JPS6230281Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a scintillation camera device, and in particular, a photomultiplier tube (PMT) that is optimal for use in the detection section of this device.
(hereinafter simply referred to as "PMT").

A radioisotope (radioisotope ~ RI) administered to a subject using a scintillator that emits light when radiation is incident and a photomultiplier tube that detects the light from the scintillator and converts it into an electrical signal.
A scintillation camera is known that measures the distribution state of .

Conventionally, this scintillation camera uses sodium iodide [NaI] as shown in Figure 1, for example.
A scintillator 1 made of a single crystal of (Tl)],
A glass plate 2 made of heat-resistant glass or the like to protect the scintillator 1, a light guide 3 made of acrylic resin or the like to guide the light of the scintillator 1, a deflector 4 made of acrylic resin or the like, these light guides 3 and A detection section 6 is constituted by an optical system consisting of a plurality of PMTs 5 that detect the light guided through the deflector 4 and output an electric signal. The scintigram is displayed on the image display device 8 based on the calculation result. On the other hand, the PMT 5 is constructed as shown in FIG. That is,
In the figure, 9 is a tubular glass container, 10 is an entrance window formed using a similar glass plate, 11 is a photocathode, 12 is a Venetian dynode, 1
3 is a collector.

In this case, in the optical system of the detection unit 6, many media such as a glass plate 2, a light guide 3, and a deflector 4 are interposed between the scintillator 1 and the PMT 5, and each of the glass plate 2, light guide 3, and deflector 4 is Since the optical refractive indexes of the scintillator 1 and
The route into PMT5 was extremely complex. In addition, since the light passes through many optical media, there is a lot of loss, which is one of the factors that reduce the position resolution.
I was used to it.

In order to improve this, as shown in Figure 3,
Same configuration as PMT5 but smaller diameter
The PMT 14 is disposed on the light guide 3 as closely as possible, and the deflector 4 is removed to configure the detection section 15, thereby improving the resolution.

In this case, the incident light L enters the PMT 14 as shown in FIG. 4, and compared to the case of FIG. 1, the number of optical media is reduced by one, and the distance between the PMT 14 and the scintillator 1 is also Although it is shorter, the refractive index between the light guide 3 and the deflector 4 and between the light guide 3 and the entrance window 10 of the PMT 14 are different, resulting in a loss in resolution. However, in this case the uniformity of the device as a whole is improved.

On the other hand, as shown in FIG. 5, it is also possible to remove the light guide 3 from the configuration shown in FIG. 3 and bring the PMT 14 into close contact with the glass plate 2 to form the detection section 16, but if you do this, The incident light L enters as shown in FIG. 6, and although the resolution is certainly improved, the uniformity of the entire device is degraded.

According to the various configurations described above, there is a mutually contradictory tendency in that an attempt to improve resolution deteriorates uniformity, and an attempt to improve uniformity results in a decrease in resolution.

The present invention was developed based on these circumstances, and provides a scintillation camera equipped with a wide field of view and highly efficient PMT that expands the field of view for incident light as much as possible and has less loss in detecting the incident light. The purpose is to

That is, the feature of the present invention is that the entrance window portion is formed by a light guide member made of a light guide having a substantially truncated conical shape or the like that expands toward the light incidence side.

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

In FIG. 7, the same parts as in FIG. 2 are given the same reference numerals, and their explanations will be omitted. Reference numeral 17 denotes an entrance window section, in which a light guide member 18 made of a light guide material such as glass having substantially the same refractive index as the glass plate 2 is disposed. The light guide member 18 has a substantially truncated conical shape as shown in the figure, expanding toward the entrance surface side, and is provided to airtightly close the entrance window portion of the tubular glass container 9. Configure. Further, a reflective layer 19 is formed on the outer peripheral surface of the glass container 9, and by reflecting light on the inner surface of the reflective layer 19, the function of the light guide member 18 is aided. The PMT 20 is configured as described above.

The PMT 20 configured in this way has a cathode 1
1, the light guide member 1 of the entrance window 17
Since the deflector 8 has almost the same configuration and function as the deflector 4 in the conventional scintillation camera shown in Fig. 1, there is little loss of incident light, and the original
The PMT's resolution can be maximized, and the field of view of the PMT can be effectively expanded.

FIG. 8 shows an example of a scintillation camera constructed using such a PMT 20. That is, in this case, the detection unit 21 is configured by directly abutting the PMT 20 against the glass plate 2.

In this case, the incident light L is
It is effectively guided by the light guide member 18 of the PMT 20, and since the refractive index of the light guide member 18 and the glass plate 2 are approximately the same, there is extremely little loss, and the incident light with a wide field of view is detected with high sensitivity. can. Therefore, both resolution and uniformity are improved as a scintillation camera.

As described above, according to the present invention, it is possible to provide a scintillation camera that has a wide field of view with respect to incident light and has a wide field of view with little loss in detecting the incident light and is equipped with a highly efficient PMT. .

The present invention is not limited to the embodiments described above and shown in the drawings, but can be implemented with various modifications without changing the gist thereof.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the configuration of an example of a conventional scintillation camera, Figure 2 is a sectional view showing the configuration of a conventional photomultiplier tube, and Figure 3 is a scintillation camera that is an improved configuration of Figure 1. FIG. 4 is a schematic diagram showing the configuration of an example of the scintillation camera. FIG. 4 is a diagram showing the state of incident light in the same example. FIG.
Figure 7 shows the state of incident light in the same example, Figure 7 is a sectional view showing the configuration of an embodiment of the present invention, and Figure 8 shows the configuration of an example of a scintillation camera constructed using the same embodiment. The schematic diagram shown in FIG. 9 is a diagram showing the state of incident light in the same example. DESCRIPTION OF SYMBOLS 11... Photocathode, 12... Venetian dynode, 13... Collector, 17... Incident window part, 18... Light guide member, 19... Reflective layer.

Claims (1)

[Scope of utility model registration request] At least in a scintillation camera having a detector in which a plurality of photomultiplier tubes are arranged on one side of a scintillator through a light-transmitting member, the light guide is formed of a light guide having substantially the same refractive index as the light-transmitting member. , and a scintillator comprising a detector in which a plurality of photomultiplier tubes are arranged, each of which is formed by airtightly closing and fixing a light guide member having a shape that expands toward the light incident side in a light incident window. Shion camera.