JP2012202746A - Radiation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detection device capable of securing reliability under actual and transient use environment.SOLUTION: A radiation detection device 10 comprises an X-ray detection panel 2, a support substrate 4, a circuit board 5 and a housing 9 for housing them. A dehumidification mechanism 20 penetrating from inside of the housing 9 to outside is provided at a part of the housing 9. The dehumidification mechanism 20 includes: a cooling part which is formed inside the housing 9 and condenses moisture generated inside the housing 9; a heating part which is formed outside the housing 9 and evaporates the moisture; and water leading part for leading out the moisture condensed at the cooling part to the heating part.

Description

  Embodiments described herein relate generally to a radiation detection apparatus that detects radiation such as X-rays and gamma rays.

  2. Description of the Related Art In recent years, a planar radiation detection apparatus including a phosphor film that converts radiation (particularly X-rays) into light and a photoelectric conversion element that converts the light into an electrical signal has been put into practical use.

  The conventional X-ray image tube requires a large and heavy detector because it requires an electron lens configuration in the vacuum tube, but the planar radiation detector forms a plurality of pixels including photoelectric conversion elements in a two-dimensional form on a glass substrate. By doing so, it becomes possible to constitute a thin planar type.

  In this planar radiation detection apparatus, an X-ray detection panel in which a plurality of pixels are two-dimensionally formed on a glass substrate as described above, and a phosphor film is formed on the pixels, and a circuit board are arranged in parallel. By adopting the structure as described above and using the main components including a housing including the X-ray detection panel and the circuit board, a reduction in size and weight is realized.

  Such planar radiation detectors are used in a wide range of fields such as medical and dental use for patient diagnosis and treatment, industrial use such as non-destructive inspection, and scientific research such as structural analysis. In each field, high-accuracy image extraction and high-speed image detection by digital information processing become possible, so that reduction of unnecessary X-ray exposure, rapid inspection, diagnosis, and the like can be expected.

  For the phosphor film of the X-ray detection panel, the scintillator material technology mainly containing Cs and I used in the conventional X-ray image tube is often used. This is because cesium iodide (hereinafter referred to as CsI), which is the main component, forms a columnar crystal, so that sensitivity and resolution can be improved by the light guide effect as compared with scintillator materials made of other particulate crystals. It is.

  For example, Patent Document 1 discloses a plate-shaped radiation scintillator mainly containing CsI as a phosphor film.

  However, although the CsI film has excellent resolution characteristics and X-ray sensitivity, it has deliquescence and a problem of optical characteristics deterioration due to moisture, and requires a moisture-proof structure.

  For this reason, for example, Patent Document 2 discloses a moisture-proof structure of an X-ray detection panel using a polyparaxylylene resin as a structure for preventing moisture from entering.

  As described above, in the conventional radiation detection apparatus, the moisture-proof property of the phosphor film and the moisture-proof structure of the X-ray detection panel are taken into consideration, but the moisture-proof property inside the housing including the X-ray detection panel and the circuit board is taken into consideration. Is hardly considered.

  This is because a normal temperature and humidity environment such as a hospital in operation is assumed as a normal use environment.

  In such a steady environment, it is considered that the moisture resistance is sufficient if only the moisture resistance such as a CsI film having a deliquescent weakness is considered.

JP 2003-75593 A JP 2000-284053 A

  However, in an actual environment where the radiation detection apparatus is used, it may be exposed to a transient temperature and humidity change.

  In such a case, a transient shift may occur between the temperature and humidity environment inside the housing of the radiation detection device and the temperature and humidity environment around the radiation detection device.

  In particular, when exposed to a high temperature and high humidity environment and then suddenly changes to a cool environment, the heat sink that forms the outer wall of the case or part of the case with high temperature and high humidity air remaining inside the case. And the like are cooled by the environment outside the casing, dew condensation occurs on the inner wall of the casing and the inner wall of the heat sink.

  When the condensed moisture comes into contact with the circuit board, the X-ray detection panel, or the respective electrical joints, it causes an electrical short circuit or corrosion, causing a problem of reducing reliability in actual use.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a radiation detection apparatus that can ensure reliability even in an actual transient use environment.

  In order to achieve the above-described object, the present radiation detection apparatus mechanically combines a radiation detection panel having a phosphor film that converts radiation into light, a photoelectric conversion element that converts the light into an electrical signal, and the radiation detection panel. A support substrate to be held; a circuit board on which an integrated circuit element for driving the radiation detection panel is mounted; and a radiation detection panel disposed on a surface of the support substrate opposite to a surface on which the radiation detection panel is held A radiation detection device having a housing including the support substrate and the circuit board, wherein the radiation detection device is provided in a part of the housing so as to penetrate from the inside of the housing to the outside, and is formed inside the housing. And a dehumidifying mechanism including a cooling unit that condenses moisture generated inside the casing and a water guide unit that guides moisture condensed in the cooling unit to the outside of the casing.

It is sectional drawing which shows the radiation detection apparatus which concerns on one embodiment of this invention. It is sectional drawing which shows the principal part of the radiation detection apparatus which concerns on one embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a radiation detection apparatus according to an embodiment of the present invention.

  In this radiation detection apparatus 10, an X-ray detection panel 2 is fixed on a support substrate 4, and a moisture-proof cover 3 is sealed on the incident X-ray 1 side of the X-ray detection panel 2.

  Further, the support substrate 4 holds the circuit substrate 5 on the surface opposite to the fixed surface of the X-ray detection panel 2 with the X-ray shielding lead plate 6 and the heat radiation insulating sheet 7 interposed therebetween. Further, the support substrate 4 is coupled to the housing 9 by a support column 8. Further, a protective plate 11 is disposed on the side of the housing 9 facing the X-ray detection panel 2, while a heat radiating plate 13 is disposed on the surface of the housing 9 facing the circuit board 5, with the heat radiating surface outside the housing 9. The dehumidifying mechanism 20 is provided while being directed.

  Hereinafter, each component will be described in more detail.

(X-ray detection panel 2)
The X-ray detection panel 2 is formed by providing a phosphor film on a photoelectric conversion substrate including a photoelectric conversion element.

  In this embodiment, a material in which Tl is added to CsI is used as the phosphor film, and a film is formed on the photoelectric conversion substrate with a thickness of 500 μm by a vapor deposition method.

  For the X-ray detection apparatus, the CsI film thickness is in the range of 100 μm to 1000 μm, and more preferably, the desired sensitivity and image resolution are evaluated and set from the range of 200 μm to 600 μm.

  The photoelectric conversion substrate is formed, for example, on a 0.7 mm thick glass substrate in a two-dimensional form including a plurality of pixels including a thin film transistor element (TFT) and a photodiode element based on amorphous silicon (a-Si). Configured.

  In addition, a plurality of terminal pads for connecting electrical signals for driving and output signals to the outside are also formed on the outer periphery of the photoelectric conversion substrate.

  The terminal pads are connected to the flexible circuit board 15. For the connection between the terminal pad and the flexible circuit board 15, for example, a thermocompression bonding method using an anisotropic conductive film (hereinafter referred to as ACF) can be used. By this method, electrical connection of a plurality of fine signal lines can be ensured.

(Dampproof cover 3)
If the moisture-proof cover 3 is too thick, X-rays attenuate and the sensitivity is lowered.

  The dimension of the moisture-proof cover 3 can be selected from the range of 50 μm to 500 μm based on the balance between the stability of the cover shape, the strength to withstand process operations, and the X-ray attenuation. In this embodiment, it is formed of a 200 μm AL alloy.

(Support substrate 4)
As described above, the X-ray detection panel 2 has a configuration in which thin members are stacked. As a result, the X-ray detection panel 2 is light and low in strength and needs to be held in some way. For this holding, the X-ray detection panel 2 is fixed on the support substrate 4.

  The support substrate 4 has sufficient strength and a flat surface to stably hold the X-ray detection panel 2 and also has a function of holding the circuit board 5.

  In the present embodiment, the support substrate 4 is formed of an AL alloy, the circuit board 5 is held by the support substrate 4 with the lead plate 6 for shielding X-rays and the heat radiation insulating sheet 7 interposed therebetween, and the support substrate 4 is It was combined with the housing 9 by the support column 8.

  The circuit board 5 is fixed on the lead plate 6 formed on the support board 4 with screws or the like via the heat radiation insulating sheet 7.

  Further, a connector corresponding to the flexible circuit board 15 is mounted on the circuit board 5, and is electrically connected to the X-ray detection panel 2 by this connector.

(Case 9 and protective plate 11)
A protective plate 11 is disposed on the side of the housing 9 facing the X-ray detection panel 2 (incident X-ray 1 side).

  Usually, since X-rays 1 are incident through the protective plate 11, the protective plate 11 is preferably made of a thin material having a low X-ray absorption rate in order to suppress X-ray scattering and ensure X-ray sensitivity.

  Further, it is desirable that the protective plate 11 is thin in order to realize the thin and light radiation detection apparatus 10.

  On the other hand, the housing 9 is configured by using an organic resin material, for example, polyphenylene sulfite, polycarbonate, epoxy containing carbon fiber, or the like.

  In addition, by applying a conductive resin to the inner wall 14 of the housing 9 made of an organic resin material and conducting it to the ground electrode, an electric shielding effect on the circuit board 5 and the X-ray detection panel 2 inside the housing 9 is achieved. Can also be given.

  Further, in the housing 9, a heat radiating plate 13 is disposed on the back surface side opposite to the incident X-ray 1 side.

(Heatsink 13)
The heat radiating plate 13 has the heat radiating surface directed to the outside of the housing 9, and the protrusion of the heat radiating plate 13 penetrates a part of the organic resin material of the housing 9, and is mounted on the circuit board 5. And is in thermal contact.

  Further, thin heat dissipating fins are formed on the heat dissipating surface of the heat dissipating plate 13 in order to improve heat dissipating efficiency.

  The heat radiating plate 13 is formed of a thin metal plate such as Cu or AL.

(Dehumidifying mechanism 20)
The dehumidifying mechanism 20 is formed in a part of the housing 9 so as to penetrate the inner surface side and the outer surface side of the housing 9.

  In FIG. 2, the schematic diagram which expanded the dehumidification mechanism 20 is shown.

  In the dehumidifying mechanism 20, the cooling unit 16 is formed on a part of the inner surface side of the housing 9, while the heating unit 17 is formed on a part of the outer surface side, and between the heating unit 17 and the cooling unit 16. The water guide part 18 is arrange | positioned.

  A Peltier element 19 is provided on the outer surface side of the housing 9 in order to cool the cooling unit 16 and heat the heating unit 17.

  In the Peltier element 19, the opposing surfaces are in a state of heat absorption and heat dissipation by energization. For this reason, the heat conducting plates 21a and 21b made of a metal having a high thermal conductivity such as AL are in thermal contact with the Peltier device 19 via the insulating thin plates 22a and 22b on the heat absorbing surface and the heat radiating surface of the Peltier device 19, respectively. Arranged.

  The heat conduction plate 21 a penetrates from the outside of the housing 9 to the inside of the housing 9 and further extends on the inner surface of the housing 9, and the tip portion forms the cooling unit 16.

  On the other hand, the heat conductive plate 21 b disposed in thermal contact with the heat radiating surface of the Peltier element 19 extends on the outer surface side of the housing 9 and constitutes the heating unit 17.

  The heat conductive plates 21a and 21b are covered with a protective film 23a and a protective film 23b, respectively.

  Furthermore, the cooling unit 16 and the heating unit 17 are thermally connected to the water guide unit 18.

  As the water guide portion 18, for example, a sheet-like one having a fine mesh structure is used. For this reason, when moisture adheres to the surface, moisture permeation and wetting are caused and diffused throughout the water guide portion 18 and absorbed.

  Any material that can permeate and penetrate moisture may be used as long as it can take advantage of the fact that water absorption occurs due to the surface tension of water in the minute gaps between the constituent members of the water guide portion 18. Is also effective.

  Hereinafter, the dehumidifying mechanism of the dehumidifying mechanism 20 will be described.

  First, when the humidity inside the housing 9 is high, condensation occurs in the cooling unit 16.

  The condensed moisture is absorbed by the water guide 18 by permeation wetting.

  The absorbed water is diffused throughout the water guide portion 18 by permeation wetting, and then reaches the heating portion 17 side, and moisture evaporation occurs due to the heating.

  Here, regarding the voltage applied to the Peltier element 19, a low voltage is applied to the Peltier element 19 in the initial stage of dehumidification, but when the condensed moisture reaches the heating unit 17, the heat of vaporization is lost due to the evaporation of moisture. Therefore, a higher voltage is applied. Thereafter, in the final stage of dehumidification, the low voltage application is controlled again.

  By doing in this way, it becomes possible to dehumidify the humidity inside the housing 9 efficiently and release it to the outside of the housing 9.

  In order to prevent the Peltier element 19 from being overloaded, a heat sensor such as a thermocouple is attached to the heat radiation surface of the Peltier element 19 or a part of the heating unit 17, and the Peltier element is based on a signal from the heat sensor. The voltage application to the element 19 may be adjusted.

  Moreover, although the example which used the Peltier element 19 was shown as a cooling and heating method in the said embodiment, a pipe is passed through the cooling part 16 and the heating part 17 in addition to this, and the cooling part 16 is passed through. While a coolant or cold water is allowed to flow, a desired temperature difference can also be formed by causing warm water or the like to flow through the heating portion 17.

  Further, in the above embodiment, the heating unit 17 is formed outside the housing 9, but when the temperature of the external environment is high, the heating unit 17 can be omitted and the humidity can be removed by simple room temperature drying. It is.

(Effect of embodiment)
As described above, the radiation detection apparatus 10 according to the present embodiment dehumidifies the high-humidity air that is transiently confined inside the housing 9 even in various actual environments, and the housing 9 due to environmental changes. Generation of internal condensation can be suppressed.

  As a result, it is possible to prevent the occurrence of an electrical short circuit and the corrosion of the circuit board / X-ray detection panel.

  Therefore, it is possible to realize a planar radiation detection apparatus that ensures high reliability.

1 incident X-ray 2 X-ray detection panel (radiation detection panel)
DESCRIPTION OF SYMBOLS 3 Moisture-proof cover 4 Support substrate 5 Circuit board 6 Lead plate 7 Radiation insulation sheet 8 Support column 9 Case 10 Radiation detection device 11 Protection plate 12 Integrated circuit element 13 Heat radiation plate 14 Inner wall 15 Flexible circuit board 16 Cooling part 17 Heating part 18 Water guide Part 19 Peltier element 20 Dehumidifying mechanism 21a, 21b Thermal conductive plate 22a, 22b Insulating thin plate 23a, 23b Protective film

Claims (4)

A radiation detection panel having a phosphor film that converts radiation into light, a photoelectric conversion element that converts the light into an electrical signal, a support substrate that mechanically holds the radiation detection panel, and the radiation detection panel in the support substrate A circuit board on which an integrated circuit element that drives the radiation detection panel is mounted, a housing that includes the radiation detection panel, the support substrate, and the circuit board. In a radiation detection apparatus comprising:
A cooling part that is provided in a part of the casing so as to penetrate from the inside of the casing to the outside and that is formed inside the casing to condense moisture generated in the casing, and moisture condensed in the cooling part A radiation detection apparatus comprising a dehumidifying mechanism including a water guide portion that guides water to the outside of the housing.   The radiation detection according to claim 1, wherein the dehumidifying mechanism further includes a heating unit that is formed outside the housing and evaporates moisture, and the water guiding unit is connected to the heating unit. apparatus.   The radiation detecting apparatus according to claim 1, wherein the water guiding portion is formed of a woven fabric or a mesh structure.   The dehumidification mechanism further includes a Peltier element, and the cooling unit and the heating unit are thermally connected to the Peltier element. Radiation detection equipment.

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