JPH058794B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an improvement of an X-ray detection device, and more particularly, to an X-ray detection device capable of inspecting the density of an ionizing gas in an ionization chamber type X-ray detector. .

(Prior art) In the ionization chamber type X-ray detector for X-ray CT,
A high-pressure ionizing gas is enclosed. The ionizing gas is sealed based on a predetermined standard pressure, but it gradually leaks out, so it is necessary to occasionally measure the pressure of the ionizing gas to check whether it is within the standard range.

(Problems to be Solved by the Invention) Leakage inspection of ionizing gas based on pressure measurement requires an expensive pressure sensor, and the standard value of pressure varies depending on the tube voltage of the X-ray tube used. , and there is a problem that the measured value of pressure varies depending on the temperature.

The present invention has been made in view of the above points, and its purpose is to eliminate the need for a pressure sensor to inspect changes in gas density due to leakage of ionizing gas, etc.
Unified standard values can be applied regardless of tube voltage, and inspection can be performed without being affected by temperature.
An object of the present invention is to provide a line detection device.

(Means for Solving the Problems) The present invention for solving the above problems has an ionization chamber-shaped X
an X-ray detector, the X-ray detector having an electrode divided into at least two in the direction of X-ray transmission;
The present invention is characterized by comprising means for inspecting the density of the ionizing gas in the X-ray detector based on the ratio of output signals taken out from each of the divided electrodes of the X-ray detector.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a conceptual diagram of a divided electrode E of an ionization chamber type X-ray detector, which is the main part of an embodiment of the present invention.
The divided electrode E is composed of a pair of electrode plates A and B formed on a common insulating substrate D along the X-ray transmission direction with a small dividing gap C between them.
Note that the electrode plates A and B may be a pair of independent electrode plates arranged in the same plane, and do not necessarily need to be an electrode pattern formed on an insulating plate.
Further, the electrode plates A and B do not need to have the same size, and the number of divisions may be greater than two.
The divided electrodes E are arranged at locations corresponding to channels at both ends of the multichannel X-ray detector 10, for example, as shown in FIG. A normal output signal extraction circuit is connected to the detection electrode of each channel (not shown). At that time, the divided electrodes A and B have
An output signal extraction circuit is connected to each of them individually.

When the X-ray detector 10 with such an electrode arrangement is irradiated with an X-ray beam, in the channel where the divided electrodes E are arranged, the intensity of the transmitted X-rays increases as shown in FIG. The range differs depending on the range of the electrode plate B, and an X-ray detection output signal corresponding to the intensity of X-rays is extracted from each electrode. When the ratio of these signals is determined, this ratio changes depending on the density of the ionizing gas, as shown in FIG. Therefore, by observing the ratio of the output signals of electrode plates A and B,
Changes in density due to leakage of ionizing gas, etc. can be seen. In other words, without using a pressure sensor,
A portion of the X-ray detector can be used to examine changes in ionizing gas density.

If the standard value for the density of ionizing gas is defined by the ratio of such signals, it is possible to determine the difference between a detector with a high density of ionizing gas for a high-energy (high tube voltage) low voltage)
Common standard values can be applied to detectors with low ionizing gas density for wire tubes. This is because, as shown in Figure 5, in X-ray detectors with the same dimensions in the X-ray transmission direction, the attenuation characteristics of X-ray intensity are different from those for high-energy X-ray tubes with high ionizing gas density. This is because the energy is almost the same for a detector with a low ionizing gas density for an X-ray tube. Furthermore, since the absorption of X-rays is directly utilized, the standard values are not affected by temperature.

(Effects of the Invention) As explained above, according to the present invention, a pressure sensor is not required to inspect changes in gas density due to leakage of ionizing gas, etc., and a unified method that does not depend on the tube voltage of the X-ray tube It is possible to realize an X-ray detection device to which standard values can be applied and which can perform inspections that are not affected by temperature.

[Brief explanation of the drawing]

FIG. 1 is a conceptual explanatory diagram of the main parts of the embodiment of the present invention, FIG. 2 is an example of the electrode arrangement of the X-ray detector of the embodiment of the present invention, and FIGS. 3, 4, and 5 are It is a graph showing an X-ray intensity curve in the radiation transmission direction. 10...X-ray detector, A, B...pair of electrode plates, E
...separation electrode, P...electrode plate.

Claims (1)

[Claims] 1. An ionization chamber-shaped X-ray detector having at least two divided electrodes in the direction of X-ray transmission, and the ratio of the output signal extracted from each of the divided electrodes of this X-ray detector. An X-ray detection device comprising means for inspecting the density of an ionizing gas in an X-ray detector based on.