JPH05100034A - Scintillation camera - Google Patents

Abstract

PURPOSE:To provide a scintillation camera having a detector capable of reducing assembling man-hours and increasing the light output reception quantity of a PMT. CONSTITUTION:A detector closely fixed with multiple photomultipliers 2 is provided on a glass plate 11 protecting the Na1 monocrystal 8 of a scintillator 1. The glass plate 11 of the scintillator 1 is formed into the thickness so that the reception quantity of the scintillation light in the photomultipliers 2 is approximately unified, thus no light guide is required.

Description

Detailed Description of the Invention

[0001]

This invention relates to a scintillator NaI
The present invention relates to a scintillation camera provided with a detector having an integrated glass plate that protects the deliquescence of a single crystal and functions as a light guide.

[0002]

2. Description of the Related Art Generally, a single crystal of deliquescent sodium iodide (NaI) is used as a scintillator used in a detector of an Anger type scintillation camera.
As shown in FIG. 5, the scintillator 21 includes a NaI single crystal 22 that emits light upon receiving radiation, a flange 23 that supports the single crystal 22, an aluminum plate 24 that protects the single crystal 22 from deliquescent, and an optical cup. It is composed of a glass plate 25 that also serves as a ring.

The detector of the scintillation camera is a light guide 27 made of an acrylic plate on the glass plate 25 of the scintillator 21 with a hardening type two-part silicone 26 in between.
And a photomultiplier tube (PMT) 29 on the upper surface of the light guide 27 via a silicon coupling agent 28.
The structure is a dense array of. Here, the light guide 27 is inserted as an optical buffer in order to optimize the uniformity which is important for the basic characteristics of the detector and to configure the scintillation image with high accuracy.

The photomultiplier tube 29 has a socket 3
It is fixed by pressing it with a pressing plate 32 via a spring 31 which is provided around 0, and a rubber plate 33 is laid on the pressing plate 32.

[0005]

However, in the conventional detector, since the light guide is attached to the glass plate of the scintillator, the number of assembling steps becomes large, and such a process requires a long time of about 2 days. is there. In addition, the optical adhesion between the glass plate of the scintillator having a different refractive index and the light guide reduces the amount of scintillation light output received by the PMT, which deteriorates the positional resolution and energy resolution of incident radiation. The problem of causing

The present invention has been made in order to solve these problems, and provided with a detector capable of reducing the number of assembling steps at the time of manufacturing and increasing the light output light receiving amount in the PMT. It is intended to provide a scintillation camera.

[0007]

The scintillation camera of the present invention comprises a detector in which a plurality of photomultiplier tubes are closely fixed to the upper surface of a glass plate which covers and protects a single crystal such as NaI of a scintillator, The glass plate of the scintillator is characterized in that it is formed to have a thickness that makes the received amount of scintillation light in each photomultiplier tube approximately uniform.

Further, markings and uneven shapes for attaching the photomultiplier tube are provided on the upper surface of the glass plate of the scintillator, and pattern printing and uneven shape for adjusting the received amount of scintillation light in the photomultiplier tube. Should be applied.

[0009]

In the scintillation camera of the above means, since the glass plate of the scintillator constituting the detector is formed thick, it also serves as a light guide and a glass plate for protecting the single crystal such as NaI from deliquescent. Therefore, the light guide of the acrylic plate is not required, and only a single glass plate is inserted between the single crystal such as NaI and the photomultiplier tube. As a result, it is possible to prevent a reduction in the amount of light output received by the PMT that occurs when the scintillation light from the single crystal passes through a glass plate and an acrylic plate having different refractive indexes.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a detector in a scintillation camera. The detector has a structure in which the light guide is not provided on the upper surface of the scintillator 1 and the photomultiplier tubes (PMT) 2 are densely arranged,
A silicon coupling agent 3 having a low viscosity is placed between the scintillator 1 and the photomultiplier tube 2. Then, the spring 5 provided around the socket 4 of the photomultiplier tube 2 is pressed by the pressing plate 6 so that the photomultiplier tube 2 is closely fixed to the upper surface of the scintillator 1, and the rubber plate 7 is laid on the pressing plate 6. ing.

The scintillator 1 of this detector comprises a single crystal 8 of sodium iodide (NaI) which emits scintillation light when exposed to gamma rays and a flange which is provided around the single crystal 8 and is supported by the case of the detector. 9, an aluminum plate 10 for protecting the NaI single crystal 8 from deliquescent, and this aluminum plate 1
Like 0, it is composed of an integrated glass plate 11 having both a deliquescent protection function and a light guide function.

The glass plate 11 has a thickness of 13 mm to 1 when the thickness of the single crystal 8 of the scintillator 1 is about 9.5 mm.
Make a thickness of 6mm. The thickness of the glass plate 11 is the same as the conventional glass plate in proportion to the optical distance of the thickness of the light guide of the acrylic plate inserted between the photomultiplier tube and the scintillator in the detector of the conventional scintillation camera. Decide as a guide to increase the thickness of. Therefore, the amount of scintillation light received by each photomultiplier tube 2 can be approximately equalized without inserting a light guide.

By removing the light guide in the detector in this way, the reflection generated at the boundary surface between the conventional light guide and the glass plate can be prevented, so that the light output received amount by the photomultiplier tube 2 is relatively large. Can be increased. As a result, the position resolution and energy resolution are improved. Specifically, the actual measurement shows that the position resolution is around FWHM 0.2 mm and the energy resolution is 0.8%.
A front-back improvement is obtained.

Next, an embodiment in which a glass plate of a scintillator is processed in the same manner as a conventional light guide will be described.

FIG. 2 is a view showing the glass plate of the scintillator according to the first embodiment.

As shown in FIG. 2, the glass plate 12 of the first embodiment is provided with a ring-shaped marking 13 on its upper surface, which indicates the position for densely mounting the photomultiplier tube. Accordingly, when manufacturing a scintillation camera, the photomultiplier tube can be accurately arranged on the glass plate 12 using the marking 13 as a guide.

FIG. 3 is a view showing the glass plate of the scintillator according to the second embodiment.

The glass plate 14 of the second embodiment has a substantially triangular coating portion 15 surrounded by each photomultiplier tube coated with a coating material containing a reflecting agent by silk printing. As a result, the amount of scintillation light output received by each photomultiplier tube increases, and the uniformity required for the detector can be improved.

FIG. 4 is a view showing the glass plate of the scintillator according to the third embodiment.

The detector of FIG. 4 has the same structure as the detector of the embodiment of FIG. 1 except for the glass plate of the scintillator.

As shown in the sectional view of FIG. 4, the glass plate 16 of the third embodiment is provided with a groove 17 having a V-shaped cross section between the photomultiplier tubes 2 so that the surface of the glass plate 16 is uneven. It has a shape and the like. The concavo-convex shape of the glass plate 16 serves as a guide for the mounting position of the photomultiplier tube 2, and also serves to reduce the thickness of the glass plate itself or reduce the number of photomultiplier tubes 2 to be arranged. Therefore, it is suitable for manufacturing a simple and inexpensive scintillation camera.

[0023]

According to the scintillation camera of the present invention, since the detector of the scintillator uses an integrated glass plate having a NaI single crystal protective cover and a light guide function, a light guide having a different refractive index is used. The problem of reflection and the like is eliminated, the light output light receiving amount in the photomultiplier tube can be increased, its uniformity can be improved, and the resolution and resolution as a detector can be improved.

Further, since the light guide is removed, there is no problem such as mechanical deformation that occurs when members having different coefficients of thermal expansion are fixed to each other, and the structure of the detector can be simplified to shorten the manufacturing period of the scintillation camera. Can be promoted.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a detector used in a scintillation camera according to the present invention.

FIG. 2 is a plan view showing a first embodiment of the glass plate of the scintillator.

FIG. 3 is a plan view showing a second embodiment of the glass plate of the scintillator.

FIG. 4 is a cross-sectional view of essential parts showing a configuration of a detector to which a third embodiment of a scintillator glass plate is applied.

FIG. 5 is a cross-sectional view of essential parts showing the configuration of a conventional detector.

[Explanation of symbols]

 1 scintillator 2 photomultiplier tube 8 single crystal 11, 12, 14, 16 glass plate 13 marking 15 coating part

Claims (3)

[Claims] 1. A scintillator comprising a detector in which a plurality of photomultiplier tubes are closely fixed to the upper surface of a glass plate that covers and protects a single crystal such as NaI, and the scintillator glass plate comprises:
A scintillation camera, characterized in that the photomultiplier tube is formed to have a thickness that approximately equalizes the amount of received scintillation light. 2. The scintillation camera according to claim 1, wherein a marking for mounting a photomultiplier tube, a concavo-convex shape and the like are provided on the upper surface of the glass plate of the scintillator. 3. The scintillation camera according to claim 1, wherein a pattern printing for adjusting the received amount of scintillation light in the photomultiplier tube, a concavo-convex shape or the like is provided on the upper surface of the glass plate of the scintillator.