JP6199282B2 - Radiation measurement apparatus and radiation measurement system - Google Patents

Description

  The present invention relates to a radiation measurement apparatus for identifying a radiation source, determining a radiation dose and a flying direction, or measuring a spatial intensity distribution of radiation, and a radiation measurement system incorporating such a radiation measurement apparatus.

  As a radiation measurement device, a device including three detection units each having a scintillator, a photomultiplier tube, and an orientation-dependent collimator is known in order to detect the radiation direction of radiation (Patent Document 1). reference).

  However, identification of a radiation source, determination of an accurate dose and direction of radiation, and measurement of a spatial distribution of radiation intensity from an object have not been sufficiently performed so far. Even when a scintillator is used as described above, the reaction frequency of a single substance, that is, the incidence of radiation is only counted, and the energy of radiation cannot be identified even if the incident direction can be identified by a collimator.

  As a conventional gamma ray detector, there is one that detects gamma rays by pixel reading of a semiconductor element. In this case, imaging is possible, but sensitivity is limited. That is, in a sensor of a semiconductor element, most of gamma rays pass through without leaving a reaction trace, and it is difficult to increase reaction efficiency at a low cost.

JP 2004-170125 A

  The present invention provides a radiation measurement apparatus and a radiation measurement system capable of identifying a radiation source, determining an accurate dose of radiation and a flying direction, or measuring a spatial distribution of radiation intensity from an object. Objective.

Multiple order to achieve the above object, a radiation measuring device according to the present invention, having an azimuth limiting unit for limiting the incident direction of radiation, the radiation that has passed through the orientation limiting portion and a primary detector for converting the optical signal, respectively And a secondary detection unit that detects an optical signal from the detection unit of the detection window unit as, for example, a two-dimensional optical signal distribution. A sensor in which a direction is limited to an orientation in a predetermined cross section arranged linearly, and the primary detection unit has a plurality of sensor units arranged in the depth direction corresponding to the orientation in the predetermined cross section restricted by the orientation restriction unit. Ri array der, the plurality of detection units, the primary detector constituting the plurality of detection units is arranged to or converged so as to be parallel to each other.

In the radiation measurement device comprises an azimuth limiting portion in which a plurality of detection units provided in the detection window section limits the incident direction of radiation, the radiation that has passed through the orientation limiting portion and a primary detector for converting the optical signal, respectively Therefore, only radiation from a specific direction can be selectively detected. Furthermore, since the secondary detection unit detects the optical signal from the detection unit as a two-dimensional optical signal distribution, it is possible to process detection outputs from a plurality of detection units in parallel, and to perform high-speed and high-sensitivity radiation measurement. An apparatus can be provided. In addition, since the azimuth restriction unit restricts the incident direction of radiation to the azimuth in a predetermined cross section that is linearly arranged, not only can the radiation from the azimuth in the predetermined cross section be selectively detected, but such a cross section By changing, it is possible to arbitrarily extract radiation from an orientation in a desired cross section. Furthermore, since the primary detection unit is a sensor array in which a plurality of sensor units are arranged in the depth direction corresponding to the direction in a predetermined cross section limited by the direction limiting unit, the sensor array efficiently and efficiently emits radiation. It can be detected and the source can be identified. In particular, when the primary detection units constituting the plurality of detection units are arranged so as to be parallel to each other, the plurality of detection units are in a state of being focused at infinity, Radiation can be detected efficiently. In addition, when the primary detection units constituting the plurality of detection units are arranged so as to converge with each other, the plurality of detection units are focused on a finite distance, and radiation from an object separated by a finite distance Can be detected efficiently.

  In a specific aspect or viewpoint of the present invention, in the radiation measurement apparatus according to the first aspect of the present invention, the azimuth restriction unit is a slit-shaped collimator in which a plurality of shielding flat plates are arranged close to each other in parallel. In this case, it is possible to improve the selectivity of the azimuth and improve the measurement accuracy regarding the azimuth.

  In another aspect of the present invention, the sensor array is a fiber array having a plurality of scintillation fibers doped with a fluorescent material as a plurality of sensor portions. In this case, a plurality of sensor units can be arranged in a space-saving manner, and the primary detection unit and the radiation measurement apparatus can be easily reduced in weight.

  In still another aspect of the present invention, the fibers constituting the fiber array are arranged in parallel to each other at equal intervals along a predetermined cross section.

  In still another aspect of the present invention, an adjustment device that adjusts the arrangement state of the plurality of detection units is further provided. In this case, it is possible to change the focus state in which a plurality of detection units are set as one set.

  In still another aspect of the present invention, the relative arrangement relationship of the plurality of detection units is adjusted based on the detection output of the secondary detection unit. That is, the focal lengths of a plurality of detection units can be automatically controlled.

  In still another aspect of the present invention, in the radiation measuring apparatus according to the first and second inventions, the detection window part and the secondary detection part are coupled by a bundle of fibers. In this case, the optical signal detected by the detection window part can be transmitted to the secondary detection part with little loss.

  In still another aspect of the present invention, the secondary detection unit is a photoelectric imaging device having a photoelectric conversion surface. In this case, a weak optical signal can be detected with high sensitivity and high speed.

  According to still another aspect of the present invention, the apparatus further includes a storage device that stores the signal detected by the secondary detection unit in association with the incident direction of radiation. In this case, the spatial distribution of the radiation intensity from the object can be measured and stored by accumulating signals.

  In still another aspect of the present invention, the apparatus further includes a control device that detects energy information related to the radiation source based on the signal detected by the secondary detection unit. That is, the radiation source can be identified.

  In still another aspect of the present invention, the control device stores the energy information in the storage device in association with the incident direction of the radiation. In this case, information regarding the identification of the radiation source and information regarding the orientation of the radiation source can be stored as a set.

  A radiation measurement system according to the present invention includes a first measurement unit including the first radiation measurement apparatus described above, a second measurement unit including the second radiation measurement apparatus described above, a first measurement unit, and a first measurement unit. And an overall control unit that operates the two measurement units in synchronization.

  In the radiation measurement system of the present invention, two measurement units can simultaneously measure the orientations in two different cross sections.

It is a figure explaining the radiation measuring device which concerns on one Embodiment of this invention. It is a figure explaining the scintillation fiber blade which is a detection unit which comprises the radiation measuring device shown in FIG. It is a figure explaining the fixing method of the scintillation fiber integrated in a scintillation fiber blade. It is a figure explaining the example of arrangement | positioning of a scintillation fiber blade, and a function. It is a figure explaining the structure of an image intensifier part and an imaging part. It is a figure explaining the modification of the detection unit of FIG. 4, or a scintillation fiber blade. It is a figure explaining another modification of the detection unit of FIG. 8A to 8C are diagrams illustrating a specific detection example and a detection principle. It is a figure explaining the radiation measurement system incorporating a plurality of radiation measuring devices shown in FIG. 10A and 10B are diagrams illustrating a modification of the scintillation fiber blade.

  Hereinafter, a radiation measuring apparatus according to an embodiment of the present invention and a radiation measuring system incorporating the same will be described.

  As shown in FIG. 1, the radiation measurement apparatus 10 includes a detection window unit 20, a fiber bundle unit 30, an image intensifier unit 40, an imaging unit 50, a stage 60, and a control device 80.

  The detection window 20 is a case in which a large number of scintillation fibers (not shown) extending in the upper and lower Z directions are regularly and densely arranged in the case 21 and is also called a scintillation fiber clade.

  The detection window 20 includes a case 21 supported by the stage 60 and a large number of scintillation fiber blades 22 accommodated in the case 21. The case 21 is a member having a rectangular cylindrical outer shape having a rectangular opening OP in the lateral direction, and is formed of a material that efficiently shields radiation, such as lead. The scintillation fiber blade 22 is a member (detection unit) that has a rectangular plate-like outer shape and converts radiation incident from a specific direction into an optical signal. The scintillation fiber blade 22 stands in a vertical state extending in the YZ direction in the figure. A large number are arranged in the X direction and are tightly housed and fixed in the case 21. In the case 21, for example, 250 scintillation fiber blades 22 are densely packed and stacked. The vertical dimension and number of the scintillation fiber blades 22 are related to the sensitivity. If the vertical and horizontal width of the case 21, that is, the opening OP is wide, the detection sensitivity of the target incident radiation number is increased. Moreover, if the depth of the case 21 in the Y direction is equal to or greater than a certain value, the intended radiation can be reliably captured. In a specific embodiment, the vertical and horizontal width of the opening OP is, for example, 0.5 m × 0.5 m, and the depth width is, for example, 0.5 m.

  As shown in FIG. 2, the scintillation fiber blade (detection unit) 22 includes a collimator unit 21a, a scintillation fiber unit 21b, and a frame 21c.

  The collimator unit 21a is fixed to the frame 21c. The collimator unit 21a includes two radiation shielding plates 24 arranged in parallel, and functions as an azimuth limiting unit that limits the incident direction of radiation. Each radiation shielding plate 24 is a lead plate having a thickness of, for example, about 0.5 to 1 mm, and the pair of radiation shielding plates 24 are disposed apart from each other with a gap GA of, for example, about 1 to 2 mm. With the collimator unit 21a, only the radiation incident along the YZ cross section of the scintillation fiber blade 22 can be selectively guided to the scintillation fiber unit 21b. In a specific embodiment, the opening angle of the scintillation fiber blade 22 for gamma ray detection is about 0.5 ° to several degrees with respect to the horizontal X direction and about 90 ° with respect to the vertical Y direction. That is, one scintillation fiber blade 22 captures gamma ray flux with an effective area solid angle of (0.5 m × 0.5 m) × (about 1 ° × 90 °).

  Note that the background ratio of the atmospheric natural radiation dose that enters a solid angle of 1 ° × 90 ° is considered to be about 200 Hz with respect to a sensitive area of 0.5 m × 0.5 m. Assuming that about 250 fiber blades 22 are laminated, the single scintillation fiber blade 22 has an average detection frequency of 1 Hz or less. A gamma ray flux that comes at the same frequency as the atmospheric natural radioactivity dose has the ability to measure with an accuracy of about 10% error per second. Further, as will be described in detail later, when the number of tracks of Compton scattered electrons by gamma rays is higher than the resolution of the scintillation fiber 25, the total amount of fluorescence in the region expected by each pixel of the coarse image capturing unit 53 described later is calculated as the charge amount. The measurement dynamic range can be made extremely high.

  The scintillation fiber portion 21b is composed of a large number of scintillation fibers 25, ie, scintillation fiber arrays 125, extending in the Z direction and densely arranged in the Y direction at regular intervals, and converts the radiation that has passed through the collimator portion 21a into an optical signal. Functions as a detection unit. Specifically, the scintillation fiber 25 is an acrylic or other plastic fiber doped with a phosphor, corresponds to a sensor unit for converting radiation into an optical signal, and serves as an active index for gamma rays. In a specific embodiment, the scintillation fiber 25 scatters, for example, 0.622 MeV gamma rays originating from cesium 137, and outputs scintillation emission generated by Compton electrons as detection light.

  As shown in FIG. 3, a large number of scintillation fibers 25 constituting the scintillation fiber array 125 are fixed so as to be sandwiched between a pair of metal plates 26a and 26a and kept in parallel at equal intervals. The scintillation fiber 25 has a rectangular cross section of 1 to 2 mm square, for example. A large number of grooves 26d are formed in each metal plate 26a, and the scintillation fiber 25 is held in a stable state in each groove 26d. Each metal plate 26a is formed, for example, by pressing a tin plate. By sandwiching the metal plates 26a, 26a between the pair of metal plates 26a, 26a and fixing the metal plates 26a, 26a to the frame 21c, a large number of scintillation fibers 25 can be precisely aligned with the collimator portion 21a.

  Returning to FIG. 2, the scintillation fiber array 125 has a length of about 0.5 m in the upper and lower (left and right on the paper) Z direction. That is, the length of the scintillation fiber 25 constituting the scintillation fiber array 125 is also about 0.5 m. Each scintillation fiber array 125 has a length of about 0.5 m in the Y direction of the depth, that is, the arrangement direction. 250 scintillation fibers 25 constituting each scintillation fiber array 125 are arranged in a depth width of about 0.5 m. That is, the scintillation fibers 25 are densely arranged at intervals of 1 to 2 mm in the embodiment. As already described, since 250 scintillation fiber blades 22 are laminated in the X direction, when considered in a horizontal XY cross section, the laminated scintillation fibers 25 are closely packed in a 250 × 250 matrix. It will be arranged. In other words, a three-dimensional detection space is formed by the laminated body of scintillation fiber blades 22. One end of the scintillation fiber array 125 is connected to the fiber bundle unit 30 via an optical socket 27 that can be attached and detached. The fluorescence detected by each scintillation fiber 25 is individually transmitted by the fiber bundle unit 30.

  In the scintillation fiber portion 21b, the metal plates 26a and 26a as holders are fixed to the frame 21c as described above and supported in the case 21 via the frame 21c. The optical socket 27 is also fixed to the frame 21 c and exposed to an opening (not shown) formed on the lower surface of the case 21.

  FIG. 4 is a diagram schematically illustrating the mutual arrangement relationship of the plurality of scintillation fiber blades 22. Since the plurality of scintillation fiber blades 22 are arranged in close contact with each other and aligned in parallel with each other, the incident direction of radiation is limited to the direction of the vertical XZ cross section, and the detection window 20 as a whole is formed. Sensitivity is also limited to the direction of the vertical XZ cross section. That is, the detection window 20 can be considered as an infinite focus system in the horizontal Y direction.

  Returning to FIG. 1, the fiber bundle unit 30 is connected to the laminated body of the scintillation fiber array 125 at one end and positioned and fixed to the light receiving unit 42 (see FIG. 1) of the image intensifier unit 40 at the other end. Yes. As shown in FIG. 2, the fiber bundle unit 30 is a collection of a large number of guide optical fibers 31. One end of each guide optical fiber 31 is connected to the optical socket 27 and optically coupled to each scintillation fiber blade 22. The optical signal is transmitted to the light receiving unit 42 of the image intensifier unit 40 while maintaining the arrangement relationship of the scintillation fibers 25 constituting each scintillation fiber array 125. That is, the scintillation fibers 25 arranged in the Y direction and stacked in the Y direction in the case 21 are arranged in a matrix of 250 × 250 with respect to the XY cross section, so that the pixel pattern maintaining this lattice point arrangement is imaged. The intensifier unit 40 detects and amplifies the image.

  As shown in FIG. 5, the image intensifier unit 40 has a structure housed in a vacuum vessel 41, and converges the light receiving unit 42, which is an input unit for photoelectric conversion, and the electrons after photoelectric conversion. And an output unit 44 that converts an incident electron in a converged state into light to form an image. Here, the light receiving unit 42 is fixed to one end of the vacuum container 41 on the open side. The light receiving unit 42 includes a glass optical window 42a having a spherical shell-like outer shape, and a photoelectric conversion surface 47 is formed inside the optical window 42a by vapor deposition of a photoelectric conversion material having predetermined characteristics. Yes. The electrostatic focusing system 43 is supported on the inner surface of the side wall of the vacuum vessel 41. The electrostatic focusing system 43 has a plurality of electron focusing electrode portions 43a. The output unit 44 is fixed to the bottom of the vacuum vessel 41. The output unit 44 is formed of, for example, a fiber optic plate 44a, and the incident surface 48 is coated with a phosphor having predetermined characteristics. The incident surface 48 of the fiber optic plate 44 a is disposed at the position of the imaging surface of the electrostatic focusing system 43 and has a surface shape that matches the imaging surface of the electrostatic focusing system 43.

  The image intensifier unit 40 cooperates with the imaging unit 50 as a secondary detection unit that detects the optical signal from the scintillation fiber blade (detection unit) 22 as a two-dimensional optical signal distribution. Function.

  The imaging unit 50 includes a relay optical system 51, a fine imaging unit 52, a coarse image imaging unit 53, and a drive circuit 54.

  Here, the relay optical system 51 includes a distributor 51a disposed on the upstream side of the optical path along the optical axis OA and a main body optical system 51b disposed on the downstream side of the optical path from the distributor 51a. Of the relay optical system 51, the distributor 51a is a beam splitter. The main body optical system 51 b is a projection optical system that projects the image of the output surface 49 of the image intensifier unit 40 onto the imaging surface of the fine imaging unit 52 at approximately the same magnification. The fine imaging unit 52 includes, for example, a solid-state imaging device that is a CMOS-type imaging device and a drive circuit that causes the solid-state imaging device to perform an imaging operation. An imaging operation is performed. The fine imaging unit 52 converts a fine image of weak light incident on the photoelectric conversion surface 47 of the image intensifier unit 40 into a pixel digital signal at a video rate and outputs it. The coarse image capturing unit 53 is, for example, a multi-anode type photomultiplier, and operates under the control of the drive circuit 54. The coarse image capturing unit 53 outputs a coarse image of weak light incident on the photoelectric conversion surface 47 as a photometric signal.

  Returning to FIG. 1, the stage 60 includes a pedestal 61, a turntable 62, and a rotation drive mechanism 63. The turntable 62 is supported by the pedestal 61 and is rotatable about a rotation axis AX extending in the Z direction. The rotation drive mechanism 63 operates under the control of the control device 80, and rotates the turntable 62 with respect to the pedestal 61, thereby rotating the detection window portion 20 around the rotation axis AX extending in the vertical direction (that is, the Z direction). To the desired azimuth angle. The rotation operation of the turntable 62 may be continuous, but can be discretely moved to a target or a specified azimuth angle.

  In the space in the pedestal 61, the image intensifier unit 40, the imaging unit 50, and the control device 80 are housed in a stable state.

  The control device 80 monitors image signals and intensity signals output from the fine imaging unit 52 and the coarse image imaging unit 53 and stores them in the storage device 81. The control device 80 monitors the azimuth angle of the turntable 62, and associates the image signal obtained by the fine imaging unit 52 and the coarse image imaging unit 53 with the direction (detection azimuth angle) of the detection window unit 20. Store in the storage device 81. As a result, when the detection window 20 on the stage 60 faces a specific azimuth on the XY plane, the gamma rays from the measurement target are within a range of several degrees or less in that azimuth and about 90 degrees in the elevation direction. Other radiation can be detected. That is, the surrounding radiation emitted from the measurement object can be detected within a narrow solid angle range or a cross-sectional range limited to a specific orientation.

FIG. 6 is a diagram for explaining a modified example of the detection window portion 20 of FIG. 1 and corresponds to FIG. In this case, the plurality of scintillation fiber blades 22 are arranged so as to go to one point. That is, the detection window 20 in FIG. 6 can be considered as a finite focal system in the horizontal X direction. In this case, since the distance of the measurement target can be reduced and the solid angle to be expected can be increased, it is useful when it is desired to improve the detection sensitivity of the target object at a specific distance even if the detection range is sacrificed. The scintillation fiber blades 22 are fixed to the support 28 in order to maintain the mutual angular relationship. The support 28 may include an adjusting device 128 that adjusts an angle formed between adjacent scintillation fiber blades 22. In this case, the focal length of the detection window portion 20 can be adjusted freely according to the target object by controlling the operation of the adjusting device 128.
When the detection window 20 as shown in FIG. 6 is used, the control device 80 adjusts the relative arrangement relationship of the plurality of scintillation fiber blades (detection units) 22 based on the detection output of the imaging unit 50. Thus, the focal length of the detection window 20 in which a plurality of scintillation fiber blades 22 are combined can be automatically controlled. At this time, it is possible to optimize and achieve automatic focusing by real-time image processing.

  FIG. 7 is a diagram for explaining another modified example. In the case of the detection window portion 20 shown in FIG. 7, scintillation fibers 25 are two-dimensionally arranged in the X direction perpendicular to the collimator portion 21a to form a cubic plastic scintillator 123. In this case, similar measurement similar to the detection window 20 shown in FIGS. 1 and 2 is possible. Since fluorescence is observed with the scintillation fiber 25 corresponding to the track of the gamma ray, the output of each scintillation fiber 25 is synchronized, and various filter processes such as statistical processing are performed, for example, the incident direction with respect to the elevation angle of the gamma ray and the gamma ray from that direction. It is also possible to specify the energy and frequency (see FIGS. 8B and 8C).

  Hereinafter, the principle of detection of radiation by the radiation measuring apparatus 10 of FIG. 1 will be described. The reaction of 0.622 MeV gamma rays emitted from cesium 137 was investigated using an established EGS simulator to reproduce the behavior of gamma rays and electrons in the material in advance. FIG. 8A shows a side view of a track (white solid line) of 100 gamma rays shot at the same point from one direction on a plastic scintillator made of the same material as that of the scintillation fiber 25. The 0.622 MeV gamma rays emitted from cesium 137 mainly cause Compton scattering in the material. Scattering occurs at the point where the direction is changed in the track of the gamma rays in FIG. 8A, and the electrons are recoiled. This energy gamma ray repeatedly undergoes Compton scattering in the material, and eventually disappears due to the photoelectric absorption reaction while losing energy. It should be noted here that 0.622 MeV gamma rays pass almost all of their energy to electrons in a laminate of scintillation fiber array 125 with a depth of 0.5 m, that is, a plastic scintillator with 0.5 m cubes. It does n’t come out, it ’s all absorbed. Therefore, the energy of electrons can be converted into light using a 0.5 m cubic plastic scintillator, and the amount of light corresponding to the total energy of 0.622 MeV can be measured and confirmed. From this, it can be considered that the average output value from the scintillation fiber 25 arranged on the back side farthest from the opening OP in the scintillation fiber array 125 represents the background level. 25 output values can be used for S / N separation.

  The scattered electrons cause an ionization reaction while running in a 0.5 m cubic plastic scintillator, and emit fluorescence by a scintillation emission phenomenon. An electron generated by Compton scattering that occurs first when 0.622 MeV gamma rays are incident travels about 1 mm and emits light during that time. As shown in FIG. 8B, only a track of electrons of 10 keV or more generated from the previous gamma ray irradiation simulation example is shown by a white point, and as shown in FIG. 8C, 100 keV or more generated from the previous gamma ray irradiation simulation example. Only the tracks of electrons are shown as white dots. As can be seen from the figure, when electrons of 100 keV or higher are selected, electrons are more concentrated in the arrival direction of gamma rays and generated in a straight line. That is, if a light emission point of about 1 mm corresponding to 100 keV or more is selected, the gamma rays have first seen electrons due to Compton scattering, and if the point sequence is followed, the arrival direction of the gamma rays can be determined. Desired. By combining such a result with side light corresponding to the total absorbed energy of 0.622 MeV, it is possible to accurately measure where and how much the gamma rays coming from cesium 137 have arrived.

Here, the significance of performing the decomposition or separation of the optical signal in the Y direction, that is, the depth direction by the scintillation fiber array 125 will be described. It is advantageous from the viewpoint of background removal to capture and analyze the image of the emission point by gamma ray scattered electrons with the scintillation fiber array 125. The probability that gamma rays enter the plastic scintillator and scatter is determined by the scattering cross section of the particle,
1-exp (-x / L)
Distribution. Here, x is the distance in the depth direction, and L is the mean free path coming from the scattering cross section. That is, the detection frequency of the incident-side scintillation fiber 25 is the highest, and the scattering frequency attenuates as it enters the back. By using the scintillation fiber array 125, the above phenomenon can be imaged and measured.
Note that if the distance from the incident side of the signal gamma ray is X and the distance from the back side is Xb,
{1-exp (-xs / L)}
{1-exp (-xb / L)}
Since it is the sum of two dual distributions, it is possible to clarify the intrusion background evaluation and subtraction for signal extraction. That is, it becomes easy to separate only the target signal.

  That is, for example, from a series of light intensity data detected by one scintillation fiber part 21b shown in FIG. 2, the energy and attenuation state of gamma rays incident on the scintillation fiber part 21b can be measured, and the orientation of the radiation source And radioactive materials can be identified. Furthermore, information related to the amount of radioactive material can also be obtained from the frequency detected by the plurality of scintillation fiber portions 21b.

  FIG. 9 is a diagram for explaining a radiation measurement system 100 in which three radiation measurement units 10A, 10B, and 10C having the same structure as that of the radiation measurement apparatus 10 in FIG. 1 are incorporated.

  In this case, the first radiation measurement unit 10 </ b> A has substantially the same structure as the radiation measurement apparatus 10 in FIG. 1, and includes a measurement unit 11 and a scanning unit 12. The detection window unit 20, the fiber bundle unit 30, the image intensifier unit 40, the imaging unit 50, and the like of FIG. 1 function as the measurement unit 11, and the stage 60, the control device 80, and the like function as the scanning unit 12. The first radiation measurement unit 10A detects gamma rays from the gamma ray source by performing azimuth scanning. The second radiation measurement unit 10B has substantially the same structure as the radiation measurement apparatus 10 in FIG. The second radiation measurement unit 10B detects gamma rays from the gamma ray source by performing azimuth scanning. The third radiation measurement unit 10 </ b> C has substantially the same structure as the radiation measurement apparatus 10 in FIG. 1, and includes a measurement unit 11 and a scanning unit 12. The third radiation measurement unit 10C detects gamma rays from the gamma ray source by performing zenith angle scanning. The overall control unit 90 operates the three radiation measurement units 10A, 10B, and 10C in synchronization, and monitors the detection result of gamma rays. Three radiation measurement units 10A, 10B, and 10C can simultaneously monitor gamma rays from arbitrary positions in the three-dimensional space. In the case of illustration, 10 A of 1st radiation measurement units change the azimuth angle cross section S1 which is a radiation detection direction or a window direction around the rotating shaft AX extended to a perpendicular direction. The second radiation measurement unit 10B changes the azimuth angle cross section S2, which is the radiation detection direction or the window direction, around the rotation axis AX extending in the vertical direction. The third radiation measurement unit 10 </ b> C changes the zenith angle section S <b> 3, which is the radiation detection direction or the window direction, around the rotation axis AX extending in the vertical direction. For example, when gamma ray intensity is measured by the three radiation measurement units 10A, 10B, and 10C, the measurement results obtained by operating the three radiation measurement units 10A, 10B, and 10C in synchronization are monitored. Specifically, by processing detection outputs from the three radiation measurement units 10A, 10B, and 10C as, for example, products or as sums, an intensity distribution of radiation corresponding to scanning in a three-dimensional space is obtained. The spatial position and radiation intensity of the gamma ray source OB can be detected. In addition, it is also possible to perform the measurement which determines the incident direction of each radiation measurement unit 10A, 10B, 10C.

  Note that the measurement method by the radiation measurement system 100 is an example, and it is also possible to calculate the spatial distribution of gamma ray intensity by performing various arithmetic processes on the outputs of the three radiation measurement units 10A, 10B, and 10C.

  Further, the gamma ray source OB may be a moving body. In this case, it is necessary to make the operation of the scanning unit 12 correspond to the moving speed of the gamma ray source OB.

According to the radiation measuring apparatus 10 and the radiation measuring system 100 of the embodiment described above, the collimator unit (azimuth limiting unit) in which the scintillation fiber blade (detection unit) 22 provided in the detection window unit 20 limits the incident direction of radiation. Since it has 21a and the scintillation fiber array (primary detection part) 125 which converts the radiation which passed through the collimator part 21a into an optical signal, only the radiation from a specific direction can be detected selectively. Further, since the secondary detection unit including the image intensifier unit 40 and the like detects the optical signal from the scintillation fiber blade 22 as a two-dimensional optical signal distribution, parallel processing of the detection output of the scintillation fiber blade 22 Therefore, it is possible to provide a high-speed and highly sensitive radiation measuring apparatus. In addition, since the collimator unit (azimuth limiting unit) 21a limits the incident direction of radiation to a direction in a predetermined cross section linearly arranged, radiation from a direction in the predetermined cross section can be selectively detected, By changing such a cross section, radiation from a desired direction in the cross section can be arbitrarily extracted. Further, the scintillation fiber array (primary detection unit) 125 is a sensor array in which a plurality of sensor units are arranged in the depth direction corresponding to the direction in a predetermined cross section limited by the collimator unit (direction limiting unit) 21a. Therefore, the scintillation fiber array 125 can detect the radiation efficiently without leakage, and the source can be identified.
Further, according to the radiation measurement apparatus 10 or the like, a plurality of laminated bodies of scintillation fiber blades 22 as primary detection units provided in the detection window unit 20 are arranged so as to be distributed in a three-dimensional detection space. Since it has a scintillation fiber (sensor unit) 25, it can be considered that incident radiation passes through a three-dimensional detection space, and detects not only the incident direction of radiation but also three-dimensional events such as radiation scattering. can do. As a result, it is possible to identify the radiation source, determine the exact dose and direction of flight of the radiation, or measure the spatial distribution of the radiation intensity from the object.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and can be implemented in various modes without departing from the gist thereof. Such modifications are also possible.

  That is, the size and arrangement direction of the scintillation fiber blades 22 in the detection window 20 can be arbitrarily changed according to the detection object, application, and the like. At this time, it is desirable from the viewpoint of identifying the radiation source, improving sensitivity, and the like to secure the depth of the plastic scintillator in which the scintillation fiber array 125 is laminated to a certain degree or more and completely absorb the gamma rays to be detected in the plastic scintillator. Furthermore, the scintillation fiber blade 22 may include a plurality of collimator portions 21a as shown in FIG. 10A, and includes a plurality of scintillation fiber portions 21b or a scintillation fiber array 125 as shown in FIG. 10B. It may be. Further, the scintillation fiber blade 22 can be used alone.

Further, in the scintillation fiber portion 21b, a large number of scintillation fibers 25 are arranged at equal intervals in the Y direction of FIG. 2, but the multiple scintillation fibers 25 are, for example, proportionally increased in distance or periodically increased or decreased. It is also possible to arrange them at non-uniform intervals. In this case, a model in which radiation is scattered in an isotropic space cannot be applied, but the identification and intensity of the radiation source can be determined by statistical processing adapted to such an arrangement.
In the above embodiment, the scintillation fibers 25 are basically arranged in the same direction. However, the scintillation fiber array 125 of the first layer is arranged so that the scintillation fibers 25 extend in the Z direction, and the second The scintillation fiber array 125 in the first layer is arranged so that the scintillation fiber 25 extends in the Y direction, and the scintillation fiber array 125 in the third layer is arranged so that the scintillation fiber 25 extends in the Z direction. It is also possible to stack by changing the direction.

  Further, the collimator unit 21a can be omitted. In this case as well, if a large number of scintillation fiber arrays 125 are stacked and the scintillation fibers 25 are arranged at an appropriate density in a three-dimensional measurement space, for example, direction determination and gamma rays can be determined from an image of a trace of reacted electrons. Energy, its attenuation, etc. can be determined.

  In addition, the radiation measurement system 100 can be configured by two radiation measurement units 10A and 10C, for example.

Claims (12)

A detection window unit including a plurality of detection units each having an azimuth limiting unit that limits the incident direction of radiation and a primary detection unit that converts the radiation that has passed through the azimuth limiting unit into an optical signal;
A second detection unit that detects an optical signal from the detection unit of the detection window unit as a distribution of the optical signal;
The azimuth restriction unit restricts the incident direction of radiation to a azimuth within a predetermined cross section arranged linearly,
The first primary detector, Ri sensor array der in which a plurality of the sensor unit in the depth direction corresponding to the orientation of the said predetermined cross-section is limited by the orientation limiting unit,
The plurality of detection units are arranged to be arranged so that the primary detection units constituting the plurality of detection units are parallel to each other or converge .   The radiation measurement apparatus according to claim 1, wherein the azimuth restriction unit is a slit-like collimator in which a plurality of shield plates are arranged close to each other in parallel.   The radiation measurement apparatus according to claim 1, wherein the sensor array is a fiber array having a plurality of scintillation fibers doped with a fluorescent material as the plurality of sensor units. The radiation measuring apparatus according to claim 3 , wherein the fibers constituting the fiber array are arranged in parallel with each other at equal intervals along the predetermined cross section. Further comprising an adjustment device for adjusting the arrangement of the plurality of detection units, the radiation measuring device according to claim 1. The radiation measurement apparatus according to claim 5 , wherein a relative arrangement relationship of the plurality of detection units is adjusted based on a detection output of the secondary detection unit. The radiation measurement apparatus according to claim 1 , wherein the detection window part and the secondary detection part are coupled by a bundle of fibers. The radiation measurement apparatus according to claim 1 , wherein the secondary detection unit is a photoelectric imaging apparatus having a photoelectric conversion surface. Further comprising a storage device for storing a signal detected by the secondary detector in association with the incident direction of the radiation, the radiation measuring device according to claim 1. Further comprising a control device for detecting the energy information related to the radiation source based on the signal detected by said secondary detector, a radiation measuring device according to claim 1. The radiation measurement apparatus according to claim 10 , wherein the control device stores the energy information in a storage device in association with an incident direction of radiation. A first measurement unit comprising a first radiation measurement device according to claim 1,
A second measurement unit comprising the second radiation measurement apparatus according to claim 1 ;
A radiation measurement system comprising: an overall control unit that operates the first measurement unit and the second measurement unit in synchronization.

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