Radiation detector

Abstract

A radiation detector capable of detecting the amount of moisture intruding into the inside is provided. The radiation detector includes a photoelectric conversion substrate having a detection region and a non-detection region; a scintillator layer; a frame-shaped sealing portion; a cover covering the scintillator layer together with the photoelectric conversion substrate and the sealing portion; and a moisture absorbing layer. The moisture absorbing layer is provided between the scintillator layer and the cover, is located at least in the detection region, and has a light transmittance that changes according to a change in the amount of moisture in the inside.

Description

Technical Field

[0001] Embodiments of the present invention relate to radiation detectors. Background Technology

[0002] As a radiation detector, an X-ray detector (X-ray planar detector) is known, for example. An X-ray detector has a photoelectric conversion substrate with multiple photoelectric conversion elements arranged in a lattice pattern, a scintillator layer disposed on the photoelectric conversion substrate, and a cover that covers the entire formation area of ​​the scintillator layer. The cover is bonded to the photoelectric conversion substrate on the outside of the scintillator layer.

[0003] The aforementioned cover is a moisture-proof body, and it has a composite film formed by laminating a resin layer and a metal layer. The metal layer is formed of metals such as aluminum and metal oxides such as aluminum oxide. The cover is bonded to the photoelectric conversion substrate with a thermoplastic resin. A hygroscopic resin is provided on the inside of the cover. This suppresses moisture permeation from the outside to the scintillator layer.

[0004] Furthermore, the hygroscopic resin inside the cap has a saturation point for moisture absorption. Therefore, after absorbing a certain amount of moisture, the hygroscopic resin loses its hygroscopic function and becomes unable to retain the moisture that has penetrated into the cap. Then, the moisture reaches the scintillator layer, leading to its deterioration.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-98130 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] This embodiment provides a radiation detector capable of detecting the amount of water that has penetrated into the interior.

[0010] Technical means for solving technical problems

[0011] One embodiment of the radiation detector includes:

[0012] A photoelectric conversion substrate having a detection area and a non-detection area outside the detection area; a scintillator layer disposed on the photoelectric conversion substrate, at least located in the detection area; a frame-shaped sealing portion located in the non-detection area, surrounding the scintillator layer and bonded to the photoelectric conversion substrate; a cover disposed above the scintillator layer, located in the detection area and the non-detection area, bonded to the sealing portion, and together with the photoelectric conversion substrate and the sealing portion, covering the scintillator layer; and a moisture-absorbing layer disposed between the scintillator layer and the cover, at least located in the detection area, and whose light transmittance varies according to changes in internal moisture content. Attached Figure Description

[0013] Figure 1 This is a cross-sectional view showing the X-ray detector involved in the comparative example.

[0014] Figure 2 This is a perspective view showing the support substrate, X-ray detection panel, circuit board, and multiple FPCs of the aforementioned X-ray detector, and also shows the image transmission unit.

[0015] Figure 3 This is an enlarged cross-sectional view showing a portion of the X-ray detection module of the aforementioned X-ray detector.

[0016] Figure 4 This is a top view showing the X-ray detection module described above.

[0017] Figure 5 This is a cross-sectional view along line VV showing a portion of the aforementioned X-ray detection module.

[0018] Figure 6 This is a cross-sectional view showing a portion of the X-ray detection module of an X-ray detector according to one embodiment.

[0019] Figure 7 It is shown Figure 6 The top view of the X-ray detection module shown.

[0020] Figure 8 This is a cross-sectional view showing a portion of the X-ray detection module of the X-ray detector according to Variation 1 of the above-described embodiment.

[0021] Figure 9 It is shown Figure 8 The top view of the X-ray detection module shown.

[0022] Figure 10 This is a cross-sectional view showing a portion of the X-ray detection module of the X-ray detector involved in Variation 2 of the above-described embodiment. Detailed Implementation

[0023] Hereinafter, embodiments and comparative examples of the present invention will be described with reference to the accompanying drawings. Furthermore, the disclosed content is merely an example, and appropriate modifications will readily conceive by those skilled in the art while retaining the spirit of the invention; such modifications are also naturally included within the scope of the invention. In addition, for the purpose of clearer explanation using the drawings, the width, thickness, shape, etc., of various parts are sometimes schematically represented compared to the actual embodiment; however, this is merely an example and should not be used to limit the interpretation of the invention. Moreover, in this specification and the various drawings, the same reference numerals are used for the same parts that have appeared in existing drawings, and detailed descriptions are appropriately omitted.

[0024] (Comparative Example)

[0025] First, let's explain the comparative examples. Figure 1 This is a cross-sectional view showing the X-ray detector 1 involved in the comparative example. The X-ray detector 1 is an X-ray image detector and an X-ray planar detector utilizing an X-ray detection panel.

[0026] like Figure 1 As shown, the X-ray detector 1 includes an X-ray detection module 10, a support substrate 12, a circuit board 11, spacers 9a, 9b, 9c, and 9d, a housing 51, an FPC (flexible printed circuit board) 2e1, and an entrance window 52. The X-ray detection module 10 includes an X-ray detection panel PNL and a moisture cover 7. The X-ray detection panel PNL is located between the support substrate 12 and the moisture cover 7. The moisture cover 7 is opposite to the entrance window 52.

[0027] An entrance window 52 is installed at an opening in the housing 51. The entrance window 52 allows X-rays to pass through. Therefore, X-rays pass through the entrance window 52 and enter the X-ray detection module 10. The entrance window 52 is formed in a plate shape, serving to protect the interior of the housing 51. The entrance window 52 is preferably made of a thin material with low X-ray absorptivity. Therefore, X-ray scattering and attenuation of the X-ray quantity generated in the entrance window 52 can be reduced. This allows for the realization of a thin and lightweight X-ray detector 1.

[0028] The X-ray detection module 10, support substrate 12, circuit board 11, FPC2e1, etc. are housed inside the space surrounded by housing 51 and entrance window 52.

[0029] The X-ray inspection module 10 is constructed by stacking thin components, thus it is lightweight and has low mechanical strength. Therefore, the X-ray inspection panel PNL (X-ray inspection module 10) is fixed to the flat side of the support substrate 12 via adhesive sheets. The support substrate 12 is formed into a plate shape, for example, from aluminum alloy, and has the strength required to stably hold the X-ray inspection panel PNL. Therefore, damage to the X-ray inspection panel PNL can be suppressed when vibration or impact is applied to the X-ray detector 1 from the outside.

[0030] The circuit board 11 is fixed to the other side of the support board 12 via spacers 9a and 9b. By using spacers 9a and 9b, an electrically insulating distance can be maintained between the support board 12, which is mainly made of metal, and the circuit board 11.

[0031] The circuit board 11 is fixed to the inner surface of the housing 51 via spacers 9c and 9d. By using spacers 9c and 9d, an electrically insulating distance can be maintained between the housing 51, which is mainly made of metal, and the circuit board 11. The housing 51 supports the support substrate 12 and the like via the circuit board 11 and the spacers 9a, 9b, 9c, and 9d.

[0032] A connector corresponding to FPC2e1 is mounted on the circuit board 11, and FPC2e1 is electrically connected to the circuit board 11 via the connector. The connection between FPC2e1 and the X-ray inspection panel PNL uses a thermoforming method utilizing ACF (anisotropic conductive film). This method ensures electrical connection between the multiple fine pads of the X-ray inspection panel PNL and the multiple fine pads of FPC2e1. The pads of the X-ray inspection panel PNL will be described later.

[0033] As described above, the circuit board 11 is electrically connected to the X-ray detection panel PNL via the aforementioned connector, FPC2e1, etc. The circuit board 11 electrically drives the X-ray detection panel PNL and electrically processes the output signals from the X-ray detection panel PNL.

[0034] Figure 2 This is a perspective view showing the support substrate 12, X-ray detection panel PNL, circuit board 11, and multiple FPCs 2e1 and 2e2 of the X-ray detector 1 of this comparative example, and also shows the image transmission unit 4. Additionally, Figure 2 Not all components of the X-ray detector 1 are shown in the diagram. Illustrations of several components of the X-ray detector 1, such as the sealing part, which will be described later, are shown in... Figure 2 Omitted in .

[0035] like Figure 2As shown, the X-ray detection panel PNL includes a photoelectric conversion substrate 2, a scintillator layer 5, etc. The photoelectric conversion substrate 2 has a substrate 2a, a photoelectric conversion unit 2b, multiple control lines (or gate lines) 2c1, multiple data lines (or signal lines) 2c2, etc. Furthermore, the number and arrangement of the photoelectric conversion unit 2b, control lines 2c1, and data lines 2c2 are not limited to... Figure 2 Examples.

[0036] Multiple control lines 2c1 extend in the row direction X and are arranged at predetermined intervals in the column direction Y. Multiple data lines 2c2 extend in the column direction Y, intersect with the multiple control lines 2c1, and are arranged at predetermined intervals in the row direction X.

[0037] Multiple photoelectric conversion units 2b are provided on one main surface of substrate 2a. The photoelectric conversion units 2b are disposed in a quadrilateral region divided by control line 2c1 and data line 2c2. One photoelectric conversion unit 2b corresponds to one pixel in an X-ray image. The multiple photoelectric conversion units 2b are arranged in a matrix. As described above, the photoelectric conversion units 2b are an array substrate.

[0038] Each photoelectric conversion unit 2b has a photoelectric conversion element 2b1 and a TFT (thin-film transistor) 2b2 as a switching element. The TFT 2b2 is connected to a corresponding control line 2c1 and a corresponding data line 2c2. The photoelectric conversion element 2b1 is electrically connected to the TFT 2b2.

[0039] Control line 2c1 is electrically connected to circuit board 11 via FPC2e1. Circuit board 11 provides control signal S1 to multiple control lines 2c1 via FPC2e1. Data line 2c2 is electrically connected to circuit board 11 via FPC2e2. Image data signal S2 (charge stored in photoelectric conversion unit 2b) converted by photoelectric conversion element 2b1 is transmitted to circuit board 11 via TFT 2b2, data line 2c2 and FPC2e2.

[0040] The X-ray detector 1 also includes an image transmission unit 4. The image transmission unit 4 is connected to the circuit board 11 via wiring 4a. Alternatively, the image transmission unit 4 may be mounted on the circuit board 11. The image transmission unit 4 generates an X-ray image based on the signal of image data converted into a digital signal by a plurality of analog-to-digital converters (not shown). The generated X-ray image data is output from the image transmission unit 4 to an external device.

[0041] Figure 3 This is an enlarged cross-sectional view showing a portion of the X-ray detection module 10 of the X-ray detector 1 involved in this comparative example.

[0042] like Figure 3As shown, the photoelectric conversion substrate 2 has a substrate 2a, multiple photoelectric conversion units 2b, and insulating layers 21, 22, 23, 24, and 25. The multiple photoelectric conversion units 2b are located in the detection area DA. Each photoelectric conversion unit 2b includes a photoelectric conversion element 2b1 and a TFT 2b2.

[0043] TFT2b2 has a gate electrode GE, a semiconductor layer SC, a source electrode SE, and a drain electrode DE. The photoelectric conversion element 2b1 is, for example, a photodiode. Alternatively, the photoelectric conversion element 2b1 can be composed of a CCD (Charge Coupled Device) or the like, as long as it is configured to convert light into charge.

[0044] The substrate 2a has a plate-like shape and is formed of an insulating material. Examples of such insulating materials include alkali-free glass and other types of glass. The planar shape of the substrate 2a is, for example, quadrilateral. The thickness of the substrate 2a is, for example, 0.7 mm. An insulating layer 21 is provided on the substrate 2a.

[0045] A gate electrode GE is formed on the insulating layer 21. The gate electrode GE is electrically connected to the control line 2c1. An insulating layer 22 is disposed on the insulating layer 21 and the gate electrode GE. A semiconductor layer SC is disposed on the insulating layer 22, opposite to the gate electrode GE. The semiconductor layer SC is formed of semiconductor materials such as amorphous silicon as an amorphous semiconductor and polycrystalline silicon as a polycrystalline semiconductor.

[0046] The source electrode SE and drain electrode DE are disposed on the insulating layer 22 and the semiconductor layer SC. The gate electrode GE, source electrode SE, drain electrode DE, control line 2c1 and data line 2c2 are formed using low-resistance metals such as aluminum or chromium.

[0047] The source electrode SE is electrically connected to the source region of the semiconductor layer SC. Furthermore, the source electrode SE is electrically connected to the aforementioned data line 2c2. The drain electrode DE is electrically connected to the drain region of the semiconductor layer SC.

[0048] An insulating layer 23 is disposed on the insulating layer 22, the semiconductor layer SC, the source electrode SE, and the drain electrode DE. The photoelectric conversion element 2b1 is electrically connected to the drain electrode DE. An insulating layer 24 is disposed on the insulating layer 23 and the photoelectric conversion element 2b1. A bias line BL is disposed on the insulating layer 24 and connected to the photoelectric conversion element 2b1 through a contact hole formed in the insulating layer 24. An insulating layer 25 is disposed on the insulating layer 24 and the bias line BL.

[0049] Insulating layers 21, 22, 23, 24, and 25 are formed of insulating materials such as inorganic and organic insulating materials. Examples of inorganic insulating materials include oxide insulating materials, nitride insulating materials, and nitrogen oxide insulating materials. Examples of organic insulating materials include resins.

[0050] A scintillator layer 5 is disposed on the photoelectric conversion substrate 2 (multiple photoelectric conversion units 2b). The scintillator layer 5 is located at least in the detection region DA and covers the multiple photoelectric conversion units 2b. The scintillator layer 5 is configured to convert incident X-rays into light (visible light, fluorescence).

[0051] Furthermore, the photoelectric conversion element 2b1 converts the light incident from the scintillator layer 5 into electrical charge. The converted charge is stored in the photoelectric conversion element 2b1. The TFT 2b2 can switch between storing and discharging the charge from the photoelectric conversion element 2b1. In addition, when the self-capacitance of the photoelectric conversion element 2b1 is insufficient, the photoelectric conversion substrate 2 can also have a capacitor (storage capacitor) to store the charge converted by the photoelectric conversion element 2b1 in the capacitor.

[0052] The scintillator layer 5 is formed, for example, from thallium-activated cesium iodide (CsI:Tl). If the scintillator layer 5 is formed using a vacuum evaporation method, a scintillator layer 5 formed by an aggregate of multiple columnar crystals will be obtained. The thickness of the scintillator layer 5 is, for example, 600 μm. On the outermost surface of the scintillator layer 5, the thickness of the columnar crystals of the scintillator layer 5 is 8 to 12 μm.

[0053] The material forming the scintillator layer 5 is not limited to CsI:Tl. The scintillator layer 5 can be formed from thallium-activated sodium iodide (NaI:Tl), sodium-activated cesium iodide (CsI:Na), europium-activated cesium bromide (CsBr:Eu), sodium iodide (NaI), gadolinium oxysulfide (Gd2O2S), etc.

[0054] Furthermore, when forming the scintillator layer 5 using vacuum evaporation, a mask with an opening can be used. In this case, the scintillator layer 5 is formed in a region opposite to the opening on the photoelectric conversion substrate 2. Additionally, the scintillator material formed by evaporation is also deposited on the surface of the mask. Then, the scintillator material also accumulates near the opening of the mask, and crystals grow, gradually extending into the interior of the opening. As the crystals extend from the mask into the interior of the opening, evaporation of the scintillator material to the photoelectric conversion substrate 2 is suppressed near the opening. Therefore, as... Figure 2 As shown, the thickness near the periphery of scintillator layer 5 gradually decreases towards the outer edge.

[0055] Alternatively, the scintillator layer 5 may have multiple scintillator sections arranged in a matrix, one-to-one disposed on the photoelectric conversion section 2b, and each having a quadrangular prism shape. When forming such a scintillator layer 5, a scintillator material, composed of gadolinium sulfide phosphor particles and a binder material, is coated onto the photoelectric conversion substrate 2, and the scintillator material is then fired to solidify it. Afterwards, a grid-like groove is formed on the scintillator material by cutting with a cutter or the like. In the above case, air or an inert gas such as nitrogen (N2) to prevent oxidation is sealed between the multiple scintillator sections. Alternatively, the space between the multiple scintillator sections may be set as a space depressurized relative to atmospheric pressure.

[0056] A moisture-proof cover (moisture-proof membrane) 7, acting as a film-like cap, is disposed above and covers the scintillator layer 5. The moisture-proof cover 7 is provided to suppress the degradation of the properties of the scintillator layer 5 due to moisture contained in the atmosphere. The moisture-proof cover 7 completely covers the exposed portion of the scintillator layer 5. The moisture-proof cover 7 is in contact with the scintillator layer 5.

[0057] The moisture-proof cover 7 is formed of a sheet containing metal. Examples of such metals include aluminum, copper, magnesium, tungsten, stainless steel, and Kovar alloy. When the moisture-proof cover 7 contains metal, it can prevent or significantly inhibit the penetration of moisture.

[0058] Furthermore, the moisture-proof cover 7 can be formed from a laminated sheet material consisting of a resin layer and a metal layer. In this case, the resin layer can be formed from materials such as polyimide resin, epoxy resin, polyethylene terephthalate resin, Teflon (registered trademark), low-density polyethylene, high-density polyethylene, or elastic rubber. The metal layer can, for example, contain the aforementioned metals. The metal layer can be formed using methods such as sputtering or lamination.

[0059] In this case, it is preferable to provide the metal layer on one side of the scintillator layer 5 relative to the resin layer. Since the metal layer can be covered by the resin layer, damage to the metal layer due to external forces or the like can be suppressed. Furthermore, if the metal layer is provided on one side of the scintillator layer 5 relative to the resin layer, the deterioration of the characteristics of the scintillator layer 5 caused by moisture permeation through the resin layer can be suppressed.

[0060] Examples of moisture-proof covers 7 include sheets containing a metal layer, sheets containing an inorganic insulating layer, laminated sheets formed by laminating a resin layer and a metal layer, and laminated sheets formed by laminating a resin layer and an inorganic insulating layer. As described above, the inorganic layer of the moisture-proof cover 7 is not limited to a metal layer and may also be an inorganic insulating layer. Alternatively, the moisture-proof cover 7 may have both a metal layer and an inorganic insulating layer. The inorganic insulating layer may be formed from a layer containing silicon oxide, aluminum oxide, etc. The inorganic insulating layer may be formed using sputtering or the like. In this comparative example, the moisture-proof cover 7 is formed from a relatively thin aluminum foil.

[0061] Figure 4 This is a top view showing the X-ray detection module 10. Figure 4 In the diagram, the scintillator layer 5 is marked with an upward diagonal line to the right, the sealing part 8 is marked with a downward diagonal line to the right, and the moisture-absorbing component 3 is marked with a dotted pattern. Figure 5 This is a cross-sectional view along line VV showing a portion of the X-ray detection module 10.

[0062] like Figure 4 and Figure 5 As shown, the photoelectric conversion substrate 2 has a detection area DA and a non-detection area outside the detection area DA. The detection area DA is a quadrilateral area. The non-detection area of ​​the photoelectric conversion substrate 2 has a frame-shaped first non-detection area NDA1 located around the detection area DA, and a second non-detection area NDA2 outside the first non-detection area NDA1. In this comparative example, the second non-detection area NDA2 has a frame-shaped shape.

[0063] The scintillator layer 5 is located at least in the detection area DA. The scintillator layer 5 has a side surface 5a and a top surface 5b. The side surface 5a is located in the first non-detection area NDA1. The side surface 5a is a positive cone surface. The top surface 5b of the scintillator layer 5 is opposite to the moisture cover 7.

[0064] The photoelectric conversion substrate 2 also has multiple pads 2d1 and multiple pads 2d2. Pads 2d1 and 2d2 are located in the second non-detection area NDA2. In this comparative example, the multiple pads 2d1 are arranged along the left side of the substrate 2a, and the multiple pads 2d2 are arranged along the bottom side of the substrate 2a. For example, pads 2d1 and 2d2 are disposed on insulating layer 23 and are not covered by insulating layers 24 and 25.

[0065] in addition, Figure 4 The diagram schematically illustrates multiple pads; the number, shape, size, position, and spacing of these pads are not limited to... Figure 4 The example shown.

[0066] A control line 2c1 extends in the detection area DA, the first non-detection area NDA1, and the second non-detection area NDA2, and is electrically connected to one of the plurality of pads 2d1. A data line 2c2 extends in the detection area DA, the first non-detection area NDA1, and the second non-detection area NDA2, and is electrically connected to one of the plurality of pads 2d2.

[0067] One of the multiple traces in FPC2e1 is electrically connected to a pad 2d1, and one of the multiple traces in FPC2e2 is electrically connected to a pad 2d2. Figure 2 ).

[0068] The X-ray detection module 10 also includes a sealing portion 8. The sealing portion 8 is located in the first non-detection region NDA1 and surrounds the scintillator layer 5. The sealing portion 8 has a frame-like shape and extends continuously around the scintillator layer 5. The sealing portion 8 is bonded to the photoelectric conversion substrate 2 (e.g., the insulating layer 25 described above). In this comparative example, the sealing portion 8 is in contact with the side surface 5a of the scintillator layer 5.

[0069] If the outer surface 8a of the sealing part 8 is a curved surface protruding outwards, the periphery of the moisture cover 7 can easily mimic the outer surface 8a of the sealing part 8. Therefore, the moisture cover 7 can easily fit tightly against the sealing part 8. Furthermore, since the moisture cover 7 can deform smoothly, even if the thickness of the moisture cover 7 becomes thinner, the occurrence of defects such as cracks in the moisture cover 7 can be suppressed.

[0070] The moisture cover 7 is located in the detection area DA and the first non-detection area NDA1. Figure 4 In the top view shown, the moisture cover 7 completely covers the scintillator layer 5. (As shown...) Figure 5 As shown, the portion of the scintillator layer 5 not covered by the photoelectric conversion substrate 2 and the sealing portion 8 is completely covered by the moisture-proof cover 7. In other words, the moisture-proof cover 7, together with the photoelectric conversion substrate 2 and the sealing portion 8, covers the scintillator layer 5.

[0071] The moisture cover 7 is directly adhered to the outer surface 8a of the sealing part 8. The moisture cover 7 covers at least a portion of the sealing part 8. For example, if the moisture cover 7 and the sealing part 8 are joined in an environment with reduced pressure compared to atmospheric pressure, the moisture cover 7 can come into contact with the upper surface 5b of the scintillator layer 5, etc.

[0072] Furthermore, the scintillator layer 5 typically contains voids comprising approximately 10% to 40% of its volume. Therefore, if these voids contain gas, the gas may expand and damage the moisture cover 7 if the X-ray detector 1 is transported by aircraft or similar means, or if it is used at high altitudes. By joining the moisture cover 7 and the sealing portion 8 in an environment depressurized compared to atmospheric pressure, damage to the moisture cover 7 can be prevented even when the X-ray detector 1 is transported by aircraft or similar means. Therefore, the pressure in the space defined by the photoelectric conversion substrate 2, the sealing portion 8, and the moisture cover 7 is preferably lower than atmospheric pressure.

[0073] Furthermore, as described later, the periphery of the moisture-proof cover 7 is heated to join it to the sealing part 8. In this case, if the temperature near the periphery of the moisture-proof cover 7 and the temperature of the sealing part 8 decrease, thermal stress is generated between the periphery of the moisture-proof cover 7 and the sealing part 8. If thermal stress is generated between the periphery of the moisture-proof cover 7 and the sealing part 8, peeling may occur between the periphery of the moisture-proof cover 7 and the sealing part 8. If peeling occurs, the moisture-proof performance may be significantly reduced.

[0074] In this embodiment, the moisture-proof cover 7 is formed of a relatively thin aluminum foil, therefore, the moisture-proof cover 7 is prone to stretching when thermal stress is generated. Therefore, thermal stress can be mitigated, and peeling of the moisture-proof cover 7 from the sealing part 8 near its periphery can be suppressed.

[0075] The sealing part 8 is formed of a material containing thermoplastic resin. The sealing part 8 is formed of a material containing thermoplastic resin as a main component. The sealing part 8 can be formed of 100% thermoplastic resin. Alternatively, the sealing part 8 can also be formed of a material in which additives are mixed into the thermoplastic resin. If the sealing part 8 contains thermoplastic resin as a main component, the sealing part 8 can bond the photoelectric conversion substrate 2 and the moisture-proof cover 7 together by heating.

[0076] Thermoplastic resins that can be used include nylon, PET (polyethylene terephthalate), polyurethane, polyester, polyvinyl chloride, ABS (acrylonitrile butadiene styrene), acrylic acid, polystyrene, polyethylene, and polypropylene. In this case, the water vapor transmission rate of polyethylene is 0.068 g·mm / day·m. 2 The water vapor transmission rate of polypropylene is 0.04 g·mm / day·m. 2 These water vapor permeability rates are low. Therefore, if the sealing part 8 contains at least one of polyethylene and polypropylene as the main component, the amount of moisture that permeates through the interior of the sealing part 8 to reach the scintillator layer 5 can be significantly reduced.

[0077] The rigidity of thermoplastic resin can be lower than that of moisture cover 7.

[0078] The X-ray detection module 10 also includes a moisture-absorbing member 3. The moisture-absorbing member 3 is disposed in the space surrounded by the photoelectric conversion substrate 2, the scintillator layer 5, the sealing portion 8, and the moisture-proof cover 7. In this embodiment, the moisture-absorbing member 3 contacts the side surface 5a of the scintillator layer 5 and the outer surface 8a of the sealing portion 8, but does not contact the photoelectric conversion substrate 2. The moisture-absorbing member 3 is provided to fill the gap 13 formed by the scintillator layer 5, the sealing portion 8, and the moisture-proof cover 7. After the scintillator layer 5 and the sealing portion 8 are formed, a moisture-absorbing material is coated along the groove between the scintillator layer 5 and the sealing portion 8 to form the moisture-absorbing member 3.

[0079] The moisture-absorbing component 3 is formed from a resin containing sodium polyacrylate. The moisture-absorbing component 3 is formed from a material containing sodium polyacrylate as a main component. The moisture-absorbing component 3 can be formed from 100% sodium polyacrylate. Alternatively, the moisture-absorbing component 3 can also be formed from a material in which additives are mixed into sodium polyacrylate.

[0080] Sodium polyacrylate is a highly absorbent polymer used in diapers and sanitary products. Furthermore, sodium polyacrylate possesses hydrophilic hydroxyl groups, and its network structure incorporates a large number of water molecules to form a gel structure, enabling it to absorb and retain hundreds to thousands of times its own weight in water without dissolving in water.

[0081] Regarding moisture, the moisture-absorbing member 3 has a higher absorption rate than the sealing portion 8. In this comparative example, the moisture-absorbing member 3 has a greater absorption capacity than the sealing portion 8. When moisture permeates from the sealing portion 8 due to prolonged use, the moisture-absorbing member 3 fills the gaps 13 that form the moisture permeation path, thereby absorbing moisture before it reaches the scintillator layer 5. Therefore, even if moisture permeates from the sealing portion 8, the moisture-absorbing member 3 can absorb and retain moisture, suppressing the deterioration of the scintillator layer 5 caused by moisture.

[0082] In this comparative example, the space (gap 13) surrounded by the photoelectric conversion substrate 2, the sealing part 8, and the moisture-proof cover 7, and where the moisture-absorbing member 3 is located, is a space after the pressure has been reduced compared to atmospheric pressure. In addition, the sealing part 8 is melted by heating from the outside of the moisture-proof cover 7, so that the resin of the melted sealing part 8 adheres tightly to the surface of the moisture-proof cover 7, and then the sealing part 8 is cooled to bond the sealing part 8 to the moisture-proof cover 7.

[0083] The X-ray detector 1 is configured as described above.

[0084] According to the comparative example of the X-ray detector 1 constructed as described above, the moisture cover 7 is bonded to the photoelectric conversion substrate 2 via the sealing portion 8, thereby suppressing moisture from reaching the scintillator layer 5. However, even when the moisture cover 7 is used to cover the scintillator layer 5, considerable moisture permeation still occurs from the sealing portion 8, which acts as an adhesive, and the scintillator layer 5 may deteriorate.

[0085] To suppress this degradation, the X-ray detector 1 includes a moisture-absorbing member 3. Even when moisture permeates from the sealing portion 8, the moisture-absorbing member 3 can prevent moisture from reaching the scintillator layer 5. However, the moisture-absorbing member 3 has a moisture saturation point. Therefore, after absorbing a certain amount of moisture, the moisture-absorbing member 3 loses its moisture-absorbing function and becomes difficult to capture moisture that has penetrated into the space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the moisture-proof cover 7. As a result, moisture reaches the scintillator layer 5, causing degradation of the scintillator layer 5.

[0086] (One implementation method)

[0087] Next, one embodiment will be described. Except for the structure described in this embodiment, the X-ray detector 1 is configured in the same way as in Comparative Example 1. Figure 6 This is a cross-sectional view showing a portion of the X-ray detection module 10 of the X-ray detector 1 according to this embodiment. Figure 7It is shown Figure 6 The top view of the X-ray detection module 10 shown. Figure 7 In the diagram, the scintillator layer 5 is marked with an upward slant line to the right, and the sealing part 8 is marked with a downward slant line to the right.

[0088] like Figure 6 and Figure 7 As shown, a moisture-proof cover 7, serving as a lid, is disposed above the scintillator layer 5, located between the detection area DA and the first non-detection area NDA1, and is adhered to the sealing portion 8. The moisture-proof cover 7, together with the photoelectric conversion substrate 2 and the sealing portion 8, covers the scintillator layer 5. Then, the scintillator layer 5 is sealed by the photoelectric conversion substrate 2, the sealing portion 8, and the moisture-proof cover 7.

[0089] The X-ray detector 1 also includes a moisture-absorbing layer 6. The moisture-absorbing layer 6 is disposed between the scintillator layer 5 and the moisture-proof cover 7. The moisture-absorbing layer 6 is in contact with the scintillator layer 5. The moisture-absorbing layer 6 is stacked on the surface of the moisture-proof cover 7 opposite to the scintillator layer 5 and adhered to the moisture-proof cover 7. The moisture-absorbing layer 6 is located at least in the detection area DA. The moisture-absorbing layer 6 has the characteristic that its light transmittance varies according to changes in the internal moisture content.

[0090] The moisture-absorbing layer 6 comprises aluminosilicates, alumina, or silica gel. Examples of aluminosilicates include zeolite. Specifically, the moisture-absorbing layer 6 contains 50% or more by weight of aluminosilicates (zeolite), alumina, or silica gel. The moisture-absorbing layer 6 may be formed solely of aluminosilicates (zeolite), alumina, or silica gel. Alternatively, the moisture-absorbing layer 6 may be a mixture of aluminosilicates (zeolite), alumina, or silica gel, and a resin.

[0091] Aluminosilicate (zeolite) materials, used as physical desiccants, have a porous surface structure, utilizing their ability to absorb moisture through their pores. For example, the moisture-absorbing layer 6, under conditions of 25°C and 50% humidity, exhibits a substantial moisture content of 5.1 g / m³. 2 The saturated moisture absorption capacity. Furthermore, if the composition and content of the moisture-absorbing layer 6 are illustrated, the moisture-absorbing layer 6 contains 30 to 95 wt% polyethylene and 5 to 70 wt% synthetic zeolite. Even if moisture permeates from the sealing portion 8, the moisture-absorbing layer 6 can absorb and retain moisture within the space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the moisture-proof cover 7. Therefore, the deterioration of the scintillator layer 5 can be suppressed.

[0092] In its initial state, when it does not absorb moisture, the moisture-absorbing layer 6 is, for example, white. When saturated with moisture-related absorbency, the moisture-absorbing layer 6 is, for example, transparent. Therefore, as the internal moisture content increases, the moisture-absorbing layer 6 changes from white to transparent.

[0093] The white hygroscopic layer 6 functions as a light-reflecting layer. The hygroscopic layer 6 helps improve the utilization efficiency of light (fluorescence) and achieves improved resolution and sensitivity. The hygroscopic layer 6 reflects light generated in the scintillator layer 5 towards the side opposite to the side where the photoelectric conversion unit 2b is located, thus directing the light towards the photoelectric conversion unit 2b.

[0094] On the other hand, the transparent moisture-absorbing layer 6 reveals the color of the moisture-proof cover 7, which is an aluminum foil, when viewed from the scintillator layer 5 side. Compared to the white moisture-absorbing layer 6, the moisture-proof cover 7 has a lower reflectivity. If the moisture-absorbing layer 6 becomes saturated, the resolution and sensitivity of the X-ray image both decrease by about 10%.

[0095] Therefore, by monitoring resolution and sensitivity, the amount of moisture that has intruded into the space surrounded by the photoelectric conversion substrate 2, the sealing part 8, and the moisture cover 7 can be detected. This can be used as a standard to determine when the moisture-absorbing layer 6 loses its moisture-absorbing function, or as a standard for determining the repair time of the X-ray detector 1, such as the replacement of the moisture-absorbing layer 6 (the laminate of the moisture-absorbing layer 6 and the moisture cover 7). Furthermore, the X-ray detector 1 can be repaired before the scintillator layer 5 deteriorates.

[0096] Furthermore, when replacing or repairing the moisture-absorbing layer 6, it is necessary to disassemble the laminated body of the moisture-absorbing layer 6 and the moisture-proof cover 7. However, since the laminated body is only bonded to the thermoplastic sealing part 8, disassembly is relatively easy.

[0097] The moisture-absorbing layer 6 covers the entire scintillator layer 5 when viewed from above. The moisture-absorbing layer 6 extends together with the moisture-proof cap 7 above the sealing portion 8. In this embodiment, the moisture-absorbing layer 6 has the same dimensions as the moisture-proof cap 7 when viewed from above and completely overlaps with it. The moisture-absorbing layer 6 is directly bonded to the sealing portion 8. Therefore, the moisture-proof cap 7 is indirectly bonded to the sealing portion 8.

[0098] As described above, by maximizing the size of the moisture-absorbing layer 6 when viewed from above, the moisture absorption capacity of the moisture-absorbing layer 6 can be increased. For example, in an environment with a temperature of 25°C and a humidity of 50%, and with a thickness T of 80 μm for the moisture-absorbing layer 6, the moisture absorption capacity of the moisture-absorbing layer 6 is 5.1 g / m³. 2 As the area of ​​the moisture-absorbing layer 6 increases, the amount of moisture absorbed by the moisture-absorbing layer 6 also increases. Furthermore, the thickness T is not limited to 80 μm.

[0099] The elastic modulus of the moisture-absorbing layer 6 is lower than that of the moisture-proof cover 7, therefore, the rigidity of the moisture-absorbing layer 6 is lower than that of the moisture-proof cover 7. This is because the thermoplastic sealing part 8 is melted by heating from the outside of the moisture-proof cover 7, so that the molten sealing part 8 adheres tightly to the surface of the moisture-proof cover 7, and then the moisture-proof cover 7 bonds to the sealing part 8 by cooling.

[0100] During the heating and cooling processes used for this bonding, shrinkage of the moisture-absorbing layer 6 is unavoidable, and this shrinkage applies stress to the interface between the moisture-proof cover 7 and the moisture-absorbing layer 6. Therefore, it is preferable that the rigidity (modulus of elasticity) of the moisture-absorbing layer 6 is not high. This is because the stress may cause the interface between the moisture-absorbing layer 6 and the moisture-proof cover 7 to peel off.

[0101] To avoid the above situation, in this embodiment, the elastic modulus of the moisture-absorbing layer 6 is reduced, and the elastic modulus of the moisture-absorbing layer 6 is lower than that of the moisture-proof cover 7. As a result, the stress at the interface can be reduced, and "wrinkles" or "bending" on the surface of the moisture-proof cover 7 caused by the stress at the interface are less likely to occur, thus suppressing the deterioration of the moisture-proof performance caused by "wrinkles" or "bending".

[0102] On the other hand, to avoid the above situation, the stress at the interface between the moisture-absorbing layer 6 and the moisture-proof cover 7 can be reduced by lowering the rigidity (elastic modulus) of the moisture-proof cover 7. However, if the rigidity of the moisture-proof cover 7 is reduced, "wrinkles" and "bending" are easily generated on the surface of the moisture-proof cover 7 due to the aforementioned interface stress. Delamination and bubbles occur at the interface between the sealing part 8 and the moisture-proof cover 7 in the "wrinkled" and "bent" parts. Moreover, since water vapor from the outside can easily penetrate, the scintillator layer 5 deteriorates due to moisture. Therefore, reducing the rigidity of the moisture-proof cover 7 is not preferable.

[0103] According to one embodiment configured as described above, the X-ray detector 1 includes a photoelectric conversion substrate 2, a scintillator layer 5, a sealing portion 8, and a moisture-proof cover 7. The moisture-proof cover 7, together with the photoelectric conversion substrate 2 and the sealing portion 8, hermetically seals the scintillator layer 5. Even though the scintillator layer 5 is sealed by the photoelectric conversion substrate 2, the sealing portion 8, and the moisture-proof cover 7, considerable moisture can still permeate from the sealing portion 8 over long-term use, potentially causing degradation of the scintillator layer 5. For example, the scintillator layer 5 is hygroscopic; therefore, it is necessary to prevent it from absorbing moisture and liquefying. If the scintillator layer 5 deteriorates, the conversion from X-rays (radiation) to light (fluorescence) becomes difficult.

[0104] Therefore, the X-ray detector 1 also includes a moisture-absorbing layer 6. Regarding moisture, the moisture-absorbing layer 6 has a higher absorption rate than the sealing portion 8. When the X-ray detector 1 includes the moisture-absorbing layer 6, it can better suppress the permeation of moisture into the scintillator layer 5. In other words, an X-ray detector 1 with high moisture-proof performance can be obtained. Furthermore, an X-ray detector 1 with a long product lifespan can be obtained.

[0105] The moisture-absorbing layer 6 has the characteristic that its light transmittance varies according to the change in internal moisture content. Therefore, the X-ray detector 1 can be repaired before the scintillator layer 5 deteriorates.

[0106] Therefore, an X-ray detector 1 can be obtained that can detect the amount of water that has penetrated into the interior.

[0107] While one embodiment of the invention has been described, it is presented as an example and is not intended to limit the scope of the invention. The novel embodiment described above can be implemented in various other ways, with various omissions, substitutions, and modifications possible without departing from the spirit of the invention. The above embodiments and their variations are included within the scope and spirit of the invention, and also within the scope of the invention and its equivalents as set forth in the patent claims.

[0108] For example, such as Figure 8 and Figure 9 As shown, when viewed from above, the size of the moisture-absorbing layer 6 can be smaller than the size of the moisture-proof cover 7. Figure 8 and Figure 9 In the modified example 1 shown, the moisture-absorbing layer 6 also covers the entire scintillator layer 5 when viewed from above. The moisture-absorbing layer 6 does not extend above the sealing portion 8. The moisture-proof cover 7 is directly adhered to the sealing portion 8. The entire moisture-absorbing layer 6 is located inside the space surrounded by the photoelectric conversion substrate 2, the sealing portion 8, and the moisture-proof cover 7. The moisture-absorbing layer 6 is not exposed to the outside of the aforementioned space, thus preventing unwanted moisture from entering the moisture-absorbing layer 6. In this modified example 1, an X-ray detector 1 capable of detecting the amount of moisture that has entered the interior can also be obtained. In addition, Figure 9 In the diagram, the scintillator layer 5 is marked with an upward diagonal line to the right, the sealing part 8 is marked with a downward diagonal line to the right, and the moisture-absorbing layer 6 is marked with a dotted pattern.

[0109] like Figure 10 As shown, the X-ray detector 1 in Modified Example 2 may further include a light-reflecting layer 15. The light-reflecting layer 15 is disposed between the scintillator layer 5 and the moisture-absorbing layer 6. The light-reflecting layer 15 is located at least in the detection region DA. The light-reflecting layer 15 is provided to improve the utilization efficiency of light (fluorescence) and to improve resolution and sensitivity. That is, the light-reflecting layer 15 reflects light generated in the scintillator layer 5 towards the side opposite to the side where the photoelectric conversion unit 2b is located, thereby directing the light towards the photoelectric conversion unit 2b.

[0110] A portion of the light incident from the scintillator layer 5 passes through the light-reflecting layer 15 and enters the moisture-absorbing layer 6, where it is either reflected or transmitted through the moisture-absorbing layer 6. Even though the X-ray detector 1 has the light-reflecting layer 15, the photoelectric conversion substrate 2 can still detect changes in the transmittance of the moisture-absorbing layer 6. In this modified example 2, an X-ray detector 1 capable of detecting the amount of moisture that has penetrated into the interior can also be obtained.

[0111] For example, a coating material consisting of light-scattering particles such as titanium oxide (TiO2), resin, and solvent can be coated onto the scintillator layer 5, and then the coating material can be dried to form a light-reflecting layer 15.

[0112] Furthermore, the structure and manufacturing method of the light-reflecting layer 15 are not limited to the examples described above, and various modifications can be made. For example, the light-reflecting layer 15 can be formed by forming a thin film of a metal layer with high light reflectivity, such as a silver alloy or aluminum, on the scintillator layer 5. Alternatively, the light-reflecting layer 15 can be formed by providing a sheet with a metal layer of high light reflectivity, such as a silver alloy or aluminum, or a resin sheet containing light-scattering particles on the surface of the scintillator layer 5.

[0113] Furthermore, when a paste-like coating material is applied to the scintillator layer 5 and allowed to dry, the coating material shrinks as it dries, thus applying tensile stress to the scintillator layer 5, which can sometimes cause it to peel off from the photoelectric conversion substrate 2. Therefore, it is preferable to provide a sheet-like light-reflecting layer 15 on the scintillator layer 5. In this case, for example, double-sided tape or the like can be used to bond the light-reflecting layer 15 to the scintillator layer 5, but it is preferable to place the light-reflecting layer 15 on the scintillator layer 5. When the sheet-like light-reflecting layer 15 is placed on the scintillator layer 5, it is easy to suppress the peeling of the scintillator layer 5 from the photoelectric conversion substrate 2 caused by the expansion or contraction of the light-reflecting layer 15.

[0114] The light transmittance of the moisture-absorbing layer 6 can be adjusted according to the change in internal moisture content. The moisture-absorbing layer 6 is not limited to changing from white to transparent; it can be deformed in various ways.

[0115] The techniques described in the above embodiments and various modifications are not limited to the X-ray detector 1 described above, but can also be applied to other X-ray detectors and various radiation detectors. The radiation detector may have a radiation detection panel to detect radiation, replacing the X-ray detection panel PNL.

Claims

1. A radiation detector, characterized in that, include: A photoelectric conversion substrate having a detection area and a non-detection area outside the detection area; A scintillator layer is disposed on the photoelectric conversion substrate and is located at least in the detection area; A frame-shaped sealing portion is located in the non-detection area, surrounds the scintillator layer, and is bonded to the photoelectric conversion substrate; A cover is disposed above the scintillator layer, located in the detection area and the non-detection area, adhered to the sealing portion, and together with the photoelectric conversion substrate and the sealing portion, covers the scintillator layer; as well as A moisture-absorbing layer is disposed between the scintillator layer and the cover, at least in the detection area, and its light transmittance varies according to changes in the internal moisture content. The moisture-absorbing layer covers the entire detection area when viewed from above.

2. The radiation detector as described in claim 1, characterized in that, The moisture-absorbing layer contains aluminosilicates.

3. The radiation detector as described in claim 2, characterized in that, The aluminosilicates are zeolites.

4. The radiation detector as described in claim 1, characterized in that, The moisture-absorbing layer contains aluminum oxide.

5. The radiation detector as described in claim 1, characterized in that, The moisture-absorbing layer contains silica gel.

6. The radiation detector as claimed in claim 1, characterized in that, The moisture-absorbing layer is adhered to the cover. The rigidity of the moisture-absorbing layer is lower than that of the cover.

7. The radiation detector as described in claim 6, characterized in that, The elastic modulus of the moisture-absorbing layer is lower than that of the cover.

8. The radiation detector as claimed in claim 6, characterized in that, The sealing part is formed of a material containing a thermoplastic resin.

9. The radiation detector as claimed in claim 1, characterized in that, The moisture-absorbing layer is white, and changes from white to transparent as the amount of moisture inside increases.

10. The radiation detector as claimed in claim 1, characterized in that, The cover is directly adhered to the sealing part.

11. The radiation detector as claimed in claim 1, characterized in that, The moisture-absorbing layer is adhered to the cover, extends together with the cover above the sealing portion, and is directly adhered to the sealing portion.

12. The radiation detector as claimed in claim 1, characterized in that, It also includes a light-reflecting layer disposed between the scintillator layer and the moisture-absorbing layer.

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