JP2012007905A - Glass dosimeter readout apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a downsized glass dosimeter readout apparatus at low cost, capable of accurate readout of a radiation dose amount exposed to a fluorescent glass element in a wide range.SOLUTION: A glass dosimeter readout apparatus that reads a radiation dose amount exposed to a fluorescent glass element 10 comprises an irradiation part 20, a photoelectron multiplying tube 30, a photon counting part 50, a light source control part 60, and a radiation dose amount calculation part 80. The irradiation part 20 comprising a light source 22 that emits ultraviolet rays 20a with an intensity corresponding to a current value supplied from a power source 24 emits the ultraviolet rays 20a to the fluorescent glass element 10. The photon counting part 50 counts the number of output pulses obtained from a signal outputted from the photoelectron multiplying tube 30 through A/D conversion. The light source control part 60 controls the current value supplied to the light source 22 based on the number of output pulses. The radiation dose amount calculation part 80 calculates a radiation dose amount exposed to the fluorescent glass element 10 based on the number of output pulses and the current value supplied to the light source 22.

Description

  The present invention relates to a glass dosimeter reader for reading a radiation dose irradiated to a fluorescent glass element based on the intensity of fluorescence emitted from the fluorescent glass element by ultraviolet excitation.

  A fluorescent glass element is widely used as a detection element for measuring radiation exposure dose in the field of handling radiation, such as the nuclear field and the medical field. The fluorescent glass element is made of, for example, phosphate glass containing silver ions. The fluorescent glass element activated by irradiation with radiation emits fluorescence when excited by irradiation with ultraviolet rays having a wavelength of 300 to 400 nm (so-called radiophotoluminescence phenomenon, hereinafter referred to as “RPL phenomenon”). Since this fluorescence intensity is proportional to the radiation dose irradiated to the fluorescent glass element (hereinafter referred to as “irradiated dose”), the irradiated dose can be read by measuring the fluorescence intensity (for example, (See Patent Documents 1 and 2).

  The irradiation dose of the fluorescent glass element is read using a glass dosimeter reading device (hereinafter referred to as “reading device”). A typical reading device includes an excitation light source such as a solid-state laser oscillator, a photomultiplier tube, an analog integration unit, and a dose calculation unit.

  The irradiation dose is read by attaching a fluorescent glass element to a reading device. First, the laser light emitted from the solid-state laser oscillator is passed through an ultraviolet transmission filter to selectively extract ultraviolet rays and irradiate the fluorescent glass element. Then, the fluorescent glass element emits fluorescence having an intensity proportional to the irradiation dose. Subsequently, after the fluorescence emitted from the fluorescent glass element is converted into a current signal using a photomultiplier tube, the analog integration unit obtains the signal amounts at the first and second sampling times having different times.

  Thereafter, the dose calculation unit calculates the fluorescence intensity, and hence the irradiation dose of the fluorescent glass element, from the signal amounts at the first and second sampling times. Here, the fluorescent component emitted from the fluorescent glass element includes a noise component in addition to the component due to the RPL phenomenon. The noise component includes a first noise component having a short decay time constant inherent to the fluorescent glass element (so-called pre-dose component), a second noise component having a short decay time constant emitted from dirt attached to the surface of the glass element, and the like. The third noise component having a long decay time constant whose cause is unknown is included. Therefore, the dose calculation unit uses the difference in the decay time constant of each component to time-resolve the component due to the RPL phenomenon and the noise component, and remove the noise component. Then, the irradiation dose is calculated from the component due to the RPL phenomenon. In this way, the irradiation dose of the fluorescent glass element can be accurately read (for example, see Patent Document 3).

JP 2005-114410 A JP-A-8-220235 JP 59-190681 A

  As described above, a light source with high output energy such as a solid-state laser oscillator is usually used as the excitation light source of the reader. However, since the solid-state laser oscillator is large and expensive, the reader is also large and expensive. Become. Therefore, in order to meet the needs for downsizing and cost reduction of the reading apparatus, it has been proposed to use a light emitting diode (LED) as an excitation light source of the reading apparatus.

  However, light emitting diodes (LEDs) have lower output energy than solid state laser oscillators. Therefore, if the irradiation dose of the fluorescent glass element is small, the fluorescence intensity generated by the RPL phenomenon becomes weak. In such a case, if the output signal from the photomultiplier tube is processed using the analog integration method described above, the S / N ratio becomes small, and the dose calculation unit uses components due to the RPL phenomenon and noise components. Cannot be sufficiently decomposed, and the irradiation dose cannot be calculated with high accuracy. That is, when the analog integration method is used, it is impossible to accurately read a low dose.

  Therefore, it is conceivable to use a photon counting method (photon counting method) instead of the analog integration method described above. In reading using the photon counting method, a pulsed electric signal from a photomultiplier tube is subjected to current / voltage conversion (hereinafter referred to as “I / V conversion”) and analog / digital conversion (hereinafter referred to as “A”) in a photon counting unit. / D conversion ”) to obtain output pulses, and count the number of output pulses (hereinafter referred to as“ count value ”) per first sampling time and second sampling time having different times. Then, the dose calculation unit calculates the irradiation dose from the count value.

  Here, FIG. 8 is a graph showing an example of the relationship between the count value and the count omission ratio. From FIG. 8, it is understood that almost no count omission occurs until the count value reaches 10,000, but when the count value exceeds 10,000, the omission of count increases. When the irradiation dose of the fluorescent glass element is large and the fluorescence intensity is strong, the output pulses are overcrowded and a plurality of output pulses are overlapped. Then, in the photon counting unit, a plurality of overlapping output pulses are counted as one output pulse, and count omission occurs. As a result, the reading amount is calculated lower than the actual irradiation dose in the dose calculation unit. That is, when the photon counting method is used, it is impossible to accurately read a high dose.

  Accordingly, the present invention has been made to solve the above-described problems, enables downsizing and cost reduction, and accurately reads the radiation dose irradiated to the fluorescent glass element over a wide range. An object of the present invention is to provide a glass dosimeter reader capable of performing the above.

  In order to achieve the above object, a glass dosimeter reading device according to the present invention is a device for reading a radiation dose irradiated to a fluorescent glass element, according to a power source and a current value supplied from the power source. An irradiation unit that irradiates the fluorescent glass element with ultraviolet light, a photoelectric conversion unit that detects fluorescence emitted from the fluorescent glass element and outputs an electrical signal, and the photoelectric conversion unit A photon counting unit that counts the number of output pulses obtained by analog / digital conversion of the electrical signal output from the light source, and the number of output pulses counted by the photon counting unit and the current value supplied to the light source A dose calculation unit for calculating the radiation dose irradiated to the fluorescent glass element, and a current value supplied to the light source based on the number of output pulses counted by the photon counting unit. A light source control unit, characterized by comprising a.

  ADVANTAGE OF THE INVENTION According to this invention, the glass dosimeter reader which can be reduced in size and cost and can read the radiation dose irradiated to the fluorescent glass element over a wide range with high precision can be provided.

1 is an overall configuration diagram of a glass dosimeter reading device according to a first embodiment of the present invention. It is the fragmentary sectional view showing the schematic structure of the glass dosimeter reading device concerning a 1st embodiment of the present invention. It is a partial block diagram for demonstrating the photon counting part of the glass dosimeter reading device which concerns on the 1st Embodiment of this invention. It is a partial block diagram for demonstrating the light source control part and dose calculation part of the glass dosimeter reader which concerns on the 1st Embodiment of this invention. It is the table | surface which showed the electric current value which the electric current value determination part of the glass dosimeter reader which concerns on the 1st Embodiment of this invention determines. It is a partial block diagram for demonstrating the light source control part and dose calculation part of the glass dosimeter reading apparatus which concern on the 2nd Embodiment of this invention. It is the table | surface which showed the correspondence of the count value which the count part of the glass dosimeter reader which concerns on the 2nd Embodiment of this invention counted, and the current value which a current value determination part determines. It is the graph which showed the relationship between the count value which the photon counting part of the glass dosimeter reading device counted, and the ratio of count omission.

[First Embodiment]
A glass dosimeter reading apparatus according to a first embodiment of the present invention will be described with reference to FIGS.

  First, an outline of the structure and configuration of the glass dosimeter reading apparatus according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is an overall configuration diagram of a glass dosimeter reading apparatus. FIG. 2 is a partial cross-sectional view showing a schematic structure of the glass dosimeter reading apparatus.

  The glass dosimeter reading device according to the present embodiment is a device that reads the radiation dose irradiated to the fluorescent glass element 10. The fluorescent glass element 10 is a detection element for measuring an irradiation dose, and is made of, for example, phosphate glass containing silver ions. The fluorescent glass element 10 activated by irradiation with radiation emits fluorescence 10a when excited by irradiation with ultraviolet light 20a having a wavelength of 300 to 400 nm. The reading device reads the irradiation dose of the fluorescent glass element 10 using a characteristic that the intensity of the fluorescence 10 a emitted from the fluorescent glass element 10 is proportional to the irradiation dose of the fluorescent glass element 10.

  The glass dosimeter reading device according to the present embodiment includes an irradiation unit 20, a photoelectric conversion unit, a controller unit 40, and the like. In the present embodiment, the photoelectric conversion unit is a photomultiplier tube 30.

  The irradiation unit 20 plays a role of irradiating the fluorescent glass element 10 with ultraviolet rays 20a. The irradiation unit 20 includes a light source 22, a power supply 24, a hemispherical lens 26, and an ultraviolet transmission filter 28.

  In the present embodiment, the light source 22 is a light emitting diode, for example, and emits light having an intensity corresponding to the current value supplied from the power supply 24. The power source 24 is a variable current power source, for example, and is controlled by a light source control unit 60 described later.

  The light emitted from the light source 22 is collected through the hemispherical lens 26, then passes through the ultraviolet transmission filter 28, and only the ultraviolet rays 20 a are irradiated on the side surfaces of the fluorescent glass element 10. Here, the ultraviolet transmission filter 28 selectively transmits the ultraviolet rays 20a having a wavelength of 300 to 400 nm among the light emitted from the light source 22. As described above, the fluorescent glass element 10 irradiated with radiation emits fluorescence 10a when irradiated with the ultraviolet rays 20a from the irradiation unit 20.

  As illustrated in FIG. 2, the irradiation unit 20 is housed in a rectangular first case 120. The first case 120 includes a bottom plate 122 and an upper lid 124, and the upper lid 124 is attached to the bottom plate 122 so as to be openable and closable.

  As shown in FIG. 2, the bottom plate 122 is formed with a partition wall 126 that partitions the inside of the first case 120 into a first space 120a and a second space 120b. The light source 22, the power source 24, the hemispherical lens 26, and the ultraviolet transmission filter 28 are accommodated in the first space 120a. Moreover, the fluorescent glass element 10 is installed in the second space 120b. A slit 126 a is formed in the partition wall 126, and the ultraviolet light 20 a that has passed through the ultraviolet transmission filter 28 passes through the slit 126 a and is irradiated onto the fluorescent glass element 10. The partition 126 plays a role of preventing scattered light in the first space 120 a from entering the fluorescent glass element 10.

  The irradiation dose is read by opening the upper lid 124 and mounting the rectangular plate-shaped fluorescent glass element 10 on the glass element holding portion 122a formed on the second space 120b side of the bottom plate 122, and then closing the upper lid 124. Is called. When the upper lid 124 is closed, the interior of the first case 120 is a dark room.

  When the side surface of the fluorescent glass element 10 is irradiated with the ultraviolet rays 20a, the fluorescent light 10a is emitted from the lower surface side of the fluorescent glass element 10. The fluorescent light 10 a passes through the emission window 122 b formed in the bottom plate 122 and enters the second case 128 provided below the first case 120. The fluorescent light 10 a that has entered the second case 128 passes through the hemispherical lens 112 to be converted into parallel light, and is then redirected by the mirror 114. Thereafter, the fluorescent light 10 a passes through the interference filter 116, passes through the hemispherical lens 118, is collected, and enters the photomultiplier tube 30. The incident window 128b of the second case 128 is blocked by the ultraviolet light removal filter 110 so that the ultraviolet light 20a in the first case 120 does not enter the second case 128.

  The photomultiplier tube 30 is a kind of phototube that converts light energy into electric energy using the photoelectric effect, and is a highly sensitive photodetector having a current amplification (electron multiplication) function. The fluorescence 10a incident on the photomultiplier tube 30 knocks out photoelectrons from the photocathode. The struck photoelectrons are accelerated by the applied voltage, collide with the first dynode, and knock out a plurality of secondary electrons per photoelectron. The knocked-out secondary electrons collide with the second dynode and knock out more secondary electrons. The photomultiplier tube 30 repeats this to multiply the secondary electrons, and takes out the secondary electrons that have reached the anode as a pulse current signal 30a.

  As shown in FIG. 2, the photomultiplier tube 30 is provided adjacent to the second case 128 and below the first case 120. A heat sink 32 for cooling is attached to the side surface of the photomultiplier tube 30.

  The controller unit 40 includes a photon counting unit 50, a light source control unit 60, a dose calculation unit 80, a recording unit 90, and a display unit 100.

  The photon counting unit 50 counts the number of output pulses obtained by performing I / V conversion and A / D conversion on the pulse electrical signal 30a output from the photomultiplier tube 30 using a photon counting method. The light source control unit 60 controls the current value supplied to the light source 22 based on the number of output pulses counted by the photon counting unit 50. The dose calculation unit 80 calculates the irradiation dose of the fluorescent glass element 10 based on the number of output pulses counted by the photon counting unit 50 and the current value supplied to the light source 22. The display unit 100 is, for example, a display, and displays the irradiation dose calculated by the dose calculation unit 80.

  The controller unit 40 is provided adjacent to the photomultiplier tube 30 and below the first case 120. The light source control unit 60 of the controller unit 40 is connected to the power supply 24 of the irradiation unit 20 via the cable 42.

  Next, the photon counting unit 50 will be described in detail with reference to FIG. FIG. 3 is a partial configuration diagram for explaining a photon counting unit of the glass dosimeter reading device.

  The photon counting unit 50 includes an I / V conversion / amplification unit 52, an A / D conversion unit 54, and a counting unit 56.

  The I / V conversion / amplification unit 52 receives the pulse current signal 30a output from the photomultiplier tube 30, and generates and outputs the pulse voltage signal 52a by the I / V conversion circuit and the amplification circuit.

  The A / D converter 54 receives the pulse voltage signal 52a output from the I / V converter / amplifier 52, and compares the value of the pulse voltage signal 52a with a predetermined threshold value using a comparison circuit. When the value of the pulse voltage signal 52a is lower than the threshold value, the A / D converter 54 determines that the pulse component is a noise component and outputs “0”, and the value of the pulse voltage signal 52a is equal to the threshold value. If it is higher, “1” is output as a signal component. In this way, the A / D converter 54 outputs the digital pulse signal 54a.

  The counting unit 56 receives the digital pulse signal 54a output from the A / D conversion unit 54, and counts the number of output pulses per unit time included in the digital pulse signal 54a.

  Specifically, the count unit 56 is for 5 μsec from 2 μsec to 7 μsec after light emission of the light source 22 (hereinafter referred to as “first sampling time”) and for 5 μsec from 40 μsec to 45 μsec after light emission of the light source 22 (hereinafter, “ The number of output pulses in “second sampling time”) is counted. In the present embodiment, the light source 22 emits light 20000 times and the fluorescent glass element 10 emits 20000 times per measurement. Then, the count unit 56 receives 20000 digital pulse signals 54a and integrates the number of output pulses for 20000 times. That is, the count unit 56 counts the number of output pulses accumulated in the first sampling time (hereinafter referred to as “first count value”) and the number of output pulses accumulated in the second sampling time (hereinafter referred to as “first count value”). 2) ”). The count unit 56 outputs count value data 56a including the first count value and the second count value.

  Here, when the photon counting method is used for processing the output signal from the photomultiplier tube, as described above, if the fluorescence intensity is strong and the number of photons detected at the sampling time is extremely large, the count leakage occurs. End up. On the other hand, if the fluorescence intensity is weak and the number of photons detected at the sampling time is extremely small, the variation in the count value becomes large.

  Therefore, the light source control unit 60 of the glass dosimeter reading device according to the present embodiment feedback controls the irradiation amount of the irradiation unit 20 in order to keep the count value within an appropriate range. The light source controller 60 will be described in detail with reference to FIGS. 4 and 5. FIG. 4 is a partial configuration diagram for explaining a light source control unit and a dose calculation unit of the glass dosimeter reading device. FIG. 5 is a table showing current values determined by the current value determination unit of the glass dosimeter reader.

  The light source control unit 60 includes a data transmission unit 62, a remeasurement necessity determination unit 64, a current value determination unit 66, and a control signal output unit 68.

  The data transmission unit 62 receives the count value data 56 a output from the count unit 56 and transmits the count value data 56 a to the remeasurement necessity determination unit 64 and the dose calculation unit 80.

  The re-measurement necessity determination unit 64 receives the count value data 56a, and determines whether or not the count value is within a predetermined range. In the present embodiment, the remeasurement necessity determination unit 64 determines whether or not the first count value is 1000 or more. The remeasurement necessity determination unit 64 outputs a calculation instruction signal 64a to the dose calculation unit 80 when the count value is 1000 or more.

  On the other hand, when the count value is less than 1000, the remeasurement necessity determination unit 64 outputs a remeasurement instruction signal 64b to the current value determination unit 66.

  When receiving the remeasurement instruction signal 64b, the current value determination unit 66 reads the current value data 90a including the current value (for example, 0.4 mA) supplied from the recording unit 90 to the light source 22, and the current value is larger than the current value. Determine the value (eg 4 mA). Then, the current value determination unit 66 outputs current value data 66a including the determined current value (4 mA) to the recording unit 90 and the control signal output unit 68. The recording unit 90 stores current value data 66a.

  When the control signal output unit 68 receives the current value data 66a, the control signal output unit 68 outputs the control signal 68a to the power source 24 via the cable 42 to supply a current of 40 mA from the power source 24 to the light source 22.

  In this way, the irradiation unit 20 again irradiates the fluorescent glass element 10 with the ultraviolet rays 20a to cause the fluorescent glass element 10 to emit light. Then, the count unit 56 remeasures the count value and outputs new count value data 56a. The light source control unit 60 controls the current value supplied to the light source 22 by repeating the above operation until the count value reaches 1000 or more.

  In the present embodiment, as shown in FIG. 5, the current value at the first measurement is set to 0.4 mA. The current value determination unit 66 determines the current value at the time of the second measurement as 4 mA, the current value at the time of the third measurement as 40 mA, and the current value at the time of the fourth measurement as 400 mA. As described above, the current value determination unit 66 determines a current value that is ten times the current value at the previous measurement at the time of remeasurement.

  Next, the dose calculation unit 80 will be described in detail with reference to FIG.

  When receiving the calculation instruction signal 64 a output from the re-measurement necessity determination unit 64, the dose calculation unit 80 receives the count value included in the count value data 56 a received from the data transmission unit 62 and the current read from the recording unit 90. Based on the current value included in the value data 90a, the irradiation dose of the fluorescent glass element 10 is calculated.

  Specifically, the dose calculation unit 80 uses the fact that the decay time constants of the component due to the RPL phenomenon and the noise component are different from each other, and temporally resolves the component due to the RPL phenomenon and the noise component to remove the noise component. Specifically, the dose calculation unit 80 subtracts the second count value from the first count value, removes the output pulse due to the noise component, and integrates the number of output pulses due to the RPL phenomenon (that is, , Count value after noise removal). Thereafter, the dose calculation unit 80 calculates the irradiation dose from the relationship between the current value supplied to the light source 22 and the number of output pulses due to the RPL phenomenon.

  The dose calculation unit 80 outputs dose data 80a including the calculated irradiation dose to the display unit 100. The display unit 100 receives the dose data 80a and displays the irradiation dose.

  The effect of the glass dosimeter reading device according to this embodiment will be described.

  According to the present embodiment, since the photon counting method is used for processing the output signal from the photomultiplier tube, the output energy of the light emitting diode or the like is replaced with a light source having a high output energy such as a large and expensive solid-state laser oscillator. A low light source can be employed. As a result, the glass dosimeter reader can be reduced in size and cost.

  In addition, according to the present embodiment, when the irradiation dose of the fluorescent glass element 10 is small and the fluorescence intensity is weak, the light source controller 60 causes the irradiation unit to keep the count value within an appropriate range (for example, 1000 or more). Feedback control of the irradiation amount of 20 is performed. Then, the irradiation dose is calculated based on the count value falling within the appropriate range. Therefore, it is possible to accurately read a low dose.

  Furthermore, according to the present embodiment, the light source control unit 60 gradually increases the irradiation amount of the irradiation unit 20 each time remeasurement is performed, and gradually increases the emission intensity of the fluorescent glass element 10. Therefore, the light receiving surface of the photomultiplier tube 30 is not easily damaged. Further, since the count value gradually increases from a small value, the count omission is less likely to occur. Therefore, it is possible to accurately read a high dose.

  As described above, the glass dosimeter reader according to the present embodiment is small and inexpensive, and can accurately read the irradiated dose over a wide range.

[Second Embodiment]
A glass dosimeter reading apparatus according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a partial configuration diagram for explaining a light source control unit and a dose calculation unit of the glass dosimeter reading device. FIG. 7 is a table showing a correspondence relationship between the count value counted by the counting unit of the glass dosimeter reader and the current value determined by the current value determining unit. In addition, this embodiment is a modification of 1st Embodiment, Comprising: The same code | symbol is attached | subjected to the same part or similar part as 1st Embodiment, and duplication description is abbreviate | omitted.

  In the present embodiment, the current value at the time of the first measurement is set to 10 mA. As in the first embodiment, the count unit 56 outputs count value data 56a including a first count value and a second count value.

  The data transmission unit 62 receives the count value data 56 a output from the count unit 56, and transmits the count value data 56 a to the remeasurement necessity determination unit 64, the current value determination unit 66, and the dose calculation unit 80.

  The re-measurement necessity determination unit 64 receives the count value data 56a and determines whether or not the first count value is within 1000 or more and less than 10,000. The remeasurement necessity determination unit 64 outputs a calculation instruction signal 64 a to the dose calculation unit 80 when the count value is within a predetermined range.

  On the other hand, the re-measurement necessity determination unit 64 outputs a re-measurement instruction signal 64b to the current value determination unit 66 when the first count value is not within 1000 or more and less than 10,000. When receiving the remeasurement instruction signal 64b, the current value determination unit 66 selects a current value corresponding to the count value included in the count value data 56a based on the correspondence relationship between the count value and the current value shown in FIG. . For example, when the count value at the time of the first measurement is 500, the current value determination unit 66 determines the current value to be 50 mA (third range). If the count value at the first measurement is 15000, the current value is determined to be 5 mA (fourth range).

  According to this embodiment, the irradiation dose is calculated by bringing the count value close to the appropriate range by one feedback control. Therefore, according to the present embodiment, it is possible to shorten the irradiation dose reading time as compared with the first embodiment.

[Other Embodiments]
The above embodiments are merely examples, and the present invention is not limited to these. In the above embodiment, a light emitting diode is used as the light source 22, but a laser diode may be used. In the above embodiment, the photomultiplier tube 30 is used as the photoelectric conversion unit, but an avalanche photodiode (APD) may be used. Furthermore, the photon counting unit 50, the light source control unit 60, and the dose calculation unit 80 may be configured by one or more computers.

  In the above embodiment, the remeasurement necessity determination unit 64 determines whether or not the first count value is within the appropriate range. However, whether or not the second count value is within the appropriate range. You may judge.

  In the above embodiment, the noise component removal processing is performed by the dose calculation unit 80, but may be performed by the count unit 56. That is, the count unit 56 performs a noise component removal process, and generates count value data 56a including the integrated number of output pulses (that is, the count value after noise removal) caused by the RPL phenomenon. Then, the remeasurement necessity determination unit 64 may determine whether the count value after noise removal is within an appropriate range.

  Further, as the hemispherical lenses 26 and 112 used for condensing and collimating, an aspherical lens or a spherical lens may be used as long as collimated light can be obtained. Similarly, for the hemispherical lens 118, an aspherical lens, a spherical lens, or an optical fiber cable may be used.

DESCRIPTION OF SYMBOLS 10 ... Fluorescent glass element, 10a ... Fluorescence, 20 ... Irradiation part, 20a ... Ultraviolet light, 22 ... Light source, 24 ... Power supply, 26 ... Hemispherical lens, 28 ... Ultraviolet transmission filter, 30 ... Photomultiplier tube, 30a ... Pulse current signal 32 ... heat sink, 40 ... controller unit, 42 ... cable, 50 ... photon counting unit, 52 ... I / V conversion / amplification unit, 52a ... pulse signal (voltage signal), 54 ... A / D conversion unit, 54a ... digital Pulse signal 56 ... Count unit 56a ... Count value data 60 ... Light source control unit 62 ... Data transmission unit 64 ... Re-measurement necessity determination unit 64a ... Calculation instruction signal 64b ... Re-measurement instruction signal 66 ... Current value determination unit, 66a ... current value data, 68 ... control signal output unit, 68a ... control signal, 80 ... dose calculation unit, 80a ... dose data, 90 ... recording unit, 100 ... display unit DESCRIPTION OF SYMBOLS 110 ... UV-removal filter, 112 ... Hemispherical lens, 114 ... Mirror, 116 ... Interference filter, 118 ... Hemispherical lens, 120 ... First case, 120a ... First space in the first case, 120b ... First in the first case 2 spaces, 122 ... bottom plate of the first case, 122a ... glass element holding portion, 122b ... exit window, 124 ... top cover of the first case, 126 ... partition wall, 126a ... slit, 128 ... second case, 128b ... entrance window

Claims (10)

A glass dosimeter reader for reading a radiation dose irradiated to a fluorescent glass element,
A power source, and a light source that emits ultraviolet light having an intensity corresponding to a current value supplied from the power source, and an irradiation unit that irradiates the fluorescent glass element with ultraviolet light,
A photoelectric converter that detects the fluorescence emitted by the fluorescent glass element and outputs an electrical signal;
A photon counter that counts the number of output pulses obtained by analog / digital conversion of the electrical signal output by the photoelectric converter;
A dose calculation unit for calculating a radiation dose irradiated to the fluorescent glass element based on the number of output pulses counted by the photon counting unit and a current value supplied to the light source;
A light source control unit for controlling a current value supplied to the light source based on the number of output pulses counted by the photon counting unit;
A glass dosimeter reading device comprising:   2. The glass dosimeter according to claim 1, wherein the light source control unit controls a current value supplied to the light source so that the number of output pulses counted by the photon counting unit falls within a predetermined range. Reader.   3. The glass dose according to claim 2, wherein the light source control unit increases a current value supplied to the light source when the number of output pulses counted by the photon counting unit is equal to or less than a predetermined value. Meter reading device.   The said light source control part reduces the electric current value supplied to the said light source, when the number of the output pulses which the said photon counting part counted is more than predetermined value, The said light source control part is characterized by the above-mentioned. Glass dosimeter reader.   The light source control unit repeatedly controls the current value supplied to the light source until the number of output pulses counted by the photon counting unit falls within a predetermined range. The glass dosimeter reader according to item.   The light source control unit determines whether the number of output pulses counted by the photon counting unit belongs to one of a plurality of different ranges, and a current supplied to the light source according to the range to which the light source control unit belongs The glass dosimeter reading device according to any one of claims 2 to 4, wherein the value is controlled.   The glass dosimeter reading device according to any one of claims 1 to 6, wherein the light source is a light emitting diode.   The glass dosimeter reading device according to any one of claims 1 to 6, wherein the light source is a laser diode.   9. The glass dosimeter reader according to claim 1, wherein the photoelectric conversion unit is a photomultiplier tube.   The glass dosimeter reading device according to claim 1, wherein the photoelectric conversion unit is an avalanche photodiode.

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