JPS62169074A - Multichannel radiation detector - Google Patents

Abstract

PURPOSE:To easily achieve a spatial resolution of the degree of about 1mm by providing a bag with the structure that a liquid does not leak out between a scintillator and a multiplier phototube and enclosing an optical couplant liquid in the bag. CONSTITUTION:Scintillator 2 closely arranged in multichannel and a multiplier phototube 3 are accommodated in a bag 1 with the structure that a liquid is difficult to leak out. The bag 1 is filled with a liquid 6 with a refractive index approximate to that of the light receiving surface of the phototube 3, that is, couplant liquid so that scintillation light to the phototube 3 can be efficiently transmitted. The scintillation light of the scintillator No.1 is measured and then, the phototube 3 being moved in the direction shown by an arrow, the scintillation light of the scintillator No.2 is measured. Thus, a spatial resolution of the order of about 1mm can be easily achieved.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to C
T (C', computed tomography
) device, and a CT table device detector including a positron CT device, and in particular, it relates to a multi-channel radiation detector that can improve the spatial resolution of transmission data by making the detector multi-channel.

[Background of the invention]

Hereinafter, a CT scanner will be used as an example of applied light for a multi-channel radiation detector. In addition, gamma rays will be taken as an example of a high-energy radiation source.

Conventionally, multi-channel detectors for detecting high-energy radiation such as γ-rays have been constructed using scintillators and photomultiplier tubes (PMTs).
) were combined and arranged in multiple units to form a multichannel radiation detector. Here, the spatial resolution of transmission data required in a CT table device varies depending on the condition of the subject, but as with medical width) is also 1
Must be less than mm. However, the spatial resolution of transmission data in the conventional method is determined approximately by the diameter of the light-receiving surface of the PMT. That is, the scintillator is mechanically 1. Although it is easy to manufacture a PMT with a width of about 8 mm, there are currently no PMTs with a size of 8 mm or less. Therefore, there was a problem that it could not be used directly for gamma-ray CT neck mounting, which requires a spatial resolution of about 1 mm.

Note that this type of technology is described in, for example, Price "Radiometer 111Q J Corona Publishing, Chapter 7.

[Purpose of the invention]

The purpose of the present invention is to achieve a spatial resolution of γ-ray transmission data of P M
Provides a multi-channel detector for gamma-ray CT equipment that can dramatically improve the spatial resolution of gamma-ray transmission data compared to conventional multi-channel radiation detectors determined by the "T" light receiving surface. It's about doing.

[Summary of the invention]

The present invention is different from the conventional method of directly joining a scintillator and a PMT by inserting an optical coupler between the scintillator and the PMT. As an optical element similar to this method, for example, Price "Radiation Measurement" Corona Co., Ltd.
As described in Chapter 7, there is a method using a light guide fiber, but the sensitivity of the scintillation light receiving surface and the transmission efficiency are poor (less than 1/2 Q compared to direct bonding).
It was unsuitable for specs 1 to d1.

The present invention uses an optical couplet to solve this problem, but with this alone the spatial resolution is still limited to PM.
Since it is determined by the diameter of the light-receiving surface of T, in addition to the method described above, a method of moving the PMT 3 along the scintillators 2 arranged in multiple channels as shown in FIG. 5 is adopted.

Due to this.

The scintillator width W can be selected independently of the light-receiving aperture of the PMT 3, and a high-resolution multi-channel detector can be configured.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to Examples.

1 and 2 are diagrams showing the structure of a multi-channel radiation detector according to a first embodiment of the present invention. The scintillator 2 and PMT 3 arranged in a multi-channel manner are housed in a bag 1 having a structure that prevents liquid from leaking to the outside. In addition, inside the bag, the refractive index of the PMT light receiving surface (approx.
．． It is filled with liquid 6 similar to 5). In the present invention, this liquid is, for example, a species of liquid scintillator NE21.
Bag 1, scintillator 2 and P
The joint of the MT 3 is sealed 7 to prevent the liquid 6 from flowing out. FIG. 2 is a sectional view taken along line AA' in FIG. radiation(
For example, when γ rays) are incident on the scintillator 2, the scintillator 2 emits light, and the scintillation light passes through the liquid 6 and reaches the PMT 3. FIG. 3 shows the PMT light receiving surface viewed from the scintillator 2 side. Shiny light paint 10 is PM
It is applied to the T light receiving surface 9. This is to prevent scintillation light from the adjacent scintillator 2 from entering. Next, a method of moving the PMT 3 will be explained. PM
T receiver > 1C surface 9 Surface 1-0 on which no glue or light material is applied
is always placed opposite to one of the multichannel scintillators 2. That is, the scintillation light of scintillator Nn 1 is measured at the position of PMT in FIG. 3. When the measurement is finished, the PMT moves in the direction of the arrow 11, for example to the position indicated by the dotted line, and then stops. At this time, the scintillation light of the scintillator Nα2 is determined by i(+1). Thereafter, the scintillation light of all the scintillators 2 is determined by i(+1) in the same manner.

As mentioned above, the joints between the bag 1, the scintillator 2, and the PMT 3 are sealed 7, but since the shape of the bag 1 can be changed freely, no unreasonable force is applied to the seal 7 and the seal is destroyed. Never.

FIG. 4 is a diagram showing the embodiment of FIG. 2, and corresponds to FIG. In the first embodiment, one surface of the PMT light receiving surface is processed as shown in FIG. 3 to block scintillation light from adjacent scintillators, but this is not sufficient. This embodiment further increases this light shielding effect. That is, the tip plate 13 is provided between the scintillators 2. By doing this, it is possible to effectively reduce the light from the scintillator 2 in the adjacent channel that is scattered in the liquid cuplat material 7 and enters the same, compared to the first embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, the spatial resolution of transmission data (10 m
m or more) can be improved by simply narrowing the width of the scintillator. That is, the spatial resolution that can be achieved with the present invention is the width of the scintillator, and a spatial resolution of 1 m+nFa degrees can be easily achieved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
3 is a front view showing an embodiment, FIG. 4 is a sectional view taken along line AA' in FIG. 1 showing another embodiment, and FIG. Along PMT
FIG. Heart 1 Noya 2 Ro$, 3 1ZI Jiro,, (2)

Claims (1)

[Claims] 1. In a detector that detects radiation such as gamma rays, a bag is installed between the radiation detector, which has multiple channels of miniaturized scintillators, and the photomultiplier tube, so that liquid does not leak to the outside. A multi-channel radiation detector characterized in that an optical cuprate liquid is sealed in the bag and a photomultiplier tube is moved along a scintillator.