JPH0447795B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial Application Field The present invention relates to a scintillation detector used in positron ECT devices (emission computer tomography devices), single photon ECT devices, and the like. (b) Prior art In conventional positron ECT devices, single photon ECT devices, etc., one photomultiplier tube (hereinafter referred to as PMT) is used for one scintillator 1, as shown in Figure 1.
A large number of scintillation detectors constructed by optically coupling PMTs 11 are arranged in a ring shape, but there is a limit to how small the PMTs 11 can be, so the detector width d should not be made too small. Therefore, the spatial resolution was limited. (c) Purpose This invention allows the width of the detector to be made very small.
The object of the present invention is to provide a scintillation detector with high spatial resolution that is suitable for application to an ECT device in which detectors are arranged in a ring shape. (d) Configuration In the scintillation detector according to the present invention,
A plurality (m) of scintillators and a plurality (n) of PMTs are optically coupled so that their arrangement directions are approximately perpendicular, and the combined anatomy is m×n. When an output signal is obtained from each PMT by masking the sections according to a predetermined code, the scintillator that caused scintillation can be determined from the above code by combining the output signals. I have to. (E) Example In FIG. 2, three scintillators 1, 2,
3 are arranged in a row, each scintillator 1,
Between 2 and 3, there is no optical crosstalk. In addition, a septa plate made of lead or the like is inserted between each scintillator 1, 2, and 3 to prevent radiation incident on one scintillator from penetrating this scintillator and entering an adjacent scintillator. is desirable. The front sides of these scintillators 1, 2, and 3 serve as input surfaces on which radiation enters, and the input surfaces of two PMTs 11 and 12, which are rectangular in this embodiment, are optically coupled to the output surfaces on the back side. has been done. As shown in FIG. 2, the direction in which the scintillators 1, 2, and 3 are arranged and the direction in which the PMTs 11 and 12 are arranged are approximately perpendicular to each other. Thus, the area is divided into a total of six 2×3 sections by the scintillator and PMT. These six sections are divided into sections that transmit light and sections that block light (the third In the figure, the shaded area is the light-shielding section). The output signals of PMT11 and 12 are
are sent to pulse detection circuits 21 and 22, respectively,
It is detected that a pulse output occurs in each of the PMTs 11 and 12. This pulse detection circuit 21, 22
The output of is sent to the latch circuit 31 and the OR circuit 32
The output of the pulse detection circuits 21 and 22 after passing through the
In other words, at the timing when an output is generated in either of the pulse detection circuits 21 and 22, the pulse detection circuits 21 and 22
The output of 22 is latched by this latch circuit 31. In the case of the embodiments shown in FIGS. 2 and 3, scintillation occurs when radiation enters one of the scintillators 1, 2, and 3, and the light is transmitted to the PMT 11,
When the scintillator 12 is detected, the mask 20 is formed with a code as shown in FIG.
When radiation is incident on scintillator 2, output is generated from PMT 11 but not from PMT 12, and when radiation is incident on scintillator 2, output is generated from PMT 11 and 12.
Output is generated from both, and when it enters scintillator 3, no output is generated from PMT11.
PMT 12 produces an output. In other words, PMT1
The relationship between the outputs of scintillators 1 and 12 and the scintillators 1, 2, and 3 that caused scintillation is as shown in the following table. In this table, "1" means that there was an output,
"0" indicates that there was no output.

[Table] Therefore, based on the output latched by the latch circuit 31, it is possible to determine in which scintillator scintillation occurred. The above example is a case where three scintillators 1 to 3 are discriminated using two PMTs 11 and 12, but
As shown in FIG. 4, three PMTs 11 to 13 are used to send these output signals to three pulse detection circuits 21.
It is also possible to configure the seven scintillators 1 to 7 to be discriminated by detecting each of the scintillators 1 to 23 and latching them in the same manner as in the case of FIG. in this case,
If the mask 20 is provided with a code as shown in FIG. 4, the relationship between the outputs of the PMTs 11 to 13 and the scintillators 1 to 7 that caused scintillation will be as shown in the following table.

[Table] If four more PMTs are used, it is possible to distinguish up to 15 scintillators. In this way, there is no relationship between the width d of the scintillator and the size of the PMT, which not only makes it possible to make the width d of the scintillator very small to improve spatial resolution, but also to increase the PMT compared to the number of scintillators. The number of can be reduced. Note that although a square PMT is used in the above embodiment, the PMT is not limited to a square shape. Also,
The circuit that processes the output signal of the PMT is not limited to the above, and the code of the mask, the number of scintillators, the number of PMT, etc. are not limited to the above. (F) Effects According to the present invention, a plurality of scintillators (m) and a plurality (n) of PMTs are optically arranged so that their arrangement directions are substantially perpendicular. When an output signal is obtained from each PMT, scintillation is extracted from the above code by combining the output signals. Since the scintillation detector is configured to determine which scintillator is generated, the width of each scintillator can be narrowed regardless of the PMT, increasing spatial resolution and reducing the number of PMTs. The position of the positron detector, which has detectors arranged in a ring shape, does not increase
Ideal for ECT devices and single photon ECT devices.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the external appearance of a conventional example, Fig. 2 is a perspective view showing the external appearance of an embodiment of the present invention, Fig. 3 is a block diagram of the same embodiment, and Fig. 4 is a perspective view of another embodiment. It is a block diagram. 1-7...Scintillator, 11-13...Photomultiplier tube, 20...Mask, 21-23...Pulse detection circuit, 31...Latch circuit, 32...OR circuit.

Claims (1)

[Claims] 1. When m is an integer of 2 or more, n is an integer of 2 or more so that m scintillators are arranged and a part of the output surface of all m scintillators is optically coupled to each input surface. n arranged in a direction substantially perpendicular to the direction in which the scintillators are arranged
m photomultiplier tubes and m
masking means for making each of the m×n divisions formed by the output faces of the n scintillators and the input faces of the n photomultiplier tubes into a light transmission division or a light shielding division according to a predetermined code; A scintillation detector comprising means for determining a scintillator that has caused scintillation from the above code based on a combination of output signals from a photomultiplier tube.