JPH085747A - Scintillation camera - Google Patents

Abstract

PURPOSE:To facilitate shooting by lessening the thickness of a camera head part to reduce the weight of the camera. CONSTITUTION:A number of APD (avalanche photodiode) module 31 are arranged on the rear side of a scintillator 11 through a light guide 21. The APD module 31 comprises four APD chips 32, a cooling element 33 to cool the chips and moreover, a substrate 35 coupled to the cooling element 33 through a strut 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scintillation camera.

[0002]

2. Description of the Related Art A scintillation camera emits radiation
It is detected together with the incident position. That is,
Usually, a flat scintillator made of NaI (Tl) or the like is used, and radiation such as gamma rays is guided to one surface of the scintillator through a collimator or the like, and scintillation emission is generated at one point in the plane, and the light is emitted. A position signal representing the light emitting position is obtained from the intensity of the light detected by each photoelectric converter, which is captured by the photoelectric converters arranged on the other surface, by utilizing the fact that the incident light intensity is higher at a closer position.

The structure of the scintillation camera is as follows.
A flat head scintillator, a collimator arranged on the front surface (detection surface) side thereof, a light guide closely attached to the rear surface side thereof, and a photoelectric converter arranged two-dimensionally on the surface of the light guide, thereby forming a camera head. Parts will be constructed. In the past, the PMT was used as this photoelectric converter.
(Photomultiplier) is used.

[0004]

However, when the PMT is used as in the conventional case, there is a problem that the head portion of the camera cannot be made compact. That is, PM
T has a height of about 50 mm, and a large number of Ts are arranged. Therefore, the thickness of the camera head must be correspondingly thick and the weight becomes large. Further, the PMT has a defect that the photoelectric conversion efficiency on the photocathode is not uniform. Further, the PMT is vulnerable to mechanical vibration and magnetic field, and further deteriorates with age.

In view of the above, the present invention provides a scintillation camera that reduces the thickness and weight of the camera head to facilitate handling, avoids the disadvantages of the PMT, has high performance, and is easy in quality control. The purpose is to provide.

[0006]

In order to achieve the above object, in a scintillation camera according to the present invention, one flat plate scintillator and a scintillator are arranged on a surface opposite to a radiation incident surface. A plurality of semiconductor photodetection modules, each of which is configured by arranging a plurality of semiconductor photodetection elements, and an optical interface between the photodetection surface of each semiconductor photodetection element of the semiconductor photodetection module and the scintillator surface. And light guides that are optically independent of each other.

[0007]

The semiconductor photodetection module can be formed in a thin shape because a large number of semiconductor photodetection modules, which are modularized by arranging a plurality of semiconductor photodetection elements, are arrayed on the back surface of the scintillator. Thin,
The weight can be reduced to facilitate handling as a camera head section. In the semiconductor photodetection module, each of the plurality of semiconductor photodetection elements can obtain an output according to the amount of incident light, so that the density of light detection points can be increased.
Therefore, when obtaining the position of the light emitting point from the magnitude of the output of each of these semiconductor photodetecting elements, the position accuracy can be increased. That is, the spatial resolution as a scintillation camera can be improved. The energy resolution, linearity, uniformity, and life of the scintillation camera can be improved by making each semiconductor photodetector element with high photodetection performance. Further, since the semiconductor photodetector is generally easier to manufacture and the quality control is easier than the photomultiplier, which is an electron tube, the scintillation camera can be easily manufactured and quality controlled.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, an APD module 31 is bonded to the back surface side (upper side in the drawing) of the scintillator 11 via a light guide 21. The surface side (lower side in the figure) of the scintillator 11 is a radiation incident surface, and although not shown, the scintillator 11
A collimator is attached which collimates the radiation incident on the scintillator 11 so that only the radiation in a predetermined direction enters the scintillator 11.

In this embodiment, the APD module 31 has four APD chips 32 as shown in FIG. 2, a cooling element 33 for cooling the APD chips 32, and a cooling element 33 which is connected to the cooling element 33 through a column 34. And the substrate 35 that has been formed. This APD chip 32 is an AP having a photoelectric conversion function.
D (avalanche photodiode) is formed on one silicon wafer. There is no crosstalk between the four APD chips 32. Since the amplification degree of this APD changes with changes in temperature, it is necessary to cool it to keep the temperature constant. Therefore, an electronic thermal cooling element 33 such as a Peltier element is thermally bonded to these APD chips 32. Then, a substrate 35 is fixed to the upper side of the cooling element 33 via a pillar 34 made of a heat insulating material.
The board 35 is provided with circuits such as a preamplifier for amplifying a signal from the APD chip 32 and a controller of the cooling element 33, a connector 36 for a signal or a power supply, and the like. Lead wires are provided between the cooling element 33 side and the substrate 35 side for transmitting signals and the like.

The APD chip 32 of the APD module 31 is optically coupled to the back surface of the scintillator 11 via the light guide 21. That is, scintillator 1
1 and the light guide 21, and the light guide 21
The APD chip 32 is bonded to the APD chip 32 by an optical adhesive 22. And this light guide 21 is
The scintillator 11 is independent for each PD chip 32.
Also, the reflective material 23 is applied to the surface other than the bonding surface with the APD chip 32 to ensure optical independence. The light guide 21 is made of, for example, Pyrex glass or epoxy.

When viewed from the front (upper side of FIG. 1), the APD module 31 has a square shape as shown in FIG. 2 in this embodiment, and four square APD chips 32 are shown on it as shown in FIG. Line up like this. That is, in this APD module 31, two square photoelectric detection surfaces of the APD chip 32 are arranged in a matrix in the vertical direction. As a result, the APD module 31 obtains an output corresponding to the amount of light incident on each point obtained by dividing the APD module 31 into four (2 × 2 vertically and horizontally).

APD module 3 formed in this way
As shown in FIG. 3, the camera heads 1 are arranged on the back surface of a rectangular flat scintillator 11, for example, 9 × 13 vertically and horizontally. APD module 31
Since light can be detected at each of the four divided points as described above, the light emitting position can be accurately obtained in the case of the grain-like portion 41 of FIG. 3 by calculating the light emitting position from the light amount at each of the points. Only the narrow region at the end of the entire periphery of the scintillator 11 is the region where the light emission position cannot be obtained. In other words, this grain-like portion 41 is an effective field of view as a scintillation camera, and can be made slightly larger than the size of the scintillator 11. .

By arranging the APD modules 31 on the back surface of the scintillator 11 in this manner, the thickness of the camera head portion can be reduced. Further, since the plurality of APD chips 32 are arranged in the APD module 31, each APD chip 32 can be downsized to increase the density of light detection points. Therefore, the APD can improve energy resolution, spatial resolution, linearity, uniformity, and life as a scintillation camera, in combination with excellent output characteristics as compared with the photomultiplier.

The APD module 31 may be arranged not only on the back surface of the scintillator 11 but also on the end surface thereof as shown in FIG. In this case,
Since the light directed to the end surface of the scintillator 11 can also be detected, the effective field of view 41 is expanded, and the scintillator 11 is expanded.
Can be equal to the size of.

Although the APD module 31 has a square shape in the above description, it may have another shape such as a rectangle. APD chip 3 in APD module 31
The shape of 2 can be other than a quadrangle, and the arrangement method and the number of arrangements thereof can be other than 2 × 2. Further, regarding the arrangement of the APD modules 31 with respect to one flat plate-shaped scintillator 11 in the camera head portion, not only the arrangement of 9 × 13 as described above, but also another arrangement method is possible. It is also possible to use a semiconductor photodetection element other than the APD, and this can be constructed into one chip and assembled in the same manner as described above to form a module.

[0016]

As described in the above embodiments, according to the scintillation camera of the present invention, by arranging a large number of semiconductor photodetection modules, which are modularized by arranging a plurality of semiconductor photodetection elements, on the back surface of the scintillator, Make the camera head thinner and lighter,
The handling as the camera head can be facilitated. Further, the light detection performance of the semiconductor light detection element can improve energy resolution, spatial resolution, linearity, uniformity and life as a scintillation camera, and also facilitate quality control.

[Brief description of drawings]

FIG. 1 is a sectional view showing a part of an embodiment of the present invention.

FIG. 2 is a schematic plan view of the APD module of the embodiment.

FIG. 3 is a plan view schematically showing the entire arrangement of the APD module in the same example.

FIG. 4 is a plan view schematically showing the arrangement of APD modules in another embodiment.

[Explanation of symbols]

 11 Scintillator 21 Light Guide 22 Optical Adhesive 23 Reflective Material 31 APD Module 32 APD Chip 33 Cooling Element 34 Strut 35 Board 36 Connector 41 Effective Field of View

Claims (1)

[Claims] 1. A flat scintillator and a plurality of semiconductors arranged on a surface of the scintillator opposite to a radiation incident surface, each semiconductor light detecting element being arranged. A light detection module; and a light guide optically optically independent between the light detection surface of each semiconductor light detection element of the semiconductor light detection module and the scintillator surface. Scintillation camera.