JP5326200B2 - Scintillator plate, scintillator panel, and radiation flat panel detector using them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scintillator plate, a scintillator panel and a radiation slat panel detector using them having excellence in productivity, light extraction efficiency, sharpness and low sharpness deterioration between flat light receiving elements faces. <P>SOLUTION: A scintillator panel 1a consists of: a scintillator plate 101 formed by alternately laminating a reflection layer 101c, a corrosion resistant reflection layer 101d and a scintillator layer 101b; and a first protection film 102a and a second protection film 102b sealed by seal parts 103. A clearance part 108, formed at an entire surface of the scintillator layer 101b, does not substantially bond the scintillator layer to the first protection film 102a. When the scintillator panel 1a is used as a component element of a radiation flat panel detector, the scintillator plate 101 can be used without being physicochemically bonded to the flat panel light receiving element face. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

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

  Conventionally, radiographic images such as X-ray images have been widely used for diagnosis of medical conditions in the medical field. In particular, radiographic images using intensifying screen-film systems are still the world as an imaging system that combines high reliability and excellent cost performance as a result of high sensitivity and high image quality in the long history. Used in the medical field. However, the image information is so-called analog image information, and free image processing and instantaneous electric transmission cannot be performed like the digital image information that has been developed in recent years.

  In recent years, digital radiological 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 the medical field 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 new digital X-ray imaging techniques, for example, the magazine Physics Today, November 1997, page 24, John Laurans's paper “Amorphous Semiconductor User in Digital X-ray Imaging”, magazine SPIE Vol. 32, 1997. A flat-plate X-ray detector using a thin film transistor (TFT) developed in a paper by El Antonuk on “Development of a High Resolution, Active Matrix, Flat-Panel Imager with Enhanced Fill Factor”, etc. Has been.

  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 luminous 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.

  In particular, 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 a low luminous efficiency, a mixture of CsI and sodium iodide (NaI) at an arbitrary molar ratio is used as a substrate by vapor deposition as in the method described in Japanese Patent Publication No. 54-3560. Deposited as sodium-activated cesium iodide (CsI: Na) on the substrate, and recently mixed with any molar ratio of CsI and thallium iodide (TlI) on the substrate using vapor deposition. Visible conversion efficiency is improved by performing annealing 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 the 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), and on the substrate. And a method of forming a scintillator on a transparent organic film covering the metal thin film (see, for example, 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.

  For 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. Deterioration of sharpness on the surface is inevitable.

  Conventionally, as a scintillator manufacturing method by a gas layer 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 detector 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. In addition, when the substrate is a metal, X absorption is large, which is a problem especially in terms of promoting low exposure. On the other hand, amorphous carbons that have begun to be used in recent years are useful in practical production because they have low X-ray absorption, but are not widely used for large-sized products and are very expensive. 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 can be 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. It is generally used. 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. Since the light receiving element is vulnerable to heat, the processing temperature is limited. Alternatively, there is a problem that it is necessary to incorporate cooling of the light receiving element in the heat treatment process.

Therefore, in order to improve the situation with the problems as described above, it is excellent in production, prevents deterioration of the characteristics of the scintillator (phosphor) layer over time, and chemically or physically changes the scintillator (phosphor) layer. Therefore, it is strongly desired to develop a radiation flat panel detector that protects against a strong impact, has little deterioration in sharpness between the scintillator panel and the plane light receiving element surface, and provides uniform image quality characteristics.
Japanese Patent Publication No. 7-21560 Japanese Patent Publication No. 1-240887 JP 2000-356679 A Japanese Patent No. 3669926 JP 2002-116258 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the problem to be solved is a scintillator that is excellent in production suitability, has high light emission extraction efficiency and sharpness of the scintillator, and has little deterioration in sharpness between plane light receiving element surfaces. It is to provide a plate, a scintillator panel and a radiation flat panel detector using them.

  The above-mentioned problem according to the present invention is solved by the following means.

1. A scintillator plate comprising a reflective layer and a scintillator layer provided on a heat resistant resin substrate, wherein the reflective layer has a two-layer structure of a corrosion resistant reflective layer and a reflective layer, and the corrosion resistant reflective layer is on the scintillator layer surface side. The scintillator layer is a columnar phosphor layer containing cesium iodide, formed by a vapor phase method, and, as a component of a radiation flat panel detector, without being physically and chemically bonded to a planar light receiving element surface A scintillator plate characterized by being used.

2 . 2. The scintillator plate according to 1 above, wherein the heat-resistant resin substrate is made of engineering plastic or super engineering plastic.

3 . 3. The scintillator plate according to 1 or 2 , wherein the heat resistant resin substrate is formed of polyimide or a resin containing polyimide.

4 . The scintillator plate according to any one of claims 1 to 3 , wherein the anticorrosive reflective layer is formed of a metal or an alloy, and a standard electrode potential thereof is +1.0 V or more.

5 . The scintillator plate according to any one of claims 1 to 4 , wherein the corrosion-resistant reflective layer is chromium, titanium, a chromium alloy, or a titanium alloy.

6 . The scintillator plate according to any one of 1 to 5 , wherein the corrosion-resistant reflective layer has a thickness of 10 to 100 nm.

7 . The scintillator plate according to any one of claims 1 to 6 , wherein a reflective layer of the two-layered reflective layer is formed of aluminum.

8 . The scintillator plate according to any one of 1 to 7 , wherein the corrosion-resistant reflective layer and the reflective layer are formed by vapor deposition or sputtering.

9 . A scintillator panel using the scintillator plate according to any one of 1 to 8 , wherein a first protection film disposed on the scintillator layer side and a second protection disposed on the outside of the heat resistant resin substrate. The scintillator panel, wherein the scintillator plate is sealed with a film, and the first protective film is not bonded to the scintillator layer.

10 . 10. A radiation flat panel detector using the scintillator panel according to 9 above, wherein the scintillator panel is not physicochemically bonded to the surface of the planar light receiving element.

  By the above-mentioned means of the present invention, a scintillator plate, a scintillator panel, and a radiation flat panel detector using the scintillator plate, scintillator panel, scintillator panel, scintillator plate, scintillator plate, scintillator plate, scintillator plate, and the like. Can be provided.

Scintillator plate of the present invention is a scintillator plate comprising a reflective layer and the scintillator layer on the heat-resistant resin substrate, the reflective layer is a two-layer structure of the corrosion protection reflective layer and the reflective layer, the corrosion protection reflection The layer is on the scintillator layer surface side, the scintillator layer is a columnar phosphor layer containing cesium iodide, formed by a vapor phase method, and as a constituent element of a radiation flat panel detector, It is characterized by being used without being chemically bonded. This feature is a technical feature common to the inventions according to claims 1 to 10 .

  Here, the “scintillator layer” refers to a phosphor layer containing a phosphor material. Further, “not physicochemically bonded” means that the adhesive is not used for physical interaction or chemical reaction.

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

(Configuration of scintillator plate and panel)
The scintillator plate of the present invention is formed by providing at least a reflective layer and a scintillator layer in this order on a heat resistant resin substrate. The reflective layer has a two-layer structure of a corrosion-resistant reflective layer and a reflective layer, and the corrosion-resistant reflective layer is on the scintillator layer surface side.

  In the scintillator panel according to the present invention, at least a protective layer is provided on the scintillator plate. In addition, in this invention, the aspect using a protective film mentioned later as a protective layer is preferable.

  Hereinafter, each constituent layer and constituent elements will be described.

(Scintillator layer)
As a material for forming the scintillator layer (also referred to as “phosphor layer”), the rate of change from X- ray to visible light is relatively high, and the phosphor can be easily formed into a columnar crystal structure by vapor deposition. Therefore, scattering of the emitted light in the crystal can be suppressed, and the thickness of the scintillator layer can be increased. Therefore, cesium iodide (CsI) is used .

  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. Further, for example, CsI as disclosed in Japanese Patent Application Laid-Open No. 2001-59899 is deposited, and thallium (Tl), europium (Eu), indium (In), lithium (Li), potassium (K), rubidium (Rb) ), CsI containing an activating substance such as sodium (Na) is preferred. In the present invention, thallium (Tl) and europium (Eu) are particularly preferable. Furthermore, thallium (Tl) is preferred.

  In the present invention, it is particularly preferable to use an additive 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 wide emission wavelength from 400 nm to 750 nm.

  As the thallium compound as an additive 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 additives in the columnar crystals exist non-uniformly, resulting in a decrease in luminous efficiency. 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 of the present invention, the content of the additive is desirably an optimum amount according to the target performance and the like, but is 0.001 mol% to 50 mol% with respect to the content of cesium iodide, and further 0 It is preferable that it is 1-10.0 mol%.

  Here, when the additive 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.

(Reflective layer)
The reflective layer according to the present invention is for reflecting light emitted from the scintillator to enhance light extraction efficiency. In addition, the reflective layer according to the present invention has a two-layer structure of a corrosion-resistant reflective layer having a corrosion resistance and a reflective layer, and the corrosion-resistant reflective layer is on the scintillator layer surface side.

  The reflective layer of the two-layered reflective layer according to the present invention is made of any element selected from the group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt and Au. It is preferable to form with the material containing. The reflective layer is preferably formed of aluminum. Moreover, it is preferable that the layer thickness is 20-200 nm (0.02-0.2 micrometer), and it is preferable to form by vapor deposition or sputtering.

  On the other hand, the anticorrosive reflective layer according to the present invention is also formed of a metal or alloy composed of these elements, and its standard electrode potential is preferably +1.0 V or more.

Note that the potential of the metal when the metal is in contact with the electrolyte containing a certain concentration of the metal ion is referred to as a standard electrode potential. There is another term “ionization tendency”, which is in order of the standard electrode potential, “noble: large as value, base: small as value”.
Base ← K, Na, Mg, Al, Zn, Cr, Fe, Ni, Sn, (H), Cu, Ag, Pt, Au → Noble Note that the above permutation is pure metal This is the point that In terms of chewing, the metal present around us is considered to be more susceptible to surface changes such as oxidation, especially the “base” metal, and the outermost metal surface is considered to change. It can be said that

  At this time, it is said that, on the contrary, among the “base” metals such as Al, an oxidation passivating film that is stable to chemical change is formed on the outermost surface. Passivation is a state in which an oxide film that resists corrosive action has formed on the metal surface, and this film does not dissolve away when exposed to a solution or acid, thus protecting the internal metal from corrosion. Used for.

  However, not all metals are passive. It is aluminum, nickel, iron, cobalt, chromium, titanium, tantalum, niobium, etc. and their alloys that are easily passivated. If it is a metal which forms such a passive film, a corrosion-proof effect can be expected.

  In this study, the scintillator layer could have been confirmed to have chromium, titanium, etc. as a corrosion-preventing effect against halogen.

  Therefore, in the present invention, chromium, titanium, a chromium alloy, or a titanium alloy is particularly preferable.

  The thickness of the anticorrosive reflective layer according to the present invention is preferably 10 to 100 nm (0.01 to 0.1 μm), and preferably formed by vapor deposition or sputtering.

(Undercoat layer)
In the present invention, an undercoat layer may be provided. The undercoat layer according to the present invention is preferably provided between the undercoat layer and the scintillator layer from the viewpoint of protecting the reflective layer.

  The undercoat layer preferably contains a polymer binder (binder), a dispersant and the like.

  The thickness of the undercoat layer is preferably 0.5 to 2 μm. When the thickness is 3 μm or more, light scattering in the undercoat layer increases and sharpness deteriorates. If the thickness of the undercoat layer is larger than 2 μm, columnar crystallinity is disturbed by the heat treatment.

  Hereinafter, components of the undercoat layer will be described.

<Polymer binder>
<Polymer binder>
The undercoat layer according to the present invention is preferably formed by applying and drying a polymer binder (hereinafter also referred to as “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. Of 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 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) absorbs water vapor in the air and deliquesces when exposed to a high hygroscopic property, and therefore the main purpose is to prevent this. The protective layer can be formed using various materials.

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

  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 physicochemically bonded to the scintillator layer. It is preferable that the surface is not adhered to the surface.

  Here, “not physically bonded” means that it is not bonded by physical interaction or chemical reaction using an adhesive as described above. This non-bonded state is a state in which the scintillator layer surface and the protective film can be treated as a discontinuous optically and mechanically even though 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.

  As a structural example of the protective film used for this invention, the multilayer laminated material which has the structure of a protective layer (outermost 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)>
As the innermost thermoplastic resin film, it is preferable to use EVA, PP, LDPE, LLDPE and LDPE, LLDPE produced by using a metallocene catalyst, or a film using a mixture of these films and HDPE films.

<Intermediate layer (moisture-proof layer)>
Examples of the intermediate layer (moisture-proof layer) include a layer having at least one inorganic film as described in JP-A-6-95302 and vacuum handbook revised editions p132 to p134 (ULVAC Japan Vacuum Technology KK). It is done. 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 film includes, for example, aluminum. .

Thin film handbooks p879-p901 (Japan Society for the Promotion of Science), vacuum technology handbooks p502-p509, p612, p810 (Nikkan Kogyo Shimbun), vacuum handbook revised editions p132-p134 (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) is ethylene tetrafluoroethyl copolymer (ETFE), high-density polyethylene (HDPE), expanded polypropylene (0PP), polystyrene (PS), polymethyl Film materials used for general packaging films such as methacrylate (PMMA), biaxially stretched nylon 6, polyethylene terephthalate (PET), polycarbonate (PC), polyimide, and polyether styrene (PES) can be used.

  As a method for forming a deposited film, vacuum technology handbook and packaging technology Vol 29-No. 8, for example, by resistance or high frequency induction heating method, 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>
Low density, which is a polymer film (for example, a polymer film described in Toray Research Center, Inc., a new development of functional packaging materials) used as a general packaging material as a thermoplastic resin film used via a vapor-deposited film sheet 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.

  Of these thermoplastic resin films, a multilayer film made by coextrusion with a different film, a multilayer film made by laminating at different stretching angles, etc. can be used as required. Furthermore, it is naturally possible to combine the density and molecular weight distribution of the film used to obtain the required physical properties of the packaging material. As the innermost thermoplastic resin film, 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 or may be used by laminating two or more kinds of films as required. For example, CPP / OPP, PET / OPP / LDPE, Ny / OPP / LDPE, CPP / OPP / EVOH, Saran UB / LLDPE (where Saran UB is a vinylidene chloride / acrylic acid ester copolymer resin manufactured by Asahi Kasei Corporation) A biaxially stretched film is used 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 are used. .

  As a method for producing these protective films, various generally known methods are used. For example, a wet laminate method, a dry laminate method, a hot melt laminate method, an extrusion laminate method, and a thermal laminate method are used. Is possible. Of course, the same method can be used in the case where 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, polyethylene thermoplastic resins such as various polyethylene resins, various polypropylene resins, hot melt adhesives, ethylene-propylene copolymer resins, ethylene-vinyl acetate copolymer resins, ethylene-ethyl acrylate copolymer resins, etc. There are thermoplastic resin hot-melt adhesives such as coalescence resins, ethylene-acrylic acid copolymer resins, 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). Dry laminate adhesives include isocyanate adhesives, urethane adhesives, polyester adhesives, and others, as well as paraffin wax, microcrystalline wax, ethylene-vinyl acetate copolymer resin, and ethylene-ethyl acrylate. 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. Other 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-described 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 60 μm or less, more preferably 20 μm or more, taking into consideration the formability of voids, the scintillator layer (phosphor layer) protection, sharpness, moisture resistance, workability, etc. 40 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.

  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 difficult to obtain industrially. Substantially 99% to 70% is preferable.

The moisture permeability of the protective film is preferably 50 g / m ² · day (40 ° C., 90% RH) (measured according to JIS Z0208) or less, more preferably 10 g / m, taking into account the protection and deliquescence properties of the scintillator layer. ² · day (40 ° C./90% RH) (measured according to JIS Z0208) or less is preferable, but a film with a water vapor transmission rate of 0.01 g / m ² · day (40 ° C./90% RH) or less is industrially used. Substantially 0.01 g / m ² · day (40 ° C, 90% RH) or more, 50 g / m ² · day (40 ° C, 90% RH) (measured according to JIS Z0208) The following are preferable, and more preferably 0.1 g / m ² · day (40 ° C. · 90% RH) or more and 10 g / m ² · day (40 ° C. · 90% RH) (measured according to JIS Z0208) or less.

  In addition, as a protective layer of another aspect, an organic thin film, for example, a polyparaxylylene film, can be formed on the entire surface of the scintillator and the substrate by a CVD method to form a protective layer.

(substrate)
The substrate according to the present invention is a heat-resistant resin substrate. 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 a super engineering plastic represented by polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), or the like.

  In this invention, it is preferable to form a board | substrate with resin containing polyimide like the polyimide resin or polyetherimide resin excellent in heat resistance, workability, mechanical strength, and cost.

  Note that, when the scintillator panel and the planar light receiving element surface are bonded, the image quality is not uniform within the light receiving surface of the flat panel detector due to the influence of deformation of the substrate and warpage during vapor deposition. 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 planar light receiving element surface shape, and uniform sharpness is obtained over the entire light receiving surface of the flat panel detector.

(Scintillator plate and panel manufacturing method, etc.)
Next, embodiments of the present invention will be described with reference to FIGS. 1 to 4, 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 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. 2) side of the scintillator plate 101, and a second protective film disposed on the substrate 101a side of the scintillator plate 101. 102b (see FIG. 2). 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. 2), and the sealing portions 103 a to 103 d are formed outside the peripheral edge portion of the scintillator plate 101. ing. 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. 2). It can be produced by sealing. In this case, the 1st protective film 102a and the 2nd protective film 102b (refer FIG. 2) may differ or may be the same, and can be suitably selected as needed.

  The scintillator panel 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. 2) 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 105 a and 105 b denote two sealing portions of the protective film 104 and a second protective film (not shown) arranged on the substrate side, and the sealing portions 105 a and 105 b are both outside the peripheral portion of the scintillator plate 101. Is formed. The two-side seal means a state having a sealing portion in two directions as shown in the figure. The two-way seal shown in this figure can be manufactured 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 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. 2) 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. The sealing portions 107 a to 107 c are arranged from the peripheral portion of the scintillator plate 101. Is also formed on the outside. The 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 manufactured by folding a single protective film around the center and sandwiching the scintillator plate between the two protective films that have been molded. . 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 a vapor deposition method to be described later. 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 diagram showing a schematic cross section along AA ′ of FIG. 1A and a contact state with the planar light receiving element. FIG. 2A 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. 2B is a schematic enlarged view of a portion indicated by P in FIG.

  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.

The 109 shows a gap portion formed between the point contact portion J~O that partial contact between the first protective film 102a and a planar light receiving element (air layer). 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 disposed 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 H. 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 site / 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 that in this figure.

The first protective film 102a is not turned to the state of the planar light receiving element and the entire surface adhesion, in a state of being partially in contact with point contact portion J～O. The point contact portion component locations of 0.1 points of the surface area of the planar light receiving element / mm ² or more, preferably 25 points / mm ² or less.

If the number of point contact portion of the first protective film 102a and the scintillator layer 101b, and the number of point contact portion of the first protective film 102a and a planar light receiving element exceeds a respective 25 points / mm ^2, sharpness is degraded It is one of the causes. Even when the number of point contact portions is less than 0.1 / mm ² , this is one of the causes of deterioration in 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 and the non-contact portion, and the number of contact points can be known by measuring this period.

Number of contacts for the number of total is detected, each point of the point contact part of the number, and the first protective film 102a and a planar light receiving element of the point contact portions of the first protective film 102a and the scintillator layer 101b in however this method to separate, for example, the first protective film 102a and the scintillator layer 101b is completely in close contact with an adhesive, a method of measuring only the contact points of the point contact portions of the first protective film 102a and a planar light receiving element .

  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 of covering the entire surface of the scintillator layer 101b with the first protective film 102a being not substantially adhered, the following method is exemplified.

  1) The surface roughness of the surface of the first protective film that contacts the scintillator layer is 0.05 μm to 0 in terms of Ra, taking into consideration the adhesiveness to the first protective film, the sharpness, the adhesiveness to the 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) to 2) singly or in combination, the entire surface of the scintillator layer 101b can be covered with the first protective film 102a substantially not adhered.

As a method of the state where the first protective film 102a and a planar light receiving element is not substantially bonded include the following method.
1) A method in which the scintillator panel 1a and the planar light-receiving element are arranged so as to overlap each other and then pressed from the second protective film side with an appropriate pressure using the elasticity of a foam material such as a sponge. it can be brought into a state that is not substantially bonded with the planar light receiving element and.

  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 and averaged ten places by the stylus type | mold stylus-type film thickness meter (PG-01).

  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 difficult to obtain industrially. Substantially 99% to 70% is preferable. The light transmittance indicates 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 · day (40 ° C., 90% RH) (measured according to JIS Z0208) or less, more preferably 10 g / m, taking into account the protection and deliquescence properties of the scintillator layer. ² · day (40 ° C., 90% RH) (measured according to JIS Z0208) or less is preferable.

  As shown in the figure, the scintillator plate 101 may be sealed with the first protective film 102a and the second protective film 102b by any known method. For example, the scintillator plate 101 can be efficiently sealed by thermal welding using an impulse sealer. For this reason, it is preferable that the innermost layer in contact between the protective film 102a and the protective film 102b is a resin film having heat-fusibility.

  FIG. 3 is a schematic diagram showing a light refraction state in the gap 108 shown in FIG. 2 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. 3A is a schematic diagram showing a state of light refraction in the gap 108 shown in FIG. FIG. 3B is a schematic diagram showing a state of light refraction in a state where the conventional protective film and the scintillator layer are in close contact with each other.

  This will be described with reference to FIG.

  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.

  This will be described in the case of FIG.

  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 becomes possible to manufacture a scintillator panel that does not deteriorate sharpness by making the protective film and the surface of the planar light receiving element substantially unbonded.

  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 3, 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 were difficult to use because of their high refractive index and low 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, a scintillator panel having excellent durability over a long period of time can be realized.

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

  FIG. 4 is a schematic view of a vapor deposition apparatus for forming a scintillator layer on a substrate by vapor deposition.

  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 for depositing vapor from the evaporation source 202 by rotating, a vacuum pump 205 for exhausting the vacuum container 201 and introducing 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 a boat or a heater made of a refractory metal. Also good. Further, the method of heating the scintillator layer forming material may be a method such as heating by an electron beam or heating by high frequency induction other than the resistance heating method, but in the present invention, it is easy to handle with a relatively simple configuration, inexpensive, In addition, the resistance heating method is preferable because it can be applied to a large 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 adsorbate on the surface of the substrate 3 is removed and removed, and an impurity layer is prevented from being generated between the surface of the substrate 3 and the scintillator layer forming material, and adhesion enhancement and scintillator layer 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. It is possible to prevent substances other than the object attached to the surface of the scintillator layer forming material from evaporating at the initial stage of vapor deposition and adhering to the substrate 3 by the shutter.

  In order to form a scintillator layer on the substrate 3 using the vapor deposition apparatus 2 configured in this way, first, the support 3 is 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, the distance between the substrate 3 and the evaporation source 202 is preferably set to 100 mm to 1500 mm. 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 according to the present invention, the plane light receiving element surface can convert the light emitted from the scintillator panel into electric charges, thereby converting the image into digital data.

  In the direct vapor deposition type (integrated type), the vapor deposition is directly 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 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)
As a substrate, 0.125 mm thick polyimide film (90 mm × 90 mm) and 0. A 5 mm aluminum substrate was prepared.

(Formation of reflective layer and anticorrosive reflective layer)
As shown in Table 1, with respect to the polyimide (PI) film substrate, a metal sputter layer was provided on one surface.

  In order to ensure adhesion, plasma treatment was performed on the surface of the anticorrosive reflective layer or the surface of the reflective layer, which is the outermost layer of the reflective layer in the configuration.

(Formation of scintillator layer)
Using the vapor deposition apparatus shown in FIG. 4, 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 film thickness of 600 μm, the deposition was terminated to obtain a scintillator plate.

(Post-heat treatment of scintillator plate)
The scintillator plate was post-heated at 250 ° C. for 3 hours in an inert oven under a nitrogen atmosphere.

(Preparation of protective film)
As a protective film on the scintillator layer surface side, a barrier film with a laminate layer [“Barrier Rocks” (with coat)] 1011HG-CW (# 12) Toray Film Processing Co., Ltd. was used.

  The protective film on the substrate side of the scintillator sheet was the same as the protective film on the scintillator layer surface side.

(Production of scintillator panel)
The prepared scintillator plate was sealed in the form shown in FIG.1 (c) using the prepared protective film, and the scintillator panel was produced.

  The sealing was performed so that the distance from the fused part to the peripheral part of the scintillator sheet was 1 mm under a reduced pressure of 1000 Pa. The impulse sealer used for the fusion was a 3 mm wide heater.

<Evaluation method>
It attached to each obtained sample, set to a CMOS flat panel (X-ray CMOS camera system Shad-o-Box 4KEV manufactured by Radicon) having a size of 10 cm × 10 cm, and evaluated from 12-bit output data.

  A sponge sheet was placed on the radiation incident side (the side without the phosphor) of the carbon plate of the radiation incident window and the scintillator panel, and both were fixed by lightly pressing the plane light receiving element surface and the scintillator panel.

(Measurement of relative luminance)
X-rays having a tube voltage of 80 kVp were irradiated from the back surface (surface on which the scintillator phosphor layer was not formed) of each sample, and the measured value of instantaneous light emission amount was set to “luminance (sensitivity)”. The measurement results are shown in Table 2. However, in Table 2, the value indicating luminance is the sample No. of the comparative example. This is a relative value when 1 luminance is 1.00.

(Moisture resistance test)
Humidity cycle thermo of 7 days at 20 ° C 5.5 hours → temperature rise 0.5 hours → 30 ° C 80% RH 5 hours → temperature drop 1 hour → 20 ° C, and the deterioration rate of sharpness (MTF) of this sample was measured. . (The sharpness 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.

◎ 0-5%
○ 5-20%
△ 21-30%
× 31% or more (Sharpness = MTF evaluation method)
X-rays with a tube voltage of 80 kVp were irradiated from the back of each sample (substrate surface on which the scintillator layer was not formed) through a lead MTF chart, and image data was detected by a CMOS flat panel on which the scintillator was arranged and recorded on a hard disk. . Thereafter, the recording on the hard disk was analyzed by a computer, and the modulation transfer function MTF (MTF value at a spatial frequency of 1 cycle / mm) of the X-ray image recorded on the hard disk was used as an index of sharpness. In Table 1, it shows that it is excellent in sharpness, so that MTF value is high. MTF is an abbreviation for Modulation Transfer Function.

Evaluation rank of MTF ○: MTF value at a spatial frequency of 1 cycle / mm is 0.7 or more and less than 0.9 Δ: MTF value at a spatial frequency of 1 cycle / mm is 0.6 or more and less than 0.7 ×: Spatial frequency The MTF value at 1 cycle / mm is less than 0.6. The contents of each sample are shown in Table 1, and the results of the evaluation are summarized in Table 2.

  As is clear from the results shown in Table 2, it can be seen that the sample according to the present invention is excellent in relative luminance, sharpness, and moisture resistance.

Schematic plan view of scintillator panel Schematic cross-sectional view along AA 'in FIG. Schematic diagram showing the state of light refraction in the gap shown in FIG. 2 and the state of light refraction in a state where the conventional protective film and the scintillator layer (phosphor layer) are in close contact with each other. Schematic diagram of a vapor deposition device that forms a scintillator layer on a substrate by vapor deposition.

Explanation of symbols

1a to 1c scintillator panel 101 scintillator plate 101a, 3 substrate 101b scintillator layer (phosphor layer)
101c Reflective layer 101d Corrosion-resistant reflective 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 Evaporation apparatus 201 Vacuum container 202 Evaporation source 203 Substrate holder 204 Substrate rotation mechanism 205 Vacuum pump

Claims (11)

A scintillator plate comprising a reflective layer and a scintillator layer provided on a heat resistant resin substrate, wherein the reflective layer has a two-layer structure of a corrosion resistant reflective layer and a reflective layer, and the corrosion resistant reflective layer is on the scintillator layer surface side. The scintillator layer is a columnar phosphor layer containing cesium iodide, and is formed by a vapor phase method, and as a component of a radiation flat panel detector, is in partial contact with a plane light receiving element surface at a point contact portion. And a scintillator plate that is used without being bonded by physical interaction or chemical reaction . The number of the point contact portions is 0.1 to 25 places / mm with respect to the surface area of the planar light receiving element. ² The scintillator plate according to claim 1, wherein the scintillator plate is a scintillator plate. The scintillator plate according to claim 1 or 2 , wherein the heat-resistant resin substrate is formed of engineering plastic or super engineering plastic. The scintillator plate according to any one of claims 1 to 3, wherein the heat-resistant resin substrate is formed of polyimide or a resin containing polyimide. The scintillator plate according to any one of claims 1 to 4 , wherein the corrosion-resistant reflective layer is formed of a metal or an alloy, and a standard electrode potential thereof is +1.0 V or more. The scintillator plate according to any one of claims 1 to 5 , wherein the corrosion-resistant reflective layer is made of chromium, titanium, a chromium alloy, or a titanium alloy. The scintillator plate according to any one of claims 1 to 6 , wherein the corrosion-resistant reflective layer has a thickness of 10 to 100 nm. The scintillator plate according to any one of claims 1 to 7 , wherein the reflective layer of the two-layered reflective layer is formed of aluminum. The scintillator plate according to any one of claims 1 to 8 , wherein the anticorrosive reflective layer and the reflective layer are formed by vapor deposition or sputtering. A scintillator panel using a scintillator plate according to any one of claims 1 to 9, the first protective film arranged on a side of the scintillator layer, a second protective film arranged on the outer side of the substrate The scintillator plate, wherein the scintillator plate is sealed, and the first protective film is not bonded to the scintillator layer. A radiation flat panel detector using the scintillator panel according to claim 10 , wherein the scintillator panel is not bonded to the plane light receiving element surface by physical interaction or chemical reaction .

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