Personal dosimeter

Abstract

To reduce a vibration reaching a radiation sensor via a substrate and enhance reliability of a measurement result in a personal dosimeter.SOLUTION: A detector unit 46 has a front-side shield cover 48, a rear-side shield cover 50, an assembly 55, and a first energy filter 54. The assembly 55 has a radiation sensor 56 and a second energy filter 62. The radiation sensor 56 has a sensor body 58 and a conductive leg 60. The first energy filter 54 is arranged in a concave part 52. In another detector unit, the assembly has the first energy filter and the second energy filter.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a personal dosimeter, and more particularly to the structure of a detection unit in a personal dosimeter. [Background technology]

[0002] A personal dosimeter is a radiation measuring device used to manage personal exposure in radiation handling facilities such as nuclear power plants and medical facilities. A personal dosimeter has a detection unit that includes a radiation sensor and an energy filter. The energy filter is a component that acts on the radiation detected by the radiation sensor to improve the energy characteristics of the radiation sensor. The radiation detected by a personal dosimeter includes X-rays, gamma rays, beta rays, neutrons, etc.

[0003] Patent Documents 1, 2, and 3 disclose a shielding case that blocks electromagnetic waves coming from the outside. More specifically, the shielding case encloses a radiation sensor mounted on a substrate. The shielding case is composed of a first cover fixed to the front surface of the substrate and a second cover fixed to the rear surface of the substrate.

[0004] In the personal dosimeter disclosed in Patent Document 4, a spacer is provided between the front surface of the substrate and the first sensor that detects beta rays. The spacer is a member that moves the first radiation sensor closer to the entrance window. In other words, the spacer does not have any significant effect on radiation. In addition, in the personal dosimeter disclosed in Patent Document 4, a filter is provided between the rear surface of the substrate and the second radiation sensor that detects X-rays. The filter blocks beta rays. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-137255 [Patent Document 2] Japanese Patent Application Publication No. 2017-138256 [Patent Document 3] Japanese Patent Application Publication No. 2017-138204 [Patent Document 4] Japanese Patent Application Laid-Open No. 2004-3882 Summary of the Invention [Problem to be solved by the invention]

[0006] In personal dosimeters, if the radiation sensor body (the part including the sensitive part) is directly fixed on the board, vibrations are easily transmitted to the radiation sensor via the board. If large vibrations (including shocks) are transmitted to the radiation sensor, there is a risk of false counting.

[0007] In order to improve the reliability of the measurement results of a personal dosimeter, it is desirable to improve not only the energy characteristics for radiation coming from the front, but also the energy characteristics for radiation reflected or scattered by the body wearing the personal dosimeter and the energy characteristics for radiation reflected or scattered inside the personal dosimeter.

[0008] An object of the present invention is to reduce vibrations reaching a radiation sensor via a substrate in a personal dosimeter, or to increase the reliability of measurement results in a personal dosimeter. [Means for solving the problem]

[0009] A personal dosimeter according to the present invention includes a case, a substrate disposed within the case and having a front surface, a sensor body disposed within the case at a position forward and away from the front surface of the substrate, a first energy filter provided in front of the sensor body, and a second energy filter provided between the sensor body and the front surface of the substrate. [Effects of the Invention]

[0010] According to the present invention, in a personal dosimeter, it is possible to reduce vibrations reaching a radiation sensor via a substrate, or to improve the reliability of measurement results in a personal dosimeter. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a perspective view showing the front side of the personal dosimeter according to the embodiment. [Figure 2] FIG. 2 is a perspective view showing the rear side of the personal dosimeter according to the embodiment. [Figure 3] FIG. 10 is a diagram showing an example of a wearing state. [Figure 4] FIG. 3 is a diagram showing the rear part of the detection unit according to the first embodiment. [Figure 5] FIG. 2 is a diagram showing the front part of the detection unit according to the first embodiment. [Figure 6] FIG. 2 is a cross-sectional view of a detection unit according to the first embodiment. [Figure 7] FIG. 2 is an exploded perspective view of a detection unit according to the first embodiment. [Figure 8] FIG. 10 is a cross-sectional view of a detection unit according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing the inside of a detection unit according to a second embodiment. [Figure 10] FIG. 10 is an exploded perspective view of a detection unit according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment will be described with reference to the drawings.

[0013] (1) Overview of the embodiment A personal dosimeter according to an embodiment includes a case, a substrate, a sensor body, a first energy filter, and a second energy filter. The substrate is disposed within the case. The substrate has a front surface. The sensor body is disposed within the case at a position spaced forward from the front surface of the substrate. The first energy filter is provided in front of the sensor body. The second energy filter is provided between the sensor body and the front surface of the substrate.

[0014] In the above configuration, the first energy filter and the second energy filter are each intended to improve the energy characteristics (energy dependency) of the radiation sensor.

[0015] According to the above configuration, radiation from the front passes through the first energy filter and reaches the sensor body. Furthermore, radiation from the rear, which is generated by reflection or scattering on the human body, passes through the second energy filter and reaches the sensor body. Furthermore, radiation from the rear, which is generated by reflection or scattering on the second energy filter, also reaches the sensor body. Therefore, according to the above configuration, advantages such as improved energy characteristics, improved sensitivity, and improved directional characteristics can be obtained. In other words, the reliability of the measurement results can be improved.

[0016] In the above configuration, the second energy filter is provided between the sensor body and the substrate, i.e., the second energy filter is close to the sensor body, so the size of the second energy filter can be reduced. Also, in the above configuration, the sensor body is separated from the substrate, so vibration transmitted to the sensor body via the substrate can be reduced. Furthermore, since the second energy filter is provided between the substrate and the sensor body, the detection unit can be made smaller. If the second energy filter is not provided, dead space will be generated between the substrate and the sensor body. The above configuration makes effective use of the space between the substrate and the sensor body.

[0017] The personal dosimeter according to the embodiment further includes a first cushion sheet and a second cushion sheet. The first cushion sheet is provided between the substrate and the second energy filter. The second cushion sheet is provided between the sensor body and the second energy filter. This configuration can reduce vibrations transmitted from the substrate to the sensor body via the second energy filter.

[0018] In this embodiment, the first cushion sheet and the second cushion sheet are each double-sided adhesive tape. This configuration allows the second energy filter to be easily fixed onto the substrate, and the sensor body to be easily fixed onto the second energy filter. Because the entire sensor body is indirectly supported by the substrate, the sensor body does not move relative to the substrate, and the sensor body's posture is stabilized. This reduces erroneous counting due to movement (e.g., swinging movement) of the sensor body.

[0019] The personal dosimeter according to the embodiment further includes a pair of conductor legs that electrically connect the substrate and the sensor body. In the embodiment, each conductor leg in the pair of conductor legs has an L-shape. More specifically, each conductor leg in the pair of conductor legs has a first portion and a second portion. The first portion has an end portion fixed to the sensor body and extends parallel to the substrate. The second portion is connected to the first portion via a bent portion, has an end portion fixed to the substrate, and extends perpendicular to the substrate.

[0020] According to the above configuration, physical interference between the pair of conductor legs and the second energy filter can be avoided, and vibrations transmitted from the substrate to the sensor body via the pair of conductor legs can be reduced.

[0021] In an embodiment, the case has a longitudinal direction. The substrate has a first end including a first edge and a second end including a second edge longitudinally spaced from the first end. An assembly including a second energy filter and a sensor body is provided at the first end. Each conductor leg is provided longitudinally between the sensor body and the first end.

[0022] According to the above configuration, since the detection signal from the radiation sensor can be applied near the first end of the substrate, the design of the wiring pattern is easier than when the detection signal is applied to the middle of the substrate. If the wiring length is shortened by simplifying the wiring pattern, the substrate becomes less susceptible to the effects of external electromagnetic waves.

[0023] The personal dosimeter according to the embodiment further includes a front shield cover. The front shield cover is fixed to the front surface of the substrate and houses an assembly including a second energy filter and a radiation sensor. The front shield cover is separated from the case by a first gap and from the assembly by a second gap. This configuration reduces the influence of external electromagnetic waves. It also prevents direct transmission of vibrations from the case to the front shield cover and from the front shield cover to the assembly. Since vibrations are not transmitted directly from the case to the sensor body, erroneous counting due to vibrations is suppressed.

[0024] In an embodiment, the front shield cover has a recess recessed toward the rear. The first energy filter is disposed in the recess. This configuration makes it easy to dispose the first energy filter. Furthermore, even if the holding force of the first energy filter weakens, the first energy filter will not come into contact with the assembly.

[0025] In an embodiment, the assembly includes a first energy filter. The front shield cover has a protrusion that protrudes forward. Part or all of the first energy filter fits into the internal space of the protrusion without contacting it. With this configuration, the assembly is separated from the front shield cover, preventing direct transmission of vibrations from the front shield cover to the assembly. By providing a relatively large recess or protrusion on the front surface of the front shield cover, the rigidity of the entire front shield cover can be increased. In an embodiment, the front shield cover is disposed on the substrate without contacting the case.

[0026] In this embodiment, the front shield cover and the rear shield cover form a shield case that surrounds the entire assembly. The shield case blocks electromagnetic waves coming from various directions, thereby reducing false counts caused by electromagnetic waves. The front shield cover and the rear shield cover also generally function as auxiliary energy filters.

[0027] (2) Details of the embodiment 1 shows the front side of a personal dosimeter 10 according to an embodiment. The personal dosimeter 10 is a portable radiation measuring device for managing personal radiation exposure in radiation handling facilities such as nuclear power plants and medical facilities. For example, the personal dosimeter is worn by a person (user) working in each facility.

[0028] In FIG. 1, the y direction is parallel to the longitudinal direction of the personal dosimeter 10. The y direction corresponds to the up-down direction when the personal dosimeter 10 is worn. The x direction is the width direction. The x direction corresponds to the left-right direction when the personal dosimeter 10 is worn. The z direction is the thickness direction. When viewed from the personal dosimeter 10, the +z direction is the forward direction and the -z direction is the backward direction. In other words, the +z direction corresponds to the non-human body side and the -z direction corresponds to the human body side.

[0029] The personal dosimeter 10 has a hollow case 12. The case 12 is made of, for example, resin. The case 12 has an elongated shape extending along the y direction. A clip 14 is provided on the front surface 24 of the case 12. The clip 14 is used when attaching the personal dosimeter to clothing or the like.

[0030] The case 12 is broadly divided into an enlarged portion 16, a transition portion 18, and a main body 20. These are multiple portions that are aligned from top to bottom when the personal dosimeter 10 is worn. The end of the main body 20 is a cap 22. The case 12 has a central axis C. The central axis C is parallel to the y direction. The thickness of the enlarged portion 16 in the z direction is greater than the thickness of the main body 20 in the z direction. The thickness of the transition portion 18 in the z direction varies along the y direction, and more specifically, decreases along the +y direction. The width of the case 12 in the x direction is the same at each position in the y direction. However, both ends of the case 12 in the y direction are rounded.

[0031] A detection unit is housed within the enlarged portion 16. The detection unit has a radiation sensor, as will be described later. A detection central axis 26 passes through the center of the sensitive surface of the radiation sensor disposed within the enlarged portion 16. Reference numeral 28 indicates radiation coming from the front. In this embodiment, the radiation to be detected is gamma rays or X-rays. Other types of radiation, such as beta rays, may also be detected. Multiple types of radiation may be detected simultaneously.

[0032] 2 shows the rear side of the personal dosimeter 10. A display 30 and an operation unit 32 are provided on the rear surface of the case. The display 30 is, for example, a liquid crystal display. The display 30 displays the dose equivalent rate, the cumulative dose equivalent, etc. The operation unit 32 has two buttons, specifically a power button and a display switching button.

[0033] 3 shows an example of how a personal dosimeter is worn. The personal dosimeter 10 is inserted into a pocket 36 provided in the clothing 34 of a worker 33. The clip 14 is in an open state due to an operation 39 of the worker's fingers. The clip 14 has a clip body 38. The clip body 38 has a shoulder portion 124 and an arm portion 126. The shoulder portion 124 is a portion that is fixed to the case. The arm portion 126 is a portion that extends downward from the shoulder portion 124 and is also a portion that is elastically deformable.

[0034] A slit 37 is formed between the arm 126 and the front face 24 of the case, and the fabric of the pocket 36 is inserted into the slit 37. When the clip 14 is then returned to the closed state, the fabric is sandwiched between the arm 126 and the front face 24 of the case. In the state shown in Figure 3, radiation 28 coming from the front is detected.

[0035] The detection unit 46 according to the first embodiment will be described with reference to Figures 4 to 7. The detection unit 46 according to the first embodiment detects gamma rays. X-rays may also be detected together with gamma rays.

[0036] 4 shows the rear of the detection unit 46. The detection unit 46 is fixed to the substrate 40. The substrate 40 is provided with a buzzer, a vibrator, a microcomputer, multiple electrical elements, a power supply unit, etc., but these are not shown in the figure. The detection unit 46 has a front shield cover 48 and a rear shield cover 50. The front shield cover 48 and the rear shield cover 50 form a shield case. The detection unit 46 has a radiation sensor supported by the substrate 40. The radiation sensor is enclosed in the shield case.

[0037] The front shield cover 48 and the rear shield cover 50 are intended to block electromagnetic waves coming from the outside so that they do not reach the radiation sensor. Blocking electromagnetic waves can prevent or reduce false counts.

[0038] The front shield cover 48 and the rear shield cover 50 are made of, for example, a metal having a certain thickness, such as aluminum, copper, or iron. The certain thickness is, for example, within a range of 0.2 to 1.5 mm. The front shield cover 48 and the rear shield cover 50 also function as auxiliary energy filters. All numerical values ​​given in this specification are merely examples.

[0039] The substrate 40 is, for example, a multi-layer substrate. The substrate 40 has multiple layers (for example, six or eight layers), including a ground layer. The front shield cover 48 and the rear shield cover 50 are physically fixed to the substrate 40, and are also electrically connected to the ground layer.

[0040] The reference numeral 44 denotes a coin-type battery. The reference numeral 42 denotes a battery holder. The battery holder 42 and the board 40 are connected by a twisted cable.

[0041] FIG. 5 shows the front surface of the substrate 40. The front surface is the surface facing the +z direction, that is, forward. The front shield cover 48 has a box-like shape. A recess 52 is formed at its end. The recess 52 has a rectangular shape when viewed from the z direction. A first energy filter 54 is housed within the recess 52. Specifically, the first energy filter 54 is adhesively fixed onto the bottom surface of the recess 52. The first energy filter 54 has a plate shape, and has a rectangular shape when viewed from the z direction.

[0042] 6 shows a cross section of the detection unit 46 according to the first embodiment. The detection unit 46 is housed in the case 12, and more specifically, the detection unit 46 is housed in the enlarged portion 16.

[0043] The detection unit 46 has an assembly 55, a front shield cover 48, a rear shield cover 50, and a first energy filter 54. The assembly 55 is fixed on the substrate 40. The assembly 55 has a radiation sensor 56 and a second energy filter 62. The assembly 55 is enclosed in a non-contact manner by the front shield cover 48 and the rear shield cover 50. The shape of the opening edge of the front shield cover 48 and the shape of the opening edge of the rear shield cover 50 are the same. By adopting such a configuration, it is possible to minimize the entry of electromagnetic waves from outside.

[0044] The radiation sensor 56 is, for example, a silicon photosensor. The radiation sensor 56 is made up of a sensor body 58 and conductive legs 60. The sensor body 58 has a sensitive portion. The gamma rays 28A are detected in the sensitive portion.

[0045] The conductive leg 60 consists of a pair of legs. Each leg has a first portion 67 and a second portion 68. An end (first end) of the first portion 67 is fixed to the sensor body 58. An end (second end) of the second portion 68 is fixed to the substrate 40. The first portion 67 is a horizontal portion that is approximately parallel to the y direction. The second portion 68 is a vertical portion that is approximately parallel to the z direction. The first portion 67 and the second portion 68 are connected to each other via a bent portion 70.

[0046] The substrate 40 has a first end 40A and a second end that are spaced apart in the y-direction, i.e., the longitudinal direction. In other words, the substrate 40 has a first end 41 that includes the first end 40A and a second end that includes the second end. The detection portion 46 is provided on the first end 41. The second end of each leg is connected to the substrate 40 near the first end 40A. In other words, the conductive legs 60 are provided between the sensor body 58 and the first end 40A in the y-direction.

[0047] By adopting such a configuration, it becomes easier to design the wiring pattern on the substrate 40. That is, it becomes possible to arrange multiple electronic components from upstream to downstream in the y direction in accordance with the order of signal processing. For example, a radiation sensor, a preamplifier, a linear amplifier, a comparator, etc. may be arranged in this order from upstream to downstream in the y direction. This allows the wiring length to be shortened, thereby reducing the effects of electromagnetic waves.

[0048] The front shield cover 48 has a recess 52 recessed toward the rear. A first energy filter 54 is disposed in the recess 52. The first energy filter 54 is made of a metal such as copper. The first energy filter 54 has a constant thickness and is in the form of a plate extending in the x and y directions. The center of the first energy filter 54 is on the central detection axis.

[0049] The bottom surface of the recess 52 and the back surface of the first energy filter 54 are adhered with double-sided adhesive tape 72. In other words, the first energy filter 54 is fixed inside the recess 52. A gap G1 exists between the front shield cover 48 (and the first energy filter 54) and the case 12, and the front shield cover 48 (and the first energy filter 54) is separated from the case 12.

[0050] In the assembly 55, the substrate 40 and the second energy filter 62 are bonded to each other with a double-sided adhesive tape 64, and the sensor main body 58 and the second energy filter 62 are bonded to each other with a double-sided adhesive tape 66. The double-sided adhesive tape 64 and the double-sided adhesive tape 66 each have an intermediate layer (base layer), a front adhesive layer, and a back adhesive layer. Their thicknesses are, for example, in the range of 0.1 to 3.0 mm. The double-sided adhesive tape 64 and the double-sided adhesive tape 66 each function as a cushion sheet having elasticity or vibration absorption properties. Note that the double-sided adhesive tape 72 may be the same as the double-sided adhesive tape 64 and the double-sided adhesive tape 66. The components may be fixed using materials or members other than double-sided adhesive tape (e.g., adhesives, screws).

[0051] The second energy filter 62 is made of a metal such as copper, similar to the first energy filter 54. The second energy filter 62 and the first energy filter 54 may each be made of a plurality of types of metal. The surfaces of the first energy filter 54 and the second energy filter 62 may be plated. In other words, a surface layer may be provided on the surfaces of the first energy filter 54 and the second energy filter 62.

[0052] The width of the second energy filter 62 in the x direction is smaller than the width of the first energy filter 54 in the x direction, and the width of the second energy filter 62 in the y direction is smaller than the width of the first energy filter 54 in the y direction. The width of the first energy filter 54 in the x direction is, for example, 5 to 25 mm, and the width of the first energy filter 54 in the y direction is, for example, 5 to 25 mm. The thickness of the first energy filter 54 is, for example, 0.4 to 2.0 mm. The width of the second energy filter 62 in the x direction is, for example, 3 to 10 mm, and the width of the second energy filter 62 in the y direction is, for example, 3 to 10 mm. The thickness of the second energy filter 62 is, for example, 0.4 to 2.0 mm.

[0053] Because the second energy filter 62 is bonded to the sensor body 58, the widths of the second energy filter 62 in the x and y directions can be reduced. The width of the second energy filter 62 in the x direction is the same as or smaller than the width of the sensor body 58 in the x direction. The width of the second energy filter 62 in the y direction is smaller than the width of the sensor body 58 in the y direction. When viewed from the front, the second energy filter 62 does not protrude from the sensor body 58.

[0054] A gap G2 exists between the sensor main body 58 and the front shield cover 48. That is, the sensor main body 58 is separated from the front shield cover 48. The rear shield cover 50 covers the back surface of the first end 41. A gap G3 exists between the rear shield cover 50 and the case 12, separating the rear shield cover 50 from the case 12. The detection unit 46 has multiple electronic circuits such as preamplifiers, but these are not shown in the figure. These electronic circuits are provided inside the front shield cover 48 and the rear shield cover 50.

[0055] Gamma rays 28A coming from the front pass through the first energy filter 54 and reach the sensitive part of the radiation sensor 56. The first energy filter 54 improves the energy characteristics of the radiation sensor, making it possible to accurately measure the dose of gamma rays across a range of energies from low to high.

[0056] A portion of the gamma rays reflected or scattered by the human body passes through the second energy filter 62 and reaches the sensitive part of the radiation sensor 56. A portion of the gamma rays reflected or scattered by the second energy filter 62 also reaches the sensitive part of the radiation sensor 56. The second energy filter 62 improves the energy characteristics of the radiation sensor, similar to the first energy filter 54. Since the second energy filter 62 is provided in addition to the first energy filter 54, and since the second energy filter 62 is located near the sensor main body 58, advantages such as improved energy characteristics, improved sensitivity, and improved directional characteristics can be obtained.

[0057] As described above, the front shield cover 48 and the rear shield cover 50 function as auxiliary energy filters. The shapes, materials, thicknesses, etc. of the first energy filter 54, the second energy filter 62, the front shield cover 48, and the rear shield cover 50 are adjusted so that the final energy characteristics of the radiation sensor are optimal.

[0058] 6, sensor body 58 is spaced from the front surface of substrate 40. Two double-sided adhesive tapes 64, 66 are provided between substrate 40 and sensor body 58, and each of the two double-sided adhesive tapes 64, 66 provides a cushioning effect, thereby reducing vibrations transmitted from substrate 40 to sensor body 58 in assembly 55.

[0059] The sensor body 58 is fixed onto the substrate 40 via the second energy filter 62 and the like, and movement of the sensor body 58 relative to the substrate 40 is restricted. Therefore, problems caused by movement of the sensor body 58 do not occur. Each leg constituting the conductive leg 60 has an L-shape (a horizontal portion and a vertical portion). Therefore, physical interference between the conductive leg 60 and the second energy filter 62 is avoided, and vibrations transmitted to the sensor body 58 via each leg are mitigated.

[0060] If the sensor main body 58 is simply separated from the substrate 40, a dead space will be created between the substrate 40 and the sensor main body 58. However, if the second energy filter 62 is disposed between the substrate 40 and the sensor main body 58, the space between them can be effectively utilized. As a result, the detection unit 46 can be made smaller. If double-sided adhesive tape is used to arrange the various components, assembly of the detection unit 46 will be easier.

[0061] 7 is an exploded perspective view of the detection unit 46 according to the first embodiment. As already explained, the front shield cover 48 has a recess 52, and the first energy filter 54 is placed in the recess 52. At this time, double-sided adhesive tape 72 is used. Three protrusions 48a are provided on the edge of the opening of the front shield cover 48. Three protrusions 50a are also provided on the edge of the rear shield cover 50.

[0062] An assembly 55 is fixed onto the substrate 40. Six openings 40a are formed at a first end of the substrate 40. Three protrusions 48a of the front shield cover 48 and three protrusions 50a of the rear shield cover 50 are inserted into the six openings 40a and soldered. In practice, the entire edge of the opening of the front shield cover 48 is soldered to the substrate 40, and the entire edge of the opening of the rear shield cover 50 is soldered to the substrate 40. This effectively prevents electromagnetic waves from entering the shield case.

[0063] Next, a detection unit 80 according to a second embodiment will be described with reference to Figures 8 to 10. The detection unit 80 detects X-rays. Gamma rays may also be detected together with X-rays.

[0064] 8 shows a cross section of a detection unit 80 according to the second embodiment. The detection unit 80 is housed in the case 12, and more specifically, the detection unit 80 is housed in the enlarged portion 16.

[0065] The detection unit 80 includes an assembly 86, a front shield cover 82, and a rear shield cover 84. The assembly 86 is fixed on the substrate 40. The assembly 86 includes a radiation sensor 88, an energy filter 100, an energy filter 102, and an energy filter 108. The energy filters 100 and 102, taken as a whole, are a first energy filter that acts on radiation from the front (including oblique directions). The energy filter 108 is a second energy filter that acts on radiation from the rear. The assembly 86 is enclosed in a non-contact manner by the front shield cover 82 and the rear shield cover 84. The shape of the opening edge of the front shield cover 82 and the rear shield cover 84 are the same. The front shield cover 82 has a protrusion 83 that protrudes forward.

[0066] The radiation sensor 88 is, for example, a silicon photosensor. The radiation sensor 88 is made up of a sensor body 90 and conductive legs 92. The sensor body 90 has a sensitive portion. X-rays are detected in the sensitive portion.

[0067] The conductive leg 92 consists of a pair of legs. Each leg has a first portion 94 and a second portion 96. An end of the first portion 94 is fixed to the sensor body 90. An end of the second portion 96 is fixed to the substrate 40. The first portion 94 is a horizontal portion parallel to the y direction. The second portion 96 is a vertical portion parallel to the z direction. The first portion 94 and the second portion 96 are connected to each other via a bent portion 98.

[0068] The substrate 40 has a first end 40A and a second end that are spaced apart in the y direction, i.e., the longitudinal direction. In other words, the substrate 40 has a first end 41 that includes the first end 40A and a second end that includes the second end. The detection unit 80 is provided on the first end 41. The second end of each leg is connected to the substrate 40 near the first end 40A. In other words, the conductive legs 92 are provided between the sensor body 90 and the first end 40A in the y direction.

[0069] A gap G1 exists between the front shield cover 82 and the case 12, separating the front shield cover 82 from the case 12. A gap G2 exists between the front shield cover 82 and the assembly 86, separating the assembly 86 from the front shield cover 82.

[0070] Energy filters 100 and 102 are fixed to the sensor main body 90. The energy filter 102 covers the upper surface of the sensor main body 90. The energy filter 102 also covers three of the four side surfaces of the sensor main body 90 (the three side surfaces to which the conductive legs 92 are not connected).

[0071] The energy filter 100 comprises a large diameter portion and a small diameter portion. The large diameter portion is placed on the top plate of the energy filter 102. An opening is formed in the top plate of the energy filter 102, and the small diameter portion is inserted into the opening. The energy filter 100 has a through-hole 100A. The through-hole 100A has, for example, a cylindrical shape. The through-hole 100A may also have a conical or mortar shape.

[0072] Energy filter 100 is adhered to energy filter 102 via double-sided adhesive tape 104. Energy filter 102 is adhered to sensor body 90 via double-sided adhesive tape 106. The central axis of energy filter 100 coincides with the central detection axis. The central detection axis is an axis that passes through the center of the sensitive part in sensor body 90 and is perpendicular to the sensitive part.

[0073] The sensor body 90 is spaced forward from the front surface of the substrate 40. An energy filter 108 is disposed between the sensor body 90 and the front surface of the substrate 40. Specifically, the substrate 40 and the energy filter 108 are bonded to each other with a double-sided adhesive tape 110, and the sensor body 90 and the energy filter 108 are bonded to each other with a double-sided adhesive tape 112. The double-sided adhesive tape 110 and the double-sided adhesive tape 112 each function as a cushion sheet having elasticity or vibration absorption properties.

[0074] The energy filters 100, 102, and 108 are each made of a metal such as copper. They may each be made of a plurality of types of metal. The thickness of the energy filter 100 is set within a range of 0.4 to 2.0 mm, for example. The diameter of the large diameter portion of the energy filter 100 is set within a range of 1 to 20 mm, for example. The diameter of the through-hole 100A is set within a range of 2 to 4 mm, for example. The thickness of the energy filter 102 is set within a range of 0.1 to 1.0 mm, for example. The energy filter 108 has a shape that is the same as or similar to the shape of the second energy filter shown in FIG. 6, for example.

[0075] A gap G2 exists between the assembly 86 and the front shield cover 82. In other words, the assembly 86 is separated from the front shield cover 82. A portion of the assembly 86 fits into the internal space of the protrusion 83 without contacting it. The rear shield cover 84 covers the back surface of the first end 41. A gap G3 exists between the rear shield cover 84 and the case 12. This separates the rear shield cover 84 from the case 12. The detection unit 80 has multiple electronic circuits such as a preamplifier, but these are not shown in the figure. These electronic circuits are provided inside the front shield cover 82 and the rear shield cover 84.

[0076] A portion of the X-rays 28B from the front passes through the energy filter 100 and / or the energy filter 102 and reaches the sensitive portion of the radiation sensor 88. Another portion of the X-rays 28B from the front passes through the inside of the through-hole 100A formed in the energy filter 100 and reaches the sensitive portion of the radiation sensor 88.

[0077] A portion of the X-rays reflected or scattered by the human body passes through the energy filter 108 and reaches the sensitive portion of the radiation sensor 88. In addition, a portion of the X-rays reflected or scattered by the energy filter 108 also reaches the sensitive portion of the radiation sensor 88.

[0078] The energy filters 100, 102, and 108 are each intended to improve the energy characteristics of the radiation sensor. In addition to the first energy filter, the second energy filter is provided, and moreover, the second energy filter is provided near the sensor body 90, thereby providing the advantages of improved energy characteristics, improved sensitivity, and improved directional characteristics.

[0079] The front shield cover 82 and the rear shield cover 84 function as auxiliary energy filters. The shapes, materials, thicknesses, etc. of the energy filters 100, 102, 108, the front shield cover 82, and the rear shield cover 84 are adjusted so that the final energy characteristics of the radiation sensor are optimal.

[0080] 8, the sensor body 90 is separated from the front surface of the substrate 40. This prevents vibrations transmitted through the substrate 40 from directly reaching the sensor body 90. The two double-sided adhesive tapes 110, 112 each provide a cushioning effect, thereby reducing vibrations transmitted from the substrate 40 to the sensor body 90.

[0081] The sensor body 90 is indirectly fixed to the substrate 40 via the energy filter 108 or the like, and movement of the sensor body 90 relative to the substrate 40 is restricted. Therefore, problems caused by movement of the sensor body 90 do not occur. Each leg constituting the conductive leg 92 has an L-shape (a horizontal portion and a vertical portion). Therefore, physical interference between the conductive leg 92 and the energy filter 108 is avoided, and vibrations transmitted to the sensor body 90 via each leg are mitigated.

[0082] 9 is a perspective view showing the inside of the detection unit 80 according to the second embodiment. As already explained, the front shield cover 82 has a convex portion. Three protrusions 82a are provided on the edge of the opening of the front shield cover 82. Three protrusions 84a are also provided on the edge of the opening of the rear shield cover 84.

[0083] An assembly 86 is fixed onto the substrate 40. Six openings 40a are formed at a first end of the substrate 40. Three protrusions 82a of the front shield cover 82 and three protrusions 84a of the rear shield cover 84 are inserted into the six openings 40a and soldered thereto. In practice, the entire opening edge of the front shield cover 82 is soldered to the substrate 40, and the entire opening edge of the rear shield cover 84 is soldered to the substrate 40. This effectively blocks external electromagnetic waves.

[0084] 10 is an exploded perspective view of a detection unit 80 according to the second embodiment. A front shield cover 82 is provided on the front surface of the substrate, and a rear shield cover 84 is provided on the rear surface of the substrate. An assembly 86 is enclosed by the front shield cover 82.

[0085] The assembly 86 is composed of, from top to bottom, an energy filter 100, a double-sided adhesive tape 104, an energy filter 102, a double-sided adhesive tape 106, a radiation sensor 88, a double-sided adhesive tape 112, an energy filter 108, and a double-sided adhesive tape 110. The energy filter 102 has a top plate 114 and three side plates 116. An opening 118 is formed in the top plate 114. The small-diameter portion of the energy filter 100 is inserted into the opening 118.

[0086] According to the above embodiment, the energy characteristics of the personal dosimeter can be improved, the sensitivity of the personal dosimeter can be improved, and the directional characteristics of the personal dosimeter can be improved. In other words, the reliability of the measurement results can be increased. In the above embodiment, since the second energy filter is provided between the sensor body and the substrate, that is, since the second energy filter is provided in a position close to the sensor body, the second energy filter can be made smaller. This allows the detection unit to be made smaller. Furthermore, in the above configuration, since the sensor body is separated from the substrate, vibrations transmitted to the sensor body via the substrate can be reduced. This effectively reduces erroneous counting caused by vibrations. [Explanation of symbols]

[0087] 10 personal dosimeter, 12 case, 14 clip, 46 detection unit, 48 front shield cover, 50 rear shield cover, 54 first energy filter, 55 assembly, 56 radiation sensor, 62 second energy filter, 80 detection unit, 82 front shield cover, 84 rear shield cover, 86 assembly, 88 radiation sensor, 100 energy filter, 102 energy filter, 108 energy filter.

Claims

1. Case and a substrate disposed within the case and having a front surface; a sensor body disposed in the case at a position spaced forward from the front surface of the substrate; a first energy filter provided on the front side of the sensor body; a second energy filter disposed between the sensor body and the front surface of the substrate; A personal dosimeter comprising:

2. 2. The personal dosimeter according to claim 1, a first cushion sheet provided between the substrate and the second energy filter; a second cushion sheet provided between the sensor body and the second energy filter; A personal dosimeter comprising:

3. 3. The personal dosimeter according to claim 2, The first cushion sheet and the second cushion sheet are each a double-sided adhesive tape. A personal dosimeter characterized by:

4. 2. The personal dosimeter according to claim 1, a pair of conductor legs electrically connecting the substrate and the sensor body; Each of the pair of conductor legs is a first portion having an end fixed to the sensor body and extending parallel to the substrate; a second portion connected to the first portion via a bent portion, the second portion having an end fixed to the substrate and extending perpendicular to the substrate; Including, A personal dosimeter characterized by:

5. 5. The personal dosimeter according to claim 4, the case has a longitudinal direction; the substrate includes a first end portion including a first edge and a second end portion including a second edge spaced apart from the first edge in the longitudinal direction; an assembly including the second energy filter and the sensor body is provided at the first end; Each of the conductor legs is provided between the sensor body and the first end in the longitudinal direction. A personal dosimeter characterized by:

6. 2. The personal dosimeter according to claim 1, a front shield cover fixed to the front surface of the substrate and housing an assembly including the second energy filter and the sensor body; the front shield cover is separated from the case by a first gap and from the assembly by a second gap; A personal dosimeter characterized by:

7. 7. The personal dosimeter according to claim 6, the front shield cover has a recess recessed rearward, the first energy filter is disposed within the recess; A personal dosimeter characterized by:

8. 7. The personal dosimeter according to claim 6, the assembly includes the first energy filter; the front shield cover has a protrusion protruding forward, a part or the whole of the first energy filter is inserted into the internal space of the protrusion without contacting the first energy filter; A personal dosimeter characterized by:

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