JPH044550A - Radiation monitor - Google Patents

Abstract

PURPOSE:To judge distribution of X-rays in passage precisely by arranging a plurality of collecting electrodes on both sides of an insulation sheet, wherein electrical insulation is provided, electrically connecting each pair of corresponding sides of these collecting electrodes, interposing each electrode between a pair of high tension electrodes in electrical connection, and connecting a measuring instrument with the collecting electrodes. CONSTITUTION:A plurality of collecting electrodes 8a, 8b are arranged on both sides of an insulation sheet 7 in its different positions, wherein electrical insulation is provided, and each pair of mating ones on these surfaces are connected with each other electrically through a through hole 10. A pair of high tension electrodes 1a, 1b pinch these collecting electrodes 8a, 8b from the sides with a gap interposed, wherein electric connection shall be accomplished, and a measuring instrument 4 for measurement of the dissociation current is connected with these collecting electrodes 8a, 8b. Because the high tension electrodes 1a, 1b are arranged with a constant distance held at all times, the capacity of the dissociating space for the high tension electrodes 1a, 1b does not change substantially even though the collecting electrodes 8a, 8b on the insulation sheet 7 interposed between the high tension electrodes 1a, 1b deform due to temp. change, etc., which should enable stable measuring of the dissociation current. Thus the distribution of the X-rays in passage can be judged precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radiation monitor that detects radiation such as X-rays.

[Conventional technology]

FIG. 3 is a conceptual diagram showing a conventional radiation monitor shown in U.S. Pat. , 2 is a high voltage power source that applies high voltage to the high voltage electrode 1, and 4 is a measuring device connected to each collecting electrode 3.

Next, the operation will be explained. When, for example, X-rays pass between the high voltage electrode 1 and each collector electrode 3, the gas, for example air, between the picture electrodes 1.3 is ionized and ionized, and these ions flow into the respective electrodes 1 and 3.

As mentioned above, since the collector electrode 3 is insulated and divided into four parts, the ionization current corresponding to the dose of the passing X-rays is input to the measuring device 4, and the dose distribution can be determined from this measured value. can.

[Problem to be solved by the invention]

Conventional radiation monitors are configured as described above, and since the volume between each electrode 1 and 3 is proportional to the ionizing current, when performing highly accurate dose measurement, each electrode 1 and 3 is
The distance between the two electrodes must always be maintained constant, while each electrode 1 and 3 must be made extremely thin so as not to affect the X-rays passing through them, which leads to deformation due to the influence of temperature. There were issues such as the inability to realize highly accurate dose monitors. In particular, since each collector electrode 3 is formed by depositing metal on an insulating film in an insulated state,
Compared to the high-voltage electrode 1, there were problems such as easy deformation to a large extent.

This invention was made to solve the above problems, and even if the collector electrode is deformed due to changes in ambient temperature, etc.
The purpose is to obtain a radiation monitor that can perform dose measurement with high accuracy.

[Means to solve the problem]

The radiation monitor according to the present invention includes a plurality of collector electrodes that are electrically insulated at a plurality of locations on both sides of an insulating sheet, and corresponding electrodes on both sides are electrically connected to each other, and a plurality of collector electrodes that are electrically connected to each other on both sides of the insulating sheet. It consists of a pair of high-voltage electrodes sandwiched from the sides with a gap in between and electrically connected to each other, and a measuring device for measuring ionization current connected to each of the collector electrodes.

[Operation] Since the pair of high-voltage electrodes in this invention are always arranged at a constant distance, even if the collector electrode on the insulating sheet between these high-voltage electrodes deforms due to temperature changes, etc.
Since the volume of the ionization space relative to the high-voltage electrode does not substantially change, the ionization current can be measured stably, and therefore the dose can be monitored with high accuracy.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, la and lb are a pair of high voltage electrodes electrically connected via a connecting plate 5, to which a high voltage power source 2 is connected as shown in FIG. 6 is a supporter that insulates and supports the high voltage electrode 1b. 3A is a pair of high voltage electrodes 1a
, 15, which is connected to a plurality of collector electrodes 8a via electrically insulating parts (here, gaps are provided) 9 at multiple locations on both surfaces (front and back surfaces) of the insulating sheet 7.

8b. Also, the corresponding ones of the collector electrodes 8a and 8b on both sides are connected to the second
As shown in the figure, they are electrically connected via through holes 10 formed in an insulating sheet 7. Further, 2 is a high-voltage power source that supplies high voltage to the high-voltage electrodes 1a and 1b, and 4 is a measuring device that measures ionization current.

Next, the operation will be explained. When, for example, X-rays pass through the gap between the high-voltage electrodes 1a, 1b and each collector electrode 8a, 8b, the gas, for example, air, between the circumferential electrodes 1a, lb and 8a, 8b is ionized and ionized, and these ions become ionized. It flows into electrodes 1a, lb and 8a, 8b. As mentioned above, the collector electrode 8a.

Since 8b is insulated and divided into four parts, the above-mentioned passing X
An ionizing current corresponding to the dose of the line is input to the measuring device 4, and the dose distribution can be determined from this measured value.

Furthermore, in such a structure, even if the insulating sheet 7 and the collector electrodes 8a, 8b are deformed due to the influence of temperature, the distance between the two high voltage electrodes 1a, 15 that sandwich them remains constant. Therefore, the volume between these and the collecting electrodes 8a, 8b becomes substantially constant. Therefore, the ionization current obtained in the collecting electrodes 8a, 8b is also constant corresponding to this volume, and the amount of passing X-rays can be measured stably and with high accuracy. As a result, the distribution of passing X-rays can be determined accurately.

In the above embodiment, the high-voltage electrodes 1a, lb and the collector electrodes 8a, 8b are square, but they may be round or any other shape.

Further, in the above embodiment, the collector electrodes 8a and 8b are electrically connected through the through hole 1o, but they may be connected by other methods, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a plurality of collector electrodes are electrically insulated and arranged on both sides of an insulating sheet, and corresponding electrodes on both sides of each of these collector electrodes are electrically connected. Since the electrode was interposed between a pair of electrically connected high-voltage electrodes, and a measuring device was connected to each of the collector electrodes, there could be no contact between the collector electrodes despite the deformation of the collector electrodes. It is possible to stably extract the ionizing current during the period, which has the effect of making it possible to determine the distribution of passing X-rays with high accuracy.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of a radiation monitor according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the radiation monitor of FIG. 1, and FIG. 3 is a view of a conventional radiation monitor. FIG. la and lb are high voltage electrodes, 4 is a measuring device, 8a and 8b are collector electrodes, and 7 is an insulating sheet. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. to, ratio High voltage electrode 80, collector electrode 8b collector electrode Figure 2 7 female sea 1

Claims (1)

[Claims] A plurality of collector electrodes are electrically insulated at multiple locations on both sides of an insulating sheet, and corresponding parts on both sides are electrically connected, and each of these collector electrodes is sandwiched from both sides with a gap. , and a radiation monitor comprising a pair of electrically connected high-voltage electrodes, and a measuring device for measuring ionization current connected to each of the collector electrodes.