Radiation measuring instrument and endoscope

Abstract

To enhance the stability of operation while downsizing.SOLUTION: A radiation measuring instrument includes: a cylindrical housing extending in a first direction; a scintillator disposed inside the housing; and optical fibers extending in the first direction and each having a distal end portion disposed inside the housing. The housing, the scintillator, and the optical fibers are bonded to each other by an adhesive.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a radiation dosimeter and an endoscope. [Background technology]

[0002] As a radiation dosimeter for measuring the dose of radiation such as X-rays and gamma rays, a scintillation dosimeter using a scintillator that emits fluorescence by absorbing radiation has been put into practical use. In the scintillation dosimeter, a configuration has been proposed in which the fluorescence emitted by the scintillator is transmitted to a light-receiving element via an optical fiber, and the light-receiving element converts the fluorescence into an electrical signal (for example, Patent Document 1). Furthermore, during construction or inspection of a nuclear power plant, a radiation dosimeter may be inserted into the reactor through a hole formed in the reactor to measure the radiation dose inside the reactor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-3325 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, when a radiation dosimeter is inserted into a reactor through a hole formed in the reactor to measure the radiation dose inside the reactor, it is preferable that the hole be small in order to prevent radiation from leaking outside the reactor through the hole. However, when the scintillator is made smaller to reduce the size of the radiation dosimeter, the bonding area between the scintillator and the optical fiber becomes smaller, making it difficult to ensure sufficient bonding strength between the scintillator and the optical fiber. Therefore, when force is applied to the optical fiber during use of the radiation dosimeter, there is a risk that the optical fiber will become detached from the scintillator. Therefore, it has been difficult to increase the operational stability of the radiation dosimeter while reducing its size.

[0005] The present invention has been made in consideration of the above points, and one of its objects is to provide a radiation dosimeter and an endoscope that can be made smaller while improving operational stability. [Means for solving the problem]

[0006] (1) One aspect of the present invention is a radiation dosimeter comprising a cylindrical housing extending in a first direction, a scintillator disposed inside the housing, and an optical fiber extending in the first direction and having a tip end disposed inside the housing, wherein the housing, the scintillator, and the optical fiber are bonded to each other with an adhesive.

[0007] (2) In one aspect of the present invention, in the radiation dosimeter described in (1) above, the outer diameter of the scintillator when viewed from the first direction is 1.0 mm or less.

[0008] (3) In one aspect of the present invention, in the radiation dosimeter described in (1) or (2) above, the inner surface of the housing is white.

[0009] (4) In one aspect of the present invention, in the radiation dosimeter according to any one of (1) to (3) above, the adhesive is transparent.

[0010] (5) In one aspect of the present invention, in the radiation dosimeter described in any one of (1) to (4) above, the housing is covered with a reflective material, and the reflective material is white.

[0011] (6) One aspect of the present invention is an endoscope comprising a radiation dosimeter according to any one of (1) to (5) above, an optical unit, an imaging unit having an imaging element, and a cylindrical case that houses the radiation dosimeter, the optical unit, and the imaging unit. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a radiation dosimeter and an endoscope that can be made smaller and have improved operational stability. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view showing an endoscope system according to an embodiment. [Figure 2] 1 is a cross-sectional view showing a radiation dosimeter according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] In each drawing, a first direction D1 is indicated as appropriate. The first direction D1 is the direction in which the housing of the embodiment described below extends. The side of the first direction D1 toward which the arrow points (+D1 side) is the "object side (distal side)" of the endoscope, and the side of the first direction D1 opposite to the side toward which the arrow points (-D1 side) is the "base end side (proximal side)" of the endoscope.

[0015] FIG. 1 is a cross-sectional view showing an endoscopic system 10 of this embodiment. The endoscopic system 10 of this embodiment includes an endoscope 12, a first processor 14, a monitor 15, a detector 17, a measurement unit 18, and a second processor 19. The endoscope 12 is capable of capturing an image of a measurement space, which is a space with a high radiation dose, such as the inside of a nuclear reactor in a nuclear power plant, and measuring the radiation dose in the measurement space. The first processor 14 is electrically connected to an imaging element 31 of the endoscope 12. The monitor 15 is a display device that displays an image of the measurement space generated by the first processor 14. The detector 17 is connected to a radiation dosimeter 50 of the endoscope 12 and generates an electrical signal corresponding to the radiation dose in the measurement space. The measurement unit 18 converts the electrical signal generated by the detector 17 into a digital signal. The second processor 19 calculates the radiation dose based on the digital signal generated by the measurement unit 18.

[0016] The endoscope 12 has a tubular shape extending in the first direction D1. In this embodiment, the endoscope 12 has a substantially cylindrical shape extending in the first direction D1. The endoscope 12 may have another shape, such as a rectangular tube shape extending in the first direction D1. The endoscope 12 is inserted into a measurement space, such as the interior of a nuclear reactor. The outer diameter Re of the endoscope 12 is preferably small, equal to or greater than 1 mm and equal to or less than 10 mm. By reducing the outer diameter Re of the endoscope 12, the diameter of an insertion hole formed in the reactor for inserting the endoscope 12 into the reactor can be reduced. This makes it possible to suppress an increase in the amount of radiation leaking from the insertion hole to the outside of the reactor. In this embodiment, the outer diameter Re of the endoscope 12 is approximately 4 mm. Furthermore, in this embodiment, the length of the endoscope 12 in the first direction D1 is approximately 30 m. The endoscope 12 includes a case 20, an optical unit 25, an imaging unit 30, and a radiation dosimeter 50.

[0017] The case 20 has a cylindrical shape extending in the first direction D1. In this embodiment, the case 20 has a substantially cylindrical shape extending in the first direction D1. The case 20 accommodates the optical unit 25, the imaging unit 30, and the radiation dosimeter 50 therein. The case 20 has a hard cylindrical portion 21, a flexible cylindrical portion 22, and an imaging element holder 23.

[0018] The hard cylindrical portion 21 is the object side (+D1 side) portion of the case 20. The hard cylindrical portion 21 has a substantially cylindrical shape extending in the first direction D1. The hard cylindrical portion 21 is made of a metal tube such as stainless steel. The hard cylindrical portion 21 is open on both sides in the first direction D1.

[0019] The flexible tube portion 22 is a portion on the base end side (-D1 side) of the case 20. The flexible tube portion 22 has a substantially cylindrical shape extending in the first direction D1. The flexible tube portion 22 has flexibility. An end portion on the object side (+D1 side) of the flexible tube portion 22 is fixed to an end portion on the base end side of the rigid tube portion 21.

[0020] The imaging element holding portion 23 is disposed inside the hard cylindrical portion 21. The imaging element holding portion 23 has a generally cylindrical shape extending in the first direction D1. The outer peripheral surface of the imaging element holding portion 23 is fixed to the inner peripheral surface of the hard cylindrical portion 21.

[0021] The optical unit 25 is disposed inside the rigid cylindrical portion 21. The optical unit 25 is disposed closer to the object side (+D1 side) than the imaging element holding portion 23. The optical unit 25 forms an optical image of a measurement space, such as the inside of a nuclear reactor. The optical unit 25 has a plurality of lenses 26. The lenses 26 are disposed side by side along the first direction D1. The lenses 26 are fixed to the inner surface of the rigid cylindrical portion 21.

[0022] The imaging unit 30 is disposed across the interior of the rigid cylindrical portion 21 and the interior of the flexible cylindrical portion 22. The imaging unit 30 extends inside the case 20 in the first direction D1. The imaging unit 30 is disposed closer to the base end (-D1 side) than the optical unit 25. The imaging unit 30 has an imaging element 31, an imaging board 32, and a signal cable 34.

[0023] The imaging element 31 receives an optical image of the measurement space formed by the optical unit 25 and converts it into an image signal. The imaging element 31 is, for example, an image sensor such as a CCD or CMOS. The imaging element 31 is disposed closer to the base end (-D1 side) than the optical unit 25. The light receiving surface of the imaging element 31 faces the object side (+D1 side). The imaging element 31 is fixed to the inner circumferential surface of the imaging element holding portion 23.

[0024] The imaging board 32 is connected to the imaging element 31. The imaging board 32 is a circuit board such as a flexible printed circuit board. Electronic components mounted on the imaging board 32 include a digital IC that generates a drive signal for the imaging element 31 and a capacitor that stabilizes the drive power supply for the digital IC. The imaging board 32 is disposed closer to the base end (-D1 side) than the imaging element 31. A signal cable 34 is connected to the imaging board 32.

[0025] The signal cable 34 connects the imaging board 32 and the first processor 14 so as to be able to communicate with each other. The signal cable 34 extends in the first direction D1. The signal cable 34 is passed through the interior of the flexible tube portion 22 in the first direction D1. The end of the signal cable 34 on the base end side (-D1 side) is connected to the first processor 14. The signal cable 34 is arranged inside the case 20 with a gap between it and the radiation dosimeter 50. In this embodiment, the signal cable 34 is a cable bundle formed by bundling multiple cables 34a. The end of each cable 34a on the object side (+D1 side) is joined to the imaging board 32 by, for example, soldering. An image signal of the measurement space converted by the imaging element 31 is transmitted to the first processor 14 via the signal cable 34. The first processor 14 generates an image of the measurement space based on the image signal. In this embodiment, the first processor 14 is, for example, a personal computer. The image of the measurement space generated by the first processor 14 is displayed on the monitor 15. This allows the user of the endoscope system 10 to understand the state of the measurement space, such as the inside of a nuclear reactor.

[0026] The endoscope 12 may have an optical path such as a light guide bundle (not shown) that transmits illumination light for illuminating the measurement space. In this case, the light guide bundle is preferably passed through the inside of the case 20 in the first direction D1. By illuminating the measurement space with such illumination light, the endoscope system 10 can display an image of the measurement space even if the measurement space is dark.

[0027] The radiation dosimeter 50 measures the radiation dose in a measurement space, which is a space with a high radiation dose, such as a nuclear reactor. In this embodiment, the radiation dosimeter 50 is housed inside the case 20. More specifically, the radiation dosimeter 50 is housed inside the flexible cylindrical portion 22. The radiation dosimeter 50 is disposed between the case 20 and the signal cable 34. In this embodiment, the radiation dosimeter 50 is a scintillation dosimeter. As shown in FIG. 2 , the radiation dosimeter 50 includes a measuring unit 51 and an optical fiber 56. The measuring unit 51 includes a housing 52, a scintillator 54, an adhesive 58, and a reflective material 59.

[0028] The housing 52 has a tubular shape extending in the first direction D1. In this embodiment, the housing 52 has a substantially cylindrical shape extending in the first direction D1. The housing 52 may have another shape, such as a rectangular tube extending in the first direction D1. The housing 52 has openings on both sides in the first direction D1. The housing 52 has a first opening 52a opening on the base end side (-D1 side) and a second opening 52b opening on the object side (+D1 side). The housing 52 accommodates various components of the radiation dosimeter 50, such as the scintillator 54 and the tip portion 56a, which is the end of the optical fiber 56 on the object side (+D1 side). In this embodiment, the housing 52 is made of a resin such as ABS resin (acrylonitrile butadiene styrene resin) or polyethylene. The housing 52 may also be made of ceramic such as titanium oxide or zirconium oxide. The housing 52 is white. The inner surface of the housing 52 is white. In the present embodiment, the outer diameter Rh of the housing 52 as viewed in the first direction D1 is preferably 1.0 mm or more and 2.0 mm or less, which allows the radiation dosimeter 50 and the endoscope 12 to be made more compact.

[0029] The scintillator 54 is disposed inside the housing 52. The scintillator 54 has a generally cylindrical shape extending in the first direction D1. The scintillator 54 may have another shape, such as a rectangular pillar shape extending in the first direction D1. The scintillator 54 is made of a phosphor material that emits fluorescence L when absorbing radiation such as X-rays and gamma rays. The scintillator 54 is made of a known scintillator substance. The amount of fluorescence L emitted by the scintillator 54 increases as the amount of radiation absorbed by the scintillator 54 increases. Therefore, by measuring the amount of fluorescence L emitted by the scintillator 54, the amount of radiation in a measurement space, such as the inside of a nuclear reactor, can be measured. When viewed from the first direction D1, the outer diameter Rs of the scintillator 54 is a small diameter of 1.0 mm or less. In this embodiment, the outer diameter Rs of the scintillator 54 is approximately 0.5 mm. This allows the radiation dosimeter 50 to be miniaturized.

[0030] The optical fiber 56 is an optical transmission path that transmits the fluorescence L emitted by the scintillator 54 to the detector 17. As shown in FIG. 1, the optical fiber 56 extends in a first direction D1. In this embodiment, the length of the optical fiber 56 in the first direction D1 is approximately 30 m. As shown in FIG. 2, the optical fiber 56 is disposed on the proximal side (-D1 side) of the scintillator 54. A tip portion 56a, which is the end portion on the object side (+D1 side) of the optical fiber 56, is disposed inside the housing 52. The tip portion 56a faces the scintillator 54 in the first direction D1. The tip portion 56a opens toward the object side. The fluorescence L enters the optical fiber 56 through this opening. As shown in FIG. 1, the proximal end of the optical fiber 56 is connected to the detector 17. As a result, the fluorescence L is transmitted to the detector 17 via the optical fiber 56.

[0031] As shown in FIG. 2 , in this embodiment, the radiation dosimeter 50 has multiple optical fibers 56. Although not shown, in this embodiment, the radiation dosimeter 50 has seven optical fibers 56. The number of optical fibers 56 included in the radiation dosimeter 50 may be six or less, or eight or more. In this embodiment, the outer diameter of each optical fiber is small, approximately 100 μm. This reduces the rigidity of each optical fiber 56, allowing each optical fiber 56 to bend in accordance with the shape of the flexible tubular portion 22 when the flexible tubular portion 22 is bent. Furthermore, as described above, since the radiation dosimeter 50 has multiple optical fibers 56, the total opening diameter of the optical fibers 56 can be increased. This increases the amount of fluorescence L transmitted to the detector 17 via the optical fibers 56.

[0032] The detector 17 shown in FIG. 1 receives the fluorescence L transmitted via the optical fiber 56 and generates an electrical signal Se. The detector 17 is composed of optical elements such as a photomultiplier tube and an avalanche photodiode. The electrical signal Se generated by the detector 17 correlates with the amount of fluorescence L received by the detector 17. As described above, the amount of fluorescence L emitted by the scintillator 54 increases as the amount of radiation absorbed by the scintillator 54 increases. As a result, the electrical signal Se correlates with the amount of radiation in the internal space, such as the inside of a nuclear reactor. The detector 17 is electrically connected to the measurement unit 18. The electrical signal Se generated by the detector 17 is transmitted to the measurement unit 18.

[0033] The measuring unit 18 converts the electrical signal Se generated by the detector 17 into a digital signal. The measuring unit 18 is electrically connected to the second processor 19. The digital signal converted by the measuring unit 18 is transmitted to the second processor 19. In this embodiment, the second processor 19 is, for example, a personal computer. The second processor 19 calculates the radiation dose in the internal space based on the digital signal. This allows the endoscope system 10 to measure the radiation dose in the internal space, such as the inside of a nuclear reactor.

[0034] As shown in FIG. 2 , the adhesive 58 is filled inside the housing 52. A transparent adhesive such as a modified methacrylate adhesive or a modified acrylate adhesive can be used as the adhesive 58. The adhesive 58 may also be made of other materials. The adhesive 58 contacts the inner surface of the housing 52, the outer surface of the scintillator 54, and the outer surfaces of the optical fibers 56. This bonds the housing 52, the scintillator 54, and the optical fibers 56 to one another. Therefore, the optical fibers 56 are fixed to the scintillator 54 by the adhesive 58. More specifically, the optical fibers 56 are fixed to the surface of the scintillator 54 facing the base end (−D1 side) by the adhesive 58. The scintillator 54 and the optical fibers 56 are also fixed to the housing 52 by the adhesive 58.

[0035] As described above, in this embodiment, the outer diameter Rs of the scintillator 54 is very small, at approximately 0.5 mm, making it difficult to increase the bonding area between the surface of the scintillator 54 facing the base end (-D1 side) and the optical fiber 56. Therefore, when the optical fiber 56 is bonded and fixed only to the scintillator 54 with the adhesive 58, it is difficult to increase the bonding strength between the scintillator 54 and the optical fiber 56. In contrast, the area of ​​the inner surface of the housing 52 is larger than the area of ​​the surface of the scintillator 54 facing the base end. Therefore, compared to the bonding area between the scintillator 54 and the optical fiber 56, the bonding area between the scintillator 54 and the housing 52 and the bonding area between the optical fiber 56 and the housing 52 can each be made larger. This makes it possible to increase the bonding strength between the scintillator 54 and the housing 52 and the bonding strength between the optical fiber 56 and the housing 52. Therefore, it is possible to suitably prevent the positions of the scintillator 54 and the optical fiber 56 from shifting relative to the housing 52, and therefore it is possible to suitably prevent the position of the optical fiber 56 from shifting relative to the scintillator 54. As a result, even if an external force is applied to the optical fiber 56 when the radiation dosimeter 50 is in use, it is possible to prevent the optical fiber 56 from moving relative to the scintillator 54. Furthermore, even if an external force is applied to the optical fiber 56 due to bending of the flexible tube portion 22 when the endoscope 12 is in use, it is possible to prevent the optical fiber 56 from moving relative to the scintillator 54. Therefore, it is possible to reduce the external force applied to the joint between the scintillator 54 and the optical fiber 56, and it is possible to prevent the optical fiber 56 from coming off the scintillator 54.

[0036] In the present embodiment, the adhesive 58 is transparent. This prevents the fluorescence L1 entering the inside of each optical fiber 56 from being absorbed by the adhesive 58. As described above, the inner surface of the housing 52 is white. This prevents the fluorescence L2 emitted from the scintillator 54 toward the housing 52 from being absorbed by the adhesive 58 disposed between the scintillator 54 and the housing 52 when the fluorescence L2 is reflected by the inner surface of the housing 52 and returns to the inside of the scintillator 54. The transmittance of the adhesive 58 to the fluorescence L is preferably 95% or more. The transmittance of the adhesive 58 to the fluorescence L is more preferably 99% or more.

[0037] The reflective material 59 prevents the fluorescence L from leaking outside the housing 52. The reflective material 59 covers the housing 52. That is, the housing 52 is covered with the reflective material 59. In the present embodiment, the reflective material 59 is a white paint. The reflective material 59 is white. In the manufacturing process of the radiation dosimeter 50, the reflective material 59 is formed by applying it to the housing 52 from the outside of the housing 52 to which the scintillator 54 and the optical fiber 56 are adhered and fixed with the adhesive 58. The reflective material 59 reflects the fluorescence L3 that has passed through the housing 52. This allows the reflective material 59 to return the fluorescence L3 that has passed through the housing 52 into the housing 52, thereby preventing the fluorescence L3 from leaking outside the housing 52. The reflective material 59 also blocks the first opening 52a of the housing 52. Therefore, the reflective material 59 reflects the fluorescence L4 emitted toward the first opening 52a. As a result, the reflector 59 can return the fluorescence L4 emitted toward the first opening 52a into the housing 52, thereby preventing the fluorescence L4 from leaking outside the housing 52. Furthermore, the reflector 59 closes the second opening 52b of the housing 52. As a result, the reflector 59 can reflect the fluorescence L5 emitted toward the second opening 52b. As a result, the reflector 59 can return the fluorescence L5 emitted toward the second opening 52b into the housing 52, thereby preventing the fluorescence L5 from leaking outside the housing 52.

[0038] According to the present embodiment, the radiation dosimeter 50 includes a cylindrical housing 52 extending in a first direction D1, a scintillator 54 disposed inside the housing 52, and an optical fiber 56 extending in the first direction D1 with a tip portion 56a disposed inside the housing 52. The housing 52, the scintillator 54, and the optical fiber 56 are bonded to one another with an adhesive 58. Therefore, in the present embodiment, as described above, the bonding area between the scintillator 54 and the housing 52 and the bonding area between the optical fiber 56 and the housing 52 can be made larger than the bonding area between the scintillator 54 and the optical fiber 56. This increases the bonding strength between the scintillator 54 and the housing 52 and the bonding strength between the optical fiber 56 and the housing 52. Therefore, in the present embodiment, even if the outer diameter Rs of the scintillator 54 is small, movement of the optical fiber 56 relative to the scintillator 54 can be suitably suppressed. Therefore, as described above, even if an external force is applied to the optical fiber 56 during use of the radiation dosimeter 50, the optical fiber 56 can be prevented from moving relative to the scintillator 54. This reduces the external force applied to the joint between the scintillator 54 and the optical fiber 56, thereby making it possible to reduce the size of the scintillator 54 and prevent the optical fiber 56 from coming off the scintillator 54. Therefore, it is possible to reduce the size of the radiation dosimeter 50 and improve the stability of its operation.

[0039] According to this embodiment, the outer diameter Rs of the scintillator 54 is 1.0 mm or less as viewed from the first direction D1. If the outer diameter Rs of the scintillator 54 is very small, such as 1.0 mm or less, it is difficult to ensure sufficient adhesive strength between the scintillator 54 and the optical fiber 56, as described above. In contrast, in this embodiment, the housing 52, the scintillator 54, and the optical fiber 56 are bonded to one another with the adhesive 58, as described above. This reduces the external force applied to the joint between the scintillator 54 and the optical fiber 56, as described above. This allows the radiation dosimeter 50 to be miniaturized while improving its operational stability. Therefore, for example, when measuring radiation doses inside a nuclear reactor, the diameter of an insertion hole formed in the reactor for inserting the dosimeter 50 into the reactor can be reduced. This prevents an increase in the amount of radiation leaking outside the reactor through the insertion hole. This improves the safety of the work of measuring radiation doses inside the reactor.

[0040] According to this embodiment, the inner surface of the housing 52 is white. Therefore, of the fluorescence L emitted by the scintillator 54, fluorescence L2 (see FIG. 2) emitted toward the housing 52 can be prevented from being absorbed by the housing 52, and the fluorescence L2 can be reflected by the inner surface of the housing 52 and returned to the inside of the scintillator 54. As a result, the amount of fluorescence L entering the inside of the optical fiber 56 can be increased, and therefore the amount of fluorescence L transmitted to the detector 17 can be increased. Therefore, the measurement accuracy of the radiation dose measured by the radiation dosimeter 50 can be improved.

[0041] According to the present embodiment, the adhesive 58 is transparent. This prevents the fluorescence L emitted by the scintillator 54 from being absorbed by the adhesive 58. Therefore, as described above, the fluorescence L1 entering the inside of the optical fiber 56 from the scintillator 54 can be prevented from being absorbed by the adhesive 58. Furthermore, as described above, the fluorescence L2 emitted toward the housing 52 can be prevented from being absorbed by the adhesive 58 disposed between the scintillator 54 and the housing 52 when the fluorescence L2 is reflected by the inner surface of the housing 52 and returns to the inside of the scintillator 54. This makes it possible to more suitably increase the amount of fluorescence L entering the inside of the optical fiber 56, thereby more suitably increasing the amount of fluorescence L transmitted to the detector 17. This therefore makes it possible to more suitably improve the measurement accuracy of the radiation dose measured by the radiation dosimeter 50.

[0042] According to the present embodiment, the housing 52 is covered with a reflective material 59, and the reflective material 59 is white. When the thickness of the housing 52 is reduced in order to reduce the size of the dosimeter 50, the amount of fluorescence L that passes through the housing 52 is likely to increase. Furthermore, when the housing 52 has openings on both sides in the first direction D1, some of the fluorescence L leaks out of the housing 52 through the openings. In contrast, in the present embodiment, the housing 52 is covered with the reflective material 59. As described above, the fluorescence L3 (see FIG. 2) that has passed through the housing 52 can be reflected by the reflective material 59, and therefore the fluorescence L3 can be returned into the housing 52. Furthermore, as described above, the fluorescence L4 (see FIG. 2) emitted toward the first opening 52a can be reflected by the reflective material 59, and therefore the fluorescence L4 can be returned into the housing 52. Furthermore, as described above, the fluorescence L5 (see FIG. 2) emitted toward the second opening 52b can be reflected by the reflective material 59, and therefore the fluorescence L5 can be returned into the housing 52. These features make it possible to more suitably increase the amount of fluorescence L incident on the optical fiber 56, thereby more suitably increasing the amount of fluorescence L transmitted to the detector 17. This makes it possible to more suitably increase the measurement accuracy of the radiation dose measured by the radiation dosimeter 50.

[0043] According to this embodiment, the endoscope 12 includes a radiation dosimeter 50, an optical unit 25, an imaging unit 30 having an image sensor 31, and a cylindrical case 20 that houses the radiation dosimeter 50, the optical unit 25, and the imaging unit 30. Therefore, by simply inserting the endoscope 12 into a measurement space, which is a space with a high radiation dose, such as the inside of a nuclear reactor in a nuclear power plant, it is possible to capture images of the state of the measurement space and measure the radiation dose in the measurement space. This simplifies the process of understanding the state of the measurement space.

[0044] When the endoscope 12 does not include the radiation dosimeter 50, it is necessary to form separate insertion holes into the reactor for inserting the endoscope 12 and for inserting the radiation dosimeter 50 in order to capture images of the state inside the reactor and measure the radiation dose inside the reactor. In contrast, in this embodiment, the endoscope 12 is inserted into the reactor through a single insertion hole for inserting the endoscope 12 into the reactor, thereby capturing images of the state inside the reactor and measuring the radiation dose inside the reactor. This reduces the number of insertion holes formed in the reactor, thereby suppressing an increase in the amount of radiation leaking outside the reactor through the insertion holes. This improves the safety of the work of measuring radiation doses inside the reactor.

[0045] Although an embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made within the scope that does not deviate from the spirit of the present invention.

[0046] The outer diameters of the scintillator, the housing, and the endoscope are not limited to those of this embodiment, and for example, the outer diameter of the scintillator may be greater than 1.0 mm. Even in this case, the housing, the scintillator, and the optical fiber are bonded to each other with an adhesive, thereby preventing the optical fiber from coming off the scintillator. This improves the operational stability of the radiation dosimeter.

[0047] The inner surface of the housing may be polished. This reduces the surface roughness of the inner surface of the housing, thereby increasing the reflectance of the fluorescence from the inner surface of the housing. This makes it possible to more effectively increase the amount of fluorescence L incident on the optical fiber. This in turn makes it possible to more effectively increase the measurement accuracy of the radiation dose measured by the radiation dosimeter. [Explanation of symbols]

[0048] 12...endoscope, 20...case, 25...optical unit, 30...imaging unit, 31...imaging element, 50...radiation dosimeter, 52...housing, 54...scintillator, 56...optical fiber, 58...adhesive, 59...reflective material, D1...first direction, Rs...outer diameter of scintillator

Claims

1. a cylindrical housing extending in a first direction; a scintillator disposed within the housing; an optical fiber extending in the first direction and having a tip end disposed inside the housing; Equipped with A radiation dosimeter, wherein the housing, the scintillator, and the optical fiber are bonded to one another by an adhesive.

2. The radiation dosimeter according to claim 1 , wherein the outer diameter of the scintillator when viewed from the first direction is 1.0 mm or less.

3. The radiation dosimeter according to claim 1 , wherein the inner surface of the housing is white.

4. The radiation dosimeter according to claim 1 or 2, wherein the adhesive is transparent.

5. the housing is covered with a reflective material; The radiation dosimeter according to claim 1 , wherein the reflecting material is white.

6. A radiation dosimeter according to claim 1 or 2; An optical unit; an imaging unit having an imaging element; a cylindrical case that accommodates the radiation dosimeter, the optical unit, and the imaging unit; An endoscope comprising:

Images