JP2012088152A - Radiation detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation detection device capable of realizing high resolution and high-speed driving while being thin and lightweight.SOLUTION: In a radiation detection device 10, an X-ray detection panel 2 is fixed on a support substrate 4. In the X-ray detection panel 2, a phosphor film is deposited on a photoelectric conversion substrate having a photoelectric conversion element. A moisture proof cover 3 is sealed on the X-ray detection panel 2. Further, the support substrate 4 holds, on a side opposite to a side where the X-ray detection panel 2 is fixed, a circuit board 5, with an X-ray shielding lead plate 6 and a heat radiation insulation sheet 7 therebetween, while being connected to a housing 9 by a support pillar 8. Furthermore, the housing 9 has a protective plate 11 on a side facing the X-ray detection panel 2, while the housing 9 has, on a side facing the circuit board 5, a heat radiation plate 13 containing a heat pipe therein and arranged with a heat radiation surface thereof facing outside of the housing 9.

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 X-ray detection apparatus that includes a phosphor film that converts radiation, particularly X-rays or the like, into light and a photoelectric conversion element that converts the light into an electrical signal has been put into practical use.

  This flat X-ray detector is used in a wide range of fields such as medical and dental use for patient diagnosis and treatment, industrial use such as nondestructive inspection, and scientific research such as structural analysis. In each field, high-precision image extraction by digital information processing and high-speed image detection are possible, so that effects such as reduction of unnecessary X-ray exposure amount, rapid inspection and diagnosis can be expected.

  Further, according to this flat X-ray detection apparatus, it is possible to contribute to the reduction in size and weight of the entire X-ray apparatus, and also converts image information from an inspection object via X-rays into digital electrical information, Many conveniences of digital information processing such as digital image storage can be enjoyed.

  For the phosphor film of the flat X-ray detection apparatus, the scintillator material technique 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 to scintillator materials made of other particulate crystals. is there.

  In addition, the conventional X-ray image tube requires a configuration of an electron lens in the vacuum tube, and thus becomes a large and heavy detection device. In the flat X-ray detection device, a photoelectric conversion substrate having a photoelectric conversion element is formed on a glass substrate. A thin planar X-ray detector can be formed by two-dimensionally arranging and forming a plurality of thin film elements made of amorphous silicon or the like.

  Further, the X-ray detection panel composed of the phosphor film and the photoelectric conversion element and the circuit board are arranged in parallel, and the main constituent part is a casing including the X-ray detection panel and the circuit board. As a result, it is possible to reduce size and weight.

  On the other hand, in the flat type X-ray detection apparatus, in order to drive the X-ray detection panel and obtain a fine X-ray image signal, the circuit board includes a digital circuit for driving the X-ray detection panel, an X-ray detection panel. A plurality of elements such as an analog circuit for amplifying and processing a weak signal to be output, an AD conversion circuit for digitizing the analog signal, and a power supply circuit for supplying power to each circuit are mixed.

  For this reason, there is a problem that the heat generated by each element heats the inside of the housing and fluctuates the temperature characteristics of the X-ray detection panel.

  In particular, an integrated circuit element that performs high-frequency digital clock driving for high-speed image processing or amplification processing for amplifying a weak analog signal from an X-ray detection panel generates a large amount of heat, so that the heat generated can be dissipated. Means are needed.

  As a countermeasure against this heat generation, there is a method in which the integrated circuit element on the circuit board is thermally connected to the metal casing through a heat conductive material such as thermal conductive grease, and the heat generated by the integrated circuit element is radiated to the metal casing.

JP-A-9-288184 JP 2000-258541 A

  However, in the above method, since the metal casing needs to function as a heat sink, a thick metal casing is necessary to ensure heat dissipation, and a thin and lightweight flat X-ray detection apparatus is configured. It becomes an obstacle.

  Furthermore, since heat is transmitted to the entire metal casing, there is a problem that the space inside the metal casing is secondarily heated through the inner wall of the metal casing.

  The amount of heat generated from the integrated circuit element tends to increase with high resolution and high speed driving. However, in order to dissipate the heat, it is necessary to enhance the heat sink function of the housing. It becomes more difficult to construct a line detection device.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a thin and lightweight radiation detection apparatus even in high resolution and high speed driving.

  In order to achieve the above object, a radiation detection apparatus according to an embodiment of the present invention includes a radiation detection panel including a phosphor film that converts radiation into light, and a photoelectric conversion element that converts the light into an electrical signal; A circuit having a support substrate that mechanically holds the radiation detection panel and an integrated circuit element that is disposed on a surface of the support substrate opposite to the surface on which the radiation detection panel is held and that drives the radiation detection panel A substrate, a housing including the radiation detection panel, the support substrate, and the circuit substrate; and the housing is disposed at a position facing the circuit substrate and in contact with at least one of the integrated circuit elements. And a heat sink.

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 in which a phosphor film is formed on a photoelectric conversion substrate having a photoelectric conversion element is fixed on a support substrate 4, and a moisture-proof cover is further provided on the X-ray detection panel 2. 3 is sealed.

  The support substrate 4 holds the circuit board 5 on the surface opposite to the fixed surface of the X-ray detection panel 2 with the lead plate 6 for X-ray shielding and the heat radiation insulating sheet 7 interposed therebetween, and supports 8. It is combined with the housing 9 by the above. Further, a protective plate 11 is disposed on the side of the housing 9 facing the X-ray detection panel 2, while a heat sink 13 incorporating a heat pipe is disposed on the surface of the housing 9 facing the circuit board 5. It is arranged toward the outside of the body 9.

  Hereinafter, each component will be further described.

(X-ray detection panel 2)
In the present embodiment, a material in which Tl is added to CsI is used as the phosphor film in the X-ray detection panel 2, and the film is formed on the photoelectric conversion substrate in 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.

  Further, if the moisture-proof cover 3 is too thick, X-rays attenuate and the sensitivity is lowered, so that the moisture-proof cover 3 is desirably as thin as possible.

  The dimension of the moisture-proof cover 3 is 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 the process work, and the X-ray attenuation, and in this embodiment, it is made of a 200 μm AL alloy. .

  The photoelectric conversion substrate is configured, for example, by forming a plurality of thin film transistor elements (TFTs) and photodiode elements based on amorphous silicon (a-Si) on a 0.7 mm thick glass substrate.

  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.

  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.

(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 made of an AL alloy, holds the circuit board 5 with the X-ray shielding lead plate 6 and the heat radiation insulating sheet 7 interposed therebetween, and is coupled to the housing 9 by the support column 8. ing.

  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.

  The main structure of the housing 9 is made of an organic resin material such as polyphenylene sulfite or polycarbonate, or epoxy containing carbon fiber.

  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 electrical shielding effect on the circuit board 5 and the X-ray detection panel 2 inside the housing 9 is obtained. You can also have it.

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

(Heatsink 13)
As shown in FIG. 2, the heat radiating plate 13 has a heat radiating surface directed to the outside of the housing 9, and the protrusion 18 of the heat radiating plate 13 penetrates a part of the organic resin material of the housing 9, And is in thermal contact with the integrated circuit element 12 mounted on the board.

  Further, thin heat dissipating fins 16 are formed on the heat dissipating surface of the heat dissipating plate 13 in order to improve the heat dissipating efficiency.

  Unlike the heat sink which consists of a conventional metal block, the heat sink 13 is a thin metal plate such as Cu or AL with a built-in heat pipe 17. That is, since it is specialized for the heat transfer function to the heat radiating fins 16, it does not require the heat capacity of the conventional metal heat sink, and can be made into a thin plate shape that is significantly thinner and lighter than the conventional one.

  Further, heat transfer to the heat radiation fins 16 is ensured by the built-in peat pipe 17.

  Furthermore, the conventional problem that the inside of the housing is secondarily heated can be solved by disposing an organic resin material having low thermal conductivity and high heat insulation on the inner surface side of the housing 9.

(Heat pipe 17)
A heat pipe 17 using pure water or the like as a refrigerant is built in the heat radiating plate 13.

  As a method of forming such a thin plate heat pipe 17, for example, one sheet provided with a flow path in a sealed container formed by arranging the peripheral portions of a metal foil-like sheet facing each other and joining them. The sheet-shaped first spacer and two sheet-shaped second spacers not provided with a flow path are provided between the first spacer, and the working fluid is sealed in the container. (For example, refer to JP 2008-82698 A).

  In the present embodiment, a protrusion 18 is further formed on a part of the heat radiating plate 13, and the protrusion 18 is in thermal contact with the integrated circuit element 12 on the circuit board 5 inside the housing 9. .

  Further, by forming the heat pipe 17 on the protrusion 18, the heat generated by the integrated circuit element 12 can be more efficiently transmitted to the entire heat sink 13.

  The heat radiating plate 13 is formed with a large number of thin radiating fins 16, and the heat radiating fins 16 are also formed with heat pipes 17, so that heat generated in the integrated circuit elements 12 in the heat generating portion is quickly transmitted to the radiating fins 16. In addition, the heat generated by the integrated circuit element 12 can be efficiently radiated.

  As described above, in the present embodiment, heat can be radiated more efficiently than a thin heat pipe type heat radiating plate by adopting an appropriate casing structure and heat radiating plate structure.

  Even if the heat pipe 17 is not built in the heat radiating plate 13, a similar heat radiating effect can be obtained by adopting a structure in which the heat pipe is fixed to the surface of the heat radiating plate 13.

(Effect of embodiment)
According to the radiation detection apparatus 10 according to the present embodiment, fluctuations in characteristics of the X-ray detection panel 2 due to heat generation of the integrated circuit element 12 and the like mounted on the circuit board 5 can be reduced even in high resolution and high speed driving, and compared with the related art. In addition, it is possible to realize a thin and light planar radiation detector.

DESCRIPTION OF SYMBOLS 1 Incident X-ray 2 X-ray detection panel 3 Moisture-proof cover 4 Support board 5 Circuit board 6 Lead plate 7 Radiation insulation sheet 8 Support | pillar 9 Case 10 Radiation detection apparatus 11 Protection board 12 Integrated circuit element 13 Heat radiation board 14 Inner wall 15 Flexible circuit board 16 Radiation fin 17 Heat pipe 18 Projection

Claims (5)

A radiation detection panel having a phosphor film that converts radiation into light and a photoelectric conversion element that converts the light into an electrical signal;
A support substrate for mechanically holding the radiation detection panel;
A circuit board on which an integrated circuit element that drives the radiation detection panel is mounted on a surface of the support substrate opposite to the surface on which the radiation detection panel is held;
A housing including the radiation detection panel, the support substrate, and the circuit board;
A heat dissipating plate disposed at a position facing the circuit board in the housing and in contact with at least one of the integrated circuit elements;
A radiation detection apparatus comprising:   2. The radiation detection apparatus according to claim 1, wherein heat radiation fins are formed outside the housing of the heat radiation plate.   The radiation detection apparatus according to claim 1, wherein a heat pipe is formed inside or on a side surface of the heat radiating plate.   The radiation detection apparatus according to claim 1, wherein the casing is made of an organic resin material, and a conductive film is formed on at least a part of an inner wall portion of the casing.   The radiation detection apparatus according to claim 1, wherein an organic resin material is disposed on a part of the inner surface side of the casing.

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