JPH0619434B2 - Radiation dose reading device for fluorescent glass dosimeter - Google Patents

Description

Description: [Object of the invention] (Field of industrial application) The present invention relates to a radiation dose reading device for separately measuring a radiation dose of multi-ray quality, and particularly to a fluorescent glass dosimeter having a fluorescent glass element. The present invention relates to a radiation dose reading device for a fluorescent glass dosimeter having improved means for efficiently separating and measuring β-rays from the radiation exposure dose.

(Prior Art) Generally, a fluorescent glass dosimeter uses a glass element for a fluorescent dosimeter made of phosphate glass containing silver ions. This glass element emits fluorescence when excited by ultraviolet rays having a wavelength of 300 to 400 nm after being activated by exposure to radiation, and the fluorescence intensity at this time is proportional to the amount of radiation exposure, so it is necessary to detect this fluorescence intensity. The dose of radiation can be measured by.

In measuring such a radiation dose, a rectangular parallelepiped glass element previously exposed to radiation after selectively extracting ultraviolet rays in a predetermined wavelength range by passing light projected from an excitation ultraviolet ray source through an optical filter. It is incident almost vertically on one surface. Here, the glass element which receives the ultraviolet rays in the predetermined wavelength region emits fluorescence, and the fluorescence from the glass element at this time is taken out from the direction perpendicular to the incident direction of the ultraviolet rays and the predetermined wavelength is passed through the optical filter. By selectively extracting light in the range and photoelectrically converting it with a photomultiplier tube to obtain an electric signal of a level proportional to the fluorescence intensity, the fluorescence intensity, and thus the radiation dose, can be measured from the level of this electric signal.

By the way, conventionally, in the case of separately measuring the radiation dose of multi-quality using the above glass element for a fluorescence dosimeter, as shown in Japanese Utility Model Application Laid-Open No. 64-86087, the support frame has a predetermined interval. After mounting a plurality of glass elements with the glass element, the support frame with the glass element is individually provided with a filter for separately measuring multi-ray radiation at a position corresponding to a facing position on one side or both sides of the glass element. The fluorescent glass dosimeter is completed by enclosing it in a plastic filter case that is attached. The fluorescent glass dosimeter is installed in various places such as a radiation controlled area or carried by an operator so that a plurality of glass elements are exposed to radiation of multi-ray radiation.

Therefore, after injecting ultraviolet rays for excitation almost perpendicularly to a predetermined surface of the glass element exposed as described above, the fluorescence emitted from the direction perpendicular to the ultraviolet ray incident direction of the glass element is taken out through a filter, and the microcomputer etc. By executing an appropriate calculation in
Radiation doses of rays, γ rays and β rays are measured separately.

(Problems to be Solved by the Invention) However, in the above fluorescent glass dosimeter, X
Although it is possible to separate and measure X-rays, γ-rays and β-rays, particularly in the case of separating and measuring β-rays, there are many problems as described below.

First, in the case of β-rays, the fluorescence center generated inside the glass element 1 due to β-ray exposure is formed only near the surface of the β-ray irradiation surface. Therefore, in the fluorescence detection means as shown in FIG. When the corner portion is blocked by the diaphragm 2, the ultraviolet ray for excitation does not excite the vicinity of the β-ray irradiation surface of the glass element 1, which causes a problem that the β-ray separation and measurement efficiency becomes extremely poor. 3 is a photomultiplier tube.

Therefore, as a fluorescence detecting means for eliminating the above-mentioned problems, as shown in FIG. 7, the diaphragm 2 is removed from the ultraviolet incident surface side and ultraviolet rays are made incident, and only the peripheral portion of the glass element on the fluorescent output side is incident. There is one that detects the fluorescence emitted from the glass element 1 by providing the diaphragm 2.

Although this fluorescence detecting means can efficiently excite the β-ray irradiation surface of the glass element 1 by the incidence of ultraviolet rays, it is greatly affected by the chamfered state of the edge portion of the glass element 1, and therefore the β-ray measurement accuracy is remarkably high. descend.

Further, as another fluorescence detecting means, as shown in FIG. 8, it is conceivable to inject and excite ultraviolet rays from the side opposite to the β-ray exposed side of the glass element 1. In this case, the vicinity of the β-ray irradiation surface can be efficiently excited without being affected by the edge of the glass element 1. However, with this fluorescence detection means, β
Since the γ-rays or the like irradiated simultaneously with the X-rays form fluorescent centers in the entire glass element 1, variations in the thickness of the glass element 1 affect the fluorescence detection amount of the γ-rays, and thus the γ-rays and β-rays. There is a problem that the accuracy of separation from the line is significantly reduced.

The present invention has been made in view of the above circumstances, can excite ultraviolet rays without being affected by the chamfered state of the edge portion of the glass element, and can detect fluorescence without being affected by variations in wall thickness, etc. It is an object of the present invention to provide a radiation dose reading device of a fluorescent glass dosimeter capable of efficiently separating and measuring radiation having a radiation quality.

[Means for Solving the Problems] (Means for Solving the Problems) In order to solve the above-mentioned problems, a radiation dose reading device for a fluorescent glass dosimeter according to the present invention has one surface that is perpendicular to the radiation irradiation surface of the fluorescent glass element. The excitation ultraviolet light source or the fluorescent glass element is arranged so that the excitation ultraviolet light enters from an oblique direction with an inclination of 3 ° or more from the vertical direction.

(Operation) Therefore, by taking the above-mentioned means, the present invention makes it possible for the exciting ultraviolet rays to excite the radiation irradiation surface, and forms a fluorescence center only near the radiation irradiation surface β
Even if it is a line, it can be excited without being affected by the chamfered state of the edge portion of the glass element, and the fluorescence of the γ ray component can be detected without being affected by the variation in the thickness of the glass element 1. Radiation can be separated and measured efficiently and accurately.

(Embodiment) In describing an embodiment of the device of the present invention, first, a fluorescent glass dosimeter will be described with reference to FIGS. 1 to 3. FIG. 1 is an exploded perspective view showing the relationship between a glass element and a support frame, FIG. 2 is a cross-sectional view of a filter case accommodating a support frame holding a glass element, and FIG. 3 shows a state inside the filter case. It is sectional drawing shown.

First, as a glass element for a fluorescent glass dosimeter, for example, there are four glass elements or one glass element 11 having a length corresponding to four glass elements as shown in the figure. It is held by a pair of support frames 12 and 13. The support frame 12 has four openings 14a.
14d are formed, and element holding protrusions 15, ... Are provided in the vertical direction from the outer peripheral edge of the frame body except the portion which becomes the fluorescence output optical path of the glass element 11.
5, the glass element 11 fitted in the direction of the arrow in the figure is held. The other support frame 13 has a role of accommodating and holding one support frame 12 that holds the glass element 11, and specifically, a plurality of openings 16a to 16d are formed similarly to the support frame 12. The frame 1
The U-shaped portions 17 and 17 are provided by bending both ends, which are the longitudinal direction of 3, in the same direction.
Each U-shaped portion 1 has a positional relationship corresponding to 6a to 16d.
Notches 18a to 18d are provided on the surface portions of 7 and 17, respectively. A number hole 19 for optically reading the type of glass element and the ID code of the operator is provided at one end of the support frame 13.

Then, the pair of support frames 12 and 13 holding the glass element 11 as described above are housed in the plastic filter case 20 shown in FIG. This filter case 2
In FIG. 0, the tin filter 21a is sequentially arranged from the right side to the left side in the figure.
Aluminum filter 21b, β ray detection windows 21c, 2
1d is attached or opened. A plastic film 21c'21d 'having a different thickness is attached to each of the β-ray detection windows 21c and 21d. Therefore β
Line detection window 21c, film 21c ', β ray detection window 21d
And the film 21d 'form filters.

Therefore, one set of the support frames 1 for holding the glass element 11
When the filter case 20 accommodating 2 and 13 is cut across four filters, the cross section is as shown in FIG.

Then, regarding the exposed glass element dosimeter,
The exposure dose is read by the reader shown in FIG. 4. In this case, one set of support frames 12 and 13 is taken out from the filter case 20, and one set of these support frames 1 is taken out.
It is conveyed every 2 or 13, or in a state where the glass element 11 is held only by the support frame 12 and installed at a predetermined position of the reading device. In FIG. 4, 11 is a glass element, 12
Is a support frame, 30 is a diaphragm, and 31 is a reading unit.

That is, when reading the exposure dose, the β-ray detection window 21d, the β-ray detection window 21c, the aluminum filter 2 are used.
1b, while the position of the glass element 11 corresponding to the tin filter 21a is sequentially set to the measurement position, the ultraviolet ray for excitation is incident. At this time, as shown in FIG. 5, it makes a right angle with the radiation irradiation surface of the fluorescent glass element. The glass element 11 can be excited up to the radiation irradiation surface by injecting the excitation ultraviolet light from an oblique direction with an inclination of 3 ° or more from the vertical direction with respect to one surface. Reference numeral 31a is a photomultiplier tube, which constitutes a part of the reading unit 31.

As a result, the fluorescence amounts corresponding to β rays and γ (X) rays can be detected from the fluorescence amounts emitted from the glass element 11 positions on the surfaces corresponding to the β ray detection window 21d and the β ray detection window 21c, and the aluminum filter 21b can be used. , Γ from the amount of fluorescence emitted from the position of the glass element 11 on the surface corresponding to the tin filter 21a
The amount of fluorescence corresponding to only the (X) ray can be detected.

Therefore, the aluminum filter 21b and the tin filter 2
The energy of γ (X) rays can be estimated from the difference in energy response of the amount of fluorescence emitted from the position of the glass element 11 on the surface corresponding to 1a. Then, from the sensitivity to the γ (X) ray obtained from the position of the glass element 11 on the surface corresponding to the β ray detection window 21d and the β ray detection window 21c at the energy of the γ (X) ray, only the β ray at this position is detected. The fluorescence amount corresponding to is calculated by subtraction. Further, since plastic films 21d and 21c having different thicknesses are attached to the β-ray detection window 21d and the β-ray detection window 21c, respectively, the glass on the surface corresponding to the β-ray detection window 21d and the β-ray detection window 21c. The energy of β rays can be easily obtained from the difference in sensitivity to the β rays at the position of the element 11.

Therefore, according to the configuration of the above embodiment, a plurality of filters for separating and measuring multi-quality radiation, and one or more rectangular parallelepiped fluorescent glass elements at positions facing these filters are provided. When reading the exposure dose of the fluorescent glass dosimeter having the above, the excitation ultraviolet rays are incident on the glass element from an oblique direction with an inclination of 3 ° or more from the vertical direction of the surface perpendicular to the radiation irradiation surface of the fluorescent glass element. Therefore, the radiation irradiation surface can be excited by ultraviolet rays, and fluorescence can be efficiently detected even in the case of β-rays that form fluorescence centers only near the radiation irradiation surface. Further, since the ultraviolet ray for excitation is incident on the glass element from an oblique direction, it can be detected accurately without being affected by the chamfered state of the edge of the glass element and the variation in wall thickness. In addition, β-rays can be easily detected by being unaffected by variations in wall thickness, and thus, the multi-ray radiation can be separated and measured by the same reader.

In the above-mentioned embodiment, the fluorescent glass dosimeter for γ (X) rays and β rays was described, but only γ (X) rays or γ (X) rays
It goes without saying that the same can be applied to fluorescent glass dosimeters such as (X) rays and thermal neutron rays. Other,
The present invention can be variously modified and implemented without departing from the scope of the invention.

[Effects of the Invention] As described above, according to the present invention, the radiation irradiation surface can be excited without being affected by the chamfered state of the edge portion of the glass element, the variation in wall thickness, etc. It is possible to provide a radiation dose reading device of a fluorescent glass dosimeter capable of performing separate measurement well.

[Brief description of drawings]

1 to 5 are shown for explaining an embodiment of a radiation dose reading apparatus for a fluorescent glass dosimeter according to the present invention, and FIG. 1 shows a relationship between a glass element and a supporting frame. FIG. 2 is an exploded perspective view, FIG. 2 is a cross-sectional view of a filter case accommodating a support frame holding a glass element, FIG. 3 is a cross-sectional view showing the inside of the filter case, and FIG. FIG. 5 is a perspective view of the reading device, FIG. 5 is a diagram showing the positional relationship between the glass element, the excitation ultraviolet ray and the fluorescence detection direction, and FIGS. 6 to 8 are schematic diagrams for explaining the conventional fluorescence detection means. 11 ... Glass element for fluorescent glass dosimeter, 12, 13 ...
... one set of support frames, 20 ... filter case, 21a,
21b ... filter, 21c, 21d ... beta ray detection window,
21c ', 21d' ... plastic film, 30 ...
... diaphragm, 31 ... reading section, 31a ... photomultiplier tube.

Claims (1)

[Claims] 1. An exposure dose of a fluorescent glass dosimeter having a plurality of filters for separating and measuring multi-radiation radiation, and one or a plurality of fluorescent glass elements arranged at positions facing these filters. In the reading device for reading, the excitation ultraviolet light source or the excitation ultraviolet light source is arranged so that the excitation ultraviolet light is incident from an oblique direction with an inclination of 3 ° or more from the vertical direction with respect to one surface perpendicular to the radiation irradiation surface of the fluorescent glass element. A radiation dose reading device for a fluorescent glass dosimeter, wherein the fluorescent glass element is arranged.