JP3894351B2 - Radiation measuring apparatus using stimulable phosphor and measuring method thereof - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a radiation measurement apparatus and method that require real-time monitoring of radiation intensity over a wide dynamic range at a wide range of measurement locations in and outside a nuclear reactor facility or an accelerator facility. In these facilities, a detection system that can constantly monitor a very strong radiation dose instantly generated from a very weak radiation dose in various places is required. Also. At the same time, portable radiation monitors are also required from the standpoint of personal radiation exposure management.
[0002]
For this reason, we have devised a differential and integral radiation measurement device and measurement method that combine a method of constantly monitoring radiation using a stimulable phosphor and a method of measuring while integrating radiation, as well as remote sensing. Devised a radiation measurement device and a measurement method applicable to a radiation measurement device, a radiation distribution measurement device, a portable radiation measurement device, etc.
[0003]
[Prior art]
Conventionally, ionization chambers, Geiga-Muller tubes (GM tubes), scintillation detectors combining scintillators and photomultiplier tubes, or BF for neutron dose measurements _Three Counter or ^Three He counters and the like have been used. However, it is very difficult to cover a wide dynamic range from a very weak radiation dose to a very strong radiation dose with one detector. By combining a low-sensitivity ionization chamber with a high-sensitivity scintillation detector, etc. Has been used. In addition, the measurement of high-intensity radiation that occurs instantaneously in the vicinity of an accelerator or the like or in the vicinity of a target or high-intensity radiation that occurs due to an unforeseen accident at a reactor facility, etc. causes the detector to saturate due to the radiation. It was difficult to measure.
[0004]
For this reason, the stimulable phosphor accumulates incident radiation and can read out the amount of incident radiation as stimulable fluorescence by excitation light, and the effect of promptly emitting fluorescence by incident radiation. Focusing on having an action, a method of measuring the amount of incident radiation by switching between and detecting stimulable fluorescence and prompt fluorescence in a time division has been devised [Japanese Patent Application No. 11-50301]. By using this method and using a radiation measurement device, a single detector covers a wide dynamic range from a very weak radiation dose to a very strong radiation dose, and radiation by high-intensity radiation and neutron radiation that is generated instantaneously. The amount can be measured.
[0005]
A conventional method of reading the amount of radiation accumulated in the photostimulable phosphor, which is a radiation detection medium that is an important component of the present invention [D. J. et al. Huntley et al .: Nature, Vol. 313, 10, pp. 105] is shown in FIG. After the photostimulable phosphor sheet irradiated with radiation at another location is placed on the reading table, the stimulable phosphor is irradiated with the excitation light generated from the excitation light source from the front, and the photostimulable fluorescence emitted. Is detected with a photomultiplier tube after passing through a bandpass optical filter having the stimulable fluorescence wavelength as the center wavelength. Thereafter, the signal processing device converts the signal into a digital signal according to the intensity, and determines the radiation dose.
[0006]
In addition, a small amount of stimulable phosphor is attached to the tip of the optical fiber, excitation light is put into the optical fiber, and the stimulable phosphor is irradiated. 41 to calculate the radiation dose [North Exit, etc .: JAERI-Conf 98-011, pp. 62], but it is difficult to increase the sensitivity due to the small amount of stimulable phosphor.
[0007]
Further, the conventional method shown in FIG. 42 [S. S. et al.] Reads the amount of radiation accumulated in the stimulable phosphor by irradiating the stimulable phosphor with the excitation light using a pulse light source. W. S. McKeever et al .: Radiation Protection Dosimetry, Vol. 65, Nos. 1-4, pp. 267], the stimulable fluorescence emitted according to the fluorescence lifetime after irradiation with one pulse of excitation light at the timing shown in FIG. 43 is amplified by a high-speed amplifier, counted by a high-speed counting circuit, and accumulated to obtain the radiation dose. It was. This method required an ultrafast measurement system including a photodetector.
[0008]
On the other hand, with respect to the conventional method of simultaneously measuring the amount of radiation and the measurement position with a simple device, a radiation measurement method in which the detector shown in FIGS. 44 and 45 is arranged at each measurement location and connected in series with an optical fiber, etc. [Maekawa et al .: Radiation Vol. 21, no. 3, pp. 69]. In these methods, a scintillator is used as a radiation detection medium, the fluorescence is detected by a wavelength-shifted optical fiber, and the radiation intensity and measurement position are obtained from the time difference of the fluorescence output at both ends of the wavelength-shifted optical fiber. It was difficult to obtain the position of the radiation as well as the radiation intensity.
[0009]
[Problems to be solved by the invention]
The present invention covers a wide dynamic range from a very weak radiation dose to a very strong radiation dose with a single detector, and also generates high-intensity radiation, neutron rays or atoms generated instantaneously around an accelerator or the like or around a target. A radiation measurement device that can easily and accurately measure the radiation dose from high-intensity radiation and neutron beams generated by unforeseen accidents at the reactor facility, etc., and its measurement method, and a small and simple that can also be used normally It aims at providing a radiation measuring device and its measuring method. It is another object of the present invention to provide a radiation measuring apparatus and a measuring method thereof that can easily and easily measure the amount of radiation in a wide range of measurement locations. Furthermore, it aims at providing the radiation measuring device for obtaining the two-dimensional image of radiation easily.
[0010]
[Means for Solving the Problems]
In order to develop a radiation measuring device that covers a wide dynamic range from a very weak radiation dose to a very strong radiation dose with a single detector and measures radiation dose with high-intensity radiation and neutrons that are generated instantaneously. The stimulable phosphor has two actions: the action of accumulating incident radiation and reading out the amount of incident radiation as stimulable fluorescence by the excitation light, and the action of emitting fluorescence promptly by the incident radiation. Focusing on the above, a method [Japanese Patent Application No. 11-50301] for measuring the amount of incident radiation by switching and detecting stimulable fluorescence and prompt fluorescence in a time-sharing manner is used. By using this method, the required radiation detection performance can be easily secured with a simple device. Therefore, the present invention stops the function by irradiating strong radiation in a short time and saturating the fluorescence detection mechanism. Is related to a radiation measurement device that uses a method of measuring the amount of incident radiation after reading out the stimulable fluorescence after the recovery of the fluorescence detection mechanism. Fluorescence detection by changing the amount of excitation light and fluorescence detection sensitivity so that the fluorescence detection mechanism is not saturated when reading the amount of intense radiation incident in a short time after recovery We have devised a method of reading the amount of radiation accumulated in the stimulable phosphor that measures the amount of radiation accumulated in the stimulable phosphor without the mechanism being saturated.
[0011]
As a method of reading the amount of radiation accumulated in the photostimulable phosphor, the stimulable phosphor is irradiated with excitation light of a short time width using a pulse light source, and the fact that the photostimulable fluorescence lifetime is short is used. A signal processing method using a conventional radiation detection system is used. By using this reading method, it is possible to easily measure the accumulated radiation dose by detecting and switching between stimulable fluorescence and prompt fluorescence in a time division manner.
[0012]
In addition, when reading the amount of radiation accumulated in the photostimulable phosphor, an optical fiber that emits light from the side surface is used to irradiate the stimulable phosphor with the excitation light. The stimulable phosphor can be irradiated with excitation light. By devising this method, it is not necessary to install a light source such as a laser light source in a place where the radiation dose is strong, and a small excitation light irradiation mechanism can be configured. Further, by using an optical fiber that emits light from this side surface, simple measurement of a two-dimensional radiation image using a sheet-like photostimulable phosphor can be facilitated.
[0013]
In addition, photoshift amplification is achieved by arranging wavelength-shifted optical fibers sensitive to the fluorescence wavelength used to detect photostimulable fluorescence and prompt fluorescence in parallel to ensure the detection area and detect photostimulable fluorescence. It is no longer necessary to install photo detectors such as double tubes in places with high radiation doses. In addition, by using a bundle of wavelength-shifted optical fibers bundled in parallel and an optical fiber that emits light from the side surface, and by making the photostimulable phosphor and the optical filter sandwiched in a sandwich structure, a compact structure is achieved. It has become possible to construct radiation detectors with various detection shapes.
[0014]
On the other hand, the detection part of the above laminated structure is extended long, and excitation light having an extremely short pulse width is incident on an optical fiber that emits light from the side surface, and the short pulse width excitation light propagates to irradiate the photostimulable phosphor. By detecting the emitted photostimulable fluorescence with a wavelength-shifted optical fiber, it was possible to measure the radiation dose distribution over a long distance. By switching between this method and the method for detecting prompt fluorescence, it is possible to solve the problem of radiation distribution measurement in a wide range of measurement locations.
[0015]
Gd, which is a neutron converter material that converts neutrons into radiation that can be ionized into the stimulable phosphor that is the radiation detection medium described above, ⁶ Li or ^Ten Radiation measurement apparatus capable of detecting neutrons by using a radiation detection medium for detecting neutrons containing one or more types of B, mixed with stimulable phosphors, or combined with stimulable phosphors A measurement method can be constructed.
[0016]
【Example】
An embodiment of claim 1 will be described with reference to FIG. The stimulable phosphor, which is a radiation detection medium, accumulates incident radiation and can read out the amount of incident radiation as stimulable fluorescence by excitation light (stimulable fluorescence) and the incident radiation. There are two actions of immediate fluorescence emission (prompt fluorescence). By using these two actions, incident light is detected by detecting stimulable fluorescence and prompt fluorescence in real time using a fluorescence detection mechanism. There is a radiation measurement method for measuring the amount of radiation. The present invention relates to a radiation measuring apparatus that implements this method and a method of measuring using the apparatus.
[0017]
As shown in FIG. 1, the radiation measuring apparatus using the photostimulable phosphor of the present invention reads out the stimulable phosphor as a radiation detection medium, and the radiation dose accumulated in the photostimulable phosphor in a time division manner. Output from excitation light source for irradiating stimulable phosphor to stimulable phosphor, bandpass optical filter centered on fluorescence wavelength, photodetector for detecting stimulable fluorescence and prompt fluorescence, output from photodetector Processing circuit for amplifying and processing the stimulable fluorescent signal and prompt fluorescent signal of the stimulable phosphor, and mode switching circuit for switching between the stimulable fluorescent signal and the prompt fluorescent signal of the stimulable phosphor in a time division manner Saturation monitoring circuit for monitoring the operating state of the fluorescence detection mechanism for detecting fluorescence, LED used for saturation monitoring, excitation light / light quantity changing circuit for changing the amount of excitation light, excitation light source in time division, mode switching circuit Saturation monitoring circuit, excitation・ Control circuit that controls the light intensity change circuit, stimulable fluorescence data collection circuit that measures stimulable fluorescence, prompt fluorescence data collection circuit that measures prompt fluorescence, and photostimulable fluorescence in time division while synchronizing with the control circuit And a data processing circuit that collects data of prompt fluorescence and obtains the amount of incident radiation from the data collection result.
[0018]
Details of the radiation measuring apparatus of the present invention will be described below. A sheet-like phosphor can be used as the stimulable phosphor as a radiation detection medium, and a BAS series imaging plate made by Fuji Photo Film, which is commercially available for X-ray imaging, is used. However, the rear surface of the commercially available imaging plate is not transparent, but it is easy to produce a transparent one. The photostimulable phosphor used in this imaging plate is BaFBr: Eu. ²⁺ It is. The stimulable wavelength band of this stimulable phosphor is 490 nm to 680 nm (wavelength band exhibiting more than half of the maximum efficiency). Moreover, the wavelength of the stimulable fluorescence emitted by irradiation with excitation light is 390 nm. In the Examples, this photostimulable phosphor will be described. As other photostimulable phosphor, KCl: Eu is used. ²⁺ Imaging plates using detection media such as RbBr: Tl, SrS: Eu, and Sm can also be read by changing the wavelength of excitation light, the wavelength of photostimulable fluorescence to be read, and the like.
[0019]
In the present invention, a laser light source is used as an excitation light source for generating excitation light. The required output depends on the readout speed and the readout area of the imaging plate which is a sheet-like stimulable phosphor. In the case of a detection area with a diameter of 5 mm, a maximum output of several mW or more is required. The photostimulable phosphor of the BAS series imaging plate of Fuji Photo Film is BaFBr: Eu ²⁺ Therefore, since the wavelength band that can be excited is 490 nm to 680 nm, a semiconductor laser (635 nm), a green laser (532 nm), or the like can be used as a laser of this wavelength band that can easily obtain a high output. . The laser light source that generates the excitation light can change the light amount of the excitation light by the light amount control signal output from the excitation light / light amount change circuit, and ON / OFF control of the excitation light using the ON / OFF control signal from the control circuit Is possible.
[0020]
The stimulable fluorescence emitted from the rear surface of the imaging plate, which is a sheet-like stimulable phosphor, is excited by passing it through a bandpass optical filter centered on the stimulable fluorescence wavelength placed after the imaging plate. Remove scattered light. In the case of the example, since the wavelength of the stimulable fluorescence is 390 nm, this optical filter having a center wavelength of 390 nm can be used.
[0021]
Next, the fluorescence detection mechanism will be described. As the photodetector, a photomultiplier tube having a high sensitivity near 390 nm, which is the wavelength of stimulable fluorescence, can be used. Although not shown in the figure, a high bias voltage is applied to the photomultiplier tube. The amplification factor of light depends on this bias voltage.
[0022]
The optical signal detected by the photomultiplier tube is amplified and processed by a signal processing circuit. As an embodiment, a counting method is used as an optical signal processing method. In this case, as signal processing, after the optical signal is amplified, it is discriminated from noise by a wave height discriminator and extracted as a pulse signal. In addition to this optical signal processing method, it is also possible to use a method of reading out the radiation dose by integrating the stimulable fluorescence signal sequence conventionally used for reading the image image of the imaging plate with an integration circuit. is there.
[0023]
The pulse signal processed and output by the signal processing circuit is input to the mode switching circuit. In this circuit, the mode switching signal from the control circuit is used to distribute the pulse signal to the stimulable fluorescence data collection circuit in the case of the stimulable fluorescence mode and to the prompt fluorescence data collection circuit in the case of the prompt fluorescence mode. In the embodiment of the present invention, the two data collection circuits are constituted by counting circuits.
[0024]
The mode switching between the stimulable fluorescence mode and the prompt fluorescence mode is performed by the control circuit, and is switched according to the timing shown in FIG. That is, when the excitation light is applied to the imaging plate that is a sheet-like photostimulable phosphor, the photostimulable fluorescence is read out, and in other cases, the prompt fluorescence is read out. Therefore, by controlling the excitation light source that generates excitation light and performing this operation in synchronization with the reading operation, it is possible to detect photostimulable fluorescence and prompt fluorescence using a single fluorescence detection mechanism in a time division manner.
[0025]
When detecting photostimulable fluorescence and prompt fluorescence in a time-sharing manner using a fluorescence detection mechanism for detecting stimulable fluorescence and prompt fluorescence emitted from an imaging plate, which is a sheet-like stimulable phosphor. In addition, in any case of radiation measurement with an accelerator or the like, strong radiation is incident in a short time, the fluorescence detection mechanism is saturated, and the function stops. In this case, the photodetector does not operate due to a saturation phenomenon, so that no signal comes to the signal processing circuit.
[0026]
In order to reliably capture this phenomenon, in the present invention, an LED that emits light having a wavelength that passes through an optical filter is used, and LED pulse light is incident on the photodetector at the timing shown in FIG. The fact that it can be detected is constantly monitored by the saturation monitoring circuit of the output signal of the signal processing circuit. When the LED pulse light cannot be detected, the saturation monitoring circuit sends a saturation signal to the control circuit because it is saturated. The saturation monitoring circuit continues to monitor the saturation state as it is, and waits for the incident of intense radiation that occurs in a short time to end and the fluorescence detection mechanism to recover. After the saturation state returns to the normal state, the control circuit sends a mode switching signal by the mode switching circuit, switches to the stimulable fluorescence mode, and measures the stimulable fluorescence, so that the intensity of incident light is strong for a short time. The amount of radiation can be measured.
[0027]
When performing the above-described operation for measuring photostimulable fluorescence, it is unknown how much intense radiation incident in a short time is accumulated in the photostimulable phosphor. For this reason, in the present invention, first, an imaging plate, which is a sheet-like photostimulable phosphor, is irradiated with excitation light having a very low intensity, and the amount of radiation is stored in the photostimulable phosphor. By reading the amount, the total amount of radiation accumulated in the photostimulable phosphor is measured without saturating the fluorescence detection mechanism. That is, while changing the excitation light quantity of the irradiation mechanism for irradiating the stimulable light to the stimulable phosphor using the excitation light / light quantity change circuit based on the signal from the control circuit, the saturation monitoring circuit is also assisted. The amount of radiation accumulated in the photostimulable phosphor can be read in a state where the fluorescence detection mechanism is not saturated while being used as
[0028]
An embodiment of claim 2 will be described with reference to FIG. When measuring the amount of intense radiation incident in a short time by measuring the photostimulable fluorescence after recovery of the fluorescence detection mechanism as described in the above embodiment, the fluorescence detection sensitivity of the fluorescence detection mechanism is increased. It is also possible to perform the reading operation in a state where the fluorescence detection mechanism is not saturated by changing. In the embodiment, since a photomultiplier tube is used as a photodetector, the above operation is performed by using a bias voltage changing circuit as a fluorescence detection sensitivity changing circuit and controlling this voltage by a control circuit.
[0029]
An embodiment of claim 3 will be described with reference to FIG. This embodiment uses the embodiments of claim 1 and claim 2 described above at the same time. According to the present invention, when the amount of radiation is very large, it is possible to measure the photostimulable fluorescence with the light detection sensitivity lowered using the fluorescence detection sensitivity change circuit, and to shorten the measurement time. It is possible to optimize the readout of the exhaustive fluorescence.
[0030]
An embodiment of claim 4 will be described with reference to FIG. When measuring the amount of radiation due to stimulable fluorescence in a time-sharing manner using the fluorescence detection mechanism for detecting stimulable fluorescence and prompt fluorescence described in the above example, radiation is incidentally incident within the reading time. Is incident and measured. For this reason, the amount of incident radiation is accurately corrected by correcting the contribution due to prompt fluorescence using a data processing circuit based on the amount of radiation measured by prompt fluorescence measured in a time-sharing manner using a fluorescence detection mechanism. It is possible to measure.
[0031]
An embodiment of claim 5 will be described with reference to FIG. The present invention relates to a method for reading a radiation dose accumulated in a stimulable phosphor, which is a major technical problem in a radiation measuring apparatus using the stimulable phosphor.
[0032]
When a stimulable phosphor with a short fluorescence lifetime is used as a radiation detection medium, that is, when a stimulable phosphor with a fluorescence lifetime of 2 μs or less is used, it has been conventionally used for signal processing of a semiconductor detector as described below. It is characterized by applying a signal processing method. As an example, BaFBr: Eu having a fluorescence lifetime of 0.8 μs. ²⁺ Is used.
[0033]
BaFBr: Eu with a fluorescence lifetime of 0.8 μs ²⁺ When reading the amount of radiation accumulated in the photostimulable phosphor of the photostimulable phosphor, stimulating the pulsed excitation light with a pulsed excitation light source having an irradiation time width of 0.8 μs or less of the photostimulable phosphor Irradiate the phosphor. In the embodiment, a pulse green laser is used as an irradiation pulse laser light source. The pulse width of this laser light source is very short, 2 ns. When the stimulable phosphor is irradiated with this laser excitation light, stimulable fluorescence is randomly emitted as shown in the timing chart of FIG. Many of these emissions occur during the lifetime of the photostimulable phosphor, so the fluorescence emitted from the photostimulable phosphor is detected by a photodetector such as a photomultiplier tube, and the detected signal is charged. When amplified by a sensitive preamplifier, an output signal as shown in the figure is obtained. This output signal is input to a pulse shaping amplifier composed of an integration / differentiation circuit and the like, and is shaped and amplified with a waveform shaping time constant for a time longer than the stimulable fluorescence lifetime of the stimulable phosphor. By this operation, a pulse height signal obtained by integrating the photostimulable fluorescence emitted after irradiation with pulsed excitation light can be obtained. After that, it is input to an analog / digital converter and its peak value is obtained. Using the data acquisition and processing circuit, the peak values obtained for each pulse excitation light generated by the pulse laser light source for excitation light are integrated based on the laser control signal from the pulse generator, so The amount of accumulated radiation can be determined.
[0034]
An embodiment of claim 6 will be described with reference to FIG. In the radiation detection apparatus according to claim 5, a gated photomultiplier tube is used as the photodetector. As a photomultiplier tube with a gate, R5916 manufactured by Hamamatsu Photonics Co., Ltd. can be used. As a stimulable phosphor, BaFBr: Eu ²⁺ Can be used as the excitation light source. Therefore, in synchronization with the operation of irradiating the photostimulable phosphor with this pulsed excitation light, a gate signal having a time width of 5 ns is input to the gated photomultiplier tube, and the photomultiplier tube is applied during the irradiation time period. The photomultiplier tube is operated by controlling the gate of the photomultiplier tube after irradiation of the excitation light. By this operation, the photostimulable fluorescence emitted after irradiation of the excitation light can be detected without being affected by the pulse excitation light. Therefore, it is possible to provide a radiation measuring apparatus using the stimulable phosphor that can determine the amount of radiation accumulated in the stimulable phosphor without being affected by the pulse excitation light.
[0035]
An embodiment of claim 7 will be described with reference to FIG. The present invention also relates to a method for reading out the amount of radiation accumulated in the stimulable phosphor, which is a major technical problem in a radiation measuring apparatus using the stimulable phosphor. When a stimulable phosphor having a short fluorescence lifetime is used as the radiation detection medium, that is, when a stimulable phosphor having a fluorescence lifetime of 2 μs or less is used, the amount of radiation accumulated in the stimulable phosphor is Applicable when not very strong. As an example, BaFBr: Eu having a fluorescence lifetime of 0.8 μs. ²⁺ Is used.
[0036]
BaFBr: Eu with a fluorescence lifetime of 0.8 μs ²⁺ When reading the amount of radiation accumulated in the photostimulable phosphor of the photostimulable phosphor, stimulating the pulsed excitation light with a pulsed excitation light source having an irradiation time width of 0.8 μs or less of the photostimulable phosphor Irradiate the phosphor. As an example, in order to read the amount of radiation accumulated in the photostimulable phosphor having a fluorescence lifetime of 0.8 μs, the irradiation time width of 1.6 μs, which is twice the stimulable fluorescence lifetime of the photostimulable phosphor, is used. The stimulable phosphor is irradiated with pulsed excitation light with a pulsed excitation light source having At this time, if the amount of radiation accumulated in the photostimulable phosphor is not so strong, only one photostimulable fluorescence is emitted in synchronization with the pulse excitation light as shown in the timing chart of FIG. Random times occur and when they are not released. Therefore, when the fluorescence emitted from the photostimulable phosphor is detected by a photodetector such as a photomultiplier tube and the detected signal is amplified by a preamplifier and a signal amplifier, a signal amplifier output as shown in the figure is obtained. It is done. This output signal is input to a wave height discriminator to obtain a wave height discriminator signal as a digital signal. This pulse height discriminator signal is a read signal generated by a read signal generation circuit using an irradiation time width signal of pulse excitation light generated simultaneously by a pulse generator that generates a laser control signal of a pulse laser light source for excitation light. The coincidence processing can be performed by the coincidence circuit. An output signal from the coincidence circuit is a signal corresponding to one stimulable fluorescence read by the excitation light. The amount of radiation accumulated in the photostimulable phosphor can be determined by counting the coincidence circuit output signal with the counting circuit and processing the data with the data collection / processing circuit.
[0037]
An embodiment of claim 8 will be described with reference to FIG. As an excitation light emitter of the irradiation mechanism for irradiating excitation light in the irradiation mechanism for irradiating the stimulable phosphor with excitation light that reads out the radiation dose accumulated in the stimulable phosphor as a radiation detection medium An optical fiber that emits light from the side is used. As an example, a radiation measurement method using the photostimulable phosphor according to claim 7 is applied and described. Instead of directly irradiating the stimulable phosphor with the excitation light from the excitation pulse laser light source, irradiation is performed using a side-emitting optical fiber having the structure shown in the figure. As the side-emitting optical fiber, Luminous V grade, which is a side leakage optical fiber manufactured by Asahi Kasei, can be used. In addition, a side-emitting optical fiber having a structure in which the entire surface of a normal optical fiber is thinly removed can be used. By using a side-emitting optical fiber, it is not necessary to install an excitation light source at the radiation detection site, and remote sensing is also possible.
[0038]
An embodiment of claim 9 will be described with reference to FIG. An optical fiber that emits light from a side surface that is an excitation light emitter of an irradiation mechanism for irradiating excitation light of the radiation measuring apparatus according to claim 8, wherein the circumferential direction of the optical fiber is as shown in an enlarged view in the figure. An optical fiber that emits light from a side surface at a partial angle is used. As the partial side-emission optical fiber, a partial side-emission optical fiber having a structure in which the entire surface except the light emission surface of a normal optical fiber is thinly removed can be used. The use of a partially radiating optical fiber eliminates the need for an excitation light source at the radiation detection site and emits light only in the direction of irradiation, so the amount of radiation accumulated in the photostimulable phosphor efficiently. Can be read out.
[0039]
An embodiment of claim 10 will be described with reference to FIG. As an embodiment, in the optical fiber in which light is emitted from a side surface at a partial angle in the circumferential direction of the optical fiber of the radiation measuring apparatus according to claim 9, as shown in the drawing, An object of the present invention is to increase the amount of light emitted by arranging a light reflecting material on the upper part of a partly side light emitting fiber and returning leaking light to the radiation surface. With this structure, the amount of radiation accumulated in the photostimulable phosphor can be read out more efficiently.
[0040]
An embodiment of claim 11 will be described with reference to FIG. In the embodiment, an optical fiber (side-emitting optical fiber) having a function of emitting light from the side surface and radiation arranged with a space in order to form a radiation detection unit using a cylindrical photostimulable phosphor. Stimulable phosphor as a detection medium, a bandpass optical filter centered on the fluorescence wavelength disposed outside the stimulable phosphor, and stimulable fluorescence and prompt emission disposed all around the outside of the optical filter A structure in which a number of wavelength shift fibers sensitive to the fluorescence wavelength used for detecting the fluorescence are sequentially arranged, and the periphery thereof is covered with a light shielding body. As the stimulable phosphor, BaFBr: Eu having a fluorescence lifetime of 0.8 μs and a stimulable fluorescence wavelength of 390 nm is used. ²⁺ Is used. In this embodiment, since the stimulable fluorescence wavelength is 390 nm, a fluorescent plastic fiber having a wavelength shift performance with an excitation wavelength width of 320 nm to 395 nm and a center wavelength of the fluorescence wavelength of 450 nm is used as the wavelength shifter. The lifetime of the wavelength-shifted fluorescence is 10 ns or less. In addition, by using the radiation detection part of this structure sensitive to the stimulable fluorescence wavelength of 390 nm as the wavelength shift fiber, complete remote sensing becomes possible and detection of the stimulable phosphor as a radiation detection medium is possible. Since the area can be increased, the radiation detection sensitivity can be increased. Moreover, a highly sensitive radioactive gas detector is obtained by introducing and detecting a radioactive gas in the space between the side-emitting optical fiber and the stimulable phosphor portion.
[0041]
An embodiment of claim 12 will be described with reference to FIG. Also in this example, the photostimulable phosphor is BaFBr: Eu having a fluorescence lifetime of 0.8 μs. ²⁺ Is used. Four optical fibers having a diameter of 1 mm having a function of emitting light from the side surface (side-emitting optical fiber), a stimulable phosphor as a radiation detection medium, a bandpass optical filter having a fluorescence wavelength as a central wavelength, Radiation detection with a structure in which four wavelength-shifting fibers having a diameter of 1 mm sensitive to the wavelengths of stimulable fluorescence and prompt fluorescence used for detecting stimulable fluorescence and prompt fluorescence are sequentially laminated in a planar state Part. FIG. 16 shows an embodiment of a radiation measuring apparatus using this radiation detection unit. By using the radiation detection part of this structure, complete remote sensing is possible. Also. The cross section of the radiation detection unit can be 1 cm × 1 cm or less, and radiation measurement of a place where the installation place is narrow or long is easy.
[0042]
An embodiment of claim 13 will be described with reference to FIG. In this embodiment, four optical fibers having a diameter of 1 mm having a function of emitting light from the side surface (side emission type optical fibers) are used as the central position, and the stimulable phosphor as a radiation detection medium is provided in the upper and lower directions. And four wavelength shifts of 1 mm in diameter sensitive to the wavelength of the stimulable fluorescence and the prompt fluorescence used to detect the stimulable fluorescence and the prompt fluorescence. A radiation detection unit having a structure in which fibers are sequentially laminated in a planar state is used. Since photostimulable phosphors can be used on both sides, the detection sensitivity can be increased and the incident direction of radiation can be estimated.
[0043]
An embodiment of claim 14 will be described with reference to FIG. In this embodiment, four optical fibers having a diameter of 1 mm having a function of emitting light from the side surface (side emission type optical fibers) are used as the central position, and the stimulable phosphor as a radiation detection medium is provided in the upper and lower directions. And four wavelength shifts of 1 mm in diameter sensitive to the wavelength of the stimulable fluorescence and the prompt fluorescence used to detect the stimulable fluorescence and the prompt fluorescence. A radiation detection unit having a structure in which fibers are sequentially laminated in a planar state is used. At this time, the stimulable phosphor, which is two radiation detection media stacked in the upper and lower directions with the optical fiber as the central position, one is a stimulable phosphor, and one is a stimulable phosphor, and neutrons are ionized. A neutron converter / stimulable phosphor mixture that can be detected for neutrons by mixing Gd, which is a neutron converter material that converts to possible radiation. By adopting this structure, neutrons can be detected together with ionizing radiation such as X-rays and gamma rays. In addition, the effects of sensitive X-rays and gamma rays in the neutron converter / stimulable phosphor mixture can be corrected based on the data read only by the stimulable phosphor, so that the neutrons can be accurately detected. The amount can be measured.
[0044]
An embodiment of claim 15 will be described with reference to FIG. Also in this example, the photostimulable phosphor is BaFBr: Eu having a fluorescence lifetime of 0.8 μs. ²⁺ Is used. A 1 mm diameter optical fiber having a function of emitting light from the side surface (side emitting optical fiber), a stimulable phosphor as a radiation detection medium, a bandpass optical filter having a fluorescence wavelength as a central wavelength, A radiation detector having a structure in which a number of wavelength-shifting fibers sensitive to fluorescence wavelengths used to detect stimulable fluorescence and prompt fluorescence arranged all around the outside of the optical filter are sequentially laminated in a cylindrical shape. Use. By using the radiation detection unit of this structure, complete remote sensing is possible. Also. The cross section of the radiation detection unit can be 1 cm or less in diameter, and the radiation measurement of a place where the installation place is narrow or long is easy.
[0045]
An embodiment of claim 16 will be described with reference to FIG. In order to read the radiation dose accumulated in the stimulable phosphor, which is a radiation detection medium with a long distance, including its position information, it is necessary to irradiate the stimulable phosphor with excitation light with a very short pulse width. An irradiation mechanism is used.
[0046]
In the case of the present embodiment, it is necessary to use a stimulable phosphor having a short stimulable fluorescence lifetime in order to increase the position resolution of the radiation measurement place. For this reason, as the stimulable phosphor, the stimulable fluorescence lifetime is as short as 30 ns. ₂ SiO ₂ -Ce is used. The center of the excitation wavelength of this stimulable phosphor is 620 nm. Moreover, the wavelength of the stimulable fluorescence emitted by irradiation with excitation light is 410 nm. Therefore, BaFBr: Eu that has been shown in the above embodiment. ²⁺ Therefore, the same pumping light source and wavelength shift optical fiber can be used. Radiation detectors using this stimulable phosphor are arranged along the measurement site, and excitation light having a pulse width of 2 ns or less is excited on one or more optical fibers having a function of emitting light from the side surface. Irradiate the phosphor. A semiconductor laser or the like can be used as the excitation light source. As the excitation light emitter of this irradiation mechanism, an optical fiber is used that emits light from the entire side surface or a side surface at a partial angle in the circumferential direction to two or more locations in the length direction of the optical fiber. The photostimulable phosphor used as a radiation detection medium, the bandpass optical filter centered on the fluorescence wavelength, and the photostimulability used to detect stimulable fluorescence and prompt fluorescence according to each light emission position. One or more wavelength shift fibers sensitive to the wavelengths of fluorescence and prompt fluorescence are laminated and arranged to constitute a radiation detection unit. The distribution of the incident radiation dose at the radiation measurement location is obtained using the relationship between the time when the pulsed excitation light output from the wavelength shift fiber is incident and the time distribution of the stimulable fluorescence output from the wavelength shift fiber.
[0047]
An embodiment of claim 17 will be described with reference to FIG. About the raw material of the radiation detection part of a present Example, it can be used with the structure substantially the same as the Example of the said Claim 16. FIG. As the excitation light emitter of the irradiation mechanism for irradiating the stimulable phosphor with the excitation light that reads out the radiation dose accumulated in the stimulable phosphor as the radiation detection medium, the entire side surface or a part of the circumference One or more irradiation optical fibers in which an optical fiber that emits light from an angle side surface (partial side-surface light emission type optical fiber), an optical delay mechanism, and a normal optical fiber are alternately connected in order are used. The back side of the section of the side-emitting optical fiber is laminated with a stimulable phosphor that is a radiation detection medium and an optical filter with the fluorescence wavelength as the center wavelength, and is sensitive to one or more photostimulable fluorescence on the back side. A wavelength-shifting optical fiber is disposed. As the optical delay mechanism, an optical fiber having a length corresponding to the delay time is used, and the delay time is 30 ns. By increasing the emission time interval of the excitation light in the section of each side light emitting optical fiber, the arrival time of the excitation light becomes longer, so that the radiation dose at each radiation measurement position can be obtained accurately.
[0048]
An embodiment of claim 18 will be described with reference to FIG. In the present embodiment, the radiation detector shown in claim 12 is used. In the case of this embodiment as well, it is necessary to use a photostimulable phosphor having a short photostimulable fluorescence lifetime in order to increase the position resolution of the radiation measurement place. For this reason, as the stimulable phosphor, the stimulable fluorescence lifetime is as short as 30 ns. ₂ SiO ₂ -Ce is used. The center of the excitation wavelength of this stimulable phosphor is 620 nm. Moreover, the wavelength of the stimulable fluorescence emitted by irradiation with excitation light is 410 nm. Therefore, BaFBr: Eu that has been shown in the above embodiment. ²⁺ Therefore, the same pumping light source and wavelength shift optical fiber can be used. Radiation detectors using this stimulable phosphor are arranged along the measurement site, and excitation light having a pulse width of 2 ns or less is excited on one or more optical fibers having a function of emitting light from the side surface. Irradiate the phosphor. A semiconductor laser or the like can be used as the excitation light source. Time and wavelength shift when pulsed excitation light is incident on one or more optical fibers having the function of detecting the stimulable fluorescence emitted from the stimulable phosphor by the wavelength shift fiber and emitting light from the side of the excitation light source The continuous distribution of the incident radiation dose at the radiation measurement site is obtained using the relationship of the time distribution of the photostimulable fluorescence output from the fiber. In order to realize this operation, as shown in the figure, a signal processing device composed of a photomultiplier tube, a high-speed DC signal amplifier, an analog / digital converter, a storage circuit, and a control / data collection device is used. Measure the time distribution of the output fluorescence. An analog / digital converter having a sampling rate of 100 MHz or more is used. The position resolution at this time is determined by 30 ns of the fluorescence lifetime of the photostimulable phosphor, and is about 10 m in the best case.
[0049]
Claim 19 will be described with reference to FIG. In this embodiment, a streak camera system is used instead of the signal processing device for measuring the fluorescence output from the wavelength shift fiber shown in the embodiment of FIG. The fluorescence output from the wavelength shift fiber is input to the streak tube, and the change is synchronized with the incidence of the pulsed excitation light into the side-emitting optical fiber. Measure the time distribution of the intensity of photostimulable fluorescence. The measured time distribution is recorded in an imaging device such as a CCD camera. As the streak tube, C2830 manufactured by Hamamatsu Hotonkus Co., Ltd. capable of high-speed scanning can be used. The recorded data is taken into the data collection / control apparatus, and the distribution of the incident radiation dose at the radiation measurement location can be obtained based on the time distribution of the fluorescence intensity data. The position resolution at this time is also determined by the fluorescence lifetime of the photostimulable phosphor of 30 ns, and is about 10 m in the best case.
[0050]
According to the invention of claim 20, in the radiation measuring apparatus shown in the embodiments of the above claims 16-19, the measurement work is completed in a very short time. Therefore, the measurement work is performed continuously twice or more. An object of the present invention is to read out a radiation signal accumulated in the photostimulable phosphor of the radiation detection unit. When the length of the radiation detection unit is 100 m, the process ends in 1 μs or less. For this reason, when irradiating the stimulable phosphor with the pulsed excitation light that reads the radiation dose accumulated in the stimulable phosphor, data can be collected in 1 ms even if the pulsed excitation light is repeatedly irradiated 1000 times. . This number can be determined depending on the light output of the laser light. Based on the time distribution of the accumulated fluorescence intensity, the distribution of the incident radiation dose at the radiation measurement place can be obtained with high accuracy.
[0051]
Claim 21 will be described with reference to FIG. In this embodiment, an object is to measure the radiation by arranging a stimulable phosphor as a radiation detection medium at two or more radiation measurement locations. An optical fiber used for irradiating each of the arranged stimulable phosphors with excitation light, the arranged stimulable phosphor, and the stimulable fluorescence emitted from the stimulable phosphor when irradiated with the excitation light And a band-pass optical filter centered on the fluorescence wavelength of prompt fluorescence and one or more wavelength-shifted fibers sensitive to the fluorescence wavelength used for detecting the emitted stimulable fluorescence and prompt fluorescence. The structure radiation detector is used. In order to irradiate each of the stimulable phosphors with excitation light, laser light is incident from a multi-channel excitation light source using an optical fiber. The setting of the measurement position can be selected using a control device, and the photostimulable fluorescence is read by one wavelength shift fiber. The signal processing is performed in synchronization with the excitation light source control signal, and can be performed by a conventional apparatus including a photomultiplier tube, a high-speed pulse signal amplifier, a pulse height discriminator, a counting circuit, and a control device.
[0052]
An embodiment of claim 22 will be described with reference to FIG. In this example, the conventional method is an excitation light source that generates light having a wavelength capable of exciting the stimulable phosphor, and the excitation light output from the excitation light source is rectangularly formed into a sheet-like stimulable phosphor. Exciting light irradiation mechanism, sheet-like photostimulable phosphor, bandpass optical filter centered on the wavelength of stimulable fluorescence, and wavelength-shifted optical fiber that can be excited by stimulable fluorescence Wavelength shifter bundles with side-by-side structures, bandpass optical filters centered on the wavelength of fluorescence shifted by wavelength-shifted optical fibers, and fluorescence emitted from each wavelength-shifted optical fiber of wavelength-shifted optical fiber bundles Sheet-like photostimulable phosphor composed of a multi-channel detectable photodetector and a signal processing device that processes and digitizes the multi-channel detector signal to form a radiation image image ( It is an improvement of the radiation image read-out apparatus which are commercially available) as Imaging plates. In order to irradiate the sheet-like photostimulable phosphor in a rectangular shape with the excitation light output from the excitation light source, instead of the conventional method, an optical fiber having a function of emitting light from the side is used as a sheet-like stimulant. The phosphors are arranged in a plane perpendicular to the wavelength-shifted optical fiber bundle on the surface of the phosphor, and the excitation light is incident on the optical fiber having a function of emitting light from each side in order from the excitation light source. According to the present invention, the mechanism for irradiating the excitation light becomes simple, and the amount of radiation accumulated in the sheet-like photostimulable phosphor can be easily read out including the position information.
[0053]
Claim 23 will be described with reference to FIG. In this embodiment, the fluorescence output to both ends of the wavelength shift fiber of the radiation detector described in the radiation measurement method and the radiation measurement apparatus according to claims 11 to 15 is transmitted through a band-pass optical filter whose center wavelength is the fluorescence wavelength of the fluorescence. After that, detection is performed by a photomultiplier tube which is a photodetector of the fluorescence detection mechanism described in claim 12. By performing this operation, fluorescence output to both ends of the wavelength shift fiber of the radiation detection unit is detected, and the detection efficiency can be approximately doubled.
[0054]
Claim 24 will be described with reference to FIG. The present embodiment is an example in which the radiation measurement method of claim 1 is applied to the radiation measurement apparatus described in the embodiment of claim 12. Radiation measurement method that measures the amount of incident radiation by switching between stimulable fluorescence and prompt fluorescence in a time-division manner and a short-time incidence on a small radiation detection unit that can extend the measurement distance. By adding a radiation measurement method capable of reading out the amount of intense radiation, a highly functional radiation measurement apparatus can be obtained.
[0055]
An embodiment of claim 25 will be described with reference to FIG. The present embodiment is an example in which the signal readout method according to claim 5 of the present invention is applied from the conventional pulse counting method as the signal readout method of the photostimulable fluorescence of the radiation measuring apparatus according to claim 24. As a radiation detector, an optical fiber bundle that emits light from the side surface, a stimulable phosphor that is a radiation detection medium, an optical filter that has a fluorescence wavelength as a central wavelength, and a wavelength-shifted optical fiber bundle that is sensitive to stimulable fluorescence A detector having a structure in which the layers are sequentially laminated is used. Using this radiation detection unit, it is utilized that the stimulable phosphor has two actions of stimulating fluorescence emitted depending on the amount of radiation incident upon irradiation of excitation light and prompt fluorescence due to incident radiation. Thus, a differential integration type radiation measuring apparatus that detects and switches between stimulable fluorescence and prompt fluorescence in a time division manner is constructed. Saturation of the fluorescence detection mechanism due to high-intensity radiation is monitored by a saturation monitoring circuit in a time division manner, and after the saturation state is recovered, a high-intensity radiation dose incident in a short time is read out using stimulable fluorescence.
[0056]
At this time, the amount of excitation light applied to the photostimulable phosphor is changed, and the radiation dose is measured in a state where the fluorescence detection mechanism is not saturated. To read the radiation dose, the stimulable phosphor is irradiated with pulsed excitation light with a short time width, and the emitted stimulable fluorescence is detected by a photodetector and amplified by a charge-sensitive preamplifier. After the waveform shaping by the pulse shaping amplifier, the radiation amount accumulated in the photostimulable phosphor is obtained by the data collection processing circuit based on the peak value by the analog-digital converter.
[0057]
Claim 26 will be described with reference to FIG. In this embodiment, a neutron imaging plate containing Gd, which is a neutron converter material that converts neutrons into ionizable radiation, instead of the photostimulable phosphor that is the radiation detection medium of the radiation measuring apparatus according to claim 24. This is an example using a BAS-ND series neutron imaging plate manufactured by Fuji Photo Film. By using a radiation detection medium in which a neutron converter material is mixed with stimulable fluorescence as in this embodiment, a radiation measuring apparatus capable of measuring neutrons having the functions described in the above embodiments of the present invention can be configured. .
[0058]
Claim 27 will be described with reference to FIG. In this embodiment, the radiation measuring apparatus described in the embodiment of claim 24 is used to emit the stimulable fluorescence of the stimulable phosphor that is a radiation detection medium, and to emit light with a time called fading. Focusing on the phenomenon that the radiation signal gradually disappears from the fluorescent phosphor, depending on the temperature, the temperature of the stimulable phosphor is measured by adding a temperature sensor and a temperature detection circuit. Based on this measured temperature, the data collection and processing circuit corrects the amount of radiation accumulated in the stimulable phosphor measured by the excitation light irradiation, so that the accuracy even if the temperature of the radiation detector changes The amount of radiation can be measured well.
[0059]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0060]
One detector with a wide dynamic range from a very weak radiation dose to a very strong radiation dose by determining the amount of incident radiation in real time from the measurement results of stimulable fluorescence and prompt fluorescence measured in time division It is possible to measure the radiation dose by high-intensity radiation and neutron beam that is covered by and instantly generated.
[0061]
Excitation light having a short time width is irradiated onto the stimulable phosphor, and signal processing can be performed using a conventional radiation detection system by utilizing the fact that the stimulable fluorescence lifetime is short.
By using an optical fiber that emits light from the side, it is possible to irradiate the stimulable phosphor easily and remotely, and it is necessary to install a light source such as a laser light source in a place with a strong radiation dose. A small excitation light irradiation mechanism can be configured.
[0062]
Wavelength-shift fibers sensitive to the fluorescence wavelengths of stimulable fluorescence and prompt fluorescence are arranged in parallel to ensure the detection area and to detect photostimulable fluorescence. It is possible to eliminate the need to install in a strong place.
[0063]
A combination of wavelength-shifted fibers arranged in parallel and an optical fiber that emits light from the side, and a laminated structure with a stimulable phosphor and optical filter sandwiched between them. A detection unit can be constructed.
[0064]
Extending the detection part of the above laminated structure long, the excitation light having an extremely short pulse width is incident on the optical fiber that emits light from the side surface, the short pulse width excitation light propagates and is irradiated to the photostimulable phosphor, By detecting the emitted photostimulable fluorescence with a wavelength-shifted optical fiber bundle in which wavelength-shifted optical fibers are arranged, it is possible to measure the position distribution of the radiation dose over a long distance.
[0065]
A radiation measuring device that detects neutrons by using a neutron detector containing, mixed with, or combined with a neutron converter material such as Gd that converts neutrons into ionizable radiation in a stimulable phosphor. Can do.
[0066]
By using the above radiation measurement device and measurement method, a single detector covers a wide dynamic range from very weak radiation doses to very strong radiation doses, and high-intensity radiation and neutron beams that are generated instantaneously By making it possible to measure the radiation dose due to the high-intensity radiation and neutron radiation generated by unforeseen accidents such as high-intensity radiation and neutron beams that are generated instantaneously around the accelerator, etc. or around the target The amount can be measured simply, with high sensitivity and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing a differential integration type radiation measuring apparatus using a method of reading the amount of excitation light.
FIG. 2 is a diagram showing timing for monitoring photostimulable fluorescence and saturation in a time division manner.
FIG. 3 is a diagram showing a differential integration type radiation measurement apparatus using a method of reading out photostimulable fluorescence by changing fluorescence detection sensitivity.
FIG. 4 is a diagram showing a differential integration type radiation measuring apparatus using a method of reading out stimulable fluorescence by changing the amount of excitation light.
FIG. 5 is a diagram showing a differential integration type radiation measuring apparatus using a method for correcting the effect of prompt fluorescence incidentally incident upon radiation measurement by stimulable fluorescence.
FIG. 6 is a diagram showing a method of reading the radiation dose accumulated in the stimulable phosphor by irradiating the stimulable phosphor with pulsed excitation light.
FIG. 7 is a diagram showing signal timings in a method of reading a stored radiation dose by irradiating a stimulable phosphor with pulsed excitation light.
FIG. 8 is a diagram showing a method of reading out the radiation dose accumulated in the photostimulable phosphor using a gated photomultiplier tube as a photodetector.
FIG. 9 is a diagram showing a method of reading out the radiation dose accumulated in the photostimulable phosphor, characterized in that the pulse excitation light and the photostimulable fluorescence signal are simultaneously counted.
FIG. 10 is a diagram showing timing of simultaneous counting of a read signal and a stimulable fluorescence signal produced based on pulsed excitation light.
FIG. 11 is a diagram showing a radiation measuring apparatus using a photostimulable phosphor that emits excitation light using an optical fiber that emits light from a side surface.
FIG. 12 is a diagram showing a radiation measuring apparatus using a stimulable phosphor that emits excitation light using an optical fiber that emits light from some side surfaces;
FIG. 13 is a diagram showing a radiation measuring apparatus using a stimulable phosphor that irradiates excitation light by arranging a light reflecting material behind an optical fiber that irradiates light from some side surfaces.
FIG. 14 is a diagram showing a radiation detection unit using a photostimulable phosphor using an optical fiber that emits light from the side surface and a wavelength-shifted optical fiber that is sensitive to the fluorescence wavelength.
FIG. 15 is a view showing a radiation detector having a structure in which a side-emitting optical fiber, a stimulable phosphor, an optical filter, and a wavelength-shifted optical fiber are sequentially laminated in a planar state.
FIG. 16 is a view showing a radiation measuring apparatus using a photostimulable phosphor using a radiation detection unit having a structure laminated in a planar state.
FIG. 17 is a view showing a radiation detection unit having a structure in which a side-emitting optical fiber, a photostimulable phosphor, an optical filter, and a wavelength-shifted optical fiber are sequentially stacked in a planar state.
FIG. 18 is a diagram showing a radiation detection unit characterized in that two types of photostimulable phosphors are used in a radiation detection unit having a structure in which layers are sequentially stacked in a planar state.
FIG. 19 is a diagram showing a radiation detector having a structure in which a side-emitting optical fiber, a photostimulable phosphor, an optical filter, and a wavelength-shifted optical fiber are sequentially laminated in a cylindrical shape.
FIG. 20 is a diagram showing a radiation measuring apparatus capable of measuring the position distribution of radiation by connecting a large number of radiation detecting units using stimulable phosphors in series.
FIG. 21 is a diagram showing a radiation measuring apparatus in which a large number of radiation detection units using stimulable phosphors are connected in series using an optical delay mechanism and the position distribution of radiation can be measured.
FIG. 22 is a diagram showing a radiation measuring apparatus that can measure the position distribution of radiation by a radiation detection unit having a structure in which the pulse excitation light is sequentially stacked in a planar state.
FIG. 23 is a diagram showing a radiation measuring apparatus that uses a radiation detection unit and a streak camera that are stacked in order in a planar state and that can measure the position distribution of radiation using pulsed excitation light.
FIG. 24 makes it possible to measure the position distribution of radiation, which is characterized by reading photostimulable fluorescence accumulated in a number of photostimulable phosphors arranged at a radiation measurement site with a single wavelength-shifted optical fiber bundle. It is a figure which shows a radiation measuring device.
FIG. 25 is a diagram showing a two-dimensional radiation image measurement apparatus using a side-emitting optical fiber for excitation light emission.
FIG. 26 is a diagram showing a radiation measuring apparatus characterized in that fluorescence output to both ends of a wavelength shift optical fiber of a radiation detecting unit having a structure in which layers are sequentially laminated is measured by the same light detecting unit.
FIG. 27 is a diagram showing a differential integration type radiation detector using a radiation detection unit having a structure in which layers are sequentially stacked in a planar state.
FIG. 28 shows a differential integration type radiation detector in which a stimulable fluorescence readout method using pulsed excitation light is applied to a radiation detector having a structure in which layers are sequentially stacked in a plane state.
FIG. 29 is a diagram showing a differential integration type radiation detector capable of measuring neutrons using a neutron converter and a photostimulable phosphor as a radiation detection medium.
FIG. 30 shows a differential integration type radiation detector characterized in that the amount of radiation accumulated in the stimulable phosphor is corrected based on the temperature of the stimulable phosphor measured by the temperature line sensor. FIG.
31 is omitted from FIG.
32 is omitted from FIG. 32.
33 is omitted from FIG.
FIG. 34 is omitted.
FIG. 35 is omitted.
FIG. 36 is omitted.
37 is omitted from FIG.
38 is omitted from FIG.
FIG. 39 is omitted.
FIG. 40 is a diagram showing a conventional photostimulable fluorescence readout method.
FIG. 41 is a diagram showing a radiation measurement method using a conventional photostimulable phosphor using a radiation detection unit in which a small amount of photostimulable phosphor is attached to the tip of an optical fiber.
FIG. 42 is a diagram showing a conventional method of reading the amount of radiation accumulated in the photostimulable phosphor with a pulse light source.
FIG. 43 is a diagram showing an example of the reading timing of photostimulable fluorescence after irradiation with pulsed excitation light in the conventional method and the emission characteristics of photostimulable fluorescence obtained by the conventional high-speed counting method.
FIG. 44 is a diagram showing a conventional method for simultaneously measuring a radiation dose and a measurement position using a scintillator and an optical fiber.
FIG. 45 is a diagram showing a radiation detection unit of a conventional method for simultaneously measuring a radiation dose and a measurement position using a scintillator and a wavelength shift optical fiber.

Claims (27)

Stimulable phosphor, excitation light source for irradiating the stimulable phosphor with excitation light that reads out the amount of radiation accumulated in the stimulable phosphor in a time-sharing manner, and a bandpass centered on the fluorescence wavelength Optical filter, photodetector for detecting stimulable fluorescence and prompt fluorescence, and signal for amplifying and processing the stimulable fluorescence signal and prompt fluorescence signal of the stimulable phosphor output from the photodetector A processing circuit, a mode switching circuit that switches between a stimulable fluorescent signal and an immediate fluorescent signal of the stimulable phosphor in a time-division manner, a saturation monitoring circuit that monitors the operating state of a fluorescence detection mechanism for detecting fluorescence, and a saturation LED used for monitoring, excitation light / light quantity changing circuit for changing the amount of excitation light, control circuit for controlling the excitation light source, mode switching circuit, saturation monitoring circuit and excitation light / light quantity changing circuit in a time-sharing manner, Stimulability to measure exhaustive fluorescence And an optical data acquisition circuit, and a prompt fluorescence data acquisition circuit for measuring the prompt fluorescence, a radiation measurement apparatus using a stimulable phosphor,
The stimulable phosphor, which is a radiation detection medium, accumulates incident radiation and can read out the amount of incident radiation as stimulable fluorescence by excitation light, and can emit fluorescence immediately by incident radiation. Utilizing the two functions, the fluorescence detection mechanism for detecting stimulable fluorescence and prompt fluorescence can be used in a short time to detect stimulable fluorescence and prompt fluorescence in a time-sharing manner. When intense radiation is incident and the fluorescence detection mechanism saturates and its function stops, the fluorescence detection mechanism saturates in a time division when measuring the amount of incident radiation after reading the stimulable fluorescence after the fluorescence detection mechanism recovers. When the amount of intense radiation incident in a short period of time is read after the saturation state is recovered, the amount of excitation light applied to the stimulable phosphor is changed by the excitation light / light amount change circuit, and the fluorescence is changed. Detection mechanism In the absence of saturating it was characterized by measuring the amount of radiation accumulated in the stimulable phosphor body, the device. Stimulable phosphor, excitation light source for irradiating the stimulable phosphor with excitation light that reads out the amount of radiation accumulated in the stimulable phosphor in a time-sharing manner, and a bandpass centered on the fluorescence wavelength Optical filter, photodetector for detecting stimulable fluorescence and prompt fluorescence, and signal for amplifying and processing the stimulable fluorescence signal and prompt fluorescence signal of the stimulable phosphor output from the photodetector A processing circuit, a mode switching circuit that switches between a stimulable fluorescent signal and an immediate fluorescent signal of the stimulable phosphor in a time-division manner, a saturation monitoring circuit that monitors the operating state of a fluorescence detection mechanism for detecting fluorescence, and a saturation LED used for monitoring, fluorescence detection sensitivity changing circuit, excitation light source operating in time division, control circuit for controlling mode switching circuit and saturation monitoring circuit, and stimulable fluorescence data collecting circuit for measuring stimulable fluorescence And measure immediate fluorescence That prompt and a fluorescence data acquisition circuit, a radiation measurement apparatus using a stimulable phosphor,
The stimulable phosphor, which is a radiation detection medium, accumulates incident radiation and can read out the amount of incident radiation as stimulable fluorescence by excitation light, and can emit fluorescence immediately by incident radiation. Using the fluorescence detection mechanism for detecting photostimulable fluorescence and prompt fluorescence by using two actions, a short time is required when stimulating fluorescence and prompt fluorescence are detected in time division. When the fluorescence detection mechanism saturates and the function stops when a strong radiation is incident on the light source, the stimulating fluorescence is read out after recovery of the fluorescence detection mechanism and the amount of incident radiation is measured in a time-sharing manner. When the saturation is monitored and the amount of intense radiation incident in a short time is read after the saturation state is restored, the fluorescence detection sensitivity is changed by changing the fluorescence detection sensitivity of the fluorescence detection mechanism using the fluorescence detection sensitivity change circuit. Mechanism in the absence of saturating was characterized by measuring the amount of radiation accumulated in the stimulable phosphor body, the radiation measuring device. Stimulable phosphor, excitation light source for irradiating the stimulable phosphor with excitation light that reads out the amount of radiation accumulated in the stimulable phosphor in a time-sharing manner, and a bandpass centered on the fluorescence wavelength Optical filter, photodetector for detecting stimulable fluorescence and prompt fluorescence, and signal for amplifying and processing the stimulable fluorescence signal and prompt fluorescence signal of the stimulable phosphor output from the photodetector A processing circuit, a mode switching circuit that switches between a stimulable fluorescent signal and an immediate fluorescent signal of the stimulable phosphor in a time-division manner, a saturation monitoring circuit that monitors the operating state of a fluorescence detection mechanism for detecting fluorescence, and a saturation LED used for monitoring, fluorescence detection sensitivity changing circuit, excitation light / light quantity changing circuit for changing the light quantity of excitation light, excitation light source, mode switching circuit, saturation monitoring circuit and excitation light / light quantity changing circuit in time division Control circuit to control and brightness A stimulable phosphor data acquisition circuit that measures sexual fluorescence, and a prompt fluorescence data acquisition circuit for measuring the prompt fluorescence, a radiation measurement apparatus using a stimulable phosphor,
The stimulable phosphor, which is a radiation detection medium, accumulates incident radiation and can read out the amount of incident radiation as stimulable fluorescence by excitation light, and can emit fluorescence immediately by incident radiation. Utilizing the two functions, the fluorescence detection mechanism for detecting stimulable fluorescence and prompt fluorescence can be used in a short time to detect stimulable fluorescence and prompt fluorescence in a time-sharing manner. When intense radiation is incident and the fluorescence detection mechanism saturates and its function stops, the fluorescence detection mechanism saturates in a time division when measuring the amount of incident radiation after reading the stimulable fluorescence after the fluorescence detection mechanism recovers. When the amount of intense radiation incident in a short time is read after the saturation state is recovered, the amount of excitation light irradiated to the stimulable phosphor is changed by the excitation light / light amount change circuit, and fluorescence The amount of radiation accumulated in the photostimulable phosphor is measured in a state where the fluorescence detection mechanism is not saturated by changing the fluorescence detection sensitivity of the photodetector by the output sensitivity change circuit. The device. Stimulable phosphor, excitation light source for irradiating the stimulable phosphor with excitation light that reads out the amount of radiation accumulated in the stimulable phosphor in a time-sharing manner, and a bandpass centered on the fluorescence wavelength Optical filter, photodetector for detecting stimulable fluorescence and prompt fluorescence, and signal for amplifying and processing the stimulable fluorescence signal and prompt fluorescence signal of the stimulable phosphor output from the photodetector A processing circuit, a mode switching circuit that switches between a stimulable fluorescent signal and an immediate fluorescent signal of the stimulable phosphor in a time-division manner, a saturation monitoring circuit that monitors the operating state of a fluorescence detection mechanism for detecting fluorescence, and a saturation LED used for monitoring, fluorescence detection sensitivity changing circuit, excitation light / light quantity changing circuit for changing the light quantity of excitation light, excitation light source, mode switching circuit, saturation monitoring circuit and excitation light / light quantity changing circuit in time division Control circuit to control and brightness Stimulating fluorescence data collection circuit that measures stimulating fluorescence, prompt fluorescence data collection circuit that measures prompt fluorescence, and data of stimulating fluorescence and prompt fluorescence collected in time division while synchronizing with the control circuit A radiation measurement device using a stimulable phosphor, comprising a data processing circuit for determining the amount of incident radiation from the results,
The stimulable phosphor, which is a radiation detection medium, accumulates incident radiation and can read out the amount of incident radiation as stimulable fluorescence by excitation light, and can emit fluorescence immediately by incident radiation. Utilizing the two functions, the fluorescence detection mechanism for detecting the stimulable fluorescence and the prompt fluorescence is used to detect the stimulable fluorescence and the prompt fluorescence in a time-sharing manner. The mechanism was monitored for saturation, and after the saturation state was recovered, when intense radiation was incident in a short period of time and the fluorescence detection mechanism was saturated and its function stopped, the stimulable fluorescence was read and entered after the recovery of the fluorescence detection mechanism. In measuring the amount of radiation, the amount of radiation accumulated in the photostimulable phosphor in a time-sharing manner is measured using photostimulable fluorescence using a fluorescence detection mechanism for detecting stimulable fluorescence and prompt fluorescence. Sometimes accidental Measures the amount of incident radiation by correcting the contribution due to prompt fluorescence that is incident on and measured based on the amount of radiation measured by time-divided fluorescence using the data processing circuit of the fluorescence detection mechanism. The device. Stimulable phosphors as radiation detection media, optical filters, photodetectors, charge-sensitive preamplifiers, pulse shaping amplifiers, analog / digital converters, data acquisition / processing circuits, pulse generators, and pulsed laser light sources for excitation Using a radiation measuring device that measures the amount of incident radiation with
A radiation measurement method using a stimulable phosphor that uses a stimulable phosphor having a fluorescence lifetime of 2 μs or less as a radiation detection medium and reads the amount of radiation accumulated in the stimulable phosphor. The stimulable phosphor is irradiated with pulsed excitation light having an irradiation time width less than the stimulable fluorescence lifetime of the stimulable phosphor, and the fluorescence emitted from the stimulable phosphor is detected by a photodetector. The amplified signal is amplified by a charge-sensitive preamplifier, the amplified signal is input to a pulse shaping amplifier, and the waveform is shaped with a waveform shaping time constant that is longer than the stimulable fluorescence lifetime of the stimulable phosphor. By shaping and amplifying, a pulse height signal obtained by integrating the photostimulable fluorescence emitted after irradiation with pulsed excitation light is obtained, and this pulse height signal is input to an analog / digital converter, and the peak value is obtained. Using a data collection and processing circuit The amount of radiation accumulated in the photostimulable phosphor is obtained by integrating the peak values obtained for each pulsed excitation light generated by the pulsed laser light source for excitation light based on the laser control signal from the laser, Method.   Using a photomultiplier tube with a gate as a photodetector, the photoelectron is synchronized with the operation of irradiating the stimulable phosphor with pulsed excitation light having an irradiation time width less than the stimulable fluorescence lifetime of the stimulable phosphor. Control the gate of the multiplier tube, stop the operation of the photomultiplier tube during the irradiation time zone, control the gate of the photomultiplier tube after irradiation of the excitation light, operate the photomultiplier tube, and pump light 6. The radiation measuring method according to claim 5, wherein the stimulable fluorescence emitted after the irradiation is detected to determine the amount of radiation accumulated in the stimulable phosphor. Stimulable phosphors as radiation detection media, optical filters, photodetectors, signal amplifiers, pulse height discriminators, coincidence counting circuits, counting circuits, data collection / processing circuits, pulse generators, read signal generating circuits, and excitation pulses Using a radiation measurement device equipped with a laser light source,
A radiation measurement method using a photostimulable phosphor that uses a photostimulable phosphor having a fluorescence lifetime of 2 μs or less as a radiation detection medium and reads the amount of radiation accumulated in the photostimulable phosphor. ,
The photostimulable fluorescence emitted from the photostimulable phosphor is detected by irradiating the photostimulable phosphor with pulsed excitation light having an irradiation time width less than twice the stimulable fluorescence lifetime of the photostimulable phosphor. The detected signal is amplified by a signal amplifier, the amplified output signal is input to the pulse height discriminator, and the photostimulable fluorescence signal is extracted as a pulse signal. This pulse signal and a pulse generator By using the irradiation time width signal of the generated pulse excitation light, the readout signal produced by the readout signal generation circuit and the coincidence counting process are performed simultaneously by the coincidence counting circuit, so that the stimulable fluorescence is emitted according to the fluorescence lifetime after irradiating the pulse excitation light. The method, wherein a photostimulable fluorescence signal is taken out by using the output of the signal, the signal is measured by a counting circuit, and the amount of radiation accumulated in the photostimulable phosphor is determined. Radiation comprising a stimulable phosphor as a radiation detection medium, an optical filter, a photodetector, a signal amplifier, a pulse height discriminator, a gate circuit, a counting circuit, a data collection / processing circuit, a pulse generator, and a pulse laser light source for excitation Using measuring equipment,
The photostimulable fluorescence emitted from the photostimulable phosphor is detected by a light detector, the detected signal is amplified by a signal amplifier, and the amplified signal is input to the pulse height discriminator and stimulated fluorescence. The signal is extracted as a pulse signal, and the signal obtained by the gate circuit using this pulse signal and the pulse excitation light irradiation time width signal generated by the pulse generator is measured by the counting circuit and stored in the photostimulable phosphor. A radiation measurement method using a stimulable phosphor for determining the amount of emitted radiation,
When irradiating the stimulable phosphor with the excitation light that reads out the amount of radiation accumulated in the stimulable phosphor, which is a radiation detection medium, light is emitted from the side as an excitation light emitter for irradiating the excitation light. The above-mentioned method using a side-emitting optical fiber having a function of emitting.   As a side-emitting optical fiber that emits light from the side that is used as the excitation light emitter for irradiating the excitation light, a part of the side light emission that emits light from the side of the optical fiber at a part angle The radiation measurement method according to claim 8, wherein a type optical fiber is used.   When using a side-emitting optical fiber that emits light from a side surface at a certain angle in the circumferential direction of the optical fiber, the side opposite to the angle, the side opposite to the angle, or all sides except the angle The radiation measuring method according to claim 9, wherein an optical fiber having a structure in which a light reflecting material is disposed on the optical fiber. A radiation measurement device using a stimulable phosphor equipped with a radiation detector, wavelength shift optical filter, photomultiplier tube, signal amplifier, pulse height discrimination circuit, counting circuit, control / data concentration device, and excitation light source There,
The photostimulable fluorescence emitted from the photostimulable phosphor is detected by a photodetector comprising a photomultiplier tube, the detected signal is amplified by a signal amplifier, and the amplified signal is input to the pulse height discrimination circuit. Then, the stimulable fluorescence signal is taken out as a pulse signal, this pulse signal is measured by a counting circuit, and the amount of radiation accumulated in the stimulable phosphor is determined.
Sensitive to one or more optical fibers that emit light from the side, a stimulable phosphor as a radiation detection medium, a bandpass optical filter centered on the fluorescence wavelength, and a stimulable fluorescence wavelength The apparatus using a radiation detector having a structure in which one or more wavelength-shifted optical fibers are sequentially arranged.   One or more optical fibers capable of emitting light from the side, a stimulable phosphor as a radiation detection medium, a bandpass optical filter centered on the fluorescence wavelength, and one sensitive to the stimulable fluorescence wavelength The radiation measurement apparatus according to claim 11, wherein a radiation detection unit having a structure in which the wavelength-shifted optical fibers are stacked in a planar state in order is used.   Centered on one or more optical fibers having a function of emitting light from the side surface, in the upper and lower directions, a stimulable phosphor as a radiation detection medium, a bandpass optical filter having a fluorescence wavelength as a central wavelength, and a stimulator 13. The radiation measuring apparatus according to claim 12, wherein a radiation detecting unit having a structure in which one or more wavelength-shifted optical fibers sensitive to the characteristic fluorescence wavelength are laminated in a planar state in order.   Two photostimulable phosphors laminated in a planar state with one or more optical fibers having a function of emitting light from the side as a central position and in the upper and lower directions have different detection performances for radiation 2 The radiation measuring apparatus according to claim 11, wherein a radiation detecting unit which is a kind of stimulable phosphor is used. Centering on one or more optical fibers that emit light from the side, stimulating phosphors that are radiation detection media, bandpass optical filters centered on the fluorescence wavelength, stimulating fluorescence and prompt fluorescence 12. The radiation detection unit having a structure in which one or more wavelength-shifted optical fibers sensitive to the wavelengths of stimulable fluorescence and prompt fluorescence used for detection are laminated in a cylindrical shape in order. Radiation measurement equipment. Side-emitting optical fiber, photostimulable phosphor as radiation detection medium, optical filter for stimulable fluorescence, radiation detection unit including wavelength-shifted optical fiber, wavelength-shifting optical filter, and photomultiplier tube And a radiation measurement device using a stimulable phosphor having a high-speed signal amplifier, an analog / digital converter, a storage circuit, a control / data collection device, and an excitation pulse laser light source,
The stimulable phosphor is irradiated with pulsed excitation light, the fluorescence emitted from the stimulable phosphor is detected with a photomultiplier tube, the detected signal is amplified with a high-speed signal amplifier, and the amplified signal is output. In order to obtain the amount of radiation accumulated in the photostimulable phosphor by collecting the converted signal into an analog / digital converter and collecting the converted signal in a control / data collection device via a storage circuit,
Two or more radiation detectors are used, one or more optical fibers having a function of emitting light from the side surfaces of the respective radiation detectors, and one or more wavelengths sensitive to the respective stimulable fluorescence wavelengths. A radiation measuring apparatus using a photostimulable phosphor, characterized by using a radiation detection unit having a structure in which a shift optical fiber is connected by an optical fiber.   One or more optical fibers having a function of emitting light from the side surface of each radiation detection unit using two or more radiation detection units, and one or more wavelength-shifted lights sensitive to the respective stimulable fluorescence wavelengths When a fiber is connected by an optical fiber, the optical delay mechanism is connected between optical fibers that connect one or more optical fibers having a function of emitting light from each side surface. The apparatus of claim 16.   The radiation detector is placed at a long distance along the radiation measurement site, and pulse excitation light with a time width less than the fluorescence lifetime of the stimulable phosphor is incident on one or more optical fibers that have the function of emitting light from the side. Detecting photostimulable fluorescence emitted from photostimulable phosphors through a wavelength-shifted optical fiber, and entering pulsed excitation light into one or more optical fibers having a function of emitting light from the side surface from an excitation light source The position distribution of the amount of radiation incident on the radiation measurement location is obtained using the relationship between the measured time and the time distribution of the stimulable fluorescence intensity detected by the detection unit. The apparatus in any one of. A side-emitting optical fiber, a stimulable phosphor as a radiation detection medium, an optical filter for stimulable fluorescence, and a radiation detection unit including a wavelength shift optical fiber, a wavelength shift optical filter, a streak tube, A radiation measurement device using a stimulable phosphor having an imaging device, a data collection / control device, and an excitation pulse laser light source,
Using a streak camera as a photodetector used to detect the stimulable fluorescence output from the wavelength-shifted optical fiber, measure the time distribution of the intensity of the stimulable fluorescence while synchronizing with the pulsed excitation light. Using the relationship between the time at which pulsed excitation light is incident on one or more optical fibers that emit light from the side and the time distribution of the stimulable fluorescence intensity detected by the photodetector, it is incident on the radiation measurement site. Determining the position distribution of the amount of radiation to be emitted.   Stimulated fluorescence emitted from the stimulable phosphor is incident on one or more optical fibers having a function of emitting light from the side by applying pulse excitation light having a time width less than the fluorescence lifetime of the stimulable phosphor. A function that repeats the detection operation through the wavelength-shifted optical fiber twice or more, accumulates the time distribution of the stimulable fluorescence intensity, and emits light from the excitation light source based on the time distribution of the accumulated fluorescence intensity The amount of radiation incident on the radiation measurement site is determined using the relationship between the time at which the pulse excitation light is incident on one or more optical fibers capable of performing the above and the time distribution of the stimulable fluorescence intensity detected by the photodetector. The radiation measurement apparatus according to claim 16, wherein a position distribution is obtained. An optical fiber for exciting light irradiation, a photostimulable phosphor as a radiation detection medium, an optical filter for photostimulable phosphor, and a radiation detection unit including a wavelength shift optical fiber, a wavelength shift optical filter, and a photomultiplier tube And a radiation measuring device using a stimulable phosphor having a high-speed pulse signal amplifier, a pulse height discriminator, a counting circuit, a control device, and a multi-channel excitation light source,
Two or more photostimulable phosphors are used as a radiation detection medium, an excitation light irradiation optical fiber used for irradiating each of the photostimulable phosphors with excitation light, two or more photostimulable phosphors, and An optical filter for a stimulable phosphor having a stimulable fluorescence wavelength of the stimulable fluorescence emitted from the stimulable phosphor when the stimulable phosphor is irradiated with excitation light, Stimulability characterized by using a radiation detector having a structure in which one or more wavelength-shifted optical fibers sensitive to stimulable fluorescence wavelength for detecting stimulable fluorescence output from the optical filter are arranged Radiation measurement device using phosphor. Multi-channel excitation light generator that generates light of a wavelength that can excite the stimulable phosphor, and excitation light irradiation mechanism that makes the excitation light output from the light generator rectangular to a sheet-like stimulable phosphor And a sheet-like photostimulable phosphor, a bandpass optical filter centered on the wavelength of the photostimulable fluorescence, and a wavelength-shifted optical fiber that can be excited by photostimulable fluorescence arranged in a plane. A multi-channel shift optical fiber bundle, a bandpass optical filter centered on the wavelength of the fluorescence wavelength shifted by the wavelength shift optical fiber, and the fluorescence emitted by each wavelength shift optical fiber of the wavelength shift optical fiber bundle Radiation of a sheet-like photostimulable phosphor consisting of a detectable photodetector and a signal processing device that processes and digitizes the multi-channel detector signal to form a radiation image. An image reading apparatus,
In order to irradiate the sheet-like photostimulable phosphor in a rectangular shape with the excitation light output from the excitation light source, an optical fiber having a function of emitting light from the side surface has a wavelength on the surface of the sheet-like stimulable phosphor. The amount of radiation accumulated in the sheet-like photostimulable phosphor by arranging excitation light from the excitation light source sequentially into an optical fiber that has a function of emitting light from each side, arranged in a plane perpendicular to the shift optical fiber bundle A radiation measuring apparatus using a photostimulable phosphor, characterized in that a radiation image is obtained by reading out information including positional information.   The photostimulable fluorescence output to both ends of the wavelength-shifted optical fiber is detected by a photodetector after passing through a band-pass optical filter whose center wavelength is the fluorescence wavelength of the fluorescence that is shifted in wavelength. The apparatus according to claim 11.   Using stimulable phosphors that have two functions: storing incident radiation and reading out the amount of radiation incident as stimulable fluorescence by excitation light; and generating fluorescence immediately by incident radiation The radiation measurement apparatus using the photostimulable phosphor according to any one of claims 8 to 23, wherein the radiation measurement is performed.   When measuring the amount of radiation accumulated in the photostimulable phosphor, a stimulable phosphor having a fluorescence lifetime of 2 μs is used, and radiation measurement is performed to measure the amount of radiation accumulated in the photostimulable phosphor. A radiation measurement method using the photostimulable phosphor according to any one of claims 8 to 10. A radiation detection unit including a neutron imaging plate (neutron converter / stimulable phosphor mixture), a stimulable phosphor as a radiation detection medium, an optical filter for stimulable phosphor, and a wavelength-shifted optical fiber, and a wavelength Shift optical filter, photomultiplier tube, signal multiplier, wave height discriminator, mode switching circuit, stimulating fluorescence counting circuit, data collection / processing circuit, prompt fluorescence counting circuit, A radiation measuring device using a stimulable phosphor having a control circuit, a saturation monitoring circuit, an excitation light / light quantity changing circuit, and an excitation light source,
Use a radiation detection medium for detecting neutrons containing at least one kind of Gd, ⁶ Li or ¹⁰ B, which is a neutron converter material that converts neutrons into ionizable radiation, for the stimulable phosphor that is the radiation detection medium. The neutron can be detected by the apparatus. Stimulable phosphor that is a radiation detection medium, an optical filter for stimulable fluorescence, a side-emitting optical fiber, a radiation detection unit including a wavelength shift optical fiber, an optical filter for wavelength shift, and a photomultiplier tube A signal multiplier, a pulse height discriminator, a mode switching circuit, a stimulating fluorescence counting circuit, a data collection / processing circuit, a prompt fluorescence counting circuit, a control circuit, a saturation monitoring circuit, A radiation measuring device using a stimulable phosphor having an excitation light / light quantity changing circuit, an excitation light source, a temperature sensor, and a temperature detection circuit,
The temperature of the photostimulable phosphor is measured by a temperature sensor, and the amount of radiation accumulated in the photostimulable phosphor measured by irradiation of excitation light is corrected based on the measured temperature. The device.

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