JPH05142351A - Fluoroglass dosemeter reader - Google Patents

Abstract

PURPOSE:To provide a fluoroglass dosemeter reader for reading a radiation dose after completing build-up even immediately after irradiation. CONSTITUTION:In a fluoroglass dosemeter reader 2 for reading radiation dose irradiated at a fluoroglass dosemeter 1, there is provided a radiation dose reading means 3 for reading radiation dose before completing the build-up of the fluoroglass dosemeter 1. In addition, there are provided a build-up correction means 5 for taking radiation dose after completing build-up by correcting the build-up by using correction coefficient previously obtained from a build-up characteristic against the radiation dose read by the radiation dose reading means 3, and a correction coefficient table 4 for obtaining correction coefficient based on at least one data of irradiation time data or environmental temperature data during irradiation, and elapsed time data after irradiation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent glass dosimeter reading device used in a radiation control system and the like, and particularly to a fluorescent glass for reading the radiation dose applied to a fluorescent glass dosimeter early and with high accuracy. The present invention relates to a dosimeter reading device.

[0002]

2. Description of the Related Art Generally, a fluorescent glass dosimeter uses a glass element for a fluorescent dosimeter, which is 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 irradiation of radiation, and the fluorescence intensity at this time is proportional to the radiation dose, so it is necessary to detect this fluorescence intensity. The dose of radiation can be measured by.

However, the fluorescent component in the glass element that emits fluorescence upon receiving the excitation light does not complete its generation process immediately after irradiation with radiation, but increases with the passage of time after irradiation and stabilizes after saturation. There is a characteristic. This characteristic is called a build-up characteristic and generally tends to stabilize about 24 hours after irradiation with radiation.

FIG. 2 is a build-up characteristic diagram showing a change in dose reading value after irradiation of radiation with respect to elapsed time. In the figure, the horizontal axis is the elapsed time after irradiation expressed on a logarithmic scale, and the vertical axis is the relative value of the dose reading value obtained by normalizing the dose reading value at the time of stability by one. This dose reading was about 0.6 immediately after irradiation, but gradually increased over time and reached 1.0 after about 24 hours, and then became stable.

Therefore, when the radiation dose is read immediately after the irradiation of radiation, the value is lower than the actual value because the build-up is not completed. Therefore, the reading of the fluorescent glass dosimeter is usually performed after the completion of build-up. From 24 hours onwards.

[0006]

However, since the fluorescent glass reader as described above cannot accurately read the radiation dose immediately after the irradiation of radiation, it is necessary to read the dose when the radiation control area is withdrawn. It could not be used as a dosimetry device for exit control.

Further, since the build-up characteristics change depending on the irradiation conditions of radiation, a reading error occurs when the reading conditions deviate from the standard reading conditions, which causes a problem in measurement accuracy.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a fluorescent glass dosimeter reading device capable of reading a radiation dose after completion of build-up even immediately after irradiation.

Another object of the present invention is to provide a fluorescent glass dosimeter reading device capable of accurately reading the radiation dose after the buildup is completed, even if the reading and measuring conditions change.

[0010]

First, an invention corresponding to claim 1 is a fluorescent glass dosimeter reading device for reading a radiation dose applied to a fluorescent glass dosimeter, before the completion of build-up of the fluorescent glass dosimeter. A dose reading means for reading the radiation dose, and a buildup correcting means for correcting the radiation dose read by the dose reading means by using a correction coefficient obtained in advance from the buildup characteristics to take out the radiation dose after the buildup is completed. And a fluorescent glass dosimeter reading device.

Next, in the invention according to claim 2, the build-up correction means is one or more kinds of data of radiation irradiation time data and environmental temperature data during radiation irradiation, and radiation. The fluorescent glass dosimeter reading device according to claim 1, further comprising a correction coefficient table for obtaining the correction coefficient based on elapsed time data after irradiation.

[0012]

Therefore, in the invention according to claim 1, the radiation dose read by the build-up correction means before the completion of the build-up is calculated based on the correction coefficient obtained from the build-up characteristics by the means as described above. Since it is corrected, the radiation dose after completion of buildup can be measured with high accuracy even immediately after irradiation.

Next, the invention according to claim 2 is directed to radiation irradiation time data, at least one of radiation irradiation time data and environmental temperature data during radiation irradiation, and The correction coefficient table calculates the correction coefficient based on the elapsed time data after irradiation, so even if the buildup characteristics change depending on the elapsed time after irradiation or the environmental temperature during irradiation, the radiation after the buildup is completed accurately. The amount can be read.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a block configuration of a fluorescent glass dosimeter reading device according to the present invention. In the figure,
Reference numeral 1 is a fluorescent glass dosimeter that emits fluorescence having a fluorescence intensity proportional to the dose of radiation irradiated when it receives excitation light. For example, this is for a fluorescent dosimeter made of phosphate glass containing silver ions. It is a kind of radiation detector consisting of a glass element and a holder for holding the glass element. Reference numeral 2 denotes a fluorescent glass dosimeter reading device for reading the dose of radiation applied to the fluorescent glass dosimeter 1. This reading device 2 is a dose reading means 3 for reading and transmitting an exposure dose from the fluorescence intensity emitted from the fluorescent glass dosimeter 1 before the completion of buildup, and a buildup correction coefficient based on an irradiation condition of radiation inputted from the outside. From the correction coefficient table 4 for determining the read dose of the dose reading means 3 and the buildup correction means 5 for correcting the read dose by receiving the correction coefficient, and the display section 6 for displaying the dose corrected by the correction means 5. It is configured.

The dose reading means 3 receives, for example, an excitation light source such as a nitrogen gas laser, a semi-transparent mirror for splitting the excitation light generated from the excitation light source into reflected light and transmitted light, and the reflected light. A standard fluorescent glass element that emits fluorescence that is proportional to a predetermined irradiation dose of radiation that has been previously irradiated; a first photoelectric conversion element that receives the fluorescence generated by this standard fluorescent glass element and converts it into a first electric signal; A second photoelectric conversion element that allows transmitted light to enter the fluorescent glass dosimeter 1 and receives fluorescence from the fluorescent glass dosimeter 1 to convert it into a second electric signal; and the first and second electric signals. In response to this, an arithmetic circuit for calculating the radiation dose applied to the fluorescent glass dosimeter 1 and sending it to the correction means 5 is provided.

The correction coefficient table 4 holds in advance data of changes in the dose readings after irradiation of radiation with respect to elapsed time, that is, data relating to so-called build-up characteristics. Based on any one or more kinds of environmental temperature data and the elapsed time data after irradiation of radiation, a correction coefficient is obtained from the build-up characteristics corresponding to the data and is output. It has a function.

Next, the operation of such a fluorescent glass dosimeter reading device will be described. First, the fluorescent glass dosimeter 1 irradiated with radiation is set in the dose reading means 3 of the fluorescent glass dosimeter reading device 2. In this dose reading means 3, the intensity of fluorescence generated by irradiating the fluorescent glass dosimeter 1 with excitation light before the buildup is completed is detected by the second photoelectric conversion element and converted into a second electric signal. The excitation light is also applied to the standard fluorescent glass element through the transparent mirror, and the intensity of the fluorescence generated at this time is detected by the first photoelectric conversion element and converted into a first electric signal. Second
Is corrected to read the exposure radiation dose applied to the fluorescent glass dosimeter 1.

On the other hand, the correction coefficient table 4 contains one or more kinds of data from the outside, ie, radiation irradiation time data and environmental temperature data during radiation irradiation, and elapsed time data after radiation irradiation. In response to this, the correction coefficient is obtained from the data relating to the build-up characteristics held in advance. For example, as shown in FIG. 2, when the elapsed time data after radiation irradiation is t and the relative value of the dose reading value corresponding to this elapsed time data t is F (t), the correction corresponding to the elapsed time t The coefficient H (t) is obtained by the equation (1). H (t) = 1 / F (t) (1)

As data for obtaining this correction coefficient, in addition to the elapsed time data after radiation irradiation, radiation irradiation time data is also included.
Data and environmental temperature data during radiation irradiation,
Next, the process of obtaining the correction coefficient from these data will be described. First, since the buildup of the fluorescent component related to the radiation that was initially irradiated is nearing the end for the one with a long irradiation time of the radiation, compared to the buildup characteristics of FIG. 2, it corresponds to when the elapsed time t is zero. The relative value (initial value) of the dose reading to be performed tends to be high. The data relating to the build-up characteristics having such a tendency is held in advance according to the size of the radiation irradiation time data, and the corresponding radiation irradiation time data is stored.
Select the data related to the build-up characteristics by inputting the data, and from the elapsed time data after irradiation (1)
The correction coefficient is calculated using the formula.

Further, in the case where the ambient temperature during irradiation of radiation is high, the fluorescent component is activated earlier, so that the initial value is higher than that of the build-up characteristics shown in FIG. The relative value tends to 1.0 and stabilizes without waiting for time. The data relating to the build-up characteristics of such a tendency is held in advance according to the size of the environmental temperature data during radiation irradiation, and the relevant build-up characteristics are set by inputting the environmental temperature data during the corresponding radiation irradiation. Such data is selected, and the correction coefficient is calculated from the elapsed time data after irradiation of the radiation by using the equation (1).

In response to the correction coefficient thus obtained and the radiation dose read by the dose reading means 3, the correction means 5 corrects the radiation dose to the value after the buildup is completed. This correction is performed by multiplying the radiation dose read by the dose reading means 3 by a correction coefficient. After that, the display unit 6 displays the correction means 5
The radiation dose after completion of build-up obtained by is displayed.

Therefore, according to the configuration of the above embodiment, the exposure dose of the fluorescent glass dosimeter 1 read before the completion of the build-up is corrected by the build-up correction using the correction coefficient obtained in the correction coefficient table 4. Since the means 5 corrects the radiation dose after completion of build-up, the exposure dose after completion of build-up can be known even by reading before completion of build-up, such as immediately after irradiation. Further, since the exposure dose after completion of build-up can be known even by reading immediately after irradiation, it can be used as a dose reading device for entrance / exit control of radiation control areas.

Further, the correction coefficient table 4 is made to hold the data relating to the build-up characteristics represented by the radiation irradiation time data and the environmental temperature data during radiation irradiation, and 1 of these data is stored. More than one type and the elapsed time after irradiation
Since the correction coefficient is calculated based on the data, it is possible to accurately read the radiation dose after the build-up is completed by reflecting the build-up characteristics that change depending on the irradiation time and the environmental temperature during irradiation. ..

As described above, the present invention has explained the process of obtaining the correction coefficient as a function of the elapsed time data after irradiation of the radiation, but the elapsed time data is used for the entrance / exit control of the radiation control area. When there is little variation in the data, the same operation can be performed by setting a predetermined value in advance without inputting the elapsed time data after radiation irradiation. The radiation irradiation time data and the environmental temperature data during radiation irradiation can be similarly set to predetermined values.

Further, the calculation process by the correction means may be addition or division depending on how the correction coefficient is determined, but the same process can be performed. Besides, the present invention can be variously modified and implemented without departing from the scope of the invention.

[0026]

As described above, the present invention has the following effects.

According to the first aspect of the present invention, since the build-up correction means corrects the radiation dose read before the build-up is completed based on the correction coefficient obtained from the build-up characteristics, the radiation after the build-up is completed even immediately after the irradiation. A fluorescent glass dosimeter reader capable of reading a quantity can be provided.

Next, the invention of claim 2 is characterized in that any one of the radiation irradiation time data and the environmental temperature data during radiation irradiation.
Since the correction coefficient table calculates the correction coefficient based on the data of more than one kind and the elapsed time data after irradiation of radiation,
It is possible to provide a fluorescent glass dose device that can accurately read the radiation dose after completion of build-up even if the conditions during reading and measurement change.

[Brief description of drawings]

FIG. 1 is a diagram showing a block configuration of a fluorescent glass dosimeter reading device according to the present invention.

FIG. 2 is a diagram showing build-up characteristics of a fluorescent glass dosimeter.

[Explanation of symbols]

1 ... Fluorescent glass dosimeter, 2 ... Fluorescent glass dosimeter reading device, 3 ... Dose reading means, 4 ... Correction coefficient table, 5 ... Correction means.

Claims (2)

[Claims] 1. A fluorescent glass dosimeter reading device for reading the radiation dose applied to a fluorescent glass dosimeter, comprising: a dose reading means for reading the radiation dose before the completion of build-up of said fluorescent glass dosimeter; and this dose reading means A fluorescent glass dosimeter reading device, comprising: a built-up correction unit that corrects the read radiation dose using a correction coefficient obtained in advance from a build-up characteristic and extracts the radiation dose after completion of the build-up. 2. The build-up correction means includes one or more kinds of data of radiation irradiation time data and environmental temperature data during radiation irradiation, and elapsed time data after radiation irradiation.
The fluorescent glass dosimeter reading device according to claim 1, wherein a correction coefficient table for obtaining the correction coefficient based on the data is used.