JP2009002775A - Scintillator panel and radiation flat panel detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scintillator panel wherein the rates of sharpness degradation and specific fault are low in wetproof test with high brightness maintained and there are less image nonuniformities and line noise, and to provide a radiation flat panel detector that uses the panel. <P>SOLUTION: A scintillator panel 1a uses a scintillator plate 101 which comprises a scintillator layer 101b, a reflecting layer 101c, and a subbing layer 101d, in this order, on a substrate 101a. In the scintillator plate, the first protective film 102a, arranged on the side of the scintillator layer and the second protective film 102b, arranged on the external side of the substrate are sealed by sealing parts 103b, 103d to yield a protection layer with edges. The protective layer encloses the scintillator plate and a dehydrating agent, and the first protective film is not adhered to the scintillator layer and has air gap 108. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a scintillator panel used when forming a radiographic image of a subject, and a radiation flat panel detector using the scintillator panel.

  Conventionally, radiographic images such as X-ray images are widely used for diagnosis of medical conditions in medical practice. Radiation images using intensifying screens and film systems, in particular, have been developed around the world as imaging systems that combine high reliability and excellent cost performance as a result of high sensitivity and high image quality achieved over a long history. Used in medical settings. However, these pieces of image information are so-called analog image information, and free image processing and instantaneous electric transmission such as digital image information that has been developing in recent years cannot be performed.

  In recent years, digital radiographic image detection apparatuses represented by computed radiography (CR), flat panel type radiation detectors (FPD) and the like have appeared. In these, since a digital radiographic image is directly obtained and an image can be directly displayed on an image display device such as a cathode tube or a liquid crystal panel, image formation on a photographic film is not necessarily required. As a result, these digital X-ray image detection devices reduce the need for image formation by the silver halide photography method, and greatly improve the convenience of diagnosis work in hospitals and clinics.

  Computed radiography (CR) is currently accepted in medical practice as one of the digital technologies for X-ray images. However, the sharpness is insufficient and the spatial resolution is insufficient, and the image quality level of the screen / film system has not been reached.

  Further, as a new digital X-ray imaging technique, for example, Physics Today, November 1997, page 24, John Laurans' paper “Amorphous Semiconductor User in Digital X-ray Imaging”, SPIE 1997, Vol. 32, p. Flat-plate X-ray detection apparatus using TFT (TFT) developed by TFT (TFT) described in the paper “Development of a High Resolution, Active Matrix, Flat-Panel Imager with Enhanced Fill Factor”, etc. ing.

  In order to convert radiation into visible light, a scintillator panel made of an X-ray phosphor having a characteristic of emitting light by radiation is used. In order to improve the S / N ratio in low-dose imaging, luminous efficiency is used. It is necessary to use a high scintillator panel. In general, the light emission efficiency of a scintillator panel is determined by the thickness of the scintillator layer (also referred to as “phosphor layer”) and the X-ray absorption coefficient of the phosphor, but the greater the thickness of the scintillator layer, Scattering of the emitted light occurs at, and sharpness decreases. Therefore, when the sharpness necessary for the image quality is determined, the film thickness is determined.

  Among them, cesium iodide (CsI) has a relatively high rate of change from X-rays to visible light, and phosphors can be easily formed into a columnar crystal structure by vapor deposition. Therefore, it was possible to increase the thickness of the scintillator layer.

  However, since CsI alone has low luminous efficiency, a mixture of CsI and sodium iodide (NaI) at an arbitrary molar ratio is used, for example, as described in Japanese Patent Publication No. 54-3560. Deposited on a substrate as sodium activated cesium iodide (CsI: Na), and recently, a mixture of CsI and thallium iodide (TlI) in an arbitrary molar ratio is deposited on the substrate using vapor deposition to form thallium activated cesium iodide ( Visible conversion efficiency is improved by performing annealing (heat treatment) as a post-process on those deposited as CsI: Tl) and used as an X-ray phosphor.

  As another means for increasing the light output, a method of making a substrate on which the scintillator is formed reflective (for example, see Patent Document 1), a method of providing a reflective layer on the substrate (for example, see Patent Document 2), a substrate, A method of forming a scintillator on a reflective metal thin film and a transparent organic film covering the metal thin film (for example, see Patent Document 3) has been proposed. However, these methods increase the amount of light obtained. However, there is a drawback that sharpness is remarkably lowered.

  Further, in arranging the scintillator panel on the plane light receiving element surface, for example, there are methods described in JP-A-5-329661 and JP-A-6-331749, but these have poor production efficiency, and the scintillator panel Deterioration of sharpness on the plane light receiving element surface is inevitable.

  Conventionally, as a manufacturing method of a scintillator by a vapor phase method, it is common to form a scintillator layer on a rigid substrate such as aluminum or amorphous carbon, and to cover the entire surface of the scintillator with a protective film (for example, , See Patent Document 4).

  However, when a scintillator layer is formed on these substrates that cannot be bent freely, the flat panel take-off is affected by the deformation of the substrate and the warpage during vapor deposition when the scintillator panel and the planar light receiving element surface are bonded together. There is a drawback that uniform image quality characteristics cannot be obtained within the light receiving surface of the data.

  Further, when the substrate is a metal, the X-ray absorption is large, which has been a problem particularly in terms of promoting low exposure. On the other hand, amorphous carbons that have begun to be used in recent years are useful for practical production because they have low X-ray absorption, but are not expensive and have a large general-purpose product. It was hard to say. Therefore, such a problem has become serious with the recent increase in the size of flat panel detectors.

  In order to avoid this problem, the scintillator panel is replaced with a method of forming a scintillator by vapor deposition directly on the plane light receiving element surface (on the image sensor) or a medical intensifying screen with low sharpness but flexibility. Generally, it is used as. Moreover, the example which uses flexible protective layers, such as a polyparaxylylene, as a protective layer is shown (for example, refer patent document 5).

  However, although the scintillator material deposited directly on the planar light receiving element has high image characteristics, the cost characteristic of wasting the expensive light receiving element when a defective product is deposited and the image characteristics of the scintillator material can be improved by heat treatment. However, the processing temperature is limited because the light receiving element is vulnerable to heat. In addition, there is a problem that it is necessary to incorporate cooling of the light receiving element in the heat treatment process. On the other hand, in the case of the indirect type in which the scintillator material deposited on the substrate is combined with the light receiving element, there is an advantage that the disadvantages of the above directly deposited scintillator material (direct type) are improved.

However, a vapor-deposited layer made of a phosphor, which is an image forming layer of the vapor-deposited scintillator material, has deliquescence and is a material that is vulnerable to moisture (humidity). Then, although the sealing film was used as a protective layer with respect to a water | moisture content, it might be inadequate sometimes as moisture resistance, and it was a problem.
Japanese Patent Publication No. 7-21560 Japanese Patent Publication No. 1-240887 JP 2000-356679 A Japanese Patent No. 3669926 JP 2002-116258 A

  The object of the present invention has been made in view of the above problems, and the problem to be solved is that, while maintaining high luminance, the sharpness deterioration rate and the specific failure occurrence rate in the moisture resistance test are low, and the image A scintillator panel with less unevenness and linear noise, and a radiation flat panel detector using the scintillator panel.

  The above object of the present invention is achieved by the following configurations.

  1. A scintillator panel using a scintillator plate in which a reflective layer, an undercoat layer, and a scintillator layer are provided in this order on a substrate. The scintillator plate includes a first protective film disposed on the scintillator layer side and an outer side of the substrate. The protective layer has ears of the protective layer by being sealed with the second protective film disposed on the protective layer, the protective layer encloses the scintillator plate and the dehydrating agent, and the first protective film is bonded to the scintillator layer. A scintillator panel characterized by not.

  2. 2. The scintillator panel as described in 1 above, wherein the first protective film and / or the second protective film contains a dehydrating agent as a layer having a dehydrating function.

  3. 3. The scintillator panel according to item 1 or 2, wherein the scintillator layer is a columnar phosphor layer containing cesium iodide and is formed by a vapor phase method.

  4). The scintillator panel according to any one of 1 to 3, wherein the substrate is a heat resistant resin.

  5). A radiation flat panel detector using the scintillator panel according to any one of claims 1 to 4, wherein the scintillator panel is not physicochemically bonded to the surface of the planar light receiving element. Detector.

  A scintillator panel having a low deterioration rate of sharpness and a specific failure occurrence rate in a moisture resistance test and a low image unevenness and linear noise in a state where high luminance is maintained by the above means of the present invention, and the same A radiation flat panel detector can be provided.

  Hereinafter, the present invention will be described in detail.

  The scintillator panel according to the present invention is a scintillator panel using a scintillator plate in which a reflective layer, an undercoat layer, and a scintillator layer are provided in this order on a substrate. The scintillator plate includes a first scintillator plate disposed on the scintillator layer side. There is a protective layer ear sealed by a protective film and a second protective film disposed outside the substrate, the protective layer encloses a scintillator plate and a dehydrating agent, and the first protective film Is not bonded to the scintillator layer.

  Hereinafter, the present invention and its components will be described in detail.

(Configuration of scintillator plate and panel)
The scintillator plate according to the present invention is formed by providing a reflective layer, an undercoat layer, and a scintillator layer in this order on a substrate. In the scintillator panel of the present invention, at least a protective layer is provided on the scintillator plate. In the present invention, the scintillator plate has a protective layer composed of a first protective film disposed on the scintillator layer side and a second protective film disposed on the outside of the substrate, and the protective layer is the first protective film. And an ear that is a sealed portion of the second protective film, and the protective layer further includes a scintillator plate and a dehydrating agent.

(Scintillator layer)
Various known phosphor materials can be used as the material for forming the scintillator layer, but the conversion rate from X-rays to visible light is relatively high, and the phosphor can be easily formed into a columnar crystal structure by vapor deposition. Therefore, cesium iodide (CsI) is preferable because scattering of emitted light in the crystal can be suppressed by the light guide effect and the thickness of the scintillator layer can be increased.

  However, since only CsI has low luminous efficiency, various activators are added. For example, as shown in Japanese Patent Publication No. 54-35060, a mixture of CsI and sodium iodide (NaI) at an arbitrary molar ratio can be mentioned. Also, for example, CsI as disclosed in Japanese Patent Application Laid-Open No. 2001-59899 is deposited by thallium (Tl), europium (Eu), indium (In), lithium (Li), potassium (K), rubidium ( Rs) and CsI containing an activating substance such as sodium (Na) are preferred. In the present invention, thallium (Tl) and europium (Eu) are preferable, and thallium (Tl) is particularly preferable.

  In the present invention, it is particularly preferable to use an activator containing one or more types of thallium compounds and cesium iodide as raw materials. That is, thallium activated cesium iodide (CsI: Tl) is preferable because it has a broad emission wavelength from 400 nm to 750 nm.

As the thallium compound of the activator containing one or more types of thallium compounds according to the present invention, various thallium compounds (compounds having oxidation numbers of + I and + III) can be used. In the present invention, a preferable thallium compound is thallium bromide (TlBr), thallium chloride (TlCl), thallium fluoride (TlF, TlF ₃ ), or the like.

  The melting point of the thallium compound according to the present invention is preferably in the range of 400 to 700 ° C. If the temperature exceeds 700 ° C., the activator in the columnar crystals exists non-uniformly, and the luminous efficiency decreases. In the present invention, the melting point is a melting point at normal temperature and pressure. Moreover, it is preferable that the molecular weight of a thallium compound exists in the range of 206-300.

  In the scintillator layer, it is desirable that the content of the activator is an optimal amount according to the target performance and the like, but is 0.001 to 50 mol%, and further 0.1 to 10% with respect to the content of cesium iodide. It is preferably 0 mol%. Here, when the activator is less than 0.001 mol% with respect to cesium iodide, the target light emission luminance cannot be obtained without much difference from the light emission luminance obtained by using cesium iodide alone. Moreover, when it exceeds 50 mol%, the property and function of cesium iodide cannot be maintained.

  In the present invention, after a scintillator layer is formed on the polymer film by vapor deposition of the raw material of the scintillator, it is 1 hour in an atmosphere in a temperature range of −50 to 20 ° C. based on the glass transition temperature of the polymer film. The above heat treatment is required. Thereby, the deformation | transformation of a film and generation | occurrence | production of peeling of a fluorescent substance do not occur, and a scintillator panel with high luminous efficiency is realizable.

  As can be seen from the above description, the scintillator layer according to the present invention is preferably a columnar phosphor layer containing cesium iodide, and is preferably formed by a vapor phase method.

(Reflective layer)
The reflective layer according to the present invention is for reflecting the light emitted from the scintillator to increase the light extraction efficiency. The reflective layer is preferably formed of a material containing any element selected from the element group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. In particular, it is preferable to use a metal thin film made of the above elements, for example, an Ag film or an Al film. Two or more such metal thin films may be formed.

(Undercoat layer)
The undercoat layer according to the present invention needs to be provided between the reflective layer and the scintillator layer from the viewpoint of protecting the reflective layer. The undercoat layer preferably contains a polymer binder, a dispersant and the like.

  The thickness of the undercoat layer is preferably 0.5 to 2 μm. If the thickness is 3 μm or less, light scattering in the undercoat layer is small and sharpness is good. Further, when the thickness of the undercoat layer is 2 μm or less, the columnar crystallinity is not disturbed even by heat treatment.

  Hereinafter, components of the undercoat layer will be described.

<Polymer binder>
The undercoat layer according to the present invention is preferably formed by applying and drying a polymer binder dissolved or dispersed in a solvent. Specific examples of the polymer binder include polyimide or polyimide-containing resin, polyurethane, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer. Polymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, polyester, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea resin, melamine resin , Phenoxy resin, silicon resin, acrylic resin, urea formamide resin, and the like. Among these, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, and nitrocellulose are preferably used.

  As the polymer binder according to the present invention, polyimide or polyimide-containing resin, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like are particularly preferable in terms of close contact with the scintillator layer. Moreover, it is preferable that the glass transition temperature (Tg) is a polymer having a temperature of 30 to 100 ° C. in terms of attaching a film between the deposited crystal and the substrate. From this viewpoint, a polyester resin is particularly preferable. However, if the heat treatment temperature is improved in order to improve image characteristics such as luminance, a polymer having a Tg of 30 to 100 ° C. may not be able to ensure sufficient heat resistance. In this case, polyimide or a polyimide-containing resin is used.

  Solvents that can be used to prepare the undercoat layer include N, N-dimethylacetamide, N-methyl-2-pyrrolidone, lower alcohols such as methanol, ethanol, n-propanol, and n-butanol, methylene chloride, and ethylene chloride. Chlorine atom containing hydrocarbons such as, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, aromatic compounds such as toluene, benzene, cyclohexane, cyclohexanone, xylene, lower fatty acids such as methyl acetate, ethyl acetate, butyl acetate and lower alcohol And ethers such as dioxane, ethylene glycol monoethyl ester, ethylene glycol monomethyl ester, and mixtures thereof.

  The undercoat layer according to the present invention may contain a pigment or a dye in order to prevent scattering of light emitted by the scintillator and improve sharpness and the like.

(Protective layer)
The protective layer according to the present invention focuses on protecting the scintillator layer. That is, cesium iodide (CsI) has a high hygroscopic property and, if left exposed, absorbs water vapor in the air and deliquesces, so the main purpose is to prevent this. The protective layer can be formed using various materials.

  Specific examples include a protective film, a laminate film, a protective resin layer typified by parylene by vapor deposition polymerization, a metal foil, and the like, which are laminated materials having a moisture-proof layer. Moreover, as an installation method, sealing which makes a protective film into a bag shape and adheres under reduced pressure, lamination of a laminate film, vapor deposition polymerization such as parylene, and the like can be mentioned. As described above, there are various materials and installation methods for the protective layer. In the present invention, a particularly suitable protective layer includes a protective film.

  In the scintillator panel of the present invention, a protective film can be first provided on the scintillator layer of the scintillator plate as the protective layer.

  Further, the scintillator panel is sealed by a first protective film disposed on the scintillator layer side and a second protective film disposed on the outside of the substrate, and the first protective film is physically and chemically attached to the scintillator layer. It is preferable to set it as the aspect which is not adhere | attached.

  Here, “not physically bonded” means not bonded by a physical interaction or chemical reaction using an adhesive. This unbonded state is a state in which the scintillator layer surface and the protective film can be treated as a discontinuous optically and mechanically even if the scintillator layer surface and the protective film are point contacted microscopically. It can be said.

  Next, the protective film used in the present invention will be described in detail.

(Protective film)
As a structural example of the protective film used for this invention, the multilayer laminated material which has the structure of outermost layer (protective function layer) / intermediate layer (moisture-proof layer) / innermost layer (thermal welding layer) is mentioned. Furthermore, each layer can be a multilayer as required.

<Innermost layer (thermal welding layer)>
The innermost thermoplastic resin film includes EVA, PP (polypropylene), LDPE (low density polyethylene), LLDPE (linear low density polyethylene) and LDPE, LLDPE produced using a metallocene catalyst, and these films and HDPE. It is preferable to use a film mixed with a (high density polyethylene) film.

<Intermediate layer (moisture-proof layer)>
As the intermediate layer (moisture-proof layer), a layer having at least one inorganic film as described in JP-A-6-95302 and the vacuum handbook revised edition p132 to 134 (ULVAC Japan Vacuum Technology KK) is used. Can be mentioned. Examples of the inorganic film include a metal vapor-deposited film and an inorganic oxide vapor-deposited film.

Examples of the metal vapor deposition film include ZrN, SiC, TiC, Si ₃ N ₄ , single crystal Si, ZrN, PSG, amorphous Si, W, and aluminum. Particularly preferable metal vapor deposition films include, for example, aluminum. Can be mentioned.

Thin film handbooks p879-901 (Japan Society for the Promotion of Science), vacuum technology handbooks p502-509, p612, p810 (Nikkan Kogyo Shimbun), vacuum handbook revised edition p132-134 (ULVAC Japan Vacuum Technology KK) Inorganic vapor-deposited films as described in (1). As these inorganic vapor deposition films, for example, Cr ₂ O ₃ , Si _x O _y (x = 1, y = 1.5 to 2.0), Ta ₂ O ₃ , ZrN, SiC, TiC, PSG, Si ₃ N ₄ , single crystal Si, amorphous Si, W, AI ₂ O ₃ or the like is used.

  The thermoplastic resin film used as the base material of the intermediate layer (moisture-proof layer) includes ethylene tetrafluoroethyl copolymer (ETFE), high-density polyethylene (HDPE), expanded polypropylene (OPP), polystyrene (PS), poly Film materials used for general packaging films such as methyl methacrylate (PMMA), biaxially stretched nylon 6, polyethylene terephthalate (PET), polycarbonate (PC), polyimide, polyether styrene (PES) can be used. .

  As a method for forming a vapor deposition film, vacuum technology handbook and packaging technology Vol 29, No. 1 are used. 8, for example, a resistance or high-frequency induction heating method, an electrobeam (EB) method, plasma (PCVD), or the like. The thickness of the deposited film is preferably in the range of 40 to 200 nm, more preferably in the range of 50 to 180 nm.

<Outermost layer: protective functional layer>
The thermoplastic resin film used via the vapor-deposited film sheet is a polymer film used as a general packaging material (for example, a polymer film described in Toray Research Center, Inc., a new development of functional packaging materials). Low density polyethylene (LDPE), HDPE, linear low density polyethylene (LLDPE), medium density polyethylene, unstretched polypropylene (CPP), OPP, stretched nylon (ONy), PET, cellophane, polyvinyl alcohol (PVA), stretched vinylon ( OV), ethylene-vinyl acetate copolymer (EVOH), vinylidene chloride (PVDC), a polymer of fluorine-containing olefin (fluoroolefin), a fluorine-containing olefin copolymer, or the like can be used.

  As these thermoplastic resin films, a multilayer film made by co-extrusion with a different film, a multilayer film made by bonding with different stretching angles, etc. can be used as needed. Furthermore, in order to obtain the required physical properties of the packaging material, it is of course possible to combine the density and molecular weight distribution of the film used. As the thermoplastic resin film of the innermost layer, LDPE, LLDPE produced using LDPE, LLDPE and a metallocene catalyst, or a film using a mixture of these films and HDPE films are used.

  When the inorganic vapor deposition layer is not used, the protective layer needs to have a function as an intermediate layer. In this case, the thermoplastic resin film used for the protective layer may be a simple substance as necessary, or two or more kinds of films may be laminated. For example, CPP / OPP, PET / OPP / LDPE, Ny / OPP / LDPE, CPP / OPP / EVOH, Saran UB / LLDPE (where Saran UB is a vinylidene chloride / acrylate ester co-product of Asahi Kasei Kogyo Co., Ltd.) Biaxially stretched film made of polymerized resin as a raw material.), K-OP / PP, K-PET / LLDPE, K-Ny / EVA (where K is a film coated with vinylidene chloride resin) and the like. in use.

  As a method for producing these protective films, various generally known methods are used. For example, the protective film is produced using a wet lamination method, a dry lamination method, a hot melt lamination method, an extrusion lamination method, or a thermal lamination method. It is possible. Of course, the same method can be used when a film on which an inorganic material is deposited is not used, but in addition to these, depending on the material used, it can be formed by a multilayer inflation method or a coextrusion method.

  As the adhesive used for laminating, generally known adhesives can be used. For example, polyolefin thermoplastic resins such as various polyethylene resins and various polypropylene resins, hot-melt adhesives, ethylene-propylene copolymer resins, ethylene-vinyl acetate copolymer resins, ethylene-ethyl acrylate copolymer resins, and other ethylene copolymers. There are thermoplastic resin hot-melt adhesives such as polymer resins, ethylene-acrylic acid copolymer resins and ionomer resins, and other hot-melt rubber adhesives.

  Typical examples of emulsion-type adhesives that are emulsion and latex adhesives are polyvinyl acetate resin, vinyl acetate-ethylene copolymer resin, vinyl acetate and acrylate copolymer resin, vinyl acetate and maleate ester. There are emulsions such as copolymer resins, acrylic acid copolymers, and ethylene-acrylic acid copolymers.

  Typical examples of latex adhesives include rubber latexes such as natural rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), and chloroprene rubber (CR). In addition, as adhesives for dry lamination, there are isocyanate adhesives, urethane adhesives, polyester adhesives, etc. In addition, paraffin wax, microcrystalline wax, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer. Known adhesives such as hot melt laminate adhesives, pressure sensitive adhesives, heat sensitive adhesives and the like blended with polymer resins can also be used.

  More specifically, the polyolefin-based resin adhesive for extrusion laminating includes, in addition to polymers and ethylene copolymer (EVA, EEA, etc.) resins made of polyolefin resins such as various polyethylene resins, polypropylene resins and polybutylene resins, Ionomer resin (ionic copolymer resin) such as L-LDPE resin copolymerized with ethylene and other monomers (α-olefin), DuPont Surlyn, Mitsui Polychemical Co., Ltd., and Mitsui Petrochemical Admer (adhesive polymer), etc.

  In addition, UV curable adhesives have recently begun to be used. In particular, LDPE resin and L-LDPE resin are preferable because they are inexpensive and have excellent laminating properties. A mixed resin in which two or more of the above resins are blended to cover the defects of each resin is particularly preferable. For example, when L-LDPE resin and LDPE resin are blended, spreadability is improved and neck-in is reduced, so that the lamination speed is improved and pinholes are reduced.

  The thickness of the protective film is preferably 12 μm or more and 200 μm or less, more preferably 50 μm or more, taking into consideration the formability of the voids, the scintillator layer (phosphor layer) protection, sharpness, moisture resistance, workability, etc. 150 μm or less is preferable. The haze ratio is preferably 3% or more and 40% or less, more preferably 3% or more and 10% or less in consideration of sharpness, radiation image unevenness, manufacturing stability, workability, and the like. A haze rate shows the value measured by Nippon Denshoku Industries Co., Ltd. NDH 5000W. The required haze ratio is appropriately selected from commercially available polymer films and can be easily obtained.

(substrate)
As the substrate according to the present invention, various metals, carbon, α-carbon, a heat resistant resin substrate, and the like can be used, but a heat resistant resin substrate is particularly preferable in view of image characteristics, cost, and the like.

  Conventionally known resins can be used as the heat resistant resin, but so-called engineering plastics are preferably used. Here, “engineering plastics” are high-performance plastics used in industrial applications (industrial applications), and generally have high strength, heat-resistant temperature, excellent chemical resistance, etc. Have advantages.

  The engineering plastics according to the present invention is not particularly limited. For example, polysulfone resin, polyethersulfone resin, polyimide resin, polyetherimide resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethylene terephthalate resin Polybutylene terephthalate resin, aromatic polyester resin, modified polyphenylene oxide resin, polyphenylene sulfide resin, polyether ketone resin and the like are preferably used. These engineering plastics may be used independently and 2 or more types may be used together.

  Furthermore, depending on the curing temperature, it is also preferable to use super engineering plastics represented by polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE) and the like.

  In the present invention, the substrate is preferably formed of a resin containing polyimide such as polyimide resin or polyetherimide resin, which is excellent in heat resistance, workability, mechanical strength, and cost.

  In addition, when bonding the scintillator panel and the planar light receiving element surface, due to the influence of deformation of the substrate and warpage during vapor deposition, it is not possible to obtain uniform image quality characteristics within the light receiving surface of the flat panel detector. By making the substrate a resin substrate having a thickness of 50 μm or more and 500 μm or less, the scintillator panel is deformed into a shape that matches the shape of the planar light receiving element surface, and uniform sharpness is obtained over the entire light receiving surface of the flat panel detector.

(Dehydrating agent)
The dehydrating agent in the present invention is a material having a dehydrating function. The dehydration function traps water (mainly water vapor, sometimes including water itself in some cases (such as the occurrence of pinholes)) and causes deterioration of characteristics due to moisture absorption (wetting by water) of the scintillator layer. Widely refers to materials having functions that can be suppressed. The dehydration function includes two types having a function of trapping (trapping) water vapor and water, such as a reactive one (general dehydrating agent) and an adsorbent mainly using adsorption.

  Specifically, in order to provide a dehydrating function, for example, a dehydrating agent and a scintillator plate can be enclosed (enclosed) with a protective layer.

  Examples of the dehydrating agent include silica, silica gel, calcium chloride, and the like, but commercially available products include, for example, Versunny (Kanebo) (humidity control 70%), Mosfin (Toyobo) (humidity control humidity 70%), Arrow sheet (Shinagawa Kasei) (humidity controlled humidity 50% or less), Zeo sheet (Shinagawa Kasei) (humidity controlled humidity 50% or less), Frecron sheet (OH G. Co., Ltd.) (humidity controlled humidity 70%), Dry Keep (Sasaki) Chemicals) and the like (some include an adsorbent).

  Examples of the adsorbent include a water-absorbing polymer. Below, the compound which gives a dehydration function is described.

  The water-absorbing polymer means water that absorbs 5 to 1200 times its own weight, and includes, for example, acrylic acid type, starch / acrylic acid type, maleic acid type, cellulose type and synthetic polymer type. Naturally, the amount of water absorption varies depending on the ionic species and ionic strength in the system.

  As the water-absorbing polymer, for example, acrylic acid-based materials such as Arasop (Arakawa Chemical), Wonder Gel (Kao), Sumikagel (Sumitomo Chemical), Aquakeep (Iron Seikagaku), Lanseal (Nippon Exlan), FAVOR (Stockhausen) , HYSORB (BASF), Aquaric (Nippon Shokubai Kagaku), Starch / acrylic acid type, Sanwet (Sanyo Kasei), WATER LOCK (Grain processing), Maleic acid type, KI gel (Kuraray isoprene), Cellulose type , AQUALON (Hercules), DRYTECH (Dow Chemical), and synthetic polymer systems such as Aqua reserve GP (Nippon Synthesis).

  The shape of the dehydrating agent may be a sheet shape, a fiber shape, a particle shape, a strip shape, or the like, but a sheet shape is generally preferable.

  In the case of applying a dehydrating agent to the protective film according to the present invention, means such as coating a dehydrating agent layer or forming a film having a dehydrating agent layer or a dehydrating agent layer into a laminated film by an arbitrary method such as dry lamination is exemplified. It is done.

  When producing a sheet having a dehydrating agent layer, a polyester film, a polymethacrylate film, a nitrocellulose film, a cellulose acetate film, or the like can be used as a resin film as a base, and a polypropylene film, a polyethylene terephthalate film, or a polyethylene naphthalate film can be used. Is preferable as a protective film in terms of transparency and strength, and the fluorine-containing resin-containing resin composition layer is a polymer of an olefin (fluoroolefin) containing fluorine or an olefin copolymer containing fluorine. A copolymer contained as a component is preferable in terms of scratch resistance.

(Scintillator plate and panel manufacturing method, etc.)
Next, embodiments of the present invention will be described with reference to FIGS. 1 to 6, but the present invention is not limited thereto.

  FIG. 1 is a schematic plan view of a scintillator panel. FIG. 1A is a schematic plan view of a scintillator panel in which a scintillator plate is sealed with a protective film with a four-way seal. FIG. 1B is a schematic plan view of a scintillator panel in which a scintillator plate is sealed with a protective film with a two-way seal. FIG. 1C is a schematic plan view of a scintillator panel in which a scintillator plate is sealed with a protective film with a three-way seal.

  The scintillator panel shown in FIG. In the figure, reference numeral 1a denotes a scintillator panel. The scintillator panel 1a includes a scintillator plate 101, a first protective film 102a disposed on the scintillator layer 101b (see FIG. 4) side of the scintillator plate 101, and a second protection disposed on the substrate 101a side of the scintillator plate 101. And a film 102b (see FIG. 4).

  Reference numerals 103 a to 103 d denote four sealing portions of the protective film 102 a and the second protective film 102 b (see FIG. 4), and the sealing portions 103 a to 103 d are formed outside the peripheral edge portion of the scintillator plate 101. Has been. The four-way seal means a state having sealing portions in four directions as shown in the figure. The four-sided seal shown in this figure has a scintillator plate sandwiched between two plate-like protective films of a first protective film 102a and a second protective film 102b (see FIG. 4). It can be produced by sealing.

  In this case, the 1st protective film 102a and the 2nd protective film 102b (refer FIG. 4) may differ or may be the same, and can be suitably selected as needed.

  The scintillator panel shown in FIG. In the figure, 1b represents a scintillator panel. The scintillator panel 1b includes a scintillator plate 101, a first protective film 104 disposed on the scintillator layer 101b (see FIG. 4) side of the scintillator plate 101, and a second protection disposed on the substrate 101a side of the scintillator plate 101. And a film (not shown).

  Reference numerals 105 a and 105 b denote two sealing portions of the protective film 104 and a second protective film (not shown) disposed on the substrate side, and the sealing portions 105 a and 105 b are both outside the peripheral edge of the scintillator plate 101. Is formed. The two-way seal means a state having a sealing portion in two directions as shown in the figure. The two-sided seal shown in this figure can be produced by sandwiching a scintillator plate between protective films formed into a cylindrical shape by the inflation method and sealing the two sides. In this case, the protective films used for the first protective film 104 and the second protective film (not shown) are the same.

  The scintillator panel shown in FIG. In the figure, 1c shows a scintillator panel. The scintillator panel 1c includes a scintillator plate 101, a first protective film 106 disposed on the scintillator layer 101b (see FIG. 4) side of the scintillator plate 101, and a second protective film disposed on the substrate 101a side of the scintillator plate 101. (Not shown).

  Reference numerals 107 a to 107 c denote three sealing portions of the first protective film 106 and a second protective film (not shown) disposed on the substrate side, and the sealing portions 107 a to 107 c are formed from the peripheral portion of the scintillator plate 101. Is also formed on the outside. A three-way seal means a state having a sealing portion in three directions as shown in the figure. The three-sided seal shown in this figure can be produced by folding a three-sided protective film with a scintillator plate sandwiched between two formed protective films and sealing the three-sided seal film. .

  In this case, the protective films used for the first protective film 106 and the second protective film (not shown) are the same. As shown in FIGS. 1 (a) to 1 (c), since the sealing portion of the two protective films of the first protective film and the second protective film is outside the peripheral edge of the scintillator plate, It is possible to prevent moisture from entering. The scintillator layer of the scintillator plate shown in FIGS. 1A to 1C is preferably formed on the substrate by the above-described vapor deposition method. As the vapor deposition method, an evaporation method, a sputtering method, a CVD method, an ion plating method, or the like can be used.

  The form of the scintillator panel shown in FIGS. 1A to 1C can be selected depending on the type of scintillator layer of the scintillator plate, the manufacturing apparatus, and the like.

  FIG. 2 is a schematic diagram showing an example of the configuration of the scintillator panel and the configuration of the ears of the protective layer. In the present application, the sealing of the protective film means that the heat-welded layer, which is the innermost layer of the protective film, is sealed by heating (heat-sealing). Called stop ear). The moisture-proof property (water vapor barrier property) of the protective layer is based on the moisture-proof property (water vapor barrier property) of the intermediate layer (moisture-proof layer), and is 1 to 2 for the innermost layer (thermal welding layer) and the intermediate layer support. It has a moisture resistance (water vapor barrier property) three orders of magnitude higher. Therefore, it is conceivable that if the length of the sealing ear is short, that portion causes deterioration of the scintillator layer due to intrusion of water vapor. Therefore, it can be seen that the ear portion of the protective layer has an important meaning on the moisture-proof performance of the sealed protective layer.

  FIG. 3 is a schematic diagram showing an example of the configuration of the scintillator panel and the configuration of the dehydrating agent. 3A to 3D show examples of specific arrangement of the dehydrating agent.

  FIG. 3A is a diagram in which a dehydrating agent is disposed on the four sides around the substrate without the scintillator layer when the area of the substrate> the area of the scintillator layer, and FIG. 3A-1 shows the scintillator inside the protective layer. It is the figure seen from the layer side.

  FIG. 3B is a diagram in which a dehydrating agent is applied on the back surface of the substrate (opposite surface of the scintillator layer) or a sheet of the dehydrating agent is separately provided on the back surface of the substrate.

  FIGS. 3C and 3D show the cases of the first protective film and the first protective film each containing a dehydrating agent.

  FIG. 4 is a schematic cross-sectional view taken along the line AA ′ in FIG. FIG. 4A is a diagram showing a schematic enlarged cross-section along AA ′ of FIG. 1A and a contact state with the planar light receiving element. FIG.4 (b) is a schematic enlarged view of the part shown by P of Fig.4 (a).

  The scintillator plate 101 has a substrate 101a and a scintillator layer 101b formed on the substrate 101a. Reference numeral 102b denotes a second protective film disposed on the substrate 101a side of the scintillator plate 101. Reference numeral 108 denotes a gap (air layer) formed between the point contact portions E to I that are in partial contact between the first protective film 102a and the scintillator layer 101b. The void portion (air layer) 108 is an air layer, and the relationship between the refractive index of the void portion (air layer) 108 and the refractive index of the first protective film 102a is the refractive index of the protective film 102a >> Air layer) 108 has a refractive index.

  Reference numeral 109 denotes a gap (air layer) formed between the point contact portions J to O that are partially in contact between the first protective film 102a and the planar light receiving element 201. The void portion (air layer) 109 is an air layer, and the relationship between the refractive index of the void portion (air layer) 109 and the refractive index of the first protective film 102a is the refractive index of the protective film 102a >> Air layer) 109 has a refractive index.

  In the case of the scintillator panels shown in FIGS. 1B and 1C, the relationship between the refractive index of the gaps (air layers) 108 and 109 and the refractive index of the first protective film 102a is shown in FIG. Same as the case.

That is, the first protective film 102a arranged on the scintillator layer 101b side is not in a state of close contact with the scintillator layer 101b but is in partial contact with the point contact portions E to I. . When the entire surface of the scintillator layer 101b is covered with the first protective film 102a disposed on the scintillator layer 101b side, the point contact portions E to H are at least 0.1 place / mm ^{2 with} respect to the surface area of the scintillator layer 101b. It is preferable to set it to 25 places / mm ² or less. In the present invention, such a state is referred to as a state in which the first protective film disposed on the scintillator layer side is not substantially adhered. In the case of the scintillator panels shown in FIGS. 1B and 1C, the relationship between the number of point contact portions and the surface area of the scintillator layer is the same as in the case of this figure.

Further, the first protective film 102a is not in a state of close contact with the planar light receiving element 201 but is in partial contact with the point contact portions J to O. The point contact portions J to O are preferably set at 0.1 place / mm ² or more and 25 places / mm ² or less with respect to the surface area of the planar light receiving element 201.

When the number of point contact portions between the first protective film 102a and the scintillator layer 101b and the number of point contact portions between the first protective film 102a and the planar light receiving element 201 exceed 25 locations / mm ² , sharpness deteriorates. It is one of the causes. When the number of point contact portions is less than 0.1 / mm ² , it is one of the causes of deterioration of brightness and sharpness.

  The number of point contact portions can be measured by the following method.

  The scintillator panel is irradiated with X-rays and the emitted light is read by a planar light receiving element using a CMOS or CCD to obtain signal value data. Power spectrum data for each spatial frequency is obtained by Fourier transforming this data. The number of point contact portions can be known from the position of the peak of the power spectrum. That is, a minute luminance difference occurs between the point portion where the protective layer is in contact with the non-contact portion, and the number of contact points can be known by measuring this period.

  However, in this method, since the total number of point contact portions of the first protective film 102a and the scintillator layer 101b and the number of point contact portions of the first protective film 102a and the planar light receiving element 201 is detected, each point contact is detected. In order to separate the numbers, for example, the first protective film 102a and the scintillator layer 101b are completely adhered by an adhesive, and only the number of contact points of the point contact portion between the first protective film 102a and the planar light receiving element 201 is measured. is there.

  As shown in the figure, the scintillator panel 1a includes a substrate 101a and a scintillator layer 101b, which are a first protective film 102a disposed on the scintillator layer 101b side of the scintillator plate 101 and a second protective film 102b disposed on the substrate 101a side. Is covered with the first protective film 102a in a substantially non-adhered state, and each end of the four sides of the first protective film 102a and the second protective film 102b is sealed.

  As a method for covering the entire surface of the scintillator layer 101b in a state where the scintillator layer 101b is not substantially adhered by the first protective film 102a, the following method may be mentioned.

  1) The surface roughness of the surface of the first protective film that comes into contact with the scintillator layer is 0.05 to 0 in terms of Ra in consideration of adhesion to the first protective film, sharpness, adhesion to a planar light receiving element, and the like. .8 μm. The surface shape of the first protective film can be easily adjusted by selecting a resin film to be used or coating a coating film containing an inorganic substance on the surface of the resin film. In addition, surface roughness Ra shows the value measured by Tokyo Seimitsu Co., Ltd. Surfcom 1400D.

  2) When the scintillator plate is sealed with the first protective film and the second protective film, it is performed under a reduced pressure condition of 5 Pa to 8000 Pa. In this case, the number of point contact portions between the protective film and the scintillator layer increases when sealed on the high vacuum side, whereas the number of point contact portions decreases when sealed on the low vacuum side. On the other hand, when the pressure is 8000 Pa or more, wrinkles are easily generated on the surface of the protective film, which is not realistic.

  By combining the above methods 1) and 2) alone or in combination, the entire surface of the scintillator layer 101b can be covered with the first protective film 102a in a substantially unbonded state.

  As a method for making the first protective film 102a and the planar light receiving element 201 not substantially bonded, the following method may be mentioned.

  1) A method in which the scintillator panel 1a and the planar light receiving element are arranged so as to be overlapped and then pressed from the second protective film side with an appropriate pressure using elasticity of a foam material such as sponge.

  In 1) above, the first protective film 102a and the planar light receiving element 201 can be substantially not adhered.

  The thickness of the protective film is preferably 12 μm or more and 200 μm or less, more preferably 20 μm or more and 40 μm or less, taking into consideration the formability of the voids, the scintillator layer protection, sharpness, moisture resistance, workability and the like. Thickness shows the value which measured ten places with the stylus type | mold stylus-type film thickness meter (PG-01) by Corporation | KK, and averaged.

  The haze ratio is preferably 3% or more and 40% or less, and more preferably 3% or more and 10% or less in consideration of sharpness, radiation image unevenness, manufacturing stability, workability, and the like. A haze rate shows the value measured by Nippon Denshoku Industries Co., Ltd. NDH 5000W.

  The light transmittance of the protective film is preferably 70% or more at 550 nm in consideration of photoelectric conversion efficiency, scintillator emission wavelength, etc., but a film having a light transmittance of 99% or more is substantially difficult to obtain industrially. In particular, 99% to 70% is preferable. The light transmittance is a value measured with a spectrophotometer (U-1800) manufactured by Hitachi High-Technologies Corporation.

The moisture permeability of the protective film is preferably 50 g / (m ² · 24 h) (40 ° C., 90% RH) (measured according to JIS Z0208) or less, more preferably 10 g, taking into account the protection and deliquescence properties of the scintillator layer. / (M ² · 24h) (40 ° C. · 90% RH) (measured according to JIS Z0208) is preferable.

  As shown in the figure, any known method may be used for sealing the scintillator plate 101 with the first protective film 102a and the second protective film 102b. For example, the thermal scintillator can be effectively welded by heat welding. In order to seal, it is preferable to make the innermost layer which the protective film 102a and the protective film 102b contact into the resin film which has heat-fusion property.

  FIG. 5 is a schematic diagram showing a light refraction state in the gap 108 shown in FIG. 4 and a light refraction state in a state where the conventional protective film and the scintillator layer are in close contact with each other. FIG. 5A is a schematic diagram showing the state of light refraction in the gap 108 shown in FIG. FIG.5 (b) is a schematic diagram which shows the state of light refraction in the state which the conventional protective film and the scintillator layer contact | adhered.

  The case of FIG. 5A will be described.

  In the case shown in this figure, since there is a gap (air layer) 108 between the protective film and the scintillator layer, the refractive index of the first protective film 102a and the refraction of the gap (air layer) 108 are present. The relationship with the refractive index is the refractive index of the first protective film >> the refractive index of the gap (air layer). For this reason, the light R to T emitted from the scintillator layer is incident on the protective film without being reflected at the interface between the first protective film 102a and the gap (air layer) 108 (in a state having no critical angle). The incident light is emitted to the outside without being re-reflected at the interface between the protective film and the air layer by the optical control structure of air layer (low refractive index layer) / protective film / air layer. Can be prevented.

  The case of FIG. 5B will be described.

  In the case shown in the figure, since the protective film and the scintillator layer are in close contact with each other, the light Z having an angle exceeding the critical angle θ among the light X to Z emitted from the phosphor surface is the protective layer-air layer. This increases the proportion of total reflection at the interface. For this reason, it becomes one of the causes that sharpness deteriorates.

  In the present invention, when the scintillator plate is sealed with the first protective film and the second protective film, the scintillator layer and the first protective film are not substantially adhered as shown in FIG. It became possible to manufacture a scintillator panel that does not deteriorate sharpness by making it a state and making a state in which the protective film and the planar light receiving element surface are not substantially bonded.

  In addition, by making the substrate a polymer film having a thickness of 50 μm or more and 500 μm or less and making the total thickness of the scintillator panel 1 mm or less, the scintillator panel is transformed into a shape that matches the planar light receiving element surface shape, and a flat panel detector It has been found that uniform sharpness can be obtained over the entire light receiving surface, and the present invention has been achieved.

  In the present invention, as shown in FIGS. 1 to 4, when the scintillator plate is sealed with the first protective film and the second protective film, the first protective film covering the scintillator layer is not substantially adhered. The following effects were obtained (providing a point contact location between the scintillator layer and the first protective film and providing a gap (air layer) between the point contact locations).

  1) Polypropylene film and polyethylene terephthalate film, which have been difficult to use because they have a high refractive index and reduce sharpness while having excellent physical properties as a protective film in terms of strength, The use of polyethylene naphthalate film and the like has become easier, and it has become possible to produce scintillator panels that are of high quality and prevent long-term performance degradation.

  2) Since a highly scratch-resistant protective film can be used without degrading the image quality, it has become possible to realize a scintillator panel having excellent durability over a long period of time.

  3) A protective layer having excellent durability can be realized without inhibiting the light guide effect of the phosphor crystal.

  FIG. 6 is a schematic diagram of a vapor deposition apparatus that forms a scintillator layer on a substrate by a vapor deposition method.

  In the figure, 2 indicates a vapor deposition apparatus. The vapor deposition apparatus 2 includes a vacuum vessel 201, an evaporation source 202 that is provided in the vacuum vessel 201 and deposits vapor on the substrate 3, a substrate holder 203 that holds the substrate 3, and the substrate holder 203 with respect to the evaporation source 202. A substrate rotating mechanism 204 that deposits vapor from the evaporation source 202 by rotating, a vacuum pump 205 that exhausts the vacuum container 201 and introduces the atmosphere, and the like are provided.

  Since the evaporation source 202 contains the scintillator layer forming material and is heated by a resistance heating method, the evaporation source 202 may be composed of an alumina crucible wound with a heater, or may be composed of a boat or a heater made of a refractory metal. Good. Further, the method for heating the scintillator layer forming material may be a method such as heating by an electron beam or heating by high frequency induction in addition to the resistance heating method, but in the present invention, it is easy to handle with a relatively simple configuration, inexpensive, The resistance heating method is preferable because it can be applied to a great number of substances. The evaporation source 202 may be a molecular beam source by a molecular source epitaxial method.

  The support rotating mechanism 204 includes, for example, a rotating shaft 204a that supports the substrate holder 203 and rotates the substrate holder 204, and a motor (not shown) that is disposed outside the vacuum vessel 201 and serves as a driving source for the rotating shaft 204a. It is configured.

  The substrate holder 203 is preferably provided with a heater (not shown) for heating the substrate 3. By heating the substrate 3, the adsorbed material on the surface of the substrate 3 is separated and removed, and the generation of an impurity layer between the surface of the substrate 3 and the scintillator layer forming material is prevented. The film quality can be adjusted.

  Further, a shutter (not shown) that blocks a space from the evaporation source 202 to the substrate 3 may be provided between the substrate 3 and the evaporation source 202. Substances other than the target attached to the surface of the scintillator layer forming material by the shutter can be prevented from evaporating at the initial stage of vapor deposition and adhering to the substrate 3.

  In order to form the scintillator layer on the substrate 3 using the vapor deposition apparatus 2 configured as described above, the support 3 is first attached to the substrate holder 203. Next, the vacuum vessel 201 is evacuated. Thereafter, the substrate holder 203 is rotated with respect to the evaporation source 202 by the support rotating mechanism 204, and when the vacuum container 201 reaches a vacuum degree capable of vapor deposition, the scintillator layer forming material is evaporated from the heated evaporation source 202, A phosphor is grown on the surface of the substrate 3 to a desired thickness.

  In this case, it is preferable that the distance between the substrate 3 and the evaporation source 202 is set to 100 to 1500 mm. In addition, the scintillator layer forming material used as the evaporation source may be processed into a tablet shape by pressure compression or may be in a powder state. Further, instead of the scintillator layer forming material, a raw material or a raw material mixture may be used.

(Radiation flat panel detector)
In the radiation flat panel detector of the present invention, an image can be converted into digital data by converting light emitted from the scintillator panel into electric charges by the plane light receiving element surface.

  In the direct vapor deposition type (integrated type), direct vapor deposition is performed on the surface of the planar light receiving element, and the planar light receiving element and the scintillator layer become an integrated scintillator. However, in the indirect vapor deposition type (separate independent type) of the present invention, The scintillator panel is placed. In this case, the scintillator panel is characterized in that it is not physicochemically bonded to the plane light receiving element surface.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
(Preparation of scintillator plate)
(Preparation of substrate)
A polyimide film (90 mm × 90 mm) having a thickness of 0.125 mm was prepared as a substrate.

(Formation of reflective layer)
Regarding the polyimide (PI) film substrate, aluminum was sputtered on one surface to a thickness of 0.07 μm (700 mm).

(Formation of undercoat layer)
Byron 630 (manufactured by Toyobo Co., Ltd .: polymer polyester resin) 100 parts by weight Methyl ethyl ketone (MEK) 100 parts by weight Toluene 100 parts by weight The above formulation is mixed and dispersed in a bead mill for 15 hours to obtain a coating solution for undercoating. It was. The coating solution was applied to the substrate surface with a bar coater so that the dry film thickness was 1.0 μm, and then dried at 100 ° C. for 8 hours to prepare an undercoat layer.

(Formation of scintillator layer)
Using the vapor deposition apparatus shown in FIG. 6, a phosphor (CsI: 0.003Tl) was vapor-deposited on the prepared substrate to form a scintillator layer, and a scintillator plate was produced.

  A phosphor material (CsI: 0.003 Tl) was filled in a resistance heating crucible, a substrate was placed on the support holder, and the distance between the resistance heating crucible and the substrate was adjusted to 400 mm. Subsequently, the inside of the vapor deposition apparatus was once evacuated, Ar gas was introduced and the degree of vacuum was adjusted to 0.5 Pa, and then the substrate temperature was maintained at 140 ° C. while rotating the substrate at a speed of 10 rpm. Next, the resistance heating crucible was heated to deposit a phosphor, and when the scintillator layer had a thickness of 400 μm, the deposition was terminated to obtain a scintillator plate.

  For the scintillator plate of Example 1, each side of the substrate is 5 mm larger than the scintillator layer so that it is smaller than the area of the scintillator layer (80 mm × 80 mm) and the area of the substrate (90 mm × 90 mm). It was possible to arrange a dehydrating agent at the end of the substrate without the scintillator layer.

(Annealing of scintillator plates)
The scintillator plate was annealed at 200 ° C. for 3 hours in an inert oven under a nitrogen atmosphere. Next, annealing was performed to prepare a scintillator plate.

(Preparation of protective film)
The configurations (A) to (D) shown in Table 1 were prepared as the first protective film and the second protective film.

PET: Polyethylene terephthalate CPP: Casting polypropylene The above // indicates an adhesive layer of dry laminate. This adhesive layer was made of a polyol-isocyanate (= urethane) adhesive and was laminated by a dry laminating method.

(Production of scintillator panel)
The prepared scintillator plate was used and sealed in the form shown in FIG. 1A to prepare a scintillator panel. In addition, the sealing was performed so that the length of the ears of the protective layer serving as the fused portion under a reduced pressure of 1000 Pa was as shown in Table 2. The impulse sealer used for the fusion was a 4 mm wide heater.

<Preparation of dehydrating agent>
Vapor-deposited silica gel (6 μm) / PET (12 μm) / adhesive layer (1 μm): A 12 μm thick polyethylene terephthalate (PET) film was prepared, and a 6 μm silica gel layer was installed by vapor deposition as a layer having a dehydrating function. Further, an adhesive (Byron 300: manufactured by Toyobo Co., Ltd.) was applied and dried on the surface opposite to the silica gel layer to obtain an adhesive layer (1 μm).

  An arrow sheet (Shinagawa Kasei) (humidity controlled humidity of 50% or less) was cut into 90 mm × 90 mm and prepared.

  A zeo sheet (Shinagawa Kasei) (humidity controlled humidity of 50% or less) was cut into 90 mm × 90 mm and prepared.

  Dehydrating agent-containing protective film: In the constitution (D) of the protective layer in Table 1, cut out to 100 mm × 100 mm, and each side 5 mm was stopped with a masking tape so as to be 90 mm × 90 mm, and vapor-deposited silica gel (CPP (40 μm) side) 6 μm), and a dehydrating agent-containing protective film of PET (100 μm) // aluminum foil (7 μm) // CPP (40 μm) / deposited silica gel (6 μm) was produced.

  The dehydrating agent was installed at the position shown in Table 2, and the following evaluation was performed.

(Measurement of emission luminance)
The radiation image conversion panel is set on a 10 cm × 10 cm CMOS flat panel (Radicon X-ray CMOS camera system Shadow Box 4KEV), and X-rays with a tube voltage of 80 kVp are applied to the back surface of each sample (scintillator phosphor layer). Irradiation from the surface on which no is formed), and the measured count value was defined as emission luminance (sensitivity). However, it represents with the relative value which sets the light-emitting luminance of the comparative scintillator panel to 1.0.

(Moisture resistance test)
20 ° C. 5.5 hours → temperature rise 0.5 hour → 30 ° C. 80% RH 5 hours → temperature drop 1 hour → 20 ° C. humidification cycle thermo 7 days, the deterioration rate of the sharpness of this sample was measured (sharpness The evaluation evaluation method will be described later.)

Sharpness degradation rate = {1- (sharpness after test / initial sharpness)} × 100%
The sharpness deterioration rate was evaluated as follows.

A: 0 to less than 5% B: 5 to less than 20% Δ: 20 to less than 30% ×: 30% or more.

(Specific failure rate in moisture resistance test)
The specific failure rate when 1000 samples of the above moisture resistance test were performed was calculated as follows. The specific failure occurrence means an evaluation sample that is lowered by two ranks from the average value, with the above-mentioned ◎, ◯, Δ, and × being four ranks. The occurrence rate of specific failure occurrence samples is defined as a specific failure occurrence rate (Equation 1).

Specific failure rate = (number of specific failure occurrence samples / 1000 evaluation samples) × 100% (Equation 1)
From the above-mentioned specific failure rate, the following evaluation was made.

A: 0%
○: Greater than 0 to less than 5% Δ: 5 to less than 20% ×: 20% or more.

(Sharpness evaluation)
Each sample is set in a 10 cm long × 10 cm wide CMOS flat panel (X-ray CMOS camera system Shad-o-Box 4KEV manufactured by Radicon), and the MTF is measured and calculated for each sample from the 12-bit output data.

  Specifically, X-rays with a tube voltage of 80 kVp are irradiated from the back of each sample (surface on which no phosphor layer is formed) through a lead MTF chart, and image data is detected by a CMOS flat panel and recorded on a hard disk. did. Thereafter, the recording on the hard disk was analyzed by a computer to calculate the modulation transfer function (MTF (Modulation Transfer Function)) of the X-ray image recorded on the hard disk. The calculation result (MTF value (%) at a spatial frequency of 1 cycle / mm) was obtained. The higher the MTF value, the better the sharpness.

(Evaluation of image unevenness and linear noise)
Each sample is set on a 10 cm × 10 cm CMOS flat panel (Radocon X-ray CMOS camera system Shad-o-Box 4KEV), and X-rays with a tube voltage of 80 kVp are applied to the back surface of each sample (scintillator phosphor layer). A solid image was taken by irradiating from a surface on which no is formed. This was reproduced as an image by an image reproducing apparatus, enlarged and printed out twice as much as the output apparatus, and the obtained printed image was visually observed to evaluate the appearance of image unevenness and linear noise. Each of image unevenness and linear noise was evaluated as shown below and shown in Table 3.

◎: No image unevenness or linear noise ○: Light image unevenness or linear noise is observed in less than 1 to 2 locations in the plane △: Light image unevenness or linear noise is observed in less than 2 to 4 locations in the plane X: Image unevenness and linear noise are observed at 4 or more locations in the plane, but dark areas are less than 5 locations.

  The above evaluation results are summarized in Table 3.

  As is apparent from the results shown in Table 3, in the examples according to the present invention, the sharpness deterioration rate and the specific failure occurrence rate in the moisture resistance test are low and the image unevenness is maintained in a state where the light emission luminance is maintained. It can also be seen that there is significantly less linear noise.

It is a schematic plan view of a scintillator panel. It is the schematic diagram which showed the example of the structure of the scintillator panel, and the structure of the ear | edge of a protective layer. It is the schematic diagram which showed the example of the structure of the scintillator panel, and the structure of a dehydrating agent. It is a schematic sectional drawing in alignment with AA 'of Fig.1 (a). It is a schematic diagram which shows the state of light refraction in the space | gap part shown by FIG. 4, and the state of light refraction in the state which the conventional protective film and the scintillator layer (phosphor layer) contact | adhered. It is a schematic diagram of the vapor deposition apparatus which forms a scintillator layer on a board | substrate by a vapor deposition method.

Explanation of symbols

1a to 1c scintillator panel 101 scintillator plate 101a, 3 substrate 101b scintillator layer (phosphor layer)
101c Reflective layer 101d Resin undercoat layer 102a, 104 First protective film 102b Second protective film 103a-103d, 105a, 105b, 107a-107c Sealing part 108 Air gap part (air layer)
E to H Point contact portion R to T, X to Z Light 2 Vapor deposition apparatus 201 Vacuum container 202 Evaporation source 203 Substrate holder 204 Substrate rotation mechanism 205 Vacuum pump

Claims (5)

A scintillator panel using a scintillator plate in which a reflective layer, an undercoat layer, and a scintillator layer are provided in this order on a substrate. The scintillator plate includes a first protective film disposed on the scintillator layer side and an outer side of the substrate. The protective layer has ears of the protective layer by being sealed with the second protective film disposed on the protective layer, the protective layer encloses the scintillator plate and the dehydrating agent, and the first protective film is bonded to the scintillator layer. A scintillator panel characterized by not. The scintillator panel according to claim 1, wherein the first protective film and / or the second protective film includes a dehydrating agent as a layer having a dehydrating function. The scintillator panel according to claim 1 or 2, wherein the scintillator layer is a columnar phosphor layer containing cesium iodide and formed by a vapor phase method. The scintillator panel according to claim 1, wherein the substrate is a heat resistant resin. A radiation flat panel detector using the scintillator panel according to any one of claims 1 to 4, wherein the scintillator panel is not physicochemically bonded to a planar light receiving element surface. Panel detector.

Images