JPH08313635A - Fluorescent glass dose measuring apparatus - Google Patents

Abstract

PURPOSE: To provide a fluorescent glass dose measuring apparatus having a function of accurately estimating X-ray energy and capable of measuring X-ray exposure dose. CONSTITUTION: A controller 20 includes estimation expression memory means 21 for storing a plurality of energy estimation expressions (estimated curves) in advance, an input unit 9 for inputting necessary command data, a display unit 13 for displaying various calculated results, and energy estimation expression selecting means 22 for selecting the energy estimation expression based on one QI near the spectral distribution of the emitted S-ray. The controller 20 further includes dose measured value calculating means 10 for calculating the dose measured value from a fluorescence detected value, fluorescence detected value distribution ratio calculating means 11 for calculating the fluorescence detected value distribution ratio of the ratio of the maximum value to the minimum value of the fluorescent values at the respective divided blocks, and energy estimated value calculating means 23 for calculating the energy estimated value by using the energy estimation expression selected by the means 22 based on the fluorescence detected value distribution ratio (maximum value/ minimum value).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention highly accurately estimates the quality (energy) of X-rays due to the difference in X-ray generation conditions in the measurement of environmental radiation inside and outside the X-ray generator installed in medical institutions. And a fluorescent glass dosimeter measuring device capable of measuring the X-ray exposure dose.

[0002]

2. Description of the Related Art Generally, a fluorescent glass element made of phosphate glass containing silver ions is used for measuring the radiation exposure dose. When this fluorescent glass element is exposed to ionizing radiation and exposed to light, a fluorescent center is generated in the glass body, and when excited by ultraviolet rays of a certain wavelength in this state, fluorescence is emitted from a predetermined glass surface. Since the intensity of the fluorescence emitted at this time is proportional to the radiation dose, the radiation dose of the fluorescent glass element can be measured by detecting the fluorescence dose.

Therefore, a fluorescent glass dosimeter using the above-mentioned fluorescent glass element is carried by a worker who handles radiation to measure the exposure dose, or is installed around a nuclear facility or other radiation-related facility. , Used to measure environmental dose.

In a fluorescent glass dosimeter used for such a purpose, it is usually considered sufficient to measure only the radiation dose. However, if an abnormal situation occurs in the facility, radiation leakage occurs, or if a large amount of radiation is exposed due to long-term work, not only the amount of radiation exposure, but also the radiation quality (energy)
From the viewpoint of radiation exposure accident analysis, it cannot be said that radiation control is sufficient unless the radiation incident direction is known.

In addition, as medical radiation exposure management becomes strict, in performing area monitoring of radiation controlled areas, estimation of radiation energy is becoming an important factor in addition to environmental dose measurement.

[0006] Conventionally, as an example of this type of fluorescent glass dosimeter measuring device, that is, an example of a fluorescent glass dosimeter measuring device capable of estimating the radiation quality and radiation incident direction together with the dose, the applicant of the present invention separately patents There is one disclosed in Japanese Patent No. 1807400 (Japanese Patent Publication No. 5-12675) filed and registered.

That is, in the above patented invention, the fluorescent glass element to be measured is divided into a plurality of sections using a movable diaphragm or the like, and the fluorescent intensity at each measurement position is measured to obtain the fluorescent intensity distribution of the fluorescent glass element. And the radiation quality (energy) is estimated based on the ratio of the maximum value and the minimum value. Moreover, the incident direction of the radiation is estimated from the position where the peak value of the fluorescence intensity distribution of the fluorescent glass element appears.

A conventional fluorescent glass dosimeter measuring device for estimating the energy of X-rays from a fluorescent glass dosimeter having a fluorescent glass element irradiated with X-rays will be described with reference to the above patented invention.

That is, as shown in FIG. 7, the fluorescent glass dosimeter measuring device comprises a measuring device main body 2 and a controller 3.
And printer 4.

Then, in the measuring device body 2, a microprocessor 8 for controlling operation based on a predetermined program, and a fluorescent glass element 1 to be measured based on an operation control command of the microprocessor 8 are measured at a measuring position 6. A transport device 5 for transporting to and a detection device 7 for detecting the amount of fluorescence emitted from the fluorescent glass element 1 set at the measurement position 6 are provided.

At the measuring position 6, a moving diaphragm mechanism as shown in FIG. 8 is provided. That is, the fixed diaphragm 3 having the predetermined opening 30 formed therein.
A movable diaphragm 33 having a predetermined slit 32 formed therein is attached to 1 so as to be slidable in the direction of the arrow in the figure. The size of the slit 32 corresponds to each sectional area obtained by equally dividing the glass element to be measured into n pieces.

With this moving diaphragm mechanism, first, the fluorescent glass element 1 is excited by excitation with ultraviolet rays.
Among the fluorescence generated from the above, the fluorescence passing through the predetermined opening 30 formed in the fixed diaphragm 31 is detected by the detection device 7 (this measured value is measured by the fluorescent glass element 1). It becomes the fluorescence reading value A of the entire device).

The fluorescence intensity distribution of the fluorescent glass element 1 is measured by sequentially moving the moving diaphragm 33 in the direction of the arrow in the figure and detecting the fluorescence passing through the slit 32 (this measured value is , The fluorescence readings “A ₁ ” “A ₂ ” of each divided section of the fluorescent glass element 1 ...
"A _n ").

Next, the controller 3 is provided with an input device 9 for issuing an operation command to the measuring device main body 2 and for inputting necessary data, a dose measurement value calculating means 10 for measuring a dose from the fluorescence detection amount, and each division. Fluorescence detection amount distribution ratio calculation means 11 for calculating the fluorescence detection amount distribution ratio, which is the ratio between the maximum value and the minimum value of the fluorescence amount for each section, and the energy estimation value calculation means for calculating the energy estimation value from the fluorescence detection amount distribution ratio. 12. A display device 13 for displaying the contents of the calculation result and the like is provided. Further, the printer 4 prints out the contents of the calculation result and the like.

The conventional fluorescent glass dosimeter measuring device having such a structure operates as follows. That is, the dose measuring fluorescent glass element 1 is carried to the measuring position 6 by the carrier device 5, and the whole fluorescence amount “A” and the fluorescence amounts “A ₁ ” “A ₂ ” of each divided section are conveyed by the detecting device 7. …
"A _n " is measured.

When the fluorescence amount of each divided section is thus detected, the fluorescence detection amount distribution ratio calculating means 11 obtains the fluorescence detection amount distribution ratio (maximum value / minimum value), and based on the result. Then, the energy estimation value is calculated using the energy estimation formula stored in advance, and the display device 13
And displayed and printed on the printer 4.

A curve as shown in FIG. 9 is used as the energy estimation formula. This energy estimation formula (estimation curve) is created as follows. That is, after setting a quality index (QI: Quality Index) of 0.7 to 0.8 as an index indicating the state of the X-ray spectrum emitted from the X-ray generator, the fluorescent glass dose from the X-ray generator is set. The meter is exposed to X-rays of various energies. Then, the relationship between the X-ray energy and the fluorescence detection amount distribution ratio (maximum value / minimum value) of the fluorescent glass dosimeter irradiated with X-rays of that energy is sequentially plotted. The energy estimation curve created in this way is used as the energy estimation value calculation means 12
Is stored in a memory or the like and used for the above-mentioned energy estimation calculation.

The quality index (QI) is an index showing the state of the X-ray spectrum when X-rays are irradiated by the X-ray generator, and is "0" obtained by dividing the energy by the tube voltage.
It is a numerical value between “1”, and the closer it is to 1, the sharper the spectrum is, and the closer it is to 0, the broader the spectrum is.

[0019]

By the way, the main radiation source used in medical institutions is an X-ray generator.
X-rays of various energies can be generated depending on the apparatus tube voltage and the type of filtration filter. That is, in the X-ray inventing apparatus, a filter is generally used to attenuate the X-ray beam, and Al, Cu, for example, are used as this filter. Further, since the X-ray energy value is not a single magnitude but its spectrum has a certain width, the degree of its distribution is usually represented by the quality index (QI).

However, in the conventional fluorescent glass dosimeter measuring device as described above, when estimating the radiation quality (energy), as shown in FIG. 9, a certain quality index (QI) is used. Because it was based on the X-ray of
The accuracy of energy estimation has not been sufficient to manage radiation exposure in the medical field where X-rays of various energies are generated.

Particularly, in the case of γ · X-ray, the absorbed dose to human organs such as red bone marrow, reproductive organs and lens of eye is 20.
It becomes large in the low energy range below 0 keV, especially 90
Since it has the maximum energy dependence when the energy is about keV, it is necessary to improve the accuracy of energy estimation of low energy X-rays.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art, and its purpose is to provide various lines that may be generated from an X-ray generator such as a medical institution. It is an object of the present invention to provide a fluorescent glass dosimeter measuring device which has a function of estimating the energy of low-energy X-rays of a quality index with high accuracy and is capable of measuring X-ray exposure dose.

[0023]

According to a first aspect of the present invention, a fluorescent glass element that has been irradiated with radiation is excited by ultraviolet rays, and the amount of fluorescence generated from the fluorescent detection surface of the fluorescent glass element at this time is adjusted. While reading the radiation dose based on, the fluorescence detection surface is divided into a plurality of sections, the fluorescence amount is detected for each divided section, the fluorescent glass dose to obtain the fluorescence intensity distribution of the fluorescence detection surface from each detection value In the meter measuring device, an estimation formula storage unit that stores a plurality of energy estimation formulas having different radiation quality indices in advance, and a required energy estimation from the estimation formula storage unit based on the radiation quality index when estimating radiation energy. An energy estimation formula selecting means for selecting a formula, a fluorescence detection amount distribution ratio calculating means for calculating a fluorescence detection amount distribution ratio which is a ratio of the maximum value and the minimum value of the fluorescence amount for each divided section, and the fluorescence detection Based on the distribution ratio, it is characterized in that it comprises an energy estimation value calculating means for calculating an energy estimate using the energy estimation formula selected by said energy estimate equation selection means.

Further, the invention according to claim 2 excites the fluorescent glass element, which has been irradiated with radiation, with ultraviolet rays, and at this time, the radiation exposure is performed based on the amount of fluorescence generated from the fluorescence detection surface of the fluorescent glass element. Along with reading the amount, the fluorescence detection surface is divided into a plurality of sections, the amount of fluorescence is detected for each divided section, in the fluorescent glass dosimeter measuring device to obtain the fluorescence intensity distribution of the fluorescence detection surface from each detection value , An estimation formula storage unit that stores an energy estimation formula that matches the radiation chamber that is the target of energy estimation, and based on the radiation chamber that is the target of the energy estimation when estimating the energy of radiation, Energy estimation formula selecting means for selecting a required energy estimation formula, and a fluorescence detection amount distribution ratio which is a ratio of the maximum value and the minimum value of the fluorescence amount for each divided section. A detection amount distribution ratio calculating unit; and an energy estimation value calculating unit for calculating an energy estimation value using the energy estimation formula selected by the energy estimation formula selection unit based on the fluorescence detection amount distribution ratio. It is characterized by.

[0025]

According to the first aspect of the invention, the energy estimation formula (estimation curve) for each of various quality indicators that may be generated from an X-ray generator such as a medical institution.
Is calculated, the optimal energy estimation formula is selected by the energy estimation formula selection means, and the energy is estimated based on the energy estimation formula, so that the accuracy of the energy estimation is significantly improved.

According to the second aspect of the present invention, the quality index (QI) obtained from the energy spectrum measured when the X-ray generator of an actual medical institution is operating and the corresponding X-ray. An energy estimation formula (estimation curve) in a predetermined X-ray room is obtained from the relationship between the energy and the fluorescence detection amount distribution ratio R at that time, and the energy is estimated based on this energy estimation formula. The X-ray energy in the X-ray room can be estimated more accurately.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same members as those of the conventional type shown in FIG. 7 are designated by the same reference numerals, and the description thereof will be omitted.

That is, in the fluorescent glass dosimeter measuring device of this embodiment, as shown in FIG.
0 indicates a plurality of QI values as shown in FIG. 2 in advance and an estimation formula storage means 21 for storing a plurality of energy estimation formulas (estimation curves) created based on these QI values, necessary instruction data, etc. Input device 9 for inputting, display device 13 for displaying the calculation result of exposure dose measurement value and energy estimation value, and energy estimation formula from one QI close to the spectral distribution of X-rays irradiated on the fluorescent glass dosimeter Energy estimation formula selecting means 22 for selecting, and dose measurement value calculating means 10 for calculating a dose measurement value from the fluorescence detection amount.
And a fluorescence detection amount distribution ratio calculation means 11 for calculating a fluorescence detection amount distribution ratio which is a ratio of the maximum value and the minimum value of the fluorescence amount for each divided section, and this fluorescence detection amount distribution ratio (maximum value / minimum value) Energy estimation value calculation means 23 for calculating an energy estimation value using the energy estimation equation selected by the energy estimation equation selection means 22 based on the above.

The rest of the configuration is the same as that of the conventional fluorescent glass dosimeter measuring device shown in FIG.

Here, an X-ray energy estimation formula (estimation curve) corresponding to a plurality of QI values (QI is 0.8, 0.6 and 0.4) as shown in FIG. 2 will be described. That is, the energy estimation curve for each quality index (QI) as shown in FIG. 2 is the fluorescence detection amount distribution ratio when X-ray irradiation is performed on the fluorescent glass element based on the conditions 1 to 3 shown in FIG. It is obtained by obtaining R and plotting the relationship between the X-ray energy and the fluorescence detection amount distribution ratio R sequentially.

The energy estimation curve for each quality index (QI) is approximated as a plurality of straight line equations and stored in the estimation equation storage means 21 as an energy estimation equation as shown in FIG. You can also keep it.

The fluorescent glass dosimeter measuring device of this embodiment having such a structure operates as described below. That is, the moving diaphragm 33 is sequentially moved, and the fluorescence read values “A ₁ ”, “A ₂ ” ...
The ratio between the maximum value and the minimum value of “A _n ” is calculated by the fluorescence detection amount distribution ratio calculation means 11. On the other hand, the input device 9 gives an instruction as to whether or not to perform energy estimation and an instruction as to what quality index (QI) is to be used for energy estimation.

Next, based on the instruction given by the input device 9, the energy estimation formula selecting means 22 causes
From the multiple energy estimation curves shown in Fig. 1, the spectral distribution of X-rays irradiated on the fluorescent glass dosimeter is close to 1
An energy estimation curve corresponding to one QI value is selected. Then, by using this energy estimation curve, the X-ray energy corresponding to the fluorescence detection amount distribution ratio R calculated by the fluorescence detection amount distribution ratio calculating means 11 can be obtained.

When the energy estimation formula as shown in FIG. 4 is used, the X-ray irradiated to the fluorescent glass dosimeter is selected by the energy estimation formula selecting means 22 based on the instruction given by the input device 9. The energy estimation formula group corresponding to one QI value close to the spectral distribution of is selected, and further, one energy estimation formula optimal for energy estimation is selected from the value of the fluorescence detection amount distribution ratio R. Then, by substituting the value of the fluorescence detection amount distribution ratio R into the equation, the X-ray energy corresponding to the fluorescence detection amount distribution ratio R can be obtained.

The present invention is not limited to the above-mentioned embodiment, but the quality index (QI) obtained from the energy spectrum measured during the operation of the X-ray generator of the actual medical institution, and An energy estimation formula (estimation curve) in a predetermined X-ray chamber may be obtained from the relationship between the corresponding X-ray energy and the fluorescence detection amount distribution ratio R at that time. For example, the energy estimation curve shown in FIG. 5 shows the fluorescence detection amount distribution ratio R when X-ray irradiation is performed on the fluorescent glass element based on the conditions 4 and 5 shown in FIG. 6 in a predetermined X-ray chamber. Calculate, X-ray energy and fluorescence detection amount distribution ratio R
It is obtained by plotting the relationship with.

That is, in the case of condition 4, the added filtration filter is for the Al + Cu X-ray chamber, and in the case of condition 5, the added filtration filter is for the X-ray chamber of only Al. Therefore, by using this energy estimation curve, it is possible to more accurately estimate the X-ray energy in the X-ray room of the actual medical institution.

Also in this case, the energy estimation curve shown in FIG. 5 is approximated as a plurality of straight line expressions,
It goes without saying that this can be stored in the estimation formula storage means 21 as an energy estimation formula as shown in FIG.

[0038]

As described above, according to the present invention, it is possible to accurately estimate the energy of low energy X-rays of various radiation quality indexes that may be generated from an X-ray generator such as a medical institution. It is possible to provide a fluorescent glass dosimeter measuring device which has the function of performing the X-ray exposure dose measurement.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of a fluorescent glass dosimeter measuring device of the present invention.

FIG. 2 is a diagram showing a relationship between a fluorescence detection amount distribution ratio and energy in various QIs.

FIG. 3 is a condition example of an X-ray irradiation test for determining an energy estimation formula (estimation curve).

FIG. 4 is a diagram showing an example of an energy estimation formula.

FIG. 5 is a diagram showing a relationship between a fluorescence detection amount distribution ratio and energy in an X-ray room of an actual medical institution.

FIG. 6 is a condition example of an X-ray irradiation test for determining an energy estimation formula (estimation curve) in an X-ray room of an actual medical institution.

FIG. 7 is a block diagram showing the configuration of a conventional fluorescent glass dosimeter measuring device.

FIG. 8 is a perspective view showing an example of a moving diaphragm mechanism.

FIG. 9 is a diagram showing a relationship between a fluorescence detection amount distribution ratio and energy used in a conventional fluorescent glass dosimeter measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fluorescent glass element 2 ... Measuring device main body 3 ... Controller 4 ... Printer 5 ... Conveying device 6 ... Measuring position 7 ... Detecting device 9 ... Input device 10 ... Dose measurement value calculating means 11 ... Fluorescence detection amount distribution ratio calculating means 12 ... Estimated energy value calculation means 13 ... Display device 21 ... Estimated expression storage means 22 ... Energy estimated expression selection means 23 ... Energy estimated value calculation means 30 ... Fixed diaphragm opening 31 ... Fixed diaphragm 32 ... Slit 33 ... Moving diaphragm

Claims (2)

[Claims] 1. A fluorescent glass element that has been irradiated with radiation is excited by ultraviolet rays, and at this time, the radiation dose is read based on the amount of fluorescence generated from the fluorescent detection surface of the fluorescent glass element, and the fluorescent detection surface is also read. In a fluorescent glass dosimeter measuring device, in which the fluorescence amount is detected for each divided section and the fluorescence intensity distribution of the fluorescence detection surface is obtained from each detected value. Estimation formula storage means for storing a plurality of energy estimation formulas; energy estimation formula selection means for selecting a required energy estimation formula from the estimation formula storage means based on the radiation quality index when estimating the energy of radiation; Fluorescence detection amount distribution ratio calculation means for calculating the fluorescence detection amount distribution ratio, which is the ratio of the maximum value and the minimum value of the fluorescence amount for each section, and the energy estimation based on the fluorescence detection amount distribution ratio. Fluorescent glass dosimeter measuring apparatus characterized by comprising an energy estimation value calculating means for calculating an energy estimate using the selected energy estimation formula in the formula selecting means. 2. A fluorescent glass element that has been irradiated with radiation is excited by ultraviolet rays, and at this time, the radiation dose is read based on the amount of fluorescence generated from the fluorescent detection surface of the fluorescent glass element, and the fluorescent detection surface is also read. In a fluorescent glass dosimeter measuring device that divides each into multiple sections, detects the amount of fluorescence in each divided section, and obtains the fluorescence intensity distribution of the fluorescence detection surface from each detection value. Estimating formula storing means for storing an energy estimating formula that conforms to, and energy for selecting a required energy estimating formula from the estimating formula storing means based on the radiation chamber to be subjected to the energy estimation when estimating the energy of radiation. Estimation formula selection means, fluorescence detection amount distribution ratio calculation means for calculating the fluorescence detection amount distribution ratio which is the ratio of the maximum value and the minimum value of the fluorescence amount for each divided section, Based on the fluorescence detection amount distribution ratio, an estimated energy value calculating means for calculating an estimated energy value by using the energy estimation formula selected by the energy estimation formula selecting means, and a fluorescent glass dosimeter. measuring device.