JP6686487B2 - Radiation detector - Google Patents

Description

  The present invention relates to a radiation detection device that measures a radiation dose.

  There is a dosimeter as a radiation exposure dose measuring instrument that has been conventionally used. A radiation detection element is arranged inside the dosimeter to enable measurement of radiation dose. Patent Document 1 discloses a radiation detection apparatus including a radiation detection element. In order to keep the energy characteristic of radiation within a predetermined range, a metal filter is arranged on the sensitive surface side of the radiation detection element. There is. Further, in Patent Document 1, through-holes are formed in the filter in order to ensure the energy characteristics of X-rays (or γ-rays) in the low energy region.

JP 2007-24497 A

  However, the radiation applied to the radiation detection element in the oblique direction enters the thickness of the filter in the oblique direction toward the sensitive surface. Therefore, the effective thickness of the filter until it reaches the sensitive surface becomes longer than that in the vertical direction, and the larger the angle with respect to the vertical direction, the more effective thickness increases and the energy characteristics deteriorate. Therefore, there has been a problem that the energy characteristics are significantly deteriorated with respect to low-energy radiation, and good energy characteristics cannot be obtained.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a radiation detection apparatus that can obtain good energy characteristics even with respect to radiation emitted from an oblique direction.

A radiation detection apparatus of the present invention is a radiation detection apparatus including a sensor unit mounted on a predetermined substrate, wherein the sensor unit is arranged on a radiation detection element and a sensitive surface side of the radiation detection element. Energy filter and a first shield that covers the radiation detection element, and the energy filter has a thick portion including a hole penetrating in the filter thickness direction at a position facing the sensitive surface, and the thickness. A thin portion located around the portion, the thick portion is formed to have a relatively larger thickness than the thin portion , penetrates through a through hole formed in the first shield, the radiation detection element attached adhesive or paste, characterized in Rukoto.

  According to this configuration, the effective thickness of the radiation emitted from the oblique direction until it reaches the sensitive surface after passing through the energy filter can be reduced, and the energy characteristics (especially low energy) with respect to the radiation emitted from the oblique direction can be reduced. The sensitivity characteristic to energy) can be stably improved.

  According to the present invention, it is possible to obtain good energy characteristics even with respect to radiation emitted from an oblique direction, as compared with the conventional case.

It is a longitudinal cross-sectional view of the radiation detection apparatus according to the embodiment. It is a front view of a sensor unit. It is the sectional view on the AA line of FIG. FIG. 4 is a partially enlarged view of FIG. 3. 5A to 5C are sectional views for explaining an energy filter according to a modification.

  Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments, but can be implemented by being modified appropriately within the scope of the invention. In addition, in the following drawings, a part of the configuration may be omitted for convenience of description.

  FIG. 1 is a vertical cross-sectional view of a radiation detection apparatus according to an embodiment. As shown in FIG. 1, the radiation detection apparatus 10 includes a sensor unit 13, a printed circuit board (board) 14, a notification unit 16 and a display unit 17 arranged in a housing 11. The sensor unit 13 is mounted on the printed board 14, electrically connected thereto, and covered with a metal shield (second shield) 18. The shield 18 suppresses the entry of electromagnetic waves into the sensor unit 13. The notification unit 16 is composed of a buzzer, a speaker, or the like that notifies a warning sound or the like by a signal processed by the CPU of the printed circuit board 14. The display unit 17 displays the radiation dose and the like detected by the sensor unit 13. The mounting unit 20 is provided so that the radiation detection apparatus 10 can be mounted on clothes or the like.

  FIG. 2 is a front view of the sensor unit. FIG. 3 is a sectional view taken along the line AA of FIG. As shown in FIG. 2 and FIG. 3, the sensor unit 13 includes a radiation detecting element 25 mounted on a sensor unit substrate 24 made of a printed circuit board and energy disposed on the sensitive surface 26 side of the radiation detecting element 25. It has a filter 28 and a metal shield (first shield) 29 for shielding electromagnetic waves. On the sensor unit substrate 24, an amplifier circuit, components, and the like (not shown) that process the output from the radiation detection element 25 are mounted.

  The radiation detection element 25 has, for example, a diode structure including a silicon pn junction. The radiation detecting element 25 having a diode structure is used by applying a reverse bias voltage so as to form a depletion layer of a predetermined size at the pn junction, and is directly and indirectly generated by radiation in the depletion layer. The electrons and holes that are generated are output as current pulses. The configuration of the radiation detection element 25 is not limited to this.

  FIG. 4 is a partially enlarged view of FIG. As shown in FIG. 4, the radiation detection element 25 has a sensitive section 31 and a support section 32 located around the sensitive section 31 except for the surface of the sensitive section 31. The surface of the sensitive portion 31 becomes the sensitive surface 26. The size of the sensitive surface 26 is, for example, several mm square.

  The sensitivity of the radiation detection element 25 greatly changes depending on the radiation energy. Therefore, the energy filter 28 is arranged on the sensitive surface 26 side of the radiation detection element 25 in order to keep this energy characteristic within a predetermined range.

  The energy filter 28 includes a thick portion 34 provided at a position facing the sensitive surface 26, and a thin portion 35 provided around the thick portion 34. The thick portion 34 is formed to be relatively thicker than the thin portion 35, and the thick portion 35 is formed from at least one surface side of the energy filter 28 in the filter thickness direction (Z direction, direction perpendicular to the surface of the energy filter 28). 34 is formed so as to protrude. In the present embodiment, the thick portion 34 protrudes from both sides of the thin portion 35 in the filter thickness direction.

  The thick portion 34 has a hole 36 penetrating in the filter thickness direction (Z direction). The hole 36 is open on both the radiation incident surface 34a side and the opposite surface 34b side of the radiation detecting element 25 on the opposite side. In FIG. 4, the inner peripheral surface of the hole 36 is formed parallel to the filter thickness direction, but the inner peripheral surface has a shape slightly inclined with respect to the filter thickness direction, or has some undulations. Good.

  The thick portion 34 is attached to the radiation detecting element 25 via the attaching member 38. The thick portion 34 penetrates the through hole 29 a formed in the metal shield 29, and the upper end portion in FIG. 4 is provided so as to project from the upper surface of the metal shield 29. The thick portion 34 may be attached to the radiation detecting element 25, and the attaching member 38 may be a tape or an adhesive.

  The thick portion 34 and the thin portion 35 are formed separately, and the thin portion 35 is attached to the upper surface of the metal shield 29 by sticking or adhering via the sticking member 38. An opening 40 corresponding to the outer peripheral shape of the thick portion 34 is formed in the thin portion 35, and the thick portion 34 is inserted into the opening 40 in a substantially exactly fitted state. Therefore, while the thick portion 34 and the thin portion 35 are separate bodies, the thin portion 35 is arranged so as to surround and surround the thick portion 34.

  The thin portion 35 is configured by stacking two plate-shaped bodies having a uniform (uniform) thickness. The two plate-shaped bodies may have the same thickness or different thicknesses. Although FIG. 2 illustrates a case where the two plate-shaped bodies have different planar shapes, they may have the same shape. In the present embodiment, in order to facilitate the alignment of the two plate-shaped bodies, the positions of the openings 40 formed in each plate-shaped body are aligned when the positions of the respective sides are aligned. Has been formed.

  The two plate-like members of the thick portion 34 and the thin portion 35 that constitute the energy filter 28 are metal filters such as copper, tantalum, tin, etc., and the filter thickness is selected to obtain desired energy characteristics. There is.

  When viewed from the filter thickness direction, that is, the direction shown in FIG. 2, the hole 36 of the thick portion 34 is formed in a shape that fits in the sensitive surface 26. In addition, the thick portion 34 is formed in an outer peripheral shape in which the sensitive surface 26 fits. Therefore, the opening size of the hole 36, the sensitive surface 26, and the outer peripheral shape of the thick portion 34 are formed in a plane size that increases in this order.

  Returning to FIG. 4, as for the radiation R1 emitted from the filter thickness direction (Z direction), since the irradiation direction coincides with the penetrating direction of the hole 36 of the thick portion 34, part of the radiation R1 does not pass through the hole 36. It passes through and reaches the sensitive surface 26. Therefore, the radiation R1 of low energy (about 30 keV to 50 keV) can reach the sensitive surface 26 of the radiation detecting element 25 by an amount corresponding to the predetermined sensitivity.

  On the other hand, the radiation R2 emitted from a direction obliquely inclined with respect to the filter thickness direction (Z direction) passes through the thin portion 35 and then the thick portion 34 at the inclination angle shown. And is incident on the sensitive surface 26. At this time, the effective thickness of the radiation R2 that passes through the energy filter 28 in an oblique direction and reaches the sensitive surface 26 can be reduced by the distance L1 in which the thin portion 35 is thinned. Therefore, the effective thickness of the radiation R2 is L2.

  According to such an embodiment, since the thin portion 35 having a relatively small thickness is provided around the thick portion 34, the radiation R2 from the oblique direction reaches the sensitive surface 26 in the energy filter 28. The effective thickness can be reduced. This makes it possible to effectively reach the sensitive surface 26 with the radiation R2 emitted from an oblique direction, especially the radiation R2 having low energy. The direction of the radiation R2 is an example, and when viewed from the direction (filter thickness direction) shown in FIG. 2, the radiation in any direction of 360 ° toward the sensitive surface 26 passes through the thin portion 35. If the radiation is incident on the sensitive surface 26, the effective thickness can be similarly reduced. This makes it possible to reduce the amount of radiation attenuation, improve the energy characteristics of low-energy radiation having various angles and inclinations with respect to the filter thickness direction, and ensure the directional characteristics.

  Further, since the adjacent thick portion 34 and thin portion 35 are formed separately, the thick portion 34 has a ring shape, a tubular shape, or a perforated piece shape, and the thin portion 35 has an opening 40. The plate-shaped body can be formed into a shape that can be easily processed. As a result, the product cost can be reduced by reducing the processing man-hours and processing time. Moreover, since the thin portion 35 is formed by laminating a plurality of plate-like bodies, it is possible to change the number of thin-walled portions 35 to be stacked or change the size or shape of part or all of the plate-like bodies to obtain a desired thickness. Energy characteristics can be selected.

  Furthermore, since the thick portion 34 is attached or adhered to the radiation detecting element 25, the thickness of the sensor unit 13 as a whole can be reduced as compared with the case where the thick portion 34 is adhered to the metal shield 29. However, if there is no restriction on the thickness of the sensor unit 13, it does not prevent the thick portion 34 from being bonded to the metal shield 29. Further, since the thin portion 35 is attached to the metal shield 29, the thin portion 35 can be attached and detached after the metal shield 29 is attached to the sensor unit substrate 24.

  In addition, as described above, since the opening size of the hole 36, the sensitive surface 26, and the outer peripheral shape of the thick portion 34 are formed in a plane size that increases in this order, all radiation passing through the facing surface 34b of the hole 36 is detected. 26. Further, the radiation incident on the sensitive surface 26 can pass through at least one of the thickness of the hole 36 and the thick portion 34, which can contribute to stable improvement of energy characteristics.

  Further, since the thick portion 34 is inserted into the opening 40 of the thin portion 35, when the thin portion 35 is attached to the metal shield 29, the thick portion 34 is inserted into the opening 40 to reduce the thickness 35. Can be positioned.

  The present invention is not limited to the above embodiment and can be implemented with various modifications. Further, there are no particular restrictions on the numerical values, dimensions, materials, and directions described in the above embodiments. Other changes can be made without departing from the scope of the object of the present invention.

  For example, the structure of the thin portion 35 can be replaced with the structure shown in FIGS. 5A to 5C. 5A to 5C are sectional views for explaining an energy filter according to a modification. In the energy filter 28 of FIG. 5A, the thin portion 50 is formed of a single plate-shaped body or piece. The thin portion 50 is also formed to have a relatively smaller thickness than the thick portion 34.

  In the energy filter 28 of FIG. 5B, the thin portion 51 is formed in a truncated cone shape whose thickness becomes gradually smaller as it goes away from the thick portion 34. Therefore, the surface of the thin portion 51 is formed by the tapered surface. Further, in the energy filter 28 of FIG. 5C, the thin portion 52 is formed to have a swollen surface shape while the thickness gradually decreases as the distance from the thick portion 34 increases. By changing the thickness of the thin portions 51 and 52 in this way, it is possible to change the amount of radiation attenuation in the thin portions 51 and 52 and obtain desired energy characteristics and directional characteristics.

  Further, in the above-described embodiment, the thick portion 34 protrudes from both sides of the thin portion 35, but the upper surfaces of the thin portion 35 and the thick portion 34 in FIG. The thin portion 35 may be provided inside the shield 29, and their lower surfaces in FIG. 4 may be aligned so as to be flush with each other.

  Further, the planar shapes of the thick portion 34 and the hole 36 do not have to be circular, but it is easier to stabilize the directional characteristics when the circular shape is used.

10 Radiation Detection Device 13 Sensor Unit 14 Printed Circuit Board (Substrate)
18 Shield (second shield)
25 Radiation Detection Element 26 Sensitive Surface 28 Energy Filter 29 Metal Shield (First Shield)
34 Thick part 35 Thin part 36 Hole

Claims (8)

A radiation detection apparatus comprising a sensor unit mounted on a predetermined substrate,
The sensor unit has a radiation detection element, an energy filter arranged on the sensitive surface side of the radiation detection element, and a first shield that covers the radiation detection element ,
The energy filter includes a thick portion including a hole penetrating in the filter thickness direction at a position facing the sensitive surface, and a thin portion located around the thick portion,
Radiation the thick portion, wherein the thin portion from relatively thick larger, the through the first shield formed through hole, and wherein the Rukoto attached adhesive or laminated to the radiation detecting element Detection device.   The radiation detecting apparatus according to claim 1, wherein the thick portion and the thin portion are formed separately and are arranged adjacent to each other.   The said thin part is comprised by laminating | stacking the plate-shaped object of uniform thickness, The radiation detection apparatus of Claim 1 or Claim 2 characterized by the above-mentioned.   The radiation detecting apparatus according to any one of claims 1 to 3, wherein the thin portion has a thickness that becomes smaller as it goes away from the thick portion.   The radiation detecting apparatus according to claim 4, wherein the thin portion is formed in a swollen surface shape. The radiation detection apparatus according to claim 1 , further comprising a second shield that covers the sensor unit. When viewed from the thickness direction of the filter, the hole is formed in a shape that fits in the sensitive surface, and the outer peripheral shape of the thick portion is formed in a shape that fits the sensitive surface. The radiation detection device according to any one of claims 1 to 6 . Wherein the thin portion opening is formed, the radiation detecting apparatus according to any one of claims 1 to 7, characterized in that the thick portion in the opening portion is disposed.

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