JPS5842940B2 - Ionization chamber type X-ray detector and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray detector, particularly an ionization chamber type X-ray detector suitable for use in a computerized X-ray tomography apparatus.

Conventionally, an ionization chamber type detector that measures the spatial distribution of X-ray photons has been used as a detector for this type of device.

The general structure of this detector is as shown in FIG. 1, in which a plurality of planar anode electrodes 2 and planar cathode electrodes 3 are alternately placed on an electrode holding plate (for example, an insulator) 1 at approximately parallel intervals. The electrodes are encapsulated in a high atomic weight gas (eg, xenon gas) at a pressure in the range of about 10 atmospheres to 50 atmospheres.

Note that the X-rays are incident from the direction of the arrow in the figure.

FIG. 2 is a diagram schematically showing an electrode section of the ionization chamber type X-ray detector shown in FIG. 1.

In the figure, two electrode holding plates 1 each having grooves 5 formed in an insulator at predetermined intervals are arranged vertically at a constant interval, and an anode electrode 2 and a cathode electrode 3 are inserted alternately into the grooves 5. ,
It is fixed inside the groove with adhesive 4.

In such a detector, if the density of the detection elements is to be increased, the electrode spacing d must be reduced, which naturally shortens the creepage distance of the insulator.

Therefore, in this state, it becomes difficult to maintain the insulation resistance between the anode electrode 2 and the cathode electrode 3 at a high value, and the dark current from the anode electrode 2 flows along the insulator surface to the cathode electrode 3. Therefore, it is difficult to stably detect the signal current from the cathode electrode 3.

In view of this point, an object of the present invention is to provide an X-ray detector structure and a manufacturing method thereof that make it possible to eliminate dark current flowing from an anode electrode to a cathode electrode.

Hereinafter, a detector according to the present invention will be explained with reference to the drawings.

FIG. 3 is a diagram illustrating the configuration of an embodiment of the ionization chamber type X-ray detector according to the present invention.

The electrode holding plate 1 includes an insulator 7 and a conductive member 6 bonded to the insulator 7.
A plurality of grooves 10 are provided at predetermined intervals and reach the conductive member.

The two electrode holding plates 1 (in the figure, only one electrode holding plate is shown for convenience of explanation) are arranged at a constant interval from each other, and the hair node electrodes 2 and cathode electrodes 3 are inserted alternately into the grooves 10. and hold these electrodes.

As shown in FIG. 3 1ζ, only the side surface of the above electrode is
It is bonded to the side surface of the groove 10 with an adhesive 8.

Here, as the adhesive material 8, for example, a thermoplastic resin (eg, tetrafluoroethylene copolymer) is used.

FIG. 4 and FIG. 5 are diagrams explaining the manufacturing process of the X-ray detector according to the present invention.

As shown in FIG. 4A, the electrode holding plate stacks a conductive member 6 and an insulating material (for example, glass) 7, and firmly adheres the contact surface 11 of the two.

Next, as shown in FIG. 4B, the insulator is cut into grooves that reach the conductive member using a cutting machine (for example, a multi-wire chainsaw) to form a plurality of grooves at predetermined intervals.

In the electrode holding plate which has been completely grooved, insulators are arranged on the conductive member at predetermined intervals, and the conductive member is exposed between each insulator.

After grooving, the ends of the electrode holding plate are processed as shown in FIGS. 4C and 4D to complete the processing of the electrode holding plate.

The electrode holding plates 1 manufactured through the above manufacturing process are fixed facing each other, and the anode electrodes 2 and cathode electrodes 3 are alternately inserted into the grooves.

Next, a strip of thermoplastic resin 8 (for example, tetrafluoroethylene copolymer) is inserted between the groove and the electrode plate as shown in FIG. 5A.

In this state, heat treatment in a heating furnace (280℃~290℃)
When this is done, the electrode plate and the insulator will be welded together.

FIG. 5B shows details of the bonded portion.

If you carefully observe the bonded area after heat treatment, you will notice that the thermoplastic resin shrinks and the lζ between the electrode plate and the insulator uniformly decreases from 0.01 to
It was found that a gap d1 of about 0.02 mm was generated.

This has a very advantageous effect on the electrical characteristics between the electrodes.

That is, as shown in FIG. 3, from the anode electrode 2,
The dark current flowing along the surface of the insulator 7 flows into the conductive member 6 through the path indicated by the arrow 9.

For this purpose, if the conductive member 6 is grounded, the dark current flowing from the anode electrode 2 to the cathode electrode 3 will be removed.
Output signals can be detected stably.

As described above, according to the present invention, even if the electrode spacing is reduced, output signals can be stably detected, so that high density detection elements can be realized.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional ionization chamber type X-ray detector.
2 is a diagram showing the configuration of the electrode section of the ionization chamber type X-ray detector of FIG. 1, FIG. 3 is a diagram showing the schematic configuration of the ionization chamber type X-ray detector according to the present invention, and FIG. Figures A to 4 are diagrams for explaining the manufacturing process of the electrode holding plate according to the present invention, and Figures 5A and 5B are diagrams for explaining the method of fixing the electrodes. 1... Electrode holding plate, 2... Planar anode electrode, 3... Planar cathode electrode, 4...
...adhesive, 6...conductive member, 7...
...Insulator, 8...Adhesive material, 10...
Groove, 11...Contact surface.

Claims (1)

[Claims] 1. In an ionization chamber type X-ray detector in which a plurality of planar anode electrodes and a plurality of planar cathode electrodes are arranged substantially parallel in a predetermined gas medium, the electrodes are supported. The electrode holding plate is composed of an insulating member and a conductive member bonded to the insulating member, and the electrode holding plate is provided with a plurality of grooves reaching the conductive member at predetermined intervals, and the electrode is arranged in the groove. The above-mentioned ionization chamber type
line detector. 2. manufacturing an electrode holding plate by gluing an insulating member and a conductive member together, and forming grooves at predetermined intervals on the insulating member of the electrode holding plate that reach the conductive member;
It consists of a process of inserting an electrode plate and a strip-shaped hot-drying plastic resin adhesive into the groove, and a heat treatment process at a predetermined temperature to weld the electrode plate to one side of the groove. A method for manufacturing an ionization chamber type X-ray detector, characterized in that the groove has a structure having a uniform gap between the groove and the other side surface.