JPH0572344A - Radiation detecting apparatus - Google Patents

Abstract

PURPOSE:To suppress cross talk of radiation until it enters an electron multiplying element in a first stage, by providing an optical fiber plate in close contact with one side of a scintillator array and by providing a plurality of microlens arrays on the other surface of this plate so that they correspond to a plurality of scintillators. CONSTITUTION:When radiation enters a scintillator 1, light is emitted inside of it and part of the light enters an optical fiber plate 31. In other words, only the light of a component being parallel to the optical axis of each core of the plate 31 is led to the direction of a photomultiplier tube 2. The light emitted from the plate 31 is condensed by a microlens 32, passes through a light-sensing surface plate 25 and enters a photoelectric surface 21. A photoelectron released from the photoelectric surface 21 is multiplied sequentially by an electron multiplier 22 and enters a corresponding anode 23. By providing the scintillator 1, the lens 32, a multiplying stage of each element of the multiplier 22 so that they correspond to the anode 23, in this way, cross talk is suppressed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a radiation detector.

[0002]

2. Description of the Related Art As a conventional radiation detecting apparatus, one shown in FIGS. 3 and 4 is known. This is because P. E. T
(Positron emission tomogr
FIG. 3 shows a sectional structure, and FIG. 4 shows a perspective structure. This radiation detection apparatus is composed of a scintillator array 10 in which scintillators 1 such as BGO crystals are arrayed, a multi-anode type photomultiplier tube 2, and an array 30 of tapered light guides 3 provided therebetween. ing. Here, the photomultiplier tube 2 includes a photocathode 21 formed on the light receiving surface and a photocathode 2
It has an electron multiplier 22 such as a multi-stage dynode that multiplies one emitted photoelectron, and a plurality of anodes 23 that receive the multiplied electrons and give a signal output to a terminal 24.

When a radiation such as a gamma ray is incident on the radiation detecting device, each of the incident scintillators 1 emits light, and this light is guided to a tapered light guide 3 and incident on a photomultiplier tube 2. .. Then, on the photocathode 21, photoelectrons are emitted at the position corresponding to the incident position of the radiation, multiplied by the electron multiplier 22, and detected by the anode 23 at the corresponding position. Therefore, the incident position of radiation can be detected with high sensitivity.

[0004]

However, according to the above-mentioned prior art, the light from the scintillator 1 enters the electron multiplier 22 through the tapered light guide 3, but there is a problem that so-called crosstalk occurs. there were. That is,
Light emission by the radiation in the scintillator 1 is caused by the photocathode 2.
When passing through the face plate at the interface between 1 and the tapered light guide 3, the light of one channel is incident on the photocathode 21 of another channel.

It is an object of the present invention to provide a radiation detecting device that prevents such crosstalk.

[0006]

A radiation detecting apparatus according to the present invention comprises a plurality of scintillators arranged in an array, a scintillator array emitting light by radiation incident from one side, and a scintillator array of the scintillator array. An optical fiber plate, one surface of which is closely attached to the other surface, and a microlens array including a plurality of microlenses provided corresponding to the plurality of scintillators on the other surface of the optical fiber plate, And a photodetector having a position resolution arranged such that the light receiving surface faces the microlens array.

[0007]

According to the structure of the present invention, the scintillator array is in close contact with the optical fiber plate, and the light other than the component in the vertical direction is mainly attenuated by the action of the clad portion of the optical fiber plate. Then, the light emitted from the optical fiber plate is collected by a plurality of microlenses corresponding to each scintillator and does not crosstalk in the space until it enters the multiplication section of the first stage, and the corresponding channel portion. Is incident on.

[0008]

Embodiments of the present invention will be described below with reference to the attached FIGS. 1 and 2.

FIG. 1 is a sectional view of a radiation detecting apparatus according to an embodiment, and FIG. 2 is a diagram showing a detailed structure and operation of one element thereof. As shown in the figure, the scintillator array 10 is configured by arranging a plurality of scintillators 1 in an array with a collimator 11 in between, and an optical fiber plate 31 is closely attached to this. On the other hand, an array of microlenses 32 is formed on the outer surface of the light-receiving surface plate 25 of the photomultiplier tube 2, and this array is in close contact with the optical fiber plate 31. Here, the positions of the plurality of microlenses 32 correspond to the positions of the plurality of scintillators 1, respectively, and the multiplication stages (electrons of the emitted photoelectrons on the photoelectric surface 21 due to the light collected by the plurality of microlenses 32) The respective elements of the multiplier 22) and the plurality of anodes 23 also have a positional correspondence.

The operation of the above embodiment will be described with reference to FIG. When the scintillator 1 is irradiated with radiation, it emits light inside the scintillator 1, and a part of this light is incident on the optical fiber plate 31. Here, the optical fiber plate 3
Since 1 is configured by bundling a large number of optical fibers, light other than the vertically incident component light (that is, the component light parallel to the optical axis of each core of the optical fiber plate 31) is attenuated. I will receive it. This is the first characteristic point of this embodiment. Therefore, it is possible to guide the light emitted by the incidence of radiation toward the photomultiplier tube 2 while suppressing the return light to the scintillator 1 to be low.

The light emitted from the optical fiber plate 31 is condensed by the microlens 32, passes through the light receiving face plate 25, and is incident on the photocathode 21. This is the second of the present embodiment.
Is the characteristic point of. Then, the photoelectrons emitted from the photocathode 21 are sequentially multiplied by the corresponding first-stage dynode 28 ₁ to n-th stage dynode 28 _n , and are incident on the corresponding anode 23. In this way, scintillator 1
Since the microlens 32, the multiplication stage of each element of the electron multiplier 22 and the anode 23 correspond to each other, it is possible to increase the position resolution (to reduce the crosstalk).

Various modifications can be made to the present invention. For example, the scintillator array 10 may be a one-dimensional array as well as a two-dimensional array. Further, the photodetector may be any one as long as it has positional resolution, and may be, for example, an array of avalanche photodiodes.

[0013]

As described above, according to the configuration of the present invention, since the scintillator array is in close contact with the optical fiber plate, the light other than the vertical component is attenuated by the action of the clad portion of the optical fiber plate. Then, the light emitted from the optical fiber plate is condensed by a plurality of microlenses corresponding to each scintillator and is incident on the photodetector. Therefore, it is possible to realize a radiation detection device that suppresses crosstalk to a low level.

[0014]

[Brief description of drawings]

FIG. 1 is a sectional view of a radiation detection apparatus according to an embodiment.

FIG. 2 is a diagram showing a configuration of one element in FIG.

FIG. 3 is a sectional view of a conventional example.

FIG. 4 is a perspective view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Scintillator 10 ... Scintillator array 2 ... Photomultiplier tube 21 ... Photoelectric surface 22 ... Electron multiplier 23 ... Anode 25 ... Photosensitive surface plate 28 ... Dynode 3 ... Tapered light guide 31 ... Optical fiber plate 32 ... Micro lens

Claims (2)

[Claims] 1. A scintillator array configured by arranging a plurality of scintillators in an array and emitting light by radiation incident from one side, and one surface being closely attached to the other surface of the scintillator array. An optical fiber plate, a microlens array comprising a plurality of microlenses provided corresponding to the plurality of scintillators on the other surface of the optical fiber plate, and a light receiving surface facing the microlens array. And a photodetector having a positional resolution provided. 2. The radiation detecting apparatus according to claim 1, wherein the photodetector is a multi-anode type photomultiplier tube arranged so that a photocathode faces the microlens array.