JP2971782B2 - Fluorescent glass dosimeter measuring device - Google Patents

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 caused by differences in X-ray generation conditions in measurement of environmental radiation inside and outside an X-ray generator installed in a medical institution or the like. The present invention relates to a fluorescent glass dosimeter measuring device capable of measuring an X-ray exposure dose.

[0002]

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

[0003] For this reason, a fluorescent glass dosimeter using the above fluorescent glass element is carried by a worker handling radiation to measure the exposure dose, or installed around a nuclear facility or other radiation-related facilities. Used to measure environmental dose.

In a fluorescent glass dosimeter used for such a purpose, it is generally considered that it is sufficient to measure only the radiation dose. However, if an abnormal situation occurs in the facility, radiation leaks occur, or if a large amount of radiation is exposed through long-term work, it is necessary to measure the radiation dose as well as the radiation quality (energy).
If you do not know the radiation incident direction, radiation management is not sufficient from the viewpoint of radiation accident analysis.

[0005] In addition, as medical exposure management becomes stricter, estimation of radiation energy as well as environmental dose measurement has become an important factor in monitoring the area of a radiation control area.

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

[0007] That is, the above patent invention divides the fluorescent glass element to be measured into a plurality of sections using a movable diaphragm or the like, and measures the fluorescent intensity at each measurement position, thereby obtaining a fluorescent intensity distribution of the fluorescent glass element. And estimates the radiation quality (energy) based on the ratio of the maximum value to the minimum value. Further, the direction of incidence of 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 apparatus 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 patent 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 a printer 4.

The measuring device main body 2 includes a microprocessor 8 for performing operation control based on a predetermined program, and a fluorescent glass element 1 to be measured based on an operation control command of the microprocessor 8 at a measurement position 6. And a detecting device 7 for detecting the amount of fluorescence emitted from the fluorescent glass element 1 set at the measurement position 6.

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

[0012] Then, by the moving diaphragm mechanism, first, the fluorescent glass element 1 is excited by ultraviolet light.
Out of the fluorescent light generated from the fluorescent glass element 1, the fluorescent light that has passed through the predetermined opening 30 formed in the fixed diaphragm 31 is detected by the detecting device 7. It becomes the fluorescence reading A of the whole element).

The measurement of the fluorescence intensity distribution of the fluorescent glass element 1 is performed by sequentially moving the moving diaphragm 33 in the direction of the arrow in FIG. , The fluorescent reading values “A ₁ ”, “A ₂ ” of each divided section of the fluorescent glass element 1.
"A _n ").

Next, the controller 3 includes an input device 9 for issuing an operation command to the measuring device main body 2 and inputting necessary data, a dose measurement value calculating means 10 for measuring a dose from a detected fluorescence amount, Fluorescence detection amount distribution ratio calculating means 11 for calculating a fluorescence detection amount distribution ratio which is a ratio between the maximum value and the minimum value of the fluorescence amount for each section, and energy estimation value calculating means for calculating an 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 results and the like.

The conventional fluorescent glass dosimeter measuring device having such a configuration operates as follows. That is, the fluorescent glass element 1 for dose measurement is transported to the measurement position 6 by the transport device 5, and the overall fluorescent light amount “A” and the fluorescent light amounts “A ₁ ” and “A ₂ ” for each divided section are detected by the detection device 7. …
“A _n ” is measured.

When the fluorescence amount of each divided section is detected in this way, the fluorescence detection amount distribution ratio calculating means 11 calculates the fluorescence detection amount distribution ratio (maximum value / minimum value), and based on the result, 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 above energy estimating equation. 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 irradiated with X-rays of various energies. Then, the relationship between the distribution ratio (maximum value / minimum value) of the detected fluorescence amount of the fluorescent glass dosimeter irradiated with the X-ray of the energy and the X-ray energy is sequentially plotted. Further, the energy estimation curve created in this manner is used as the energy estimation value calculating means 12.
And is used for the above-mentioned energy estimation calculation.

The radiation quality index (QI) is an index representing the state of an X-ray spectrum when irradiating an X-ray with an X-ray generator, and is "0" to which energy is divided by a tube voltage.
It is a numerical value between “1”. A value closer to 1 indicates a sharper spectrum, and a value closer to 0 indicates a broader spectrum.

[0019]

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

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

In particular, in the case of γ-X-rays, the absorbed dose to human organs such as the red bone marrow, the genital organ and the lens of the eye is 20
It becomes large in the low energy region below 0 keV, especially 90
Since it has the maximum energy dependency at an energy of 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 problems of the prior art as described above, and its object is to provide various kinds of lines which may be generated from an X-ray generator such as a medical institution. An object of the present invention is to provide a fluorescent glass dosimeter measuring device having a function of estimating low-energy X-ray energy of a quality index with high accuracy and capable of measuring an X-ray exposure dose.

[0023]

According to a first aspect of the present invention, a fluorescent glass element irradiated with radiation is excited with ultraviolet light, and the amount of fluorescence generated from a fluorescent detection surface of the fluorescent glass element at this time is reduced. A fluorescent glass dose for dividing the fluorescence detection surface into a plurality of sections, detecting a fluorescence amount for each of the divided sections, and obtaining a fluorescence intensity distribution of the fluorescence detection face from each detection value, while reading the radiation exposure dose based on An estimating formula storing means for storing a plurality of energy estimating formulas having different radiation quality indices in advance, and a required energy estimating means for estimating radiation energy from the estimating formula storing means based on the radiation quality index. Energy estimation expression selection means for selecting an expression; fluorescence detection amount distribution ratio calculating means for calculating a fluorescence detection amount distribution ratio that is a ratio between a maximum value and a minimum value of the fluorescence amount for each divided section; 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.

According to a second aspect of the present invention, the fluorescent glass element which has been irradiated with the radiation is excited with ultraviolet light, and the radiation exposure is performed based on the amount of fluorescence generated from the fluorescent light detection surface of the fluorescent glass element. While reading the amount, the fluorescence detection surface is divided into a plurality of sections, the amount of fluorescence is detected for each of the divided sections, and a fluorescence glass dosimeter measuring device that determines the fluorescence intensity distribution of the fluorescence detection face from each detection value. An estimation formula storage unit that stores an energy estimation formula that matches a radiation room to be subjected to energy estimation, and an estimation formula storage unit that estimates the energy of radiation based on the radiation room to be subjected to the energy estimation. An energy estimating equation selecting means for selecting a required energy estimating equation; A detection amount distribution ratio calculating unit, and an energy estimation value calculating unit that calculates 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 the following.

[0025]

According to the first aspect of the present invention, energy estimation formulas (estimation curves) for various radiation quality indices that may be generated from an X-ray generator such as a medical institution.
Is obtained, the optimum energy estimation formula is selected by the energy estimation formula selection means, and energy estimation is performed based on the energy estimation formula, so that the accuracy of energy estimation is greatly improved.

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

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 denoted by the same reference numerals, and description thereof will be omitted.

That is, in the fluorescent glass dosimeter measuring apparatus of the present embodiment, as shown in FIG.
For example, in Eq. 0, an estimation expression storage means 21 for storing a plurality of QI values and a plurality of energy estimation expressions (estimation curves) created based on these QI values as shown in FIG. Input device 9, a display device 13 for displaying the calculation result of the exposure dose measurement value and the energy estimation value, and an energy estimation formula from one QI close to the spectral distribution of the X-ray irradiated to the fluorescent glass dosimeter. And a dose measurement value calculating means 10 for calculating a dose measurement value from the detected amount of fluorescence.
And a fluorescence detection amount distribution ratio calculating means 11 for calculating a fluorescence detection amount distribution ratio which is a ratio between a maximum value and a minimum value of the fluorescence amount for each divided section, and the fluorescence detection amount distribution ratio (maximum value / minimum value). And an energy estimation value calculation means 23 for calculating an energy estimation value using the energy estimation formula selected by the energy estimation formula selection means 22 based on the above.

The other configuration is the same as that of the conventional fluorescent glass dosimeter measuring apparatus 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 a distribution ratio of detected fluorescence when the fluorescent glass element is irradiated with X-rays based on the conditions 1 to 3 shown in FIG. R is obtained by sequentially plotting the relationship between the X-ray energy and the fluorescence detection amount distribution ratio R.

The energy estimation curves for the respective quality indices (QI) are approximated as a plurality of straight line equations, and these are stored in the estimation equation storage means 21 as energy estimation equations as shown in FIG. You can keep it.

The fluorescent glass dosimeter measuring apparatus according to the present embodiment having such a configuration operates as described below. That is, the fluorescence reading values “A ₁ ”, “A ₂ ”,... For each divided section obtained by sequentially moving the moving diaphragm 33 and detecting the fluorescence passing through the slit 32 are obtained.
The ratio between the maximum value and the minimum value of “A _n ” is calculated by the fluorescence detection amount distribution ratio calculating means 11. On the other hand, the input device 9 issues an instruction as to whether or not to perform energy estimation and an instruction as to what energy quality index (QI) to perform energy estimation.

Next, based on the instruction given by the input device 9, the energy estimation formula selection means 22 uses FIG.
Out of a plurality of energy estimation curves shown in FIG. 1, which is close to the spectral distribution of the X-ray irradiated to the fluorescent glass dosimeter.
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 radiated on the fluorescent glass dosimeter by the energy estimation formula selection means 22 based on the instruction given by the input device 9. A group of energy estimation formulas corresponding to one QI value close to the spectrum distribution is selected, and 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.

It should be noted that the present invention is not limited to the above-described embodiment, and a radiation quality index (QI) obtained from an energy spectrum measured when an X-ray generator of an actual medical institution is operated, and a quality index (QI) obtained therefrom An energy estimation formula (estimation curve) in a predetermined X-ray room may be obtained from the relationship between the corresponding X-ray energy and the distribution ratio R of detected fluorescence amount at that time. For example, the energy estimation curve shown in FIG. 5 shows the distribution ratio R of detected fluorescence when the fluorescent glass element is irradiated with X-rays based on the conditions 4 and 5 shown in FIG. 6 in a predetermined X-ray room. X-ray energy and fluorescence detection amount distribution ratio R
This is obtained by plotting the relationship with.

That is, in the case of Condition 4, the added filtration filter is for an X-ray chamber of Al + Cu, and in the case of Condition 5, the added filtration filter is for an X-ray chamber of Al only. Therefore, by using this energy estimation curve, the X-ray energy in the actual X-ray room of the medical institution can be more accurately estimated.

Also in this case, the energy estimation curves shown in FIG. 5 are approximated as a plurality of straight line equations, respectively.
Needless to say, this can be stored in the estimation expression storage means 21 as an energy estimation expression as shown in FIG.

[0038]

As described above, according to the present invention, the energy of low-energy X-rays of various quality indices which may be generated from an X-ray generator such as a medical institution is estimated with high accuracy. A fluorescent glass dosimeter measuring device having a function of performing X-ray exposure dose measurement can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a 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 shows an example of X-ray irradiation test conditions for determining an energy estimation formula (estimation curve).

FIG. 4 shows an example of an energy estimation formula.

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

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

FIG. 7 is a block diagram showing a 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 ... Transport device 6 ... Measurement position 7 ... Detecting device 9 ... Input device 10 ... Dose measurement value calculation means 11 ... Fluorescence detection amount distribution ratio calculation means 12 ... Energy estimation value calculation means 13 ... Display device 21 ... Estimation expression storage means 22 ... Energy estimation expression selection means 23 ... Energy estimation value calculation means 30 ... Fixed diaphragm opening 31 ... Fixed diaphragm 32 ... Slit 33 ... Moving diaphragm

Claims (2)

(57) [Claims] 1. A fluorescent glass element which has been irradiated with radiation is excited with ultraviolet light, and at this time, an exposure radiation amount is read based on a fluorescent amount generated from a fluorescent detection surface of the fluorescent glass element, and the fluorescence detection surface is read. Is divided into a plurality of sections, the amount of fluorescence is detected for each of the divided sections, and a fluorescence glass dosimeter measuring device for obtaining a fluorescence intensity distribution of the fluorescence detection surface from each detection value, wherein the quality index is different in advance. Estimating equation storing means for storing a plurality of energy estimating equations; energy estimating equation selecting means for selecting a required energy estimating equation from the estimating equation storing means based on the radiation quality index when estimating the energy of radiation; A fluorescence detection amount distribution ratio calculating means for calculating a fluorescence detection amount distribution ratio that is a ratio of a maximum value and a 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 which has been irradiated with radiation is excited with ultraviolet light. At this time, an exposure radiation amount is read based on a fluorescent amount generated from a fluorescent detection surface of the fluorescent glass element, and the fluorescent detection surface is read. Is divided into a plurality of sections, the amount of fluorescence is detected for each of the divided sections, and the fluorescence intensity distribution of the fluorescence detection surface is obtained from each detection value. Estimating formula storing means for storing an energy estimating formula that matches the following: energy for selecting a required energy estimating formula from the estimating formula storing means based on the radiation room to be estimated for the energy when estimating the energy of the radiation; Estimation formula selection means, and fluorescence detection amount distribution ratio calculation means for calculating a fluorescence detection amount distribution ratio that is a ratio of the maximum value and the minimum value of the fluorescence amount for each divided section, A fluorescent glass dosimeter, comprising: an energy estimation value calculating unit that calculates 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. measuring device.