response from the adjacent scintillator element, and the light-receiving element detects it. It is possible to easily form a radiation detector that makes it possible to individually identify the responses of the two scintillator elements and has improved position discrimination performance in the peripheral portion.

An image generating apparatus of the present invention for solving the above problems is characterized by comprising the radiation detector described above and an image generating section based on detection data obtained by the radiation detector.
According to this feature, by using the detection data obtained by the radiation detector, it is possible to generate an image based on highly accurate data related to radiation incident position information. As a result, it is possible to provide an image generating apparatus with high spatial resolution that enables high-quality image generation.

According to the present invention, it is possible to provide a radiation detector and a scintillator unit with high position discrimination performance, particularly in the peripheral portion.
Further, according to the present invention, it is possible to provide an image generating apparatus with high spatial resolution capable of generating high-quality images using the radiation detector.

1 is a schematic explanatory diagram showing the structure of a radiation detector according to a first embodiment of the present invention; FIG. FIG. 3 is a schematic explanatory diagram showing an example of light leakage prevention means of the radiation detector according to the first embodiment of the present invention; FIG. 4 is a schematic explanatory diagram showing another aspect of the light leakage prevention means of the radiation detector according to the first embodiment of the present invention; FIG. 4 is a schematic explanatory diagram showing another aspect of the light leakage prevention means of the radiation detector according to the first embodiment of the present invention; FIG. 2 is a schematic explanatory diagram showing an example of light reflecting means of the radiation detector according to the first embodiment of the present invention; FIG. 4 is a schematic diagram when radiation is incident on the radiation detector according to the first embodiment of the present invention; FIG. 10 is a schematic diagram when radiation is incident on a radiation detector as a comparative example; FIG. 4 is a diagram showing response results of a scintillator element using the radiation detector according to the first embodiment of the present invention; FIG. 5 is a diagram showing response results of a scintillator element using a radiation detector as a comparative example; 1 is a schematic explanatory diagram showing the structure of an image generation device according to a first embodiment of the present invention; FIG. FIG. 5 is a schematic explanatory diagram (perspective view) showing the overall structure of a radiation detector according to a second embodiment of the present invention; FIG. 5 is a schematic explanatory diagram showing an example of a structure (structure of a scintillator array) according to another aspect of the radiation detector according to the second embodiment of the present invention; FIG. 5 is a schematic explanatory diagram showing an example of a structure (structure of a scintillator array) according to another aspect of the radiation detector according to the second embodiment of the present invention; FIG. 4 is a schematic explanatory diagram showing the structure of a scintillator array in a radiation detector (four-layer DOI detector) as a comparative example; FIG. 10 is a diagram showing response results of scintillator elements using the radiation detector according to the second embodiment of the present invention; FIG. 5 is a diagram showing response results of a scintillator element using a radiation detector as a comparative example;

Embodiments of the radiation detector, scintillator unit, and image generating apparatus of the present invention will be described in detail below.
It should be noted that the radiation detector, scintillator unit, and image generation device described in the embodiments are merely examples for explaining the present invention, and are not limited thereto.

[First embodiment]
(radiation detector)
FIG. 1 is a schematic explanatory diagram (perspective view) showing the structure of the radiation detector according to the first embodiment of the present invention.
The radiation detector 1A according to this embodiment detects radiation emitted from an object, and has a position discriminating function capable of obtaining position information of radiation incident on the radiation detector 1A.

As shown in FIG. 1, the radiation detector 1A includes a plurality of scintillator elements 2 and a light receiving element 3 arranged two-dimensionally. The radiation detector 1A also includes light leakage prevention means 4 for optically blocking the scintillator element 2A arranged on the outermost circumference and the other scintillator elements 2B arranged on the outermost circumference, and and light reflecting means 5 provided between the plurality of scintillator elements 2B.

The scintillator element 2 absorbs radiation and generates light called scintillation light. This scintillation light has a light intensity corresponding to the dose of radiation absorbed.

As the scintillator element 2, one made of a crystal mass that generates scintillation light upon incidence of radiation can be used. More specifically, for example, Bi ₄ Ge ₃ O ₁₂ (BGO), Ce-doped Lu ₂ SiO ₅ (LSO), Ce-doped Lu _2(1−X) Y _2X SiO ₅ (LYSO). , Ce-doped Gd ₃ (Al, Ga) ₅ O ₁₂ (GAGG), Ce- or Zr-doped Gd ₂ SiO ₅ (GSO), Ce-doped Lu _{2 (1-X)} G _2X SiO ₅ (LGSO), Pr-doped Lu ₃ Al ₅ O ₁₂ (LuAG), Ce-doped LaBr ₃ , Ce-doped LaCl ₃ , Ce-doped Lu _0.7 Y _0.3 AlO ₃ (LuYAP), Lutetium Fine Silicate (LFS), and the like.

Although the shape of the scintillator element 2 is not particularly limited, it is preferable to have a substantially rectangular parallelepiped outer shape in order to perform efficient two-dimensional arrangement.
Also, the size of the scintillator element 2 is not particularly limited. The size of the scintillator element 2 can be appropriately set according to, for example, the desired detection accuracy such as spatial resolution, the cost of processing the scintillator element 2, and the like.

The scintillator element 2 in this embodiment, as shown in FIG. 1, is formed of a substantially rectangular parallelepiped, and is optically connected to the upper surface 2a located on the radiation incident side and the light receiving element 3 located on the opposite side and described later. It has a connecting bottom surface 2b to be connected and four side surfaces 2c. These surfaces 2a, 2b, and 2c may be mirror-finished or may be roughened. More specifically, these surfaces 2a, 2b, and 2c may be rough surfaces as they are cut out, may be mirror-finished by mechanical polishing after being cut out, or may be immersed in a solution after being cut out. It may be mirror finished by chemical polishing to smooth the surface.

Further, the scintillator elements 2 in this embodiment are two-dimensionally arranged such that the side surfaces 2c are adjacent to each other. In FIG. 1, the scintillator elements 2 are arranged two-dimensionally in a square shape, but they may be arranged two-dimensionally in a cylindrical shape.
Here, the number of scintillator elements 2 arranged on the light receiving element 3 is not particularly limited. In general, by reducing the size of the scintillator elements 2 arranged per row, the spatial resolution of the radiation detector 1A is improved. On the other hand, this increases the number of scintillator elements 2 arranged in one row, which requires accuracy in the response difference of the scintillator elements 2 for position identification, and there is a possibility that the position discrimination performance especially in the peripheral portion may be lowered. . However, in the radiation detector 1A of this embodiment, by providing the light leakage prevention means 4 described later, it is possible to improve the position discrimination performance in the peripheral portion. Therefore, it is preferable to appropriately select the number of scintillator elements 2 arranged two-dimensionally in view of the desired spatial resolution.
The scintillator element 2 in this embodiment is described and illustrated separately for the scintillator element 2A arranged on the outermost circumference and the scintillator element 2B arranged on the outermost circumference. , and the scintillator elements 2A and 2B have the same properties and structures.

The light-receiving element 3 is optically coupled with the scintillator element 2 and outputs an electric signal corresponding to the light intensity when the scintillation light from the scintillator element 2 is incident.
As the light receiving element 3 in this embodiment, one or a plurality of light receiving elements 3 are arranged on a plane so that the incident position of the incident scintillation light can be detected. The number of light receiving elements 3 is not particularly limited as long as the light receiving elements 3 can detect the incident position of the scintillation light. For example, the number of scintillator elements 2 and the number of light receiving elements 3 may be the same, or the number of light receiving elements 3 may be less than the number of scintillator elements 2 .

Moreover, it is preferable that the arrangement area of the scintillator element 2 and the arrangement area of the light receiving element 3 are substantially the same. As a result, the entire response of the scintillator element 2 to the radiation incident on the radiation detector 1A can be detected by the light receiving element 3, so that the detection sensitivity of the radiation detector 1A can be enhanced.
In particular, as will be described later, when the radiation detector 1A of this embodiment is applied to an image generating apparatus, if the arrangement area of the scintillator element 2 is smaller than the arrangement area of the light receiving element 3, a plurality of radiation detectors 1A can be arranged. When this is done, the radiation from the object does not enter the scintillator element 2 and there is a gap where no response occurs. Due to the presence of this gap, the radiation (response of the scintillator element 2) that should be detected by the light receiving element 3 cannot be detected, and the data related to the object is lost. This data loss leads to deterioration of the image. Therefore, it is preferable that the arrangement area of the scintillator element 2 and the arrangement area of the light receiving element 3 are substantially the same, and the gap that does not cause the response of the scintillator element 2 in the radiation detector 1A is minimized.

For the light receiving element 3 in this embodiment, for example, a known position detection type photomultiplier tube or a semiconductor light receiving element can be used.

A means for optically coupling the scintillator element 2 and the light receiving element 3 is not particularly limited.
For example, an optical member transparent to scintillation light (scintillation light can pass through) may be filled between the scintillator element 2 and the light receiving element 3 . Examples of such optical members include silicone oil, silicone rubber, air, and optical transparent adhesives.

The light leakage prevention means 4 optically blocks the scintillator element 2A arranged on the outermost circumference and the other scintillator elements 2B arranged on the outermost circumference, so that the scintillation light from the scintillator element 2A is directed to the scintillator element 2B side. to prevent leakage to the
By providing the light leakage preventing means 4, the light intensity distribution when the response of the scintillator element 2A arranged on the outermost periphery is input to the light receiving element 3 and the response of the other scintillator element 2B are input to the light receiving element 3. The difference between the position calculation result relating to the response of the scintillator element 2A arranged on the outermost periphery and the position calculation result relating to the response of the other scintillator element 2B can be generated. It is possible to make a significant difference in This makes it possible to improve the position discrimination performance in the peripheral portion of the radiation detector 1A.
The details of the improvement of the position discrimination performance by the light leakage prevention means 4 will be described later.

As the light leakage prevention means 4, the scintillator element 2A arranged on the outermost circumference and the scintillator element 2B arranged on the outermost circumference are optically cut off, and the light intensity distribution related to the response of the scintillator elements 2A and 2B is provided. The specific structure is not particularly limited as long as it can make a difference in the.

FIG. 2 is a schematic explanatory diagram showing an example of light leakage prevention means in the radiation detector according to the first embodiment of the present invention. 2A is an XY plan view of FIG. 1. FIG. Moreover, FIG. 2B is a perspective view showing an example of the light leakage preventing means.
FIG. 2 is for mainly explaining the structure related to the scintillator element 2A and the light leakage preventing means 4 arranged on the outermost periphery, and the structure related to the scintillator element 2B is omitted.

As a specific example of the light leakage preventing means 4, for example, as shown in FIG. 2, a flat plate 40 having a light reflecting surface and no slits is used.
When such a flat plate 40 is installed as the light leakage prevention means 4 on the arrangement of the scintillator elements 2 arranged two-dimensionally, light is emitted from the outermost scintillator element 2A toward the other scintillator element 2B. No gaps are formed through which the liquid leaks. Further, since the flat plate 40 has a light reflecting surface, the scintillation light from the scintillator element 2A arranged on the outermost periphery is reflected in the space surrounded by the flat plate 40, and the light leaks to the other scintillator element 2B side. is suppressed. Therefore, it is possible to realize the response difference of the scintillator element by the light leakage prevention means 4 with a simple structure using a member (flat plate 40) that does not require fine processing. In addition, since detailed processing of the member related to the light leakage prevention means 4 is unnecessary, the cost of the radiation detector 1A can be reduced, and the response difference of the scintillator element can be reduced without depending on the processing accuracy of the member. There is also an effect that it is possible to generate

The flat plate 40 in this embodiment may be provided so as to optically block the space between the outermost scintillator element 2A and the other scintillator elements 2B and prevent light leakage. . For example, FIG. 2 shows that the flat plate 40 is bent so that the outermost scintillator elements 2A are individually surrounded by the flat plate 40, but it is not limited to this.

3 and 4 are schematic explanatory diagrams showing another mode of the light leakage prevention means in the radiation detector 1A in this embodiment. 3A and 4A are XY plan views of FIG. 3B and 4B are perspective views showing an example of the light leakage preventing means.
3 and 4 are for mainly explaining the structure related to the scintillator element 2A and the light leakage preventing means 4 arranged on the outermost periphery, and the structure related to the scintillator element 2B as in FIG. are omitted from the drawing.

As another example of the light leakage prevention means 4 in this embodiment, as shown in FIGS. 3 and 4, a single flat plate 41 prevents leakage of scintillation light from the plurality of scintillator elements 2A arranged on the outermost periphery. Including what you do. 3 and 4 show examples in which the flat plate 41 is arranged differently.
As a result, it is possible to reduce the number of parts related to the light leakage prevention means 4 and reduce the work load related to assembly. It is easier to create a difference from the light intensity distribution related to the response of the scintillator element 2B.

As a specific example of forming the light leakage prevention means 4 for a plurality of scintillator elements 2A with a single flat plate 41, for example, as shown in FIG. In addition, as shown in FIG. 4, the plurality of scintillator elements 2A arranged on each side of the outermost periphery are linearly arranged in parallel with the structure of the flat plate 41 shown in FIG. 41, and the like. Thereby, the flat plate 41 can optically block the space between the scintillator element 2A and the other scintillator element 2B.
Further, as shown in FIGS. 3 and 4, between the scintillator elements 2A surrounded by the flat plates 41, strip-shaped flat plates 42 having the same width as the scintillator elements 2A are separately provided to partition the scintillator elements 2A. is preferred. This makes it possible to further improve the position discrimination performance in the peripheral portion of the radiation detector 1A.
Furthermore, as shown in FIGS. 3 and 4, of the two-dimensionally arranged scintillator elements ₂ , the scintillator elements 2A1 corresponding to the corners in the four directions are individually surrounded by flat plates 43 different from the flat plate 41. It is preferable to As a result, it is possible to prevent light leakage between the scintillator element 2A1 arranged at the outermost corner and the _other scintillator elements 2A arranged at the outermost circumference, thereby improving the position discrimination performance. It becomes possible.

The combination (scintillator array) of the scintillator element 2 and the light leakage prevention means 4 in this embodiment can be made independent as a scintillator unit in the present invention. This scintillator unit can be applied as a scintillator unit (scintillator array) in an existing radiation detector. This makes it possible to easily form the radiation detector of the present invention with improved position discrimination performance in the peripheral portion.

The light reflecting means 5 is provided between the scintillator elements 2B arranged outside the outermost periphery, and reflects scintillation light.
By providing the light reflecting means 5, the scintillator elements 2B arranged outside the outermost periphery are partitioned, and the responses of the scintillator elements 2B incident on the light receiving element 3 can be partitioned. This facilitates identification of the response of the scintillator element 2B in the light receiving element 3. FIG.

As a member related to the light reflecting means 5, there is a combination of a flat plate 50 having a light reflecting surface and provided with a slit.
FIG. 5 is a schematic explanatory diagram showing an example of the light reflecting means in the radiation detector of this embodiment. FIG. 5 is for mainly explaining the structure related to the scintillator element 2B and the light reflecting means 5 arranged outside the outermost periphery, and the structure related to the scintillator element 2A and the light leakage prevention means 4 is not shown. omitted.

For example, as shown in FIG. 5, as the light reflecting means 5, a lattice structure is formed by combining a plurality of flat plates 50 provided with slits 51 at substantially the same intervals as the width of the scintillator elements 2B, and the scintillator elements 2B are arranged. For example, forming a space S for This facilitates positioning and partitioning of the scintillator elements 2B, and reduces the work load associated with assembly. In addition, in the production of the light reflecting means 5, there is no need for a working process such as laser processing, which is burdensome in terms of work cost, etc., and furthermore, it is possible to form the light reflecting means 5 from the same material. There is also the advantage that the initial cost can be reduced.

The width of the slits 51 themselves provided in the flat plate 50 is not particularly limited as long as the flat plates 50 can be combined with each other. From the viewpoint of stable holding, it is preferable to design the width of the slits 51 themselves to be longer than the thickness of the flat plate 50 so that there is a margin between the slits 51 when combined.

At this time, scintillation light leaks from the slits 51, which are the light reflecting means 5, between the scintillator elements 2B arranged outside the outermost periphery. At this time, the response of the scintillator element 2B at locations other than the outermost periphery is incident on the light receiving element 3 as a light intensity distribution having a certain spread outside the section. For this reason, a light intensity distribution wider than the originally defined range is input, and it is possible to improve the calculation accuracy in the calculation (especially the barycentric calculation) related to the identification of the response of the scintillator element 2 in the light receiving element 3. becomes. This makes it possible to improve the position discrimination ability of the radiation detector as a whole.
Also, at this time, even if a plurality of scintillator elements 2B are present on the same light receiving element 3, the proportion of light received by the adjacent light receiving element 3 is different for each scintillator element 2B. It is possible to identify the response of the scintillator element 2B. To explain with a specific example, for example, when two scintillator elements 2B are arranged side by side on the same light receiving element 3, the light intensity distribution related to the response of the scintillator element 2B on the right side is different from that of the light receiving element 3 on the right side. The magnitude of the light leaking upward and the light intensity distribution related to the response of the scintillator element 2B on the left side differ from the magnitude of the light leaking onto the light receiving element 3 adjacent to the right. Therefore, a significant difference is generated in the position calculation result by the calculation of the center of gravity, and it is possible to distinguish between the responses of the scintillator elements 2B adjacent to each other on the same light receiving element 3. FIG. Therefore, there is an advantage that the position discriminating ability of the radiation detector as a whole is improved, and precise adjustment of the arrangement of the light receiving element 3 and the scintillator element 2 becomes unnecessary.

In acquisition of radiation position information by the radiation detector 1A of the present embodiment, improvement in position discrimination performance by providing the light leakage prevention means 4 will be described with reference to FIGS. 6 and 7. FIG.
FIG. 6 is a schematic diagram when radiation is incident on the radiation detector 1A of this embodiment. FIG. 6 is a side view of the radiation detector 1A of this embodiment (corresponding to the XZ diagram of FIG. 1).
FIG. 7 is a schematic diagram of radiation incident on a radiation detector 100 having a configuration different from that of the present embodiment, and is a side view of the radiation detector 100 . The radiation detector 100 shown in FIG. 7 is provided with light reflecting means 5 over the entire surface in place of the light leakage preventing means 4 in this embodiment, and is shown for comparison.

As shown in FIGS. 6 and 7, when radiation emitted from an object enters the radiation detectors 1A and 100, the scintillator element 2 absorbs the radiation and generates scintillation light. Then, the generated scintillation light diffuses radially while proceeding from the generated position toward the light receiving element 3 . As a result, the scintillation light is detected as a light intensity distribution. By carrying out a calculation for finding the center of gravity of the light intensity distribution (calculation of the center of gravity), it is possible to obtain two-dimensional positional information relating to the position at which the scintillation light is generated.

As shown in FIGS. 6 and 7, when radiation is incident on the scintillator elements 2B arranged outside the outermost periphery, the scintillation light from the scintillator elements 2B spreads radially with respect to the light receiving element 3. _Input as D2. The inventors of the present invention found that when the light reflecting means ₅ has a structure in which a slit 51 is provided, the light intensity distribution D2 is distributed from the upper part of the scintillator element 2B through the slit 51 as shown in FIGS. It has been found that the light intensity distribution D2 spreads toward the adjacent scintillator element 2B, and that the spread width ₍ leakage of light) of this light intensity distribution D2 becomes a significant amount. In this case, detection data is acquired by the light receiving element 3 in a wider area than the range defined by the light reflecting means 5 . Therefore, it is possible to improve the calculation accuracy when performing calculations (particularly center-of-gravity calculations) for obtaining positional information on which radiation is incident.

However, as shown in FIG. 7, when the light reflection means 5 consisting of a flat plate 50 provided with a slit 51 is provided on the entire surface without providing the light leakage prevention means 4, the response ( The light intensity distribution D ₃ ) enters the light-receiving element 3 through the slit 51 of the light reflecting means 5 while being unevenly distributed toward the adjacent scintillator element 2B ₁ . For this reason, the position calculation result obtained by performing the barycentric calculation using the light intensity distribution relating to the response of the scintillator element 2A and the position calculation result relating to the response of the scintillator element 2B1 are close to _{each other} . It becomes difficult to distinguish the position information related to the position, and sufficient position discrimination ability cannot be obtained.

On the other hand, as shown in FIG. 6, by providing the light leakage prevention means 4, the light intensity distribution when the response of the scintillator element 2A arranged on the outermost periphery is input to the light receiving element 3 and the light intensity distribution of the other scintillator element 2B It is possible to make a difference between the response of , and the light intensity distribution when input to the light receiving element 3 . That is, the response (light intensity distribution D ₁ ) of the scintillator element 2A is incident only on the light receiving element 3 which is arranged directly below and optically coupled to the scintillator element 2A.
Therefore, the light intensity distribution related to the response from the scintillator element 2A arranged on the outermost circumference does not enter the light receiving element ₃ on the side of the adjacent scintillator element 2B1, and the two scintillators detected by the light receiving element 3 _A difference can be made between the light intensity distributions associated with the responses of elements 2A and 2B1. Then, _a significant difference occurs between the position calculation result related to the response from the scintillator element 2A arranged on the outermost periphery and the position calculation result related to the response from the adjacent scintillator element 2B1. It is possible to individually identify the response of the two scintillator elements 2A and 2B ₁ sensing at 3. This makes it possible to improve the position discrimination performance in the peripheral portion of the radiation detector 1A.

(Embodiment regarding response of scintillator element by radiation detector)
An example of acquisition of radiation position information by the radiation detector 1A of this embodiment will be described below.
As an example, in acquiring the position information of the radiation incident on the radiation detector 1A, the scintillation light from the scintillator element 2 is detected by the light receiving element 3, and the electric signal detected by the light receiving element 3 is calculated by the centroid calculation. An XY map related to the obtained positional information will be described as a response result of the scintillator element.

FIG. 8 is a diagram (XY map) showing the response result of the scintillator element using the radiation detector 1A in this embodiment.
FIG. 9 is a diagram (XY map) showing a response result of a scintillator element using the radiation detector 100. As shown in FIG. The radiation detector 100 in FIG. 9 has the same configuration as the radiation detector 100 shown in FIG. 7, and is shown for comparison.
In both the example (radiation detector 1A) and the comparative example (radiation detector 100), the scintillator elements 2 were arranged in 17 rows×17 rows, and the arrangement area of the scintillator elements 2 and the arrangement area of the light receiving elements 3 were substantially the same. used things. LYSO was used as the scintillator element 2 .

Radiation incident on the radiation detector 1A is detected one by one, and the positional information of the detection of one radiation obtained by the position calculation is represented as one point on the XY map. Then, by making a certain amount of radiation incident on the radiation detector 1A, position calculation results are accumulated on the XY map. Then, the accumulated position calculation results (points indicating position information) are counted, and based on this, the diagrams (XY maps) shown in FIGS. 8 and 9 are created.
In FIGS. 8 and 9, the black areas are portions where the count of points indicating position information is low, and the white points indicate the peaks of the distribution of points indicating position information. Since the scintillation light, which is a response from one scintillator element, exhibits substantially the same light intensity distribution each time, points indicating position information accumulate at the same position on the XY map to form a peak. Therefore, one white point on the XY map corresponds to one scintillator element.

XY maps such as those shown in FIGS. 8 and 9 are created in advance for each radiation detector. As a result, when radiation is newly detected by the radiation detector, it is possible to determine which scintillator element detected the radiation, depending on where on the XY map the position calculation result came.

In the XY map shown in FIG. 9 as a comparative example, it can be seen that the responses (positional information) of the scintillator elements in the peripheral portion and the neighboring scintillator elements are close to each other, and the identification of the positional information is not sufficient. This is the response from the scintillator element (corresponding to the scintillator element 2A in this embodiment) arranged at the outermost periphery (end) and the scintillator element arranged _next to it (corresponding to the scintillator element 2B1 in this embodiment). This is because the light intensity distributions are similar and the position calculation results based on the light intensity distributions are accumulated at similar positions on the XY map.
Therefore, when a new radiation detection is performed and the position calculation result shows the peripheral region, it is possible to determine whether the scintillator element arranged at the outermost periphery or the scintillator element arranged next to it detected the radiation. Gone.

On the other hand, as a response result of the scintillator element using the radiation detector 1A of this embodiment, in the XY map shown in FIG. It can be seen that the position discrimination performance in the part is improved. This is because the radiation detector _1A in this embodiment causes a difference in the light intensity distribution related to the response from the scintillator element 2A arranged at the outermost periphery (end) and the scintillator element 2B1 arranged next to it. The position calculation results based on this light intensity distribution are accumulated at different positions on the XY map and can be clearly distinguished. can also be obtained in the scintillator element 2A arranged at .
Therefore, in the radiation detector 1A according to this embodiment, when radiation detection is newly performed and the position calculation result indicates the peripheral region, the scintillator element arranged at the outermost periphery and the scintillator element arranged next to it are detected. It is possible to determine which one is detected.

As described above, in the radiation detector 1A of this embodiment, the scintillator element 2A arranged on the outermost periphery is optically blocked from the other scintillator elements 2B, and the scintillation light leaks to the other scintillator element 2B side. By providing the light leakage prevention means 4 for preventing this, the light intensity distribution when the response of the scintillator element 2A arranged on the outermost periphery is input to the light receiving element 3 and the response of the other scintillator element 2B are reflected in the light receiving element 3 It is possible to make a difference between the light intensity distribution when input to . Therefore, there is a significant difference between the position calculation result related to the response from the scintillator element 2A arranged on the outermost circumference and the position calculation result related to the response from the adjacent scintillator element 2B (2B ₁ ). Thus, it becomes possible to individually identify the responses of the two scintillator elements detected by the light receiving element 3 . This makes it possible to improve the position discrimination performance in the peripheral portion of the radiation detector 1A.

(Image generation device)
FIG. 10 is a schematic explanatory diagram showing the structure of the image generation device according to the first embodiment of the present invention.
As shown in FIG. 10, the image generation device 10 in this embodiment includes the radiation detector 1A and the image generation section 11 described above. Also, the radiation detector 1A and the image generator 11 are connected so as to be able to transmit and receive data.

Although FIG. 10 shows one radiation detector 1A and image generator 11 connected, the number of radiation detectors 1A incorporated in the image generator 10 in this embodiment is not particularly limited. . For example, a plurality of radiation detectors 1A may be arranged in a ring so as to surround the object, and detection data from each radiation detector 1A may be transmitted to the image generator 11 .

The image generator 11 uses the detection data obtained by the radiation detector 1A to generate an image.
The image generation unit 11 is not particularly limited as long as it can acquire detection data related to radiation incident position information obtained by the radiation detector 1A and generate an image based on the detection data. . For example, it may be provided with image processing means for obtaining a tomographic image related to the position information of the radiation emitted from the object based on the detection data from the radiation detector 1A.
Further, as the image generation unit 11, a calculation means for performing calculation (gravity center calculation) on the detection data obtained by the radiation detector 1A may be provided. Note that the calculation means may be incorporated in the image processing means.
Furthermore, the image generated by the image generation unit 11 may be stored in a storage unit (not shown) and output to the outside as necessary.
Note that the image generator 11 is preferably implemented by a hardware processor such as a CPU executing a program (software).

In the image generating apparatus 10, necessary programs are created for a series of operations related to acquisition of detection data related to incident position information of radiation obtained by the radiation detector 1A and image generation in the image generation unit 11, and a CPU, etc. hardware processor. As a result, a large amount of data can be quickly acquired and calculated, and a series of processes related to image generation can be smoothly performed. In addition, this program may be stored in advance in a storage device such as a HDD (Hard Disk Drive) or flash memory, or may be stored in a removable storage medium such as a DVD or CD-ROM, and the storage medium may be stored in a drive device. It may be installed in the storage device by being attached.

The image generating apparatus 10 in this embodiment uses the detection data obtained by the radiation detector 1A, so that it is possible to generate an image based on highly accurate data relating to radiation incident position information. As a result, it is possible to provide an image generating apparatus with high spatial resolution that enables high-quality image generation.

Moreover, it is preferable to use the image generating apparatus 10 in this embodiment as a PET apparatus, which is one of medical diagnostic apparatuses. By using the image generating apparatus 10 in this embodiment as a PET apparatus, it is possible to generate high-quality images, and accurately grasp the positional information of the radiation derived from the radiopharmaceutical administered to the patient. This can lead to appropriate treatment (treatment) for the patient.

[Second embodiment]
In the radiation detector 1B according to the second embodiment, a combination of the scintillator element 2 and the light leakage prevention means 4 in the radiation detector 1A according to the first embodiment is used as a scintillator array 6, and a plurality of scintillator arrays 6 are stacked. It is.

The scintillator array 6 in this embodiment is a combination of the two-dimensionally arranged scintillator elements 2 and the light leakage preventing means 4 described above. Therefore, similar to the description in the first embodiment, it is possible to improve the position discrimination performance related to the end of the scintillator array 6 based on the effect of the light leakage prevention means 4 described above.
That is, the radiation detector 1B in this embodiment is formed by forming the scintillator array 6 provided with the scintillator element 2 and the light leakage prevention means 4, and laminating them so that in each layer of the scintillator array 6, the scintillator A difference can be generated between the light intensity distribution related to the response of the element 2A and the light intensity distribution related to the response of the other scintillator element 2B, and the position calculation result related to the response from each scintillator element can be significantly different. Since such a large difference is generated, it is possible to individually identify the response of each scintillator element.
As a result, even in the stacked scintillator arrays 6, it is possible to improve the position discrimination ability related to the ends of the scintillator arrays 6 and to improve the responsiveness (sensitivity) of the radiation detector 1B.

Further, the scintillator array 6 in this embodiment may be provided with the light reflecting means 5 described above between the scintillator elements 2B arranged outside the outermost periphery. As described in the first embodiment, this makes it possible to improve the position discrimination performance of the scintillator array 6 as a whole based on the effect of the light leakage prevention means 4 and the effect of the light reflection means 5 described above.

FIG. 11 is a schematic explanatory diagram (perspective view) showing the overall structure of a radiation detector according to the second embodiment of the present invention.
As shown in FIG. 11, the radiation detector 1B according to the second embodiment is a combination of the scintillator element 2, the light leakage preventing means 4, and the light reflecting means 5 in the radiation detector 1A according to the first embodiment. is a scintillator array 6, and a plurality of scintillator arrays 6 are stacked. The description of the same structure as that of the first embodiment will be omitted.

The radiation detector 1B shown in FIG. 11 has a scintillator element 2A arranged at the end of the scintillator array 6 based on the effects of the light leakage prevention means 4 and the light reflection means 5, as described in the first embodiment. In addition, it is possible to easily identify the responses of the scintillator elements 2</b>B arranged outside the end of the scintillator array 6 .

Further, as another aspect of the radiation detector 1B in this embodiment, a scintillator array 6 comprising a scintillator element 2, a light leakage prevention means 4 and a light reflection means 5 is formed, and when laminating a plurality of scintillators, For each layer of the array 6, the arrangement of the light reflecting means 5 in the scintillator array 6 may be different.

Here, it is known that, even in conventional radiation detectors, by stacking a plurality of scintillator arrays each composed of a plurality of scintillator elements arranged two-dimensionally, the responsiveness (sensitivity) of the radiation detector is enhanced. . Such radiation detectors include, for example, what is called a four-layer DOI detector.

As a four-layer DOI detector, a structure is known in which scintillator arrays are stacked each having scintillator elements and means for partitioning the scintillator elements (corresponding to the light reflecting means 5 in this embodiment). At this time, if the means (positions of the light reflecting means 5) for partitioning the scintillator elements in the layers adjacent to each other in the stacking direction are all arranged continuously, it becomes difficult to appropriately partition the response of the scintillator elements. For this reason, it is preferable that the means for dividing the scintillator elements be designed so that they are not arranged in a continuous manner, and that the responses of the scintillator elements in all of the scintillator arrays in the stack are appropriately divided so as to be identifiable. .

An example of the structure of another aspect of the radiation detector 1B in this embodiment will be described below in comparison with the structure of a conventional four-layer DOI detector. As the radiation detector 1B of this embodiment, the scintillator array 6 includes the scintillator element 2, the light leakage prevention means 4, and the light reflection means 5. However, the radiation detector 1B is not limited to this. do not have.

12 and 13 show an example of the structure of the scintillator array 6 of each layer in the radiation detector 1B of this embodiment. 12A and 13A show the structure (plan view) of the scintillator array in each layer, and FIGS. 12B and 13B show the structure (side view) when scintillator arrays are stacked.
On the other hand, FIG. 14 shows an example of a scintillator array structure in a conventional 4-layer DOI detector. 14A shows the structure (plan view) of the scintillator array in each layer, and FIG. 14B shows the structure (side view) when the scintillator arrays are stacked. Also, the scintillator element and the light reflecting means in FIG. 14 correspond to the scintillator element 2 and the light reflecting means 5 in this embodiment, respectively.
12 to 14 show four layers of scintillator arrays 6 in which scintillator elements 2 are arranged in 6 rows×6 rows, but are not limited to this. do not have.

In a conventional radiation detector (four-layer DOI detector) 200, the scintillator array 6 is known to have a structure in which the light reflecting means 5 are arranged in different positions in each layer (first to fourth layers). . More specifically, for example, as shown in FIG. 14A, in the scintillator array 6 of the first layer (uppermost stage), the light reflecting means 5 provided between the scintillator elements 2 are arranged in rows. In the other layers (second to fourth layers), the position of the light reflecting means 5 in the scintillator array 6 of the first layer is shifted by one line of the scintillator element 2 in the X direction or the Y direction. There are several.
When the scintillator arrays 6 are stacked, as shown in FIG. 14B, in the scintillator arrays 6 in the stacked state viewed from the Y direction, the light reflecting means 5 of the scintillator arrays 6 adjacent to each other in the stacking direction are alternately arranged and continuous. It is not arranged properly. However, in the laminated scintillator array 6 viewed from the X direction, the light reflecting means 5 are continuously arranged in the first and second layers, and in the third and fourth layers.
For this reason, in the conventional radiation detector 200, the division of the scintillator elements 2 overlaps at the end of the scintillator array 6 in the X direction, leading to a decrease in position discrimination performance. In addition, in the conventional radiation detector 200, especially at the end of the scintillator array, there are large design constraints to prevent the light reflecting means 5 from being continuously arranged, and the structural design of the entire device is complicated. There is also the problem of conversion.

On the other hand, as the radiation detector 1B in this embodiment, as the scintillator array 6, light leakage prevention means 4 is provided at the end (outermost periphery) of the scintillator array 6, and each scintillator array 6 layer (first layer to fourth layer) is provided. Layer) may have a structure in which the locations where the light reflecting means 5 are arranged are different. Here, the location of the light reflecting means 5 is not particularly limited as long as it differs for each layer of the scintillator array 6, as in the conventional radiation detector 200 described above.

As an example of the radiation detector 1B in this embodiment, as shown in FIG. In the scintillator array 6 of the upper layer), the scintillator elements 2 are arranged in a row, and in the other layers (second to fourth layers), the scintillator array 6 in the first layer For example, the arrangement position of the light reflecting means 5 is shifted in the X direction or the Y direction by one row of the scintillator elements 2 . Further, scintillator elements 2A individually partitioned by light leakage preventing means 4 are provided on the outermost periphery of the scintillator array 6 of each layer.
As a result, at the end (outermost circumference) of the scintillator array 6, a difference in response from the scintillator elements is generated by the light leakage prevention means 4, so that the response of the scintillator element 2A at the end of the scintillator array 6 can be divided appropriately. become easier. On the other hand, inside the outermost periphery of the scintillator array 6, like the conventional radiation detector 200, the positions of the light reflecting means 5 are arranged differently for each layer of the scintillator array 6, so that the scintillator elements 2B The light reflecting means 5 provided on the other side may have a structure in which all the light reflecting means 5 adjacent in the stacking direction are not continuously arranged. That is, it is possible to make the response of the scintillator element 2B from each layer enter the light-receiving element 3 in a state of being appropriately divided.
Therefore, in the radiation detector 1B shown in FIG. 12, it is possible to improve both the position discrimination ability of the radiation detector 1B and the responsiveness (sensitivity) of the radiation detector 1B. In addition, there is also the effect that the structural design of the scintillator array 6 as a whole is facilitated.

As another aspect of the radiation detector 1B in this embodiment, the light reflecting means 5 may be provided between the scintillator elements 2A arranged on the outermost periphery.

As an example of another aspect of the radiation detector 1B in this embodiment, for example, as shown in FIG. , in the scintillator array 6 of the first layer (uppermost), the scintillator elements 2 are arranged so as to be arranged in rows, and in the other layers (second to fourth layers), the first The arrangement position of the light reflecting means 5 in the layered scintillator array 6 may be shifted in the X or Y direction by one row of the scintillator elements 2 .
On the other hand, for the scintillator elements 2A arranged on the outermost periphery, the light reflection means 5 are arranged so that the light reflection means 5 adjacent to each other in the stacking direction are not continuously arranged within the range partitioned by the light leakage prevention means 4. can be set. Specifically, a first light reflecting means 5A provided extending from the light reflecting means 5 provided on the scintillator element 2B, and a second light reflecting means 5B provided independently of the first light reflecting means 5A. As shown in FIG. 13A, the first light reflection means 5A and the second light reflection means 5B are not arranged continuously within the range defined by the light leakage prevention means 4 on the outermost periphery of the scintillator array 6. The arrangement locations of the respective light reflecting means 5A and 5B are set as follows.
When the scintillator arrays 6 are stacked, as shown in FIG. 13B, the light reflecting means 5A and 5B of the scintillator arrays 6 adjacent to each other in the stacking direction alternately when viewed from either the X direction or the Y direction. arranged and not in a continuous arrangement.
Further, as shown in FIG. 13A, in the radiation detector 1B of this embodiment, the light leakage preventing means 4 is provided at the end (outermost periphery) of the scintillator array 6, and the light reflecting means 5 is the first light reflecting means. By providing 5A and the second light reflecting means 5B, when designing the structure on the side of the scintillator element 2A, the structure of the light reflecting means 5 provided on the side of the scintillator element 2B is separated, and an optimum structure for enhancing the position discrimination ability is obtained. Can be designed independently. This greatly reduces restrictions on the structural design of the scintillator array 6 . In addition, the number of parts can be reduced compared to providing the light leakage prevention means 4 between all the scintillator elements 2A.
Therefore, in the radiation detector 1B shown in FIG. 13, the light from each scintillator array 6 layer can be made incident on the light receiving element 3 with a difference in the light intensity distribution related to the response of the scintillator element 2, and radiation can be detected. It is possible to improve the position discrimination ability of the detector 1B and to improve the responsiveness (sensitivity) of the radiation detector 1B. Moreover, there is an effect that the structural design and assembly of the scintillator array 6 as a whole are facilitated.

Moreover, when the scintillator arrays 6 are stacked, the light leakage preventing means 4 is preferably made of a member having an integral structure extending in the stacking direction of the scintillator arrays 6 . More specifically, the light leakage prevention means 4 has a height corresponding to the lamination of the scintillator array 6 (in FIGS. 12 and 13, a height corresponding to four layers of the scintillator array 6 (height in the Z direction)). A flat plate may be mentioned. Moreover, at this time, the height of the flat plate as the light leakage preventing means 4 is not limited to the height of the laminated portion of the scintillator array 6 . Another example of the light leakage preventing means 4 is, for example, a flat plate having a height (height in the Z direction) of two layers of the scintillator array 6 consisting of four layers. For example, the prevention means 4 may be used.
As a result, when the scintillator arrays 6 are stacked, the light leakage preventing means 4 can be easily manufactured and arranged, and the optical blocking by the light leakage preventing means 4 can be performed more reliably.

Further, the light leakage prevention means 4 may have an integral structure extending in the direction of arrangement of the scintillator elements 2 in the scintillator array 6 together with an integral structure extending in the stacking direction of the scintillator array 6 . More specifically, the scintillator array 6 has a height corresponding to the lamination of the scintillator array 6 (in FIGS. 12 and 13, a height corresponding to four layers of the scintillator array 6 (height in the Z direction)), and the scintillator array 6 A flat plate having a side length (in FIGS. 12 and 13, the length of six rows of scintillator elements 2 (the length in the X direction or the Y direction)) may be used. As a result, the number of members related to the light leakage prevention means 4 can be reduced, and the difference between the light intensity distribution related to the response of the scintillator element 2A arranged on the outermost periphery and the light intensity distribution related to the response of the other scintillator elements 2B can be reduced. It becomes easier to make a difference.
Further, as described above, the height of the flat plate serving as the light leakage prevention means 4 is not limited to matching the height of the laminated portion of the scintillator array 6. For example, the light The leakage prevention means 4 may be made of a flat plate having a height (height in the Z direction) of two layers of the scintillator array 6 and may be laminated.

(Embodiment regarding response of scintillator element by radiation detector)
An example of acquisition of radiation position information by the radiation detector 1B of this embodiment will be described below.
As an example, in acquiring the positional information of the radiation incident on the radiation detector 1B, the scintillation light from the scintillator element 2 is detected by the light receiving element 3, and the electrical signal detected by the light receiving element 3 is calculated by centroid calculation. An XY map related to the obtained positional information will be described as a response result of the scintillator element.

FIG. 15 is a diagram (XY map) showing the response result of the scintillator element using the radiation detector 1B in this embodiment.
FIG. 16 is a diagram (XY map) showing a response result of a scintillator element using a radiation detector as a comparative example. The radiation detector in FIG. 16 is provided with light reflecting means 5 over the entire surface in place of the light leakage prevention means 4 in this embodiment, and is shown for comparison.
In both the example (radiation detector 1B shown in FIG. 13) and the comparative example, the scintillator elements 2 in the scintillator array 6 are arranged in 16 rows×16 rows, and the scintillator arrays 6 are stacked in four layers. Also, the area of the scintillator array 6 and the arrangement area of the light-receiving elements 3 are substantially the same. Furthermore, GAGG is used as the scintillator element 2 .

In the XY map shown in FIG. 16 as a comparative example, it can be seen that the response (positional information) of the scintillator elements in the periphery and the adjacent scintillator elements are close to each other, and the identification of the positional information is not sufficient.
On the other hand, as a response result of the scintillator element using the radiation detector 1B of this embodiment, in the XY map shown in FIG. It can be seen that the position discrimination performance in the part is improved.

As described above, in the radiation detector 1B of this embodiment, by stacking a plurality of scintillator arrays each composed of a combination of scintillator elements capable of improving position discrimination at the periphery and light leakage prevention means, the radiation detector can be It is possible to improve the position discrimination ability of the radiation detector and increase the responsiveness (sensitivity) of the radiation detector.

Also, the radiation detector 1B in this embodiment may be used as the radiation detector in the image generating apparatus shown in the first embodiment. As a result, it is possible to provide an image generation device with high spatial resolution that enables image generation of even higher quality.

It should be noted that the embodiments described above are examples of the radiation detector, the scintillator unit, and the image generating device. The radiation detector, scintillator unit, and image generating device according to the present invention are not limited to the above-described embodiments, and the radiation detectors and scintillators according to the above-described embodiments are not limited to the scope of the claims. Modifications of the unit and the image generator may be made.

The radiation detector and scintillator unit of the present invention are used for detecting radiation emitted from a subject. In particular, it is preferably used as one having a position discriminating function capable of obtaining positional information of incident radiation.
Also, the image generating apparatus of the present invention is used for image generation based on positional information of radiation emitted from an object. In particular, it is suitably used as a PET device, which is one of medical diagnostic devices.

1A, 1B radiation detector 2, 2A, 2B scintillator element 2a upper surface 2b coupling bottom surface 2c side surface 3 light receiving element 4 light leakage preventing means 40, 41, 42, 43 flat plate 5 light reflecting means 5A First light reflecting means 5B Second light reflecting means 50 Flat plate 51 Slit 6 Scintillator array 10 Image generator 11 Image generator 100, 200 Radiation detector as a comparative example D ₁ to D ₃ light intensity distribution, S-space

Claims (10)

a plurality of scintillator elements arranged two-dimensionally;
In a radiation detector comprising the plurality of scintillator elements and a light receiving element optically coupled,
A radiation detector characterized in that the scintillator elements arranged on the outermost periphery are provided with light leakage prevention means for optically blocking other scintillator elements and preventing leakage of scintillation light to the side of other scintillator elements. . 2. The radiation detector according to claim 1, wherein said light leakage preventing means comprises a flat plate having a light reflecting surface and no slits. 3. The radiation detector according to claim 2, wherein said light leakage prevention means includes a single flat plate for preventing leakage of scintillation light to a plurality of scintillator elements arranged on the outermost periphery. Light reflecting means for reflecting scintillation light is provided between the plurality of scintillator elements arranged inside the outermost periphery,
4. The radiation detector according to any one of claims 1 to 3, wherein said light reflecting means is formed by combining a flat plate having a light reflecting surface and provided with a slit. forming a scintillator array comprising the scintillator element and the light leakage prevention means;
5. The radiation detector according to claim 1, wherein a plurality of said scintillator arrays are laminated. forming a scintillator array comprising the scintillator element, the light leakage prevention means and the light reflection means;
A plurality of the scintillator arrays are stacked,
5. The radiation detector according to claim 4, wherein each layer has a structure in which the light reflecting means in the scintillator array is arranged differently. The light reflecting means is also provided between the scintillator elements arranged on the outermost periphery,
a first light reflecting means provided extending from between the scintillator elements arranged inside the outermost periphery;
7. The radiation detector according to claim 6, further comprising a second light reflecting means provided independently of said first light reflecting means. 8. The radiation detector according to any one of claims 5 to 7, wherein said light leakage prevention means comprises a member having an integral structure extending in the stacking direction of said scintillator array. A scintillator unit comprising a plurality of scintillator elements arranged two-dimensionally,
A scintillator unit, wherein a scintillator element arranged on the outermost periphery is provided with light leakage preventing means for optically blocking other scintillator elements and preventing leakage of scintillation light to the side of other scintillator elements. a radiation detector according to any one of claims 1 to 8;
and an image generating unit based on detection data obtained by the radiation detector.

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