JPS6379087A - Scintillation camera - Google Patents

Abstract

PURPOSE:To minimize an insensitive region and to obtain a good quality image, by providing a square photoelectric surface to each of photomultiplier tubes and arranging said tubes in a square pattern. CONSTITUTION:The light incident surface of each of photomultiplier tubes 3 has a square photoelectric surface 21 and a square cross-section at a part thereof and said tubes are arranged in a square pattern. By this square arrangement, the insensitive region 8 of a detector formed between the container 6 of the detector and an effective visual field 7 can be minimized and, therefore, a good quality image is obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a scintillation camera that is widely applied in the field of nuclear medicine diagnosis. Relating to a scintillation camera detector.

[Background of the invention]

About the scintillation camera 4'l-U,S.

Pat, & 3,011,057 Hll Angsr. The general configuration of a scintillation camera detector is shown in the cross-sectional view of FIG. 1(A). That is, a flat scintillator 1% light pipe 2, a plurality of photomultiplier tubes 3. Signal matrix circuit 4. It consists of a collimator 5, a detector container 6, and the arrangement of photomultiplier tubes 3 is shown in a plan view in FIG. In this case, the diameter of scintillator 1,
The effective field of view 7 of the scintillation camera is determined by the diameter of the photomultiplier tubes 3, their arrangement shape, the number of them used, and the diameter of the collimator 5. Conventionally, by bringing the diameter of the effective field of view 7 close to the outer shape of the detector container 6, little consideration has been given to reducing the dead area 8 of the scintillation camera detector, which is caused by the difference in diameter between the detector container 6 and the effective field of view 7. It had not been done.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a scintillation camera in which the insensitive area of the detector is reduced, the detector can be set close to the side of a human head, and a sufficient field of view can be secured.

[Summary of the invention]

The detector of a scintillation camera generally has the structure shown in FIG. 1 described above, in which photomultiplier tubes 3 each having a circular photocathode are arranged in the densest manner to form a hexagon. In this case, the size of the effective field of view 7 is usually equal to the diameter of the circle inscribed in the hexagon 9 connecting the centers of the photomultiplier tubes arranged at the outermost periphery.

Further, a space 10 is provided around the photomultiplier tubes arranged in the most densely arranged hexagonal shape for a member (not shown) for shielding the earth's magnetic field and a member for assembling the detector. The outer diameter of the scintillation camera detector is determined by the provided detector container 6.

In this case, the six photomultiplier tubes 3 arranged at the vertices of a hexagon 9 connecting the centers of the photomultiplier tubes 3 arranged on the outermost periphery protrude in the radial direction from the effective field of view 7 and are arranged in the detector container 6. This is the determining factor for increasing the outer diameter.

Further, FIG. 2 shows a conventional method for making the effective field of view square. In this case as well, photomultiplier tubes 3-1. 3-2.3-3.3-4.3-
5.3-6 protrudes from the effective field of view 7, and this causes the outer diameter of the detector container 6 to be increased, which is determined by the dimensional difference between the outer diameter of the detector container 6 and the effective field of view 7. The dead area 8 is enlarged.

As explained above, the detector in which the photomultiplier tubes constituting the conventional scintillation camera are arranged in the densest arrangement has the disadvantage that the detector has a large outside area and a large dead area relative to its effective field of view.

This makes it difficult to set the detector at a position of 1 Mk when the scintillation camera is used in clinical applications, such as when setting the detector on the head or the heart.

To illustrate this situation, when photographing the head 12 of the subject 11 as shown in Fig. 3, when setting the detector 13, the insensitive area 8 of the detector 13 hits the shoulder 15 of the subject 11, so the head 12 is detected. It is difficult to bring the instruments close together and cover the entire head 12, which is the part to be imaged. In this case, it is essential to bring the detector 13 sufficiently close to the head 12 in order to obtain a high quality image. Furthermore, FIG. 4 shows that when the insensitive area 8 of the detector 13 is made small, the detector 13 can be brought close to the head 12.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 5 and 6.

FIG. 5 shows a plan view of the arrangement of photomultiplier tubes that constitute the detector of the scintillation camera. Conventionally, Fig. 1 (B
) and as shown in FIG. 2, the photomultiplier tubes 3 are arranged in a hexagonal shape around the photomultiplier tube 3-0 at the center of the field of view. In the present invention, as is clear from FIG. 5, the photomultiplier tubes 3 are arranged in a rectangular shape as a whole! I'm using ffi. With this square array,
It becomes possible to minimize the detector dead area 8 formed between the detector container 6 and the effective field of view 7. This can be understood from the fact that the photomultiplier tubes 3-1, 3-2, etc., which are not effectively used to form the effective field of view 7, as seen in the conventional arrangement shown in FIG. 2, have been eliminated. In this case, the light incident surface of the photomultiplier tube used is as shown in FIG. It is important to change the structure to a photomultiplier tube 30 that has a cross section in the direction of . This is important to minimize the amount of noise and maintain the performance of the scintillation camera. In this case, the production of a photomultiplier with a rectangular photocathode is a structure that is possible using conventional manufacturing techniques.

〔Effect of the invention〕

According to the present invention, the insensitive area of the detector, which is the difference between the outer diameter of the detector container of the scintillation camera and the diameter of the effective field of view, can be minimized. It is possible to take pictures close enough to υ to obtain high-quality images. In addition, the outside diameter of the detector container can be made smaller compared to conventional ones, resulting in a relatively small and lightweight scintillation camera detector, which also has secondary effects such as improving the operability of the scintillation camera device. big.

[Brief explanation of the drawing]

Figure 1 (A) is a vertical cross-sectional view showing the general structure of a scintillation camera detector, Figure 1 CB) is a cross-sectional view of Figure 1 (A), and Figure 2 is a scintillation camera detector with a rectangular field of view. A cross-sectional view of the camera detector, Figures 3 and 4 are diagrams of how the scintillation camera detector is set to the subject;
FIG. 5 is a cross-sectional view showing an embodiment of the detector according to the present invention;
FIG. 6 is an outline diagram of a photomultiplier tube according to an embodiment. Engineering...Scintillator, 3...Photomultiplier tube, 6...
・Detection first area (,4) CB) 〃 L

Claims (1)

[Claims] 1. In a scintillation camera detector consisting of a detector consisting of a plurality of photomultiplier tubes optically coupled to a plate-shaped scintillator and a position calculation circuit for determining the light emitting position of the scintillator, the photoelectron multiplier uses a rectangular photocathode. A scintillation camera is characterized by having photomultiplier tubes arranged in a rectangular array.