JP2006010388A - Radiation image conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel which can be used in good condition over a long term by reducing the moisture permeation into a stimulable phosphor layer formed by a gas phase lay-up method by using a moisture-proof protective film to completely seal the panel. <P>SOLUTION: In the radiation image conversion panel consisting of a stimulable phosphor plate which has at least one stimulable phosphor layer formed on a substrate by the gas phase lay-up method and the protective film located on the side of phosphors of the stimulable phosphor plate, the protective film is heat-sealed with an adhesive tape made of a heat-fused resin pasted on a substrate part which has no stimulable phosphor layer in a peripheral section of the stimulable phosphor plate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation image conversion panel in which a phosphor layer is sealed by covering the surface of a photostimulable phosphor layer formed by vapor deposition with a moisture-proof protective film.

  In recent years, a method of imaging a radiation image by a radiation image conversion panel using a stimulable phosphor has been used.

  This uses, for example, a radiation image conversion panel in which a photostimulable phosphor layer is formed on a support as disclosed in US Pat. No. 3,859,527 and JP-A-55-12144. It is. A radiation image (accumulated image) is formed by applying radiation transmitted through the subject to the stimulable phosphor layer of the radiation image conversion panel and storing radiation energy corresponding to the radiation transmittance of each part of the subject in the stimulable phosphor layer. By forming and scanning this stimulable phosphor layer with stimulating excitation light (laser light is used), the radiation energy accumulated in each part is emitted and converted into light, and the intensity of this light is read. Get an image. This image may be reproduced on various displays such as a CRT, or may be reproduced as a hard copy.

  As a photostimulable phosphor layer of a radiation image conversion panel used in this radiation image conversion method, the photostimulation is carried out on a support having a fine concavo-convex pattern as performed in, for example, JP-A No. 61-142497. There is a method using a stimulable phosphor layer composed of fine pseudo-columnar blocks formed by depositing a phosphor.

  Further, as described in JP-A-61-142500, a crack between columnar blocks obtained by depositing a stimulable phosphor on a support having a fine pattern was further developed by applying a shock treatment. A method of using a radiation image conversion panel having a photostimulable phosphor layer, and further a surface of the photostimulable phosphor layer formed on the surface of a support as described in JP-A-62-39737. A method of using a radiation image conversion panel in which a pseudo-columnar shape is formed by cracking from the side, and further, as described in JP-A-62-110200, a photostimulable phosphor layer having a cavity by vapor deposition on the upper surface of a support There has also been proposed a method in which a cavity is grown by heat treatment and a crack is formed after the formation.

  In JP-A-2-58000, radiation having a stimulable phosphor layer in which elongated columnar crystals having a certain inclination with respect to the normal direction of the support are formed on the support by vapor deposition. Image conversion panels have been proposed.

  In attempts to control the shape of these photostimulable phosphor layers, all of the photostimulable phosphor layers are made columnar to suppress the lateral diffusion of photostimulated excitation light (or photostimulated luminescence). Since it can reach the support surface while repeating reflection at the crack (columnar crystal) interface, it has a feature that the sharpness of an image by stimulated emission can be remarkably increased.

  However, in the radiation image conversion panel having the photostimulable phosphor layer formed by the vapor phase growth (deposition) method, most of the photostimulable phosphors have high hygroscopicity. It is known that when left under conditions, it gradually absorbs moisture in the air and causes a significant deterioration in performance over time.

  Conventionally, for example, as described in Patent Document 1, a stimulable phosphor layer formed by dispersing europium-activated alkaline earth metal fluoride halide phosphor particles in a binder is used as a metal oxide. A method of preventing moisture absorption of the photostimulable phosphor layer by forming and sealing a barrier using a moisture-proof protective film on which a thin film such as silicon nitride is deposited is employed.

  As for protection of hygroscopic phosphors from water vapor, for example, Patent Document 2 discloses a polyparaxylylene film and a moisture-proof film such as silica to protect phosphors such as CsI as a scintillator material from water vapor. An example using a laminated film formed by sequentially depositing layers by CVD is described.

However, the stimulable phosphor crystal formed by the vapor deposition method is a stimulable phosphor formed by dispersing the europium activated alkaline earth metal fluoride halide phosphor particles in a binder. Compared with phosphors such as CsI, which is a layer or scintillator material, the material has a high hygroscopic property, and the stimulable phosphor crystal by the vapor deposition method is not protected by a binder, Although it is more important for protection from water vapor and an improvement effect is recognized by using the above-described sealing method, a moisture-proof protective film on which a thin film such as a metal oxide is deposited is used. The above-described sealing method that encases the stimulable phosphor crystal does not provide sufficient moisture resistance, and a method for completely preventing moisture absorption is necessary.
JP-A-11-344598 JP 2001-235548 A

  Therefore, the object of the present invention is to reduce moisture permeation to the photostimulable phosphor layer formed by vapor phase growth method using a moisture-proof protective film and to completely seal the radiation image conversion panel, An object of the present invention is to provide a radiation image conversion panel that can be used in a good condition for a long time.

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

(Claim 1)
A photostimulable phosphor plate having at least one photostimulable phosphor layer formed by vapor deposition on a substrate, and a protective film disposed on the phosphor surface side of the photostimulable phosphor plate In the radiation image conversion panel, the protective film includes a pressure-sensitive adhesive tape made of a heat-fusible resin attached to a substrate portion that does not have a stimulable phosphor layer at the periphery of the stimulable phosphor plate. A radiation image conversion panel which is heat-sealed.

(Claim 2)
A photostimulable phosphor plate having at least one photostimulable phosphor layer formed by vapor deposition on a substrate, and disposed on the phosphor surface side and the back surface side of the photostimulable phosphor plate. In the radiation image conversion panel comprising the protective film, the protective films disposed on the phosphor surface side and the back surface side of the photostimulable phosphor plate are the photostimulable phosphor layer at the periphery of the photostimulable phosphor plate. In the substrate portion that does not have the above, it is heat-sealed on each of the phosphor surface side and the back surface side by an adhesive tape made of a heat-fusible resin pasted from the phosphor side to the back surface side. Radiation image conversion panel.

(Claim 3)
The radiation image conversion according to claim 1 or 2, wherein the outermost resin layer on the side of the protective film in contact with the photostimulable phosphor plate is composed of a resin layer having heat-fusibility. panel.

(Claim 4)
The radiographic image according to claim 1 or 2, wherein the protective film is a laminated film formed by laminating a plurality of resin films including a resin film on which at least one layer of metal oxide is deposited. Conversion panel.

(Claim 5)
The at least one photostimulable phosphor layer formed on a substrate by a vapor deposition method is made of an alkali halide photostimulable phosphor represented by the following general formula (1). The radiation image conversion panel according to any one of claims 1 to 6.

General formula (1)
M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
In the formula, M ¹ is at least one alkali metal selected from Li, Na, K, Rb and Cs, and M ² is a group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. at least one divalent metal selected from, M ³ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, At least one trivalent metal selected from the group consisting of Al, Ga and In, and X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I; A is selected from the group consisting of Eu, Tb, In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. At least one metal, and a, b and e each represent a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.

  According to the present invention, a radiation image conversion panel having a long service life in which a photostimulable phosphor layer formed by vapor deposition is sealed with a moisture-proof protective film is obtained.

  Next, the best mode for carrying out the present invention will be described, but the present invention is not limited thereto.

  The present invention will be described in detail below.

  In the radiation image conversion panel in which the photostimulable phosphor layer is formed on the support by the vapor deposition method, the photostimulable fluorescence is usually used because the photostimulable phosphor layer is highly hygroscopic and weak to moisture. A radiation image conversion panel with improved moisture resistance is obtained by covering and sealing a body layer surface and a support with a moisture-proof protective film, preferably a film deposited with a metal oxide, etc. .

  As described above, in order to prevent deterioration of the performance of the radiation image conversion panel due to moisture absorption of the stimulable phosphor, the stimulable phosphor layer and the support are covered with a moisture-proof protective film and sealed. It is known to prevent the invasion.

  For example, in the radiation image conversion panel described in Patent Document 1 (Japanese Patent Application Laid-Open No. 11-344598), a support having a photostimulable phosphor layer is integrated with the phosphor layer and the support as a front surface and a back surface. Is covered with a moisture-proof protective film made of a resin film deposited with a metal oxide, and the inside is sealed from moisture by adhering the periphery.

  FIG. 1 shows a cross-sectional view of a phosphor plate in which a photostimulable phosphor layer 2 made of a columnar crystal such as CsBr is formed on a support 1 such as a borosilicate glass plate by vapor deposition.

  FIG. 2 shows a sectional view in which the phosphor surface and the back surface of the phosphor plate comprising the stimulable phosphor layer 2 and the support 1 are covered with moisture-proof films 3 and 3 ′ and sealed at the end surfaces. The two moisture-proof films are heat-cured and bonded by thermosetting resin or the like, for example, urea resin-based material, at the end surfaces, and the entire phosphor plate is sealed.

  The thermosetting resin refers to a synthetic resin that cures when heated and molded. Specific examples of the thermosetting resin of the present invention include, for example, a urea resin, a silicon resin, an epoxy resin, and an acrylic resin. Examples thereof include resins. Of these, urea resins are preferred.

  For the moisture-proof protective film, for example, a film obtained by vapor-depositing a metal oxide film such as silica or alumina (for example, alumina-deposited PET (commercially available product: manufactured by Toyo Metallizing Co., Ltd.)) or a plurality of these laminated with other resin films (For example, a laminate of CPP (heat-fusible film (casting polypropylene))) can be used. Thereby, the end surface of a moisture-proof protective film can be adhere | attached with a thermosetting resin etc., and sealing with a moisture-proof protective film can be performed.

  Although these methods have a certain effect, they are excellent in deliquescence, for example, alkali halide-based stimulable phosphors, particularly CsBr, I-based phosphors, but depending on such a sealing method, It has been found that the moisture-proof performance is not sufficient, and that the lifetime of the phosphor is not sufficient in the photostimulable light emission characteristics.

  This is because the deliquescent properties of the photostimulable phosphor are particularly large, and the photostimulable light emission characteristics of the phosphor are greatly reduced by water absorption. On the other hand, as a sealing method, these methods are, for example, 500 μm. Using a moisture-proof protective film together with a stimulable phosphor layer formed by vapor deposition on a support having a thickness of up to 2,000 μm, the stimulable phosphor surface and the support surface Since the periphery of the support is adhesively sealed using, for example, a thermosetting adhesive or the like so as to be sandwiched from the back surface and both surfaces, wrinkles are likely to occur particularly at the four corners due to its thickness. It tends to cause non-uniform adhesion strength between moisture-proof protective films. Therefore, the durability is inferior and cracking is likely to occur, so that sufficient sealing strength cannot be obtained.

  By processing the moisture-proof protective film, for example, increasing the number of films deposited with a metal oxide such as silica, alumina, or increasing the thickness of the metal oxide film in order to improve moisture resistance, In order not to be the above-mentioned improvement means in the bonded portion, and to cause a decrease in sharpness, a new means for improving moisture resistance is required. In addition, the surface of the photostimulable phosphor columnar crystal formed by the vapor deposition method is not actually smooth, and there are gaps between the columnar crystals, and there is a minute gap between the moisture-proof protective film and the crystal surface. Intervention is also a factor that causes non-uniform adhesion and wrinkles between moisture-proof protective films when sealing thick phosphor plates as a unit, and is one of the causes of progressive deterioration in the performance of radiation image conversion panels. It is thought that.

  Therefore, the present invention provides a support for sealing a support (stimulable phosphor plate) on which a stimulable phosphor layer is formed by a film (moisture-proof protective film) on which a metal oxide is deposited. A new stimulable phosphor plate sealing method capable of effectively sealing only the stimulable phosphor layer irrespective of the thickness of the photostimulable phosphor plate is provided. Although the thickness of the photostimulable phosphor layer is in the range of 50 μm to 1000 μm and is relatively thick due to sensitivity requirements, the thickness of the support is even larger (mostly reaches 400 μm to 2000 μm), so the support This is characterized in that the moisture-proof film due to the thickness of the film has few wrinkles, especially at the four corners of the phosphor plate, and can provide a strong seal with strong adhesive strength.

  FIG. 3 shows an example of the radiation image conversion panel of the present invention. On the surface having the photostimulable phosphor layer of the photostimulable phosphor plate having at least one photostimulable phosphor layer 2 formed on the support (substrate) 1 by vapor deposition, The moisture-proof protective film 3 is overlaid, and a radiation image conversion panel is formed by adhering and sealing with an adhesive 4 in the peripheral portion of the substrate where the stimulable phosphor layer is not formed.

  In the conventional method of sealing and sealing the entire substrate itself having a stimulable phosphor layer with a moisture-proof protective film, the thickness of both the support and the phosphor layer is large. In particular, the generation of wrinkles in the portion near the four corners is large, so that the sealing is not sufficient, and the phosphor crystal tends to be stressed and the performance tends to be deteriorated. It is only necessary to protect the photostimulable phosphor layer, and it is not necessary to seal it integrally with the support (substrate) itself. The radiation image conversion panel sealed by this method is particularly wrinkled at the four corners as described above. And non-uniform adhesion are preferable.

  In these methods, an adhesive using the thermosetting resin can be used as an adhesive for adhering moisture-proof protective films to each other. Thus, after the moisture-proof protective films are brought into close contact with each other, the adhesive portion is heated to cure the resin and seal the phosphor layer.

  However, in the present invention, it is more preferable that the moisture-proof film and the phosphor substrate are bonded using a heat-fusible resin. That is, in FIG. 3, instead of the adhesive made of the thermosetting resin, an adhesive tape made of a heat-fusible film and an adhesive layer (for example, an adhesive tape based on CPP (casting polypropylene)) is used. A moisture-proof protective film 3 having a heat-fusible film laminated on the surface of a moisture-proof film, adhered to a support (substrate) 1 and adhered to the stimulable phosphor layer 2 as an adhesive 4. It is preferable that the heat-sealable film surface is superposed so as to face the heat-sealable film surface of the pressure-sensitive adhesive tape adhered to the substrate, and both heat-sealable films are heat-sealed by heat-seal. .

  Since the bonding is by heat fusion, the layers are fused to obtain a strong bond. Further, a heat-fusible resin such as CPP is preferable because it has a low moisture permeability, and thus the sealing effect is sustained.

  The heat fusion varies depending on the melting temperature of the heat-fusible resin to be used, but is preferably performed at a temperature in the range of 120 ° C. to 200 ° C., and a heat-fusible resin film having a heat fusion temperature in this range is used. It is preferable. In particular, those having a polypropylene base as the heat-fusible resin are preferable.

  As an adhesive layer laminated with a heat-fusible film, for example, there is an acrylic adhesive, for example, a PPS pressure-sensitive adhesive tape No. 1 manufactured by Nitto Denko Corporation. 370 series and the like are pressure-sensitive adhesive tapes having the above-mentioned polypropylene film as a base material and having an adhesive layer made of an acrylic resin, and are available.

  Using these adhesive tapes, the surface of the heat-fusible film is attached to the substrate so as to face the heat-fusible film surface of the moisture-proof protective film, heated and heat-bonded to each other, and sealed. .

  As a result, since the phosphor surface of the thick substrate and the moisture-proof protective film can be directly bonded together, only the phosphor layer having a smaller thickness than the substrate is sealed between the substrate and the moisture-proof protective film. Thus, the generation of wrinkles around the periphery of the sealing portion is small. Moreover, since the heat-fusible resin such as casting polypropylene has low moisture permeability, it is excellent in moisture sealing property, and sealing with the moisture-proof protective film is performed more uniformly and more firmly and becomes stronger.

  As the heat sealing resin, polyethylene terephthalate (PET), polyethylene (PE), low density polyethylene (LDPE), casting polypropylene (CPP) and the like can be preferably used.

  These heat-fusible resins used in the present invention are resins that are heat-sealed in the above-mentioned temperature range of 130 ° C. to 200 ° C., and the following heat-melting temperatures are in the range of 120 ° C. to 250 ° C. Is preferred.

  In the present invention, the melting temperature (melting point) of a resin is measured by placing a powdered material on a temperature-controlled heating stainless plate and observing the softened and molten state using a magnifier of about 50 times. Then, the softening point and the molten state are observed and measured. There is also a method of measuring using DSC or the like. The resin powder is measured by pulverizing to a particle size of about 10 μm.

  The melting temperature obtained in this manner varies depending on, for example, the degree of polymerization and the degree of crystallinity, but is 150 ° C. to 165 ° C. for polypropylene, and around 122 ° C. for polyethylene (LLDPE).

  Specifically, these heat-fusible resins used in the present invention are preferably heat-sealable resins, that is, the polyethylene and polypropylene.

  The heat fusion is preferably performed at a temperature close to or above the melting temperature, that is, in the range of 130 ° C to 200 ° C.

  FIG. 4 shows an example of a radiation image conversion panel in which a photostimulable phosphor plate is sealed using a more preferable sealing method according to the present invention.

  In the form of FIG. 4, the photostimulation of the peripheral part of the photostimulable phosphor plate having at least one photostimulable phosphor layer 2 formed on the support (substrate) 1 by the vapor deposition method. The adhesive tape 5 made of the heat-fusible resin film such as CPP and the adhesive layer is supported by the adhesive layer from the phosphor side to the back side around the support (substrate) that does not have the fluorescent layer. The adhesive tape 5 is attached so that the heat-fusible film surface of the CPP or the like is on the front side, and similarly has a heat-fusible film layer so as to face this. Each heat-fusible film surface of the two moisture-proof protective films 3 and 3 ′ has a structure in which the heat-fusible film surface of the pressure-sensitive adhesive tape 5 is heat-fused at the peripheral portion of the substrate.

  Sealing by this method because the two heat-proof protective films and the heat-sealing film such as CPP are completely bonded by the heat-fusible resin to cover the photostimulable phosphor plate. Since the method is completely sealed from a heat-fusible resin such as a polypropylene film having a low water permeability, the sealing method shown in FIG. 3 has a slight water permeability from an adhesive layer such as a thermosetting resin. Compared to the above, it is possible to obtain a radiation image conversion panel that is close to moisture completely and has high durability.

  Paying attention to the improvement of non-uniformity or incompleteness of sealing due to generation of wrinkles, etc., the adhesion between the moisture-proof protective film and the substrate or between the moisture-proof protective films is the same as the heat-sealable resin film and the adhesion It is not necessary to use a pressure-sensitive adhesive tape made of an agent layer, and even if an adhesive or pressure-sensitive adhesive tape made of a thermosetting or photo-curable resin is used, the effect can be sufficiently obtained. In addition to the above effects, the use of a pressure-sensitive adhesive tape having an adhesive layer with a heat-fusible resin film as a base material provides excellent moisture barrier properties and good sealing properties. As a result of the fusion, the strength is maintained even after bonding, which is preferable because of excellent durability.

  The moisture-proof protective film is a resin film in which at least one layer of metal oxide is vapor-deposited, but a laminated film in which a plurality of resin films including a resin film in which these metal oxides are vapor-deposited are bonded in layers. In particular, in the case where the adhesive tape having the heat-fusible resin film as a base is used for adhesion by heat fusion, a similar heat-fusible resin film is laminated on the side to be adhered to the adhesive tape. It is preferable that the moisture-proof protective film is made.

  The film (film) on which the metal oxide is vapor-deposited is a film in which at least one layer of metal oxide film having a thickness of 1 to 100 mm is vapor-deposited on a 1 to 30 μm resin film, such as silica or alumina. It is a resin film such as polyethylene terephthalate (PET) in which an inorganic oxide layer is formed by vapor deposition to improve moisture resistance. These are inexpensive, excellent in processability and transparency, and moisture-proof and oxygen permeability are not easily affected by temperature and humidity. Therefore, for medical stimulable phosphor plates that require stable image quality regardless of the environment. Suitable as a moisture-proof protective film. In recent years, these vapor-deposited films are transparent and can be checked for their contents, and have high thermal stability and can be sterilized by retort. Taking advantage of the fact that the contents can be heated by a microwave oven, it has been widely used as an alternative to opaque aluminum laminate film mainly in the food field.

  Examples of the film on which the metal oxide is deposited include VMPET as alumina-deposited PET (polyethylene terephthalate), which can be obtained from Toyo Metallizing Co., Ltd.

  The film deposited with the metal oxide used in the present invention is further improved in moisture resistance by using a film having a plurality of different deposited layers or by laminating a plurality of films in accordance with the required moisture resistance. Can do.

  Further, in the present invention, the vapor-deposited film is used as a protective layer or to have other functions, and in order to further improve moisture resistance, other resin films of different materials such as polyethylene terephthalate, polyethylene naphthalate, nylon, etc. It is preferable to laminate two or more types of the resin film on the film on which the metal oxide is vapor-deposited and use it as a moisture-proof protective film. Examples of the lamination method in this case include dry lamination, extrusion lamination, and coextrusion coating lamination.

  As for the method of laminating the vapor deposition film and other resin films, the dry laminating method is excellent in terms of workability. This method generally uses a curable adhesive layer of about 1.0 to 2.5 μm, but the adhesive layer thickness needs to be larger than 2.5 μm. However, when the coating amount of the adhesive is too large, tunneling, oozing, crimping, etc. may occur. More preferably, the adhesive amount is adjusted to 3 to 5 μm in terms of dry film thickness. It is preferable.

  In order to laminate the resin film, a hot melt lamination method, an extrusion lamination method and a coextrusion lamination method can be used, and the dry lamination method can be used in combination.

  Hot melt lamination is a method in which a hot melt adhesive is melted and an adhesive layer is applied to a substrate, and the thickness of the adhesive layer is generally set within a wide range of 1 to 50 μm. Commonly used base resins for hot melt adhesives include EVA, EEA, polyethylene, butyl rubber, etc., rosin, xylene resin, terpene resin, styrene resin, etc. as tackifiers, wax etc. It is added as an agent.

  The extrusion laminating method is a method in which a resin melted at a high temperature is coated on a substrate with a die, and the thickness of the resin layer can be generally set in a wide range of 10 to 50 μm.

  In general, LDPE, EVA, PP, etc. are used as the resin used for the extrusion laminate, but an adhesion promoter may be pre-coated on the base material in order to increase the adhesion to the base material. .

  These adhesion promoters include organic titanium-based, polyethyleneimine-based, isocyanate-based, polyester-based, etc. In general, these adhesion promoter layers provide fine irregularities on the surface of the base film to increase the diffusibility of the molten polymer. It is for the purpose of improving and is not included in the curable adhesive layer of 2.5 μm or less referred to in the present invention.

  Co-extrusion lamination method is different from the same or different types of thermoplastic resin from two or more extruders, each resin is extruded at the same time and laminated inside or outside a specially designed die, and multilayer film at the same time as film formation To form.

  The resins generally used for coextrusion lamination include LDPE (low density polyethylene), Ny (nylon), ION (ionomer), PP (polypropylene), EVA (ethylene vinyl acetate), HDPE (high density polyethylene), MDPE ( Medium density polyethylene), PVDC (polyvinylidene chloride), POL (polyolefin) and the like.

  As described above, in the radiation image conversion panel of the present invention, in order to seal and protect the stimulable phosphor plate from moisture, a plurality of resin films including a film on which a metal oxide is deposited are bonded in layers. It is preferable to use the laminated film as a moisture-proof protective film, but in the case of a laminated film, an adhesive layer that adheres between a film having a metal oxide layer and another resin film or between films deposited with a plurality of metal oxides Has a thickness of 2.5 μm or less and is accompanied by a curable, crosslinking reaction by heat or ultraviolet rays. Specifically, a reactive group is included in a two-component reaction type or molecular structure in which a main agent and a curing agent are mixed and used. It is preferable to use a one-component type vinyl-based, acrylic-based, polyamide-based, epoxy-based, rubber-based, urethane-based adhesive layer. In general, these adhesives are frequently used in dry lamination and the like.

  However, the hot-melt adhesive is not included in the curable adhesive layer referred to here except for the time-curing type.

  The thickness of these moisture-proof protective films is practically 1 μm to 300 μm. In order to obtain good moisture resistance and impact resistance, the thickness is preferably 5 μm or more, and particularly when sealed with a moisture-proof protective film of 10 μm or more, a conversion panel excellent in durability and durability is obtained, which is more preferable.

  However, on the other hand, when used as a moisture-proof film, it is important from the standpoint of sharpness not to make the film thickness too large. In order to use within a range where the sharpness does not deteriorate, the entire moisture-proof protective film including the film on which the metal oxide is deposited is 300 μm, preferably 150 μm or less.

  For example, a moisture-proof film on which the metal oxide is deposited and a heat-fusible film such as polyethylene terephthalate (PET), polyethylene (PE), low-density polyethylene (LDPE), and cast polypropylene (CPP) by dry lamination or the like. The laminated one can actually be used as a moisture-proof protective film. In order to heat-melt and bond the heat-meltable resin film surfaces to each other using an adhesive tape based on a heat-fusible resin film, which is bonded to a substrate having a photostimulable phosphor layer. As a protective film, what laminated | stacked the heat-fusible resin films, such as these low density polyethylene (LDPE) and castable polypropylene (CPP), in the outermost layer is preferable.

  Moreover, as an adhesive tape based on the heat-fusible resin film bonded to a moisture-proof protective film on which the heat-meltable resin film is laminated, there is one based on a PP (polypropylene) film, Specifically, PPS adhesive tape No. manufactured by Nitto Denko Corporation. 370 series etc. are mentioned. For example, no. 3703F, no. 370F, No. 3703DF and the like, which are pressure-sensitive adhesive tapes having a PP (polypropylene) film as a base and an acrylic resin-based adhesive layer. In the 370 series, the total thickness of the adhesive layer and the base film and the adhesive layer is, for example, Backing Thickness / Total Thickness 30/55, 40/65, and 30/55 (μm), respectively. Here, Backing Thickness is the thickness of the acrylic resin adhesive layer.

  The moisture-proof protective film desirably exhibits high transmittance in a wide wavelength range in order to efficiently transmit stimulated excitation light and stimulated emission, and the transmittance is 60% or more, preferably 80% or more.

Further, it is preferable to provide an antireflection layer such as MgF _{2 on} the surface because it effectively transmits the stimulating excitation light and the stimulable light emission and reduces the reduction in sharpness.

  In addition, in order to improve sharpness, the moisture-proof protective film may be colored by containing a colorant such as lead phosphate to absorb the stimulating light.

  For this purpose, a film colored with a coloring material (pigment or dye) that absorbs stimulating excitation light is laminated on the film on which the metal oxide is deposited, or a layer containing a dye or pigment on either side. There is also a method of providing by coating.

  As a method for producing a colored film, there is a method of forming a layer containing a coloring material (pigment or dye) on the surface of a plastic film or a plastic film kneaded with a coloring material, and bonding the colored plastic film. It can color by the method of sticking together to a moisture-proof protective film uniformly using an agent.

<Stimulable phosphor>
In the present invention, the stimulable phosphor forming the stimulable phosphor layer includes, for example, a divalent europium activated composite halide phosphor described in JP-A No. 61-236890. Rare earth element-activated rare earth oxyhalide-based phosphors containing, in particular, stimulable phosphors such as Eu-added BaFI compounds, but as stimulable phosphors preferably used in the radiation image conversion panel of the present invention For example, phosphors represented by BaSO ₄ : Ax described in JP-A-48-80487, phosphors represented by MgSO ₄ : Ax described in JP-A-48-80488, JP-A-48 Phosphors represented by SrSO ₄ : Ax described in No. 80489, Na ₂ SO ₄ , CaSO ₄ and BaSO ₄ described in JP-A No. 51-29889, etc. Phosphors added with at least one of n, Dy and Tb, phosphors such as BeO, LiF, MgSO ₄ and CaF ₂ described in JP-A-52-30487, JP-A-53-39277 Phosphors such as Li ₂ B ₄ O ₇ : Cu, Ag described, and phosphors such as Li ₂ O. (Be ₂ O ₂ ) x: Cu, Ag described in JP-A No. 54-47883 SrS: Ce, Sm, SrS: Eu, Sm, La ₂ O ₂ S: Eu, Sm and (Zn, Cd) S: Mnx described in US Pat. No. 3,859,527 The body is raised. Further, a ZnS: Cu, Pb phosphor described in JP-A-55-12142, a barium aluminate phosphor whose general formula is BaO.xAl ₂ O ₃ : Eu, and a general formula of M (II ) O.xSiO ₂ : An alkaline earth metal silicate phosphor represented by A can be used.

Moreover, an alkaline earth fluorohalide phosphor represented by the general formula (Ba _1-xy Mg _x Ca _y ) F _x : Eu ²⁺ described in Japanese Patent Laid-Open No. 55-12143, A phosphor in which the general formula described in Japanese Patent No. 55-12144 is represented by LnOX: xA, and a general formula described in Japanese Patent Laid-Open No. 55-12145 is (Ba _1-x M (II) _x ) F _x : A phosphor represented by yA, a phosphor represented by the general formula described in JP-A-55-84389, BaFX: xCe, yA, a formula represented by JP-A-55-160078 Is a rare earth element-activated divalent metal fluorohalide phosphor represented by M (II) FX · xA: yLn, fluorescence represented by the general formula ZnS: A, CdS: A, (Zn, Cd) S: A, X And any one of the following general formulas x described in JP-A-59-38278 M ₃ (PO ₄ ) ₂ · NX ₂ : yA
xM ₃ (PO ₄ ) ₂ : yA
A phosphor represented by the general formula nReX ₃ · mAX ′ ₂ : xEu described in JP-A-59-155487
nReX ₃ · mAX ′ ₂ : xEu, ySm
Preferred examples include phosphors represented by general formula M (I) X: xBi described in JP-A No. 61-228400, and the like.

  However, an alkali halide photostimulable phosphor represented by the following general formula (1) as described in JP-A Nos. 61-72087 and 2-58000 is particularly preferable.

General formula (1)
M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
In the formula, M ¹ is at least one alkali metal selected from Li, Na, K, Rb and Cs, and M ² is a group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. at least one divalent metal selected from, M ³ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, At least one trivalent metal selected from the group consisting of Al, Ga and In, and X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I; A is selected from the group consisting of Eu, Tb, In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. At least one metal, and a, b and e each represent a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.

In these general formulas (1), M ¹ is preferably selected from the group consisting of K, Rb and Cs, and X is preferably selected from the group consisting of Br and I.

M ² is preferably selected from the group consisting of Be, Mg, Ca, Sr and Ba, and M ³ is selected from the group consisting of Y, Ce, Sm, Eu, Al, La, Gd, Lu, Ga and In. It is preferable to be selected. Further, b is preferably 0 ≦ b ≦ 0.01, and A is preferably selected from the group consisting of Eu, Cs, Sm, Tl and Na.

  These alkali halide photostimulable phosphors are formed on a substrate by vapor deposition, so that they have a certain inclination with respect to the normal direction of the substrate (of course, there is no inclination and the substrate surface is not inclined). It forms an elongated columnar crystal (although it may be vertical). By forming such columnar crystals, it is possible to suppress the diffusion of stimulated excitation light (or stimulated emission) in the lateral direction. Therefore, it is necessary to use these phosphors that the sharpness of the image by stimulated emission is good. It is a feature when there was. Among the alkali halide photostimulable phosphors, RbBr and CsBr phosphors are preferable because of high brightness and high image quality.

  In the present invention, a phosphor represented by the following general formula (2) is particularly preferable among them.

General formula (2)
CsX: A
In the formula, X represents Br or I, and A represents Eu, In, Ga, or Ce.

  Among them, a CsBr phosphor is particularly preferable because it has a particularly high luminance and high image quality, and also has a high effect of improving adhesion (adhesiveness) to the substrate or the substrate by the production method of the present invention.

  The columnar crystals obtained by using these photostimulable phosphors that are preferable in the present invention, that is, the crystals growing in columnar form with a certain gap are described in JP-A-2-58000. Can be obtained by different methods.

  That is, a photostimulable phosphor layer composed of independent elongated columnar crystals can be obtained by supplying vapor of the stimulable phosphor or the raw material onto a substrate and performing vapor phase growth (deposition) such as vapor deposition.

  For example, by making the vapor flow of the photostimulable phosphor at the time of vapor deposition enter in the range of 0 to 5 degrees with respect to the direction perpendicular to the substrate, it is possible to obtain crystals that are substantially perpendicular to the substrate surface.

  In these cases, it is appropriate that the distance between the shortest part of the substrate and the crucible is set to approximately 10 cm to 60 cm in accordance with the average range of the stimulable phosphor.

  The stimulable phosphor as an evaporation source is uniformly dissolved or formed by pressing or hot pressing and charged in a crucible. At this time, it is preferable to perform a degassing treatment. The method for evaporating the photostimulable phosphor from the evaporation source is performed by scanning the electron beam emitted from the electron gun, but it can also be evaporated by other methods.

  The evaporation source is not necessarily a stimulable phosphor, and may be a mixture of a stimulable phosphor material.

  Moreover, what activator mixed the activator with respect to a base substance (basic substance) may be vapor-deposited, and after depositing only a base material, you may dope an activator afterwards. For example, when the base is CsBr, after depositing only CsBr, for example, In that is an activator may be doped. That is, since the crystals are independent, even if the film is thick, it can be sufficiently doped, and crystal growth hardly occurs, so the MTF does not decrease.

  Doping can be performed by thermal diffusion and ion implantation of a doping agent (activator) in the base layer of the formed phosphor.

<Phosphor layer thickness, crystal size, etc.>
The layer thickness of the stimulable phosphor layer made of columnar crystals formed by these methods varies depending on the sensitivity of the intended radiation image conversion panel to radiation, the type of stimulable phosphor, etc., but from the range of 50 μm to 1000 μm. It is preferably selected, and more preferably selected from 50 μm to 800 μm.

  In order to improve the modulation transfer function (MTF) in the photostimulable phosphor layer composed of these columnar crystals, the size of the columnar crystals (breakdown of each columnar crystal when the columnar crystal is observed from a plane parallel to the substrate). The average value of the diameter of the area in terms of a circle, calculated from a microphotograph including at least 100 columnar crystals in the visual field) is preferably about 0.5 to 50 μm, more preferably 0.5 to 20 μm. is there. That is, when the columnar crystal is thinner than 0.5 μm, the excitation excitation light is scattered by the columnar crystal, so that the MTF is lowered. When the columnar crystal is 50 μm or more, the directivity of the excitation excitation light is also reduced. , MTF decreases.

  As a method for vapor phase growth (deposition) of the photostimulable phosphor, there are an evaporation method, a sputtering method, and a CVD method.

In the vapor deposition method, after the substrate (support) is installed in the vapor deposition apparatus, the inside of the apparatus is evacuated, and at the same time, an inert gas such as nitrogen is introduced from the introduction port to be about 1.333 Pa to 1.33 × 10 ⁻³ Pa. Then, at least one of the photostimulable phosphor is heated and evaporated by a method such as resistance heating or electron beam to deposit the photostimulable phosphor on the surface of the support to a desired thickness. As a result, a photostimulable phosphor layer containing no binder is formed, but it is also possible to form the photostimulable phosphor layer in a plurality of times in the vapor deposition step. In the vapor deposition step, vapor deposition can be performed using a plurality of resistance heaters or electron beams. In the vapor deposition method, the stimulable phosphor material is deposited using a plurality of resistance heaters or electron beams, and the desired stimulable phosphor layer is synthesized on the support at the same time. It is also possible to form. Further, in the vapor deposition method, the substrate (support) may be cooled or heated as necessary during vapor deposition. Moreover, you may heat-process a photostimulable phosphor layer after completion | finish of vapor deposition.

In the sputtering method, after the substrate is placed in the sputtering apparatus, the inside of the apparatus is once evacuated to a vacuum, and then an inert gas such as Ar or Ne is introduced into the apparatus as a sputtering gas. The gas pressure is set to about 1.33 Pa to 1.33 × 10 ⁻³ Pa. Next, the stimulable phosphor is deposited to a desired thickness on the substrate surface by sputtering using the stimulable phosphor as a target. In this sputtering process, it is possible to form the stimulable phosphor layer by dividing into multiple times as in the vapor deposition method. It is also possible to form In addition, in the sputtering method, it is possible to form a desired stimulable phosphor layer on a substrate by using a plurality of photostimulable phosphor materials as a target and sputtering them simultaneously or sequentially. If necessary, reactive sputtering may be performed by introducing a gas such as O ₂ or H ₂ . Furthermore, in the sputtering method, the substrate may be cooled or heated as necessary during sputtering. Alternatively, the photostimulable phosphor layer may be heat-treated after the end of sputtering.

  The CVD method does not contain a binder on the substrate by decomposing the target stimulable phosphor or organometallic compound containing the stimulable phosphor raw material with heat, high-frequency power, or other energy. In any case, the phosphor layer can be vapor-phase grown into independent elongated columnar crystals with a specific inclination with respect to the normal direction of the substrate.

  These columnar crystals are obtained by the method described in JP-A-2-58000 as described above, that is, a method in which vapor of stimulable phosphor or the raw material is supplied onto a substrate and vapor phase growth (deposition) such as vapor deposition is performed. Can be obtained at

  FIG. 5 is a schematic view showing a state in which a photostimulable phosphor layer is formed on the support 12 by vapor deposition. Reference numeral 11 schematically represents a stimulable phosphor layer formed of the stimulable phosphor columnar crystals to be formed. Assuming that the incident angle of the vapor flow V of the stimulable phosphor with respect to the normal direction (P) of the substrate surface is θ2, the angle of the formed columnar crystal with respect to the normal direction (P) of the substrate surface is represented by θ1. . A columnar crystal is formed at a constant angle θ1 depending on the incident angle θ2. The angle of the formed columnar crystals varies depending on the stimulable phosphor material. For example, among the alkali halide phosphors, in the case of the CsBr phosphor particularly preferable in the present invention, for example, the stimuli during vapor deposition are used. By making the vapor flow of the fluorescent phosphor incident in the range of 0 to 5 degrees with respect to the direction perpendicular to the substrate (that is, θ2 is 0 to 5 degrees), it is substantially perpendicular to the substrate surface (θ1 is approximately 0 degrees). Can be obtained.

  Since the photostimulable phosphor layer 11 formed on the substrate in this way does not contain a binder, it has excellent directivity, high directivity of stimulated excitation light and stimulated emission, and high brightness. The layer thickness can be made thicker than that of a radiation image conversion panel having a dispersive stimulable phosphor layer in which a stimulable phosphor is dispersed in a binder. Furthermore, the sharpness of the image is improved by reducing the scattering of the stimulating light in the stimulable phosphor layer.

  In addition, the gap between the columnar crystals may be filled with a filler or the like, which reinforces the photostimulable phosphor layer. Further, a substance having a high light absorption rate, a substance having a high light reflectance, or the like may be filled. As a result, the above-mentioned reinforcing effect can be provided, and the light diffusion in the lateral direction of the stimulated excitation light incident on the stimulable phosphor layer can be almost completely prevented.

  The substance having high light reflectance means a material having high reflectance with respect to stimulating excitation light (500 to 900 nm, particularly 600 to 800 nm), such as white pigment and green to red, such as aluminum, magnesium, silver, indium and other metals. Area colorants can be used.

White pigments can also reflect stimulated emission. As white pigments, TiO ₂ (anatase type, rutile type), MgO, PbCO ₃ .Pb (OH) ₂ , BaSO ₄ , Al ₂ O ₃ , M (II) FX (where M (II) is Ba, Sr and At least one of Ca, and X is at least one of Cl and Br.), CaCO ₃ , ZnO, Sb ₂ O ₃ , SiO ₂ , ZrO ₂ , lithopone (BaSO ₄ .ZnS), silicic acid Examples include magnesium, basic lead silicate, basic lead phosphate, and aluminum silicate. Since these white pigments have a strong hiding power and a high refractive index, they can easily scatter scattered light by reflecting or refracting light, and can significantly improve the sensitivity of the resulting radiation image conversion panel.

  Moreover, as a substance having a high light absorption rate, for example, carbon, chromium oxide, nickel oxide, iron oxide and the like and a blue color material are used. Of these, carbon also absorbs stimulated luminescence.

The color material may be either an organic or inorganic color material. Examples of organic colorants include Zavon First Blue 3G (Hoechst), Estrol Brill Blue N-3RL (Sumitomo Chemical), D & C Blue No. 1 (made by National Aniline), Spirit Blue (made by Hodogaya Chemical), Oil Blue No. 1 603 (made by Orient), Kitten Blue A (made by Ciba Geigy), Eisen Katyron Blue GLH (made by Hodogaya Chemical), Lake Blue AFH (made by Kyowa Sangyo), Primocyanin 6GX (made by Inabata Sangyo), Brill Acid Green 6BH (Hodogaya) Chemical Blue), Cyan Blue BNRCS (Toyo Ink), Lionoyl Blue SL (Toyo Ink), etc. are used. The color index No. 24411, 23160, 74180, 74200, 22800, 23154, 23155, 24401, 14830, 15050, 15760, 15707, 17941, 74220, 13425, 13361, 13420, 11836, 74140, 74380, 74350, 74460, etc. There are also materials. Examples of inorganic color materials include ultramarine, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—Co—NiO pigments.

<Support>
As the support (substrate) used in the radiation image conversion panel of the present invention, those having low moisture permeability are preferable, and various types of glass, polymer materials, metals and the like are used. For example, quartz, borosilicate glass, chemical Plate glass such as mechanically tempered glass, plastic film such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film, metal sheet such as aluminum sheet, iron sheet, copper sheet or the like A metal sheet having a metal oxide coating layer is preferred. The surface of these supports may be a smooth surface, or may be a matte surface for the purpose of improving the adhesion to the stimulable phosphor.

  In the present invention, in order to improve the adhesion between the substrate and the stimulable phosphor, an adhesive layer may be provided in advance on the surface of the substrate as necessary.

  Although the thickness of these substrates varies depending on the material of the substrate used, it is generally 80 μm to 2000 μm, and more preferably 80 μm to 1000 μm from the viewpoint of handling.

  Among the alkali halide photostimulable phosphors, RbBr and CsBr phosphors are preferable because of high brightness and high image quality.

  Since phosphor columnar crystals formed by these vapor deposition methods are vulnerable to moisture, sealing is performed using a waterproof protective film including a film having a metal oxide deposition layer as described above.

<Embodiment>
Below, the specific structural example and manufacture of a radiographic image conversion panel are described by this invention.

  The two photos of the moisture-proof protective film shown in FIG. 4 cover the front and back surfaces of the phosphor plate, and the photostimulable phosphor layer on the surface on which the photostimulable phosphor layer is formed is formed. Radiation image by heat-sealing with each moisture-proof protective film using adhesive tape made of heat-fusible resin that is pasted back from the phosphor side (front surface) to the back surface side About the method of manufacturing a conversion panel, the specific embodiment is described below.

  FIG. 6 shows an adhesive tape 5 (a PPS adhesive tape manufactured by Nitto Denko Corp.) having a base of a heat-meltable resin tape on a peripheral portion (a part of which is shown) where the phosphor of the phosphor plate is not formed on the support. No. 3703F was used so as to cover the front side and back side of the peripheral part where the phosphor is not formed and the end face thereof. In this manner, the adhesive tape including the four corners is attached to the entire periphery of the phosphor plate.

  Next, a moisture-proof protective film obtained by laminating a moisture-proof protective film, specifically 12 μm VMPET; alumina-deposited polyethylene terephthalate (manufactured by Toyo Metallizing Co., Ltd.) with 30 μm cast polypropylene (CPP) and dry lamination on the top and bottom of the support. The casting polypropylene film is disposed so as to face the phosphor surface of the phosphor plate and the support surface (FIG. 7), and may be from the surrounding portion or a part thereof. As shown in FIG. 8, the moisture-proof protective film on the front and back surfaces is brought into close contact with the surface on which the phosphor layer and the surrounding adhesive tape are attached, and the back surface of the support.

  After the moisture-proof films are brought into close contact with each other in this way, while maintaining the state, the peripheral edge (arrow) to which the front and back adhesive tapes are attached is from the moisture-proof film side, for example, 200 ° C. for polypropylene. Heat and fuse at temperature. For example, a laminating system in which the peripheral edge is heated and fused with an impulse sealer, or heated under pressure between two heated rollers may be used. Accordingly, the adhesive tape and the moisture-proof protective film can be bonded to each other by thermally fusing the heat-meltable resin films with each other to seal the phosphor plate (FIG. 8).

  The remaining portion of the moisture-proof protective film around the heat-sealed portion can be cut after heat-sealing (as shown by a broken line) as shown in FIG. 9 to finally obtain a radiation image conversion panel.

  The heat fusion method is not particularly limited, and sealing may be performed in an atmospheric pressure environment. However, in the method of heat fusion using the impulse sealer, the heat fusion is performed in a reduced pressure environment as described above. It is more preferable to wear the phosphor sheet in terms of preventing displacement of the phosphor sheet in the moisture-proof protective film and eliminating moisture in the atmosphere.

  In sealing the phosphor sheet with the moisture-proof protective film on which the metal oxide layer according to the present invention is formed, the outermost resin layer on the side in contact with the phosphor sheet of the moisture-proof protective film is heat-bonded. By using the resin film, the moisture-proof protective film can be fused, and the phosphor sheet sealing work is made efficient.

  In addition, the resin film having heat-fusibility may contain 0.01% by mass to 1.0% by mass of inorganic fine particles such as silica, titanium, zeolite, etc. It is preferable because image irregularities with a large period caused by the sheet sealing operation can be prevented. When the amount is 0.01% by mass or less, the effect is small, and when the amount is 1.0% by mass or more, the transparency and haze value of the laminated protective film deteriorate.

  For the purpose of improving the adhesiveness of the adhesion portion between the moisture-proof protective film and the stimulable phosphor, the phosphor surface is further provided with an undercoat layer on the adhesive surface with the moisture-proof protective film, or roughened. Can also be applied.

  In the radiation image conversion panel of the present invention, the moisture-proof protective film on the support side of the phosphor plate may be optically opaque. Therefore, in order to improve moisture resistance, the moisture-proof protective film on the support side is made of aluminum. A laminate film is preferred.

  The aluminum foil film used for laminating is desirably 9 μm or more from the viewpoint of deterioration of moisture resistance due to pinholes or the like. Further, it is desirable that the moisture-proof protective film on the support side has a film thickness of 200 μm or less, similarly to the moisture-proof protective film on the phosphor surface side. That is, in FIG. 4, it is preferable to make a laminated moisture-proof film obtained by laminating one or more aluminum films on the moisture-proof protective film 3 on the support surface side. Thereby, the penetration | invasion of a water | moisture content can be reduced reliably.

  The outermost heat-sealable resin layer and the phosphor surface of the moisture-proof protective film of the radiation image conversion panel of the present invention may be bonded or substantially not bonded. The adhesion is improved by forming the organic layer.

  In the radiation image conversion panel of the present invention, if the film thickness of the moisture-proof protective film exceeds 200 μm, the film handleability at the time of sealing work deteriorates and it becomes difficult to perform heat fusion with an impulse sealer or the like described later. Is preferably 200 μm or less.

<Low refractive index layer>
In the present invention, a low refractive index layer may be provided in the above configuration. The low refractive index layer is made of a material having a refractive index lower than that of the resin material constituting the moisture-proof protective film, and the presence of this layer reduces the reduction in sharpness even when the protective layer and the moisture-proof protective film are thickened. can do. For example, the following materials can be used and are preferably used in the state of a thin film formed by vapor deposition such as vapor deposition.

Material Refractive index CaF 1.23-1.26
Na ₂ AlF ₆ 1.35
MgF ₂ 1.38
SiO ₂ 1.46
Alternatively, the following liquid layer can be used.

Substance Refractive Index Ethyl Alcohol 1.36
Methyl alcohol 1.33
Diethyl alcohol 1.35
In addition, when a layer having a refractive index of substantially 1 such as a gas layer such as air, nitrogen or argon or a vacuum layer is used as the low refractive index layer of the present invention, the effect of preventing sharpness deterioration is particularly high. .

  The thickness of the low refractive index layer of the present invention is practically from 0.05 μm to 3 mm.

  The low refractive index layer of the present invention may be in close contact with the photostimulable phosphor layer or may be separated.

<Shooting method>
FIG. 10 schematically shows a radiation image conversion method using the radiation image conversion panel of the present invention.

  That is, in FIG. 10, 21 is a radiation generator, 22 is a subject, 23 is a radiation image conversion panel according to the present invention, 24 is a stimulating excitation light source (such as a laser), and 25 is a stimulant emitted by the conversion panel. A photoelectric conversion device that detects fluorescence, 26 is a device that reproduces the signal detected in 25 as an image, 27 is a device that displays the reproduced image, and 28 is a device that separates the stimulated excitation light and the stimulated fluorescence. This is a filter that transmits only exhaust fluorescent light. It should be noted that anything after 25 can be used as long as the optical information from 23 can be reproduced as an image in some form, and is not limited to the above.

  As shown in FIG. 11, the radiation (R) from the radiation generator 21 enters the radiation image conversion panel 23 through the subject 22 (RI). The incident radiation is absorbed by the stimulating layer of the panel 23, the energy is accumulated, and an accumulated image of a radiation transmission image is formed.

  Next, this accumulated image is excited by stimulated excitation light from the stimulated excitation light source 24 and emitted as stimulated emission.

  Since the intensity of the photostimulated luminescence emitted is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 25 such as a photomultiplier tube and reproduced as an image by an image reconstruction device 26. By displaying on the display device 27, a radiation transmission image of the subject can be observed.

  Therefore, with such a configuration of the present invention, a radiation image conversion panel having a high moisture-proof performance and a long service life can be obtained.

  3 or 4 of the present invention, the phosphor layer is sealed between the support and the moisture-proof protective film, and therefore the four corners of the sealed phosphor plate are particularly thin because the thickness of the sealed portion is small. There is no large generation of wrinkles in the portion, the sealing is uniform, and the sealing effect is high.

  According to the configuration of FIG. 4, since the phosphor is completely sealed by a heat-fusible resin such as polypropylene having a low moisture permeability, there is no generation of wrinkles, and the moisture permeability is low and more durable. A high radiation image conversion panel can be obtained.

It is a figure which shows the cross section of the fluorescent substance plate in which the photostimulable fluorescent substance layer was formed. It is sectional drawing which shows the place which sealed the fluorescent substance surface and the back surface of the fluorescent substance plate with the moisture proof film. It is sectional drawing which shows an example of the sealed radiation image conversion panel of this invention. It is sectional drawing which shows another example of the sealed radiation image conversion panel of this invention. It is a schematic diagram which shows a mode that a stimulable fluorescent substance layer is formed by vapor deposition on a support body. It is a figure which shows a mode that the adhesive tape was affixed so that the surface side and back surface side of the surrounding part of a fluorescent substance plate, and its end surface might be covered. It is a figure which shows the place which has arrange | positioned a moisture-proof protective film so that it may each oppose to the fluorescent substance surface of a fluorescent substance plate, and a support body surface. It is a figure which shows the place which sealed the fluorescent substance plate between moisture proof protective films. It is sectional drawing of the obtained radiographic image conversion panel. It is a figure which shows roughly the radiographic image conversion method using the radiographic image conversion panel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 Stimulable phosphor layer 3 Moisture-proof protective film 4 Adhesive 21 Radiation generation device 22 Subject 23 Radiation image conversion panel 24 Stimulation excitation light source 25 Photoelectric conversion device 26 Image reproduction device 27 Image display device 28 Filter V Vapor Flow

Claims (5)

A photostimulable phosphor plate having at least one photostimulable phosphor layer formed on a substrate by a vapor deposition method, and a protective film disposed on the phosphor surface side of the photostimulable phosphor plate In the radiation image conversion panel, the protective film includes an adhesive tape made of a heat-fusible resin attached to a substrate portion that does not have a stimulable phosphor layer at the periphery of the stimulable phosphor plate; A radiation image conversion panel which is heat-sealed. A photostimulable phosphor plate having at least one photostimulable phosphor layer formed by vapor deposition on a substrate, and disposed on the phosphor surface side and the back surface side of the photostimulable phosphor plate. In the radiation image conversion panel comprising the protective film, the protective films disposed on the phosphor surface side and the back surface side of the photostimulable phosphor plate are the photostimulable phosphor layer at the periphery of the photostimulable phosphor plate. In the substrate portion that does not have an adhesive, it is heat-sealed on the phosphor surface side and the back surface side by an adhesive tape made of a heat-fusible resin pasted from the phosphor side to the back surface side. Radiation image conversion panel. The radiation image conversion according to claim 1 or 2, wherein the outermost resin layer on the side of the protective film in contact with the photostimulable phosphor plate is composed of a resin layer having heat-fusibility. panel. The radiographic image according to claim 1, wherein the protective film is a laminated film formed by laminating a plurality of resin films including a resin film on which at least one layer of metal oxide is deposited. Conversion panel. The at least one photostimulable phosphor layer formed on a substrate by a vapor deposition method is made of an alkali halide photostimulable phosphor represented by the following general formula (1). The radiation image conversion panel according to any one of claims 1 to 4.
General formula (1)
M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
In the formula, M ¹ is at least one alkali metal selected from Li, Na, K, Rb and Cs, and M ² is a group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. at least one divalent metal selected from, M ³ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, At least one trivalent metal selected from the group consisting of Al, Ga and In, and X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I; A is selected from the group consisting of Eu, Tb, In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. At least one metal, and a, b and e each represent a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.

Images