JP2014202689A - Fluoroglass dosimeter measuring apparatus, and calibration method of fluoroglass dosimeter measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluoroglass dosimeter measuring apparatus and a calibration method of the fluoroglass dosimeter measuring apparatus which are capable of performing calibration using a standard glass dosimeter for calibration with higher accuracy.SOLUTION: The fluoroglass dosimeter measuring apparatus according to the present invention comprises: a light source which has a plurality of measuring positions and irradiates standard glass dosimeter for calibration, with which radiation is irradiated by a reference value for each measuring position via different types of filters, with ultraviolet light for excitation; measuring means for measuring fluorescence generated by the standard glass dosimeter for calibration by each measuring position; storage means for storing a measurement result of fluorescence and the reference value associating with by each measuring position; and exposure dose calculating means for calibrating fluorescence measurement result of a fluoroglass dosimeter being an object to be measured of radiation exposure dose based on correspondence stored in the storage means and calculating radiation exposure dose of the fluoroglass dosimeter.

Description

  The present invention relates to a fluorescent glass dosimeter measuring device and a calibration method for the fluorescent glass dosimeter measuring device.

  A fluorescent glass dosimeter measuring apparatus is known as a method for measuring the radiation exposure dose. The fluorescent glass dosimeter measuring apparatus measures the radiation exposure dose using a phosphate glass (silver activated phosphate glass) containing silver ions. When phosphoric acid glass (hereinafter, fluorescent glass dosimeter) is irradiated with ultraviolet light for excitation (for example, 355 nm), radiophotoluminescence (RPL: Radio Photo Luminescence) of orange color (light having a peak wavelength at 600 nm to 700 nm) is emitted. It has the nature to occur. The fluorescence intensity generated by the fluorescent glass dosimeter is proportional to the exposure dose. For this reason, the exposure dose of the fluorescent glass dosimeter can be measured from the fluorescence intensity generated by the fluorescent glass dosimeter.

  By the way, a fluorescent glass dosimeter measuring apparatus capable of measuring a plurality of line types (for example, α rays, β rays, γ rays, X rays, neutron rays) has been proposed (for example, see Patent Document 1). In this fluorescent glass dosimeter measuring apparatus capable of measuring a plurality of line types, the fluorescent glass dosimeter is exposed through a filter (for example, tin (Sn), aluminum (Al), plastic) which is different for each measurement position. Thereafter, the fluorescence intensity generated by irradiating the fluorescent glass dosimeter with ultraviolet light for excitation is measured, and the exposure dose of a plurality of line types can be calculated using a conversion factor determined in advance.

JP-A-5-2078

  By the way, the fluorescent glass dosimeter measuring device is relative to the measured value of the fluorescent glass dosimeter measuring device with respect to the measured value of the calibration standard glass dosimeter whose exposure dose is strictly controlled. The exposure dose of the fluorescent glass dosimeter is obtained by measuring the exposure dose. Therefore, it is necessary to periodically perform calibration using a standard glass dosimeter for calibration that serves as a reference for exposure dose. In addition, measurement errors may occur in fluorescent glass dosimeters due to changes over time, deterioration, and natural exposure (hereinafter sometimes referred to as background), and this requires periodic calibration. is there.

 This calibration includes a calibration using a standard glass dosimeter for calibration (hereinafter sometimes referred to as external calibration) performed once every several months to ensure the traceability of the measured dose, and a fluorescent glass dosimeter. There is a periodic calibration using an internal correction glass dosimeter built in the measuring device (hereinafter, sometimes referred to as internal calibration). In the external calibration, a calibration standard glass dosimeter irradiated with radiation up to a reference value is used to determine the dose value of the internal correction glass dosimeter built in the fluorescent glass dosimeter measuring device. The internal calibration is performed at a higher frequency than the external calibration, and is performed mainly for the purpose of correcting the sensitivity change due to the room temperature change with respect to the calibration by the external calibration.

  Here, in the case of a fluorescent glass dosimeter measuring apparatus capable of measuring the exposure dose of a plurality of line types, a fluorescent glass dosimeter provided with a plurality of different types of filters is used. Such a fluorescent glass dosimeter measures the fluorescence at each measurement position corresponding to the filter position, calculates the exposure dose for each of the plurality of line types by appropriately combining the measurement results and using a conversion coefficient or the like. Yes.

  However, in the conventional fluorescent glass dosimeter measuring device, when the standard glass dosimeter for calibration having a plurality of measurement positions is used in the external calibration, only the measurement result of one measurement position is calibrated and the other measurement positions are calibrated. As for, the calibration was performed using the correlation coefficient with the calibrated measurement position. Therefore, when using a standard glass dosimeter for calibration with multiple measurement positions, it is necessary to collect a huge amount of data in order to calculate the correlation coefficient for each measurement position, which is very laborious. Yes. In addition, the correlation coefficient is deficient due to the specifications of the filter used (for example, variations in thickness) and slight differences in raw materials (for example, differences in origin), so it is necessary to calculate the correlation coefficient again. May occur.

  The present invention has been made to solve the above problems, and a fluorescent glass dosimeter measuring device and a fluorescent glass dosimeter measuring device capable of performing calibration using a standard glass dosimeter for calibration with higher accuracy. The purpose is to provide a calibration method.

  The fluorescent glass dosimeter measuring apparatus according to the present invention has a plurality of measurement positions, and excitation ultraviolet rays are applied to a calibration standard glass dosimeter irradiated with only a reference value through different types of filters for each measurement position. A light source to irradiate, a measuring means for measuring the fluorescence generated by the calibration standard glass dosimeter for each measurement position, a storage means for storing the measurement result of the fluorescence and the reference value in association with each measurement position, and storage Exposure dose calculation means for calibrating the fluorescence measurement result of the fluorescent glass dosimeter, which is the measurement target of the radiation exposure dose, based on the correspondence stored in the means, and calculating the radiation exposure dose of the fluorescent glass dosimeter, It is characterized by providing.

  According to the present invention, since external calibration is performed for each measurement position of the standard glass dosimeter for calibration, the fluorescent glass dosimeter measuring apparatus and the calibration method for the fluorescent glass dosimeter measuring apparatus capable of performing external calibration with higher accuracy Can be provided.

It is a block diagram of the standard glass dosimeter for calibration. It is a schematic diagram of the fluorescent glass dosimeter measuring device which concerns on embodiment. It is an example of the data memorize | stored in memory. It is a flowchart which shows operation | movement of the fluorescent glass dosimeter measuring apparatus. It is a flowchart which shows operation | movement of the fluorescent glass dosimeter measuring apparatus.

  Hereinafter, a fluorescent glass dosimeter measuring method and a fluorescent glass dosimeter measuring apparatus calibration method according to an embodiment will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a configuration diagram of a calibration standard glass dosimeter G1. FIG. 2 is a schematic diagram of the fluorescent glass dosimeter measuring apparatus 100 according to the embodiment. FIG. 3 is a diagram illustrating an example of data stored in the memory 210 of the fluorescent glass dosimeter measuring apparatus 100. Hereinafter, the fluorescent glass dosimeter measuring method and the calibration method of the fluorescent glass dosimeter measuring apparatus according to the embodiment will be described with reference to FIGS.

  First, the configuration of the calibration standard glass dosimeter G1 used in the fluorescent glass dosimeter measuring apparatus 100 will be described with reference to FIG. FIG. 1A is an overhead view of the calibration standard glass dosimeter G1 and the metal frame 310 holding the calibration standard glass dosimeter G1. FIG. 1B is a cross-sectional view of the calibration standard glass dosimeter G1 and the holder 320 containing the calibration standard glass dosimeter G1 along the line XX in FIG.

  The calibration standard glass dosimeter G1 exposes a specific radiation type (for example, γ rays using cesium) by a specific radiation dose (reference value). The calibration standard glass dosimeter G1 is divided into a plurality of sections A to E (hereinafter also referred to as positions A to E). An ID is assigned to the calibration standard glass dosimeter G1. The calibration standard glass dosimeter G1 is accommodated in the holder 320 in a state of being held by the metal frame 310 in which the fluorescence detection windows 310A to 310E that expose the sections A to E are formed.

  The holder 320 is provided with filters A to E at positions corresponding to the sections A to E of the standard glass dosimeter G1 for calibration. The filters A to E are made of different materials or thicknesses, for example, plastics R1 and R2, aluminum (Al), copper (Cu), tin (Sn), and the like. The plastics R1 and R2 are the same in material but have different thicknesses. When the standard glass dosimeter G1 for calibration is exposed to the reference value, radiation is irradiated through the filters A to E.

  FIG. 2 is a schematic diagram of the fluorescent glass dosimeter measuring apparatus 100 according to the embodiment. As shown in FIG. 2, the fluorescent glass dosimeter measuring device 100 includes a transport device 110, a light source 120, a detecting device 130 (measuring means), a control device 200, and an internal correction glass dosimeter G2. The configuration of the internal correction glass dosimeter G2 is the same as the configuration of the calibration standard glass dosimeter G1 described with reference to FIG.

  The conveyance device 110 is, for example, a linear motor or the like, and the calibration glass dosimeter G1 and the fluorescent glass dosimeter G3 that is a measurement target of the radiation exposure amount are measured from the set position (set position) P1 to the measurement position (measurement position) Transport to P2. Further, the internal correction glass dosimeter G2 is transported to the measurement position P2.

  The light source 120 irradiates excitation ultraviolet rays (for example, a central wavelength of 355 nm) in a pulse shape. The light source 120 is, for example, a solid-state laser (Diode-Pump Solid-State Laser), a nitrogen gas laser, a flash lamp, an LED, a laser diode, or the like.

  The detection device 130 detects fluorescence generated by the calibration standard glass dosimeter G1, the internal correction glass dosimeter G2, and the fluorescent glass dosimeter G3 which are transported to the measurement position by the transport device 110. The detection device 130 is, for example, a photodiode or a photomultiplier tube, and converts the detected fluorescence into an electrical signal.

  The control device 200 controls the fluorescent glass dosimeter measuring device 100. The control device 200 includes a memory 210 (storage means), a drive circuit 220, an exposure dose calculation circuit 230 (exposure dose calculation means), an input device 240, and a calibration circuit 250 (update means).

The memory 210 stores arithmetic expressions (1) to (3) necessary for calculating the exposure dose.
[Nst] = [Hst] / [mst] (1)
[Nc] = [mc (j = 0)] / [mc (j = n)] (2)
[H] = [msamp] × [Nst] × [nc] (3)

[Nst]: Coefficient for converting the measured fluorescence value into a dose value (dose conversion coefficient)
[Hst]: Dose value (reference dose) at the time of calibration of the standard glass dosimeter G1 for calibration (including background)
[Mst]: Fluorescence reading (measured value) of the standard glass dosimeter G1 for calibration
[Nc]: coefficient for correcting the sensitivity change of the measuring instrument from the calibration standard glass dosimeter G1 [mc]: fluorescence reading value of the glass dosimeter G2 for internal correction
j = 0: During calibration (external calibration) with a standard glass dosimeter for calibration
j = n: During internal calibration [H]: Exposure dose of fluorescent glass dosimeter G3 [msamp]: Fluorescent reading value (measured value) of fluorescent glass dosimeter G3

  Further, the memory 210 stores values (data) necessary for calculations using the calculation formulas (1) to (3). FIG. 2 is a diagram illustrating an example of data stored in the memory 210. As shown in FIG. 2, the memory 210 has values ([Hst], [mst], [mc] (j = 0) necessary for calculating the exposure dose for each position A to E of the calibration standard glass dosimeter G1. ), [Mc] (j = n)) are stored.

   [Mst] is a value read in the state of the detection device 130 when external calibration is performed. For this reason, when the fluorescence of the fluorescent glass dosimeter G3 is read, if the sensitivity of the detection device 130 is changed due to a temperature change or the like, an error occurs in the reading of the fluorescence.

  In order to correct this, internal calibration using the internal correction glass dosimeter G2 is performed immediately before reading the fluorescence of the fluorescent glass dosimeter G3 and at regular intervals, and the fluorescence reading value [mc of the internal correction glass dosimeter G2] ] (J = n) and the ratio [nc] of the fluorescence reading [mc] (j = 0) of the internal correction glass dosimeter G2 when external calibration is performed, and this [nc] is multiplied This corrects the radiation exposure dose [H].

  The drive circuit 220 controls the irradiation of ultraviolet rays from the light source 120. Specifically, the drive circuit 220 controls the light source 120 so as to irradiate ultraviolet rays in a pulse form (for example, several ns (nanoseconds)).

  The exposure dose calculation circuit 230 calculates the exposure dose of the fluorescent glass dosimeter G3 based on the electrical signal output from the detection device 130. Specifically, the fluorescence intensity (fluorescence reading value) is calculated from the electrical signal output from the detection device 130, and the fluorescence reading value is substituted into the arithmetic expression (1) stored in the memory 210. The exposure dose for the total G3 is calculated.

  The input device 240 is used to set or update the exposure dose ([Hst]) at positions A to E of the calibration standard glass dosimeter G1 when performing external calibration using the calibration standard glass dosimeter G1. As described above, the calibration standard glass dosimeter G1 is exposed to a specific line type (for example, γ-ray). For this reason, when setting or updating the exposure dose ([Hst]) at each position A to E of the calibration standard glass dosimeter G1, filters A to E arranged at positions corresponding to the positions A to E are used. Exposure dose is set as the reference dose.

  The calibration circuit 250 updates the value (data) stored in the memory 210. When calibration using the calibration standard glass dosimeter G1 and / or the internal correction glass dosimeter G2 is performed, the calibration circuit 250 updates the value of the memory 210 based on the result of the external calibration. Specifically, the calibration circuit 250 stores [mst] and [mc] (mc) stored in the memory 210 each time calibration is performed using the calibration standard glass dosimeter G1 and / or the internal correction glass dosimeter G2. j = 0) and [mc] (j = n) are updated for each of the positions A to E. When the exposure dose [Hst] of the standard glass dosimeter G1 for calibration is input from the input device 240 by the user, the update circuit 250 sets the value of [Hst] stored in the memory 210 for each position A to E. Update to

(Operation of fluorescent glass dosimeter measuring apparatus 100)
FIG. 4 is a flowchart showing the operation of the fluorescent glass dosimeter measuring apparatus 100 during external calibration. FIG. 5 is a flowchart showing an operation of calculating the radiation exposure amount of the fluorescent glass dosimeter measuring apparatus 100. Hereinafter, the operation of the fluorescent glass dosimeter measuring apparatus 100 will be described with reference to FIGS. 4 and 5.

(Operation during external calibration)
First, the operation at the time of external calibration will be described with reference to FIG.
The calibration standard glass dosimeter G1 described with reference to FIG. 3 is set at the set position P1 (step S101). The transport apparatus 110 transports the calibration standard glass dosimeter G1 so that the section A of the calibration standard glass dosimeter G1 is at the measurement position P2 (step S102).

  Next, the control device 200 measures the fluorescence generated in the section A of the calibration standard glass dosimeter G1 (step S103). Specifically, the control device 200 controls the light source 120 to emit ultraviolet light for excitation, and the detection device 130 detects the fluorescence in the section A of the calibration standard glass dosimeter G1. Then, the fluorescence reading value [mst] of the section A is calculated by the exposure dose calculation circuit 230. Further, the control device 200 calculates the fluorescence reading value [mst] for the sections B to E in the same manner as the section A.

  Moreover, the control apparatus 200 receives the exposure dose [Hst] of each section AE of the calibration standard glass dosimeter G1 input by the user using the input device 240 (step S104).

  The calibration circuit 250 uses the measured fluorescence readings [mst] of the respective sections A to E and the input exposure dose [Hst], and outputs [mst] and [mst] of each section A to E stored in the memory 210. Hst] is updated (step S105).

(Exposure dose calculation operation)
Next, with reference to FIG. 5, the operation for calculating the exposure dose will be described.
The fluorescent glass dosimeter G3, which is the subject of exposure dose measurement, is set at the set position P1 (step S201). The transport apparatus 110 transports the fluorescent glass dosimeter G3 to the measurement position P2 (step S202).

  Next, the control device 200 measures the fluorescence generated by the fluorescent glass dosimeter G3 (step S203). Specifically, the control device 200 controls the light source 120 to emit ultraviolet light for excitation, and the detection device 130 detects the fluorescence of the fluorescent glass dosimeter G3.

  The exposure dose calculation circuit 230 calculates the exposure dose [H] of the fluorescent glass dosimeter G3 based on the electrical signal output from the detection device 130 (step S204). Specifically, the fluorescence reading value [msamp] of the fluorescent glass dosimeter G3 is obtained from the fluorescence detected by the detection device 130, and is substituted into the arithmetic expression (3) stored in the memory 210, so that the fluorescent glass dosimeter G3 Calculate the exposure dose [H].

  As described above, in the present invention, fluorescence is measured only for one position (for example, position A) of a plurality of measurement positions and external calibration is not performed, but fluorescence is measured for all positions A to E. To perform external calibration. For this reason, the exposure dose can be determined with higher accuracy for all the line types that can be measured by the fluorescent glass dosimeter measuring apparatus 100 of the present invention. Further, there is no need to calculate a correlation coefficient between measurement positions. For this reason, it is not necessary to perform a very time-consuming work of collecting a large amount of data.

  The present invention can determine the exposure dose with higher accuracy. For this reason, it is suitable for the calibration method of the fluorescent glass dosimeter measuring apparatus and fluorescent glass dosimeter measuring apparatus which measure the exposure dose of several line types.

  DESCRIPTION OF SYMBOLS 100 ... Fluorescent glass dosimeter measuring device, 110 ... Conveyance device, 120 ... Light source, 130 ... Detection device, 200 ... Control device, 210 ... Memory, 220 ... Drive circuit, 230 ... Dose calculation circuit, 240 ... Input device, 250 ... Calibration circuit, 310 ... metal frame, 310A-310E ... fluorescence detection window, 320 ... holder, G1 ... standard glass dosimeter for calibration, G2 ... glass dosimeter for internal correction, G3 ... fluorescent glass dosimeter, P1 ... set position, P2: Measurement position, R1, R2: Plastic.

Claims (4)

A light source for irradiating a calibration standard glass dosimeter having a plurality of measurement positions and a standard glass dosimeter for radiation irradiated with a reference value through different types of filters for each measurement position;
Measuring means for measuring the fluorescence generated by the standard glass dosimeter for calibration at each measurement position;
Storage means for storing the measurement result of the fluorescence and the reference value in association with each measurement position;
Based on the correspondence stored in the storage means, the exposure dose calculation means for calibrating the fluorescence measurement result of the fluorescent glass dosimeter which is the measurement target of the radiation exposure dose and calculating the radiation exposure dose of the fluorescent glass dosimeter When,
A fluorescent glass dosimeter measuring device comprising:   The update means for reflecting the measurement result in the relationship stored in the storage means each time the fluorescence generated in the calibration standard glass dosimeter is measured for each measurement position. The fluorescent glass dosimeter measuring device according to 1. A step of irradiating a calibration standard glass dosimeter with excitation ultraviolet rays having a plurality of measurement positions and irradiated with only a reference value through a different type of filter for each measurement position;
Measuring fluorescence generated by the standard glass dosimeter for calibration at each measurement position;
Storing the fluorescence measurement result and the reference value in association with each measurement position;
Calibrating the fluorescence measurement result of the fluorescent glass dosimeter that is the measurement target of the radiation exposure dose based on the stored correspondence, and calculating the radiation exposure dose of the fluorescent glass dosimeter;
A method for calibrating a fluorescent glass dosimeter measuring device, comprising:   4. The fluorescence according to claim 3, further comprising a step of reflecting the measurement result in the stored correspondence relationship every time the fluorescence generated in the calibration standard glass dosimeter is measured at each measurement position. Calibration method for glass dosimeter measuring device.

Images