JP4461860B2 - Radiation image conversion panel and method for manufacturing radiation image conversion panel - Google Patents

Description

  The present invention relates to a radiation image (hereinafter also simply referred to as a radiation image) conversion panel and a method for manufacturing a radiation image conversion panel (hereinafter also simply referred to as a manufacturing method).

  Conventionally, in order to obtain a radiographic image, a method of taking out a light signal from a latent image obtained by radiation irradiation using a laser beam or the like has been taken. In order to take out an optical signal after a lapse of time after absorbing radiation, a stimulable phosphor layer (hereinafter also simply referred to as a phosphor layer) is required. Although there has been a method by coating, since the coating material contains a component such as a binder that does not contribute to light emission, a vapor deposition method such as vapor deposition has recently been adopted.

  Conventionally, so-called radiography using a silver salt has been used to obtain a radiographic image, but a method for imaging a radiographic image without using a silver salt has been developed. That is, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited with a certain energy to emit the radiation energy accumulated in the phosphor as fluorescence, and this fluorescence is detected. A method for imaging is disclosed.

  As a specific method, a radiation image conversion method using a panel having a photostimulable phosphor layer on a support and using one or both of visible light and infrared light as excitation energy is known (for example, patents). Reference 1).

As a radiation image conversion method using a stimulable phosphor with higher brightness and higher sensitivity, for example, BaFX: Eu ²⁺ system (X: Cl, Br, I) described in JP-A-59-75200, etc. Radiation image conversion method using phosphor, Radiation image conversion method using alkali halide phosphor as described in JP-A-61-72087, etc., JP-A-61-73786, JP-A-61-73787, etc. As described above, alkali halide phosphors containing Tl ⁺ and Ce ³⁺ , Sm ³⁺ , Eu ³⁺ , Y ³⁺ , Ag ⁺ , Mg ²⁺ , Pb ²⁺ , and In ³⁺ metals as coactivators Has been developed.

  In recent years, there has been a demand for a radiation image conversion panel with higher sharpness in analysis of diagnostic images. As means for improving the sharpness, for example, attempts have been made to improve the sensitivity and sharpness by controlling the shape of the photostimulable phosphor to be formed.

  As one of these attempts, for example, it is composed of a fine pseudo-columnar block formed by depositing a photostimulable phosphor on a support having a fine concavo-convex pattern described in, for example, JP-A No. 61-142497. There is a method using a stimulable phosphor layer.

  Further, as described in JP-A-61-142500, a crack between columnar blocks obtained by depositing a photostimulable 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 crack from the surface side of a photostimulable phosphor layer formed on a support described in JP-A-62-39737. And a stimulable phosphor layer having a cavity formed by vapor deposition on a support, as described in JP-A-62-110200. There has also been proposed a method in which a cavity is grown by heat treatment and a crack is formed after the formation.

Furthermore, a radiation image conversion panel having a photostimulable 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 is described. (For example, see Patent Document 2)
In any of the methods for controlling the shape of the photostimulable phosphor layer, the stimulable phosphor layer is formed into a columnar shape, thereby suppressing the lateral diffusion of the photostimulated excitation light or the photostimulated luminescence (crack ( The columnar crystal) can reach the support surface while repeating reflection at the interface), and is therefore characterized in that the sharpness of the image due to stimulated emission can be remarkably increased.

  Recently, a radiation image conversion panel using a stimulable phosphor obtained by activating Eu with an alkali halide such as CsBr as a base has been proposed, and in particular, X-ray conversion efficiency which has been impossible in the past by using Eu as an activator. It was expected that improvement would be possible.

  However, depending on the surface energy and hardness of the substrate on the side of the photostimulable phosphor layer, the phosphor crystal growth at the initial stage of vapor deposition may not be successful.

  Moreover, even though it seemed that good crystal formation was made at first glance, the properties such as luminance and sharpness and durability were not satisfactory.

For this reason, improvements in brightness, sharpness, and durability required for the radiation image conversion panel have been demanded.
US Pat. No. 3,859,527 JP 2002-72381 A

  An object of the present invention is to produce a radiation image conversion panel and a radiation image conversion panel that have excellent luminance and sharpness characteristics and have excellent durability that can maintain the characteristics over time (2 to 3 years). It is to provide a method.

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

(1)
A radiation image conversion panel having a heat resistant resin layer selected from a fluororesin or a poly (amide) imide resin and a phosphor layer formed by a vapor deposition method in this order on a carbon fiber reinforced resin substrate. A radiation image conversion panel, wherein the residual solvent amount is 0.05 to 10 g / m ² .

( 2 )
2. The radiation image conversion panel according to 1 , wherein the stimulable phosphor contained in the phosphor layer is a compound represented by the following general formula (1).

General formula (1)
M ¹ X · aM ² X ′ · bM ³ X ″: eA
[Wherein, M ¹ is at least one alkali metal atom selected from Li, Na, K, Rb and Cs atoms, and M ² is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu. And at least one divalent metal atom selected from each atom of Ni, and M ³ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, At least one trivalent metal atom selected from each atom of Tm, Yb, Lu, Al, Ga and In, and X, X ′ and X ″ are at least selected from each atom of F, Cl, Br and I 1 type of halogen atom, A is Eu, Tb, In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu and Mg. At least one metal atom selected from each atom; And, a, b, e each represent a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.]
( 3 )
3. The radiation image conversion panel according to 2 , wherein the photostimulable phosphor is represented by the following general formula (2).

General formula (2)
CsX: yA
[Wherein, X represents Cl, Br or I, and A represents Eu, Sm, In, Tl, Ga or Ce. y represents a numerical value from 1 × 10 ⁻⁷ to 1 × 10 ⁻² . ]
( 4 )
The production of a radiation image conversion panel, wherein the residual solvent amount in the heat-resistant resin layer of the radiation image conversion panel according to any one of 1 to 3 is 0.05 to 10 g / m ^2. Method.

  The radiation image conversion panel and the method for producing a radiation image conversion panel according to the present invention are excellent in luminance and sharpness characteristics, and can maintain the characteristics even after a lapse of time (2 to 3 years), and have excellent durability. Have

  Hereinafter, the present invention will be described in more detail.

  In the formation of the photostimulable phosphor layer by vapor deposition or the like, it is important that the substrate has heat resistance (80 ° C. to 200 ° C.) because of vapor flow or crucible radiant heat at the time of vapor deposition and the necessity of heating the substrate. In a system in which irradiation radiation such as X-rays is incident from the substrate side, a substrate that absorbs a small amount of X-rays or the like is required, and carbon fiber reinforced resin is preferable because of its rigidity.

The present invention is characterized in that the support (substrate) has a heat-resistant resin layer, and the amount of residual solvent in the heat-resistant resin layer is 0.05 to 10 g / m ² .

  In the present invention, as the heat resistant resin in the heat resistant resin layer, a fluorine resin, a poly (amide) imide resin or the like is preferably used.

When the residual solvent exceeds 10 g / m ² , the heat-resistant resin layer lacks scientific and functional stability, and when the residual solvent is a solvent having an affinity for water, the phosphor layer on the resin layer has Adversely affect. If it is less than 0.05 g / m ² , the flexibility necessary for forming the phosphor layer is lost, which is not preferable. A more preferable range of the residual solvent amount is 0.1 to 8 g / m ² .

  A known spray coater, bar coater, die coater or the like can be used as a method of providing a heat-resistant resin layer (hereinafter also simply referred to as a resin layer) on the support (substrate). In the present invention, a spray coater is preferable.

Specifically, for example, using a spray coater with a fluororesin or the like on a carbon substrate or the like, after uniformly coating the entire surface of the substrate with a substrate-spray gun distance of 20 cm and a spray gun nozzle pressure of 4 kgf / cm ² , A primary drying (80 ° C., 30 minutes) and then secondary drying (150 ° C., 30 minutes) can be performed in a drying furnace to provide a resin layer.

  The thickness of the resin layer is preferably 10 μm to 80 μm.

  Examples of the solvent capable of dissolving the resin include methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, N-butyl pyrrolidone toluene, xylene, and acetone.

Stimulable phosphor used in the radiation image conversion panel of the present invention (hereinafter also referred to as phosphor)
Next, the stimulable phosphor represented by the following general formula (1) preferably used in the present invention will be described.

In the photostimulable phosphor represented by the general formula (1), M ¹ represents at least one alkali metal atom selected from each of atoms such as Li, Na, K, Rb, and Cs, among which Rb and At least one kind of alkaline earth metal atom selected from each atom of Cs is preferable, and Cs atom is more preferable.

M ² represents at least one divalent metal atom selected from atoms such as Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu, and Ni, and among them, Be, Mg are preferably used. , A divalent metal atom selected from atoms such as Ca, Sr and Ba.

M ³ is at least selected from each atom such as Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga and In. One kind of trivalent metal atom is represented, and among these, trivalent metal atoms selected from each atom such as Y, Ce, Sm, Eu, Al, La, Gd, Lu, Ga and In are preferred. is there.

  A is at least one selected from the atoms of Eu, Tb, In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. Metal atom.

  From the viewpoint of improving the photostimulable luminance of the photostimulable phosphor, X, X ′ and X ″ each represents an atom with at least one halogen selected from F, Cl, Br and I atoms. Of these, at least one halogen atom selected from these atoms is preferred.

  Among these, in the present invention, the photostimulable phosphor represented by the general formula (2) is more preferable.

In the general formula (2), X represents Cl, Br, or I, and A represents Eu, Sm, In, Tl, Ga, or Ce. y represents a numerical value from 1 × 10 ⁻⁷ to 1 × 10 ⁻² .

  The photostimulable phosphor is manufactured, for example, by the manufacturing method described below.

  First, as a phosphor material, an acid (HI, HBr, HCl, HF) is added to a carbonate so as to have the following composition, mixed and stirred, and then filtered at a neutralization point. Is evaporated to produce the following crystals.

As the phosphor material,
(A) At least one compound selected from NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr and CsI is used.

_{(B) MgF 2, MgCl 2} , MgBr 2, MgI 2, CaF 2, CaCl 2, CaBr 2, CaI 2, SrF 2, SrCI 2, SrBr 2, SrI 2, BaF 2, BaCl 2, BaBr 2, BaBr 2 2H ₂ O, BaI ₂ , ZnF ₂ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , CdF ₂ , CdCl ₂ , CdBr ₂ , CdI ₂ , CuF ₂ , CuCl ₂ , CuBr ₂ , CuI, NiF ₂ , NiCl ₂ , NiBr _At least one compound selected from ₂ and NiI ₂ compounds is used.

  (C) In the general formula (1), Eu, Tb, In, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu And a compound having a metal atom selected from each atom such as Mg.

  (D) The activator A includes, for example, Eu, Tb, In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. At least one metal atom selected from atoms is used.

  In the compound represented by the general formula (1), a is 0 ≦ a <0.5, preferably 0 ≦ a <0.01, b is 0 ≦ b <0.5, preferably 0 ≦ b ≦ 0. 01 and e are 0 <e ≦ 0.2, preferably 0 <e ≦ 0.1.

  The phosphor materials (a) to (d) are weighed so as to have a mixed composition in the above numerical range, and dissolved in pure water.

  At this time, the mixture may be sufficiently mixed using a mortar, ball mill, mixer mill or the like.

  Next, a predetermined acid is added so that the pH value C of the obtained aqueous solution is adjusted to 0 <C <7, and then water is evaporated.

  Next, the obtained raw material mixture is filled in a heat-resistant container such as a quartz crucible or an alumina crucible and fired in an electric furnace. The firing temperature is preferably 500 to 1000 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature and the like, but is preferably 0.5 to 6 hours.

  The firing atmosphere includes a nitrogen gas atmosphere containing a small amount of hydrogen gas, a weak reducing atmosphere such as a carbon dioxide gas atmosphere containing a small amount of carbon monoxide, a neutral atmosphere such as a nitrogen gas atmosphere and an argon gas atmosphere, or a small amount of oxygen gas. A weak oxidizing atmosphere is preferred.

  After firing once under the above firing conditions, the fired product is taken out from the electric furnace and pulverized, and then the fired product powder is again filled in a heat-resistant container and placed in the electric furnace, and again under the same firing conditions as described above. If the calcination is performed, the emission luminance of the phosphor can be further increased. When the baked product is cooled to the room temperature from the calcination temperature, the desired fluorescence can also be obtained by removing the baked product from the electric furnace and allowing it to cool in the air. The body can be obtained, but it may be cooled in the same weakly reducing atmosphere or neutral atmosphere as at the time of firing. In addition, by moving the fired product from the heating unit to the cooling unit in an electric furnace and quenching in a weak reducing atmosphere, neutral atmosphere or weak oxidizing atmosphere, the emission luminance due to the phosphor phosphors obtained can be increased. It can be further increased.

  Further, the photostimulable phosphor layer of the present invention is formed by a vapor phase growth method.

  Vapor deposition methods, sputtering methods, CVD methods, ion plating methods, and others can be used as the vapor phase growth method of the photostimulable phosphor.

  In the present invention, for example, the following methods can be mentioned.

In the vapor deposition method of the first method, first, after the support is installed in the vapor deposition apparatus, the inside of the apparatus is evacuated to a degree of vacuum of about 1.333 × 10 ⁻⁴ Pa.

  Next, at least one of the photostimulable phosphor is heated and evaporated by a resistance heating method, an electron beam method, or the like to grow 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, it is possible to co-evaporate using a plurality of resistance heaters or electron beams to synthesize the desired photostimulable phosphor on the support and simultaneously form the photostimulable phosphor layer. is there.

  After the vapor deposition is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the side opposite to the support side of the photostimulable phosphor layer as necessary. In addition, after forming a photostimulable phosphor layer on a protective layer, a procedure for providing a support may be taken.

  Furthermore, in the vapor deposition method, the vapor deposition target (support, protective layer or intermediate layer) may be cooled or heated as necessary during vapor deposition.

Further, the stimulable phosphor layer may be heat-treated after the vapor deposition. In the vapor deposition method, reactive vapor deposition may be performed by introducing a gas such as O ₂ or H ₂ as necessary.

In the sputtering method as the second method, like the vapor deposition method, after a support having a protective layer or an intermediate layer is placed in the sputtering apparatus, the inside of the apparatus is once evacuated to about 1.333 × 10 ⁻⁴ Pa. The degree of vacuum is set, and then an inert gas such as Ar or Ne is introduced into the sputtering apparatus as a sputtering gas to obtain a gas pressure of about 1.333 × 10 ⁻¹ Pa. Next, a stimulable phosphor layer is grown on the support to a desired thickness by sputtering using the stimulable phosphor as a target.

  Various applied treatments can be used in the sputtering step as in the vapor deposition method.

  The third method is a CVD method, and the fourth method is an ion plating method.

  The growth rate of the stimulable phosphor layer in the vapor phase growth is preferably 0.05 μm / min to 300 μm / min. When the growth rate is less than 0.05 μm / min, the productivity of the radiation image conversion panel of the present invention is unfavorable. If the growth rate exceeds 300 μm / min, it is difficult to control the growth rate.

  When the radiation image conversion panel is obtained by the above-described vacuum deposition method, sputtering method, etc., since there is no binder, the packing density of the photostimulable phosphor can be increased, and preferable radiation image conversion in terms of sensitivity and resolution. A panel is obtained and preferred.

  The film thickness of the photostimulable phosphor layer varies depending on the intended use of the radiation image conversion panel and the type of stimulable phosphor, but is 50 μm to 1 mm, preferably 50 from the viewpoint of obtaining the effects of the present invention. It is -300 micrometers, More preferably, it is 100-300 micrometers, Most preferably, it is 150-300 micrometers.

  In the production of the photostimulable phosphor layer by the vapor phase growth method, the temperature of the support on which the photostimulable phosphor layer is formed is preferably set to 50 ° C. or more, more preferably 80 ° C. or more. Especially preferably, it is 100-400 degreeC.

  Since the photostimulable phosphor layer formed on the support in this manner 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, and in addition to reinforcing the stimulable phosphor layer, it may be filled with a high light absorption substance, a high light reflectance substance, or the like. Thus, in addition to providing the above-mentioned reinforcing effect, it is effective for reducing the light diffusion in the lateral direction of the stimulated excitation light incident on the stimulable phosphor layer.

  A highly reflective substance refers to a substance having a high reflectivity with respect to stimulated excitation light (500 to 900 nm, particularly 600 to 800 nm). For example, white pigments such as aluminum, magnesium, silver, indium, and other metals In addition, a color material in the green to red region can be used. White pigments can also reflect stimulated emission.

Examples of the white pigment include 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 Ca, and X is a Cl atom or a Br atom.), CaCO ₃ , ZnO, Sb ₂ O ₃ , SiO ₂ , ZrO ₂ , lithopone (BaSO ₄ ZnS), magnesium silicate, basic silicate, basic lead phosphate, aluminum silicate and the like.

  Since these white pigments have a strong hiding power and a high refractive index, they can easily scatter photostimulated luminescence by reflecting or refracting light, thereby significantly improving the sensitivity of the resulting radiation image conversion panel. it can.

  In addition, as a material having a high light absorption rate, for example, carbon black, chromium oxide, nickel oxide, iron oxide, and the like and a blue color material are used. Among these, carbon black absorbs stimulated light emission.

  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.

  In addition, 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 the inorganic color material include inorganic pigments such as ultramarine, for example, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—Co—NiO.

  Moreover, the photostimulable phosphor layer of the present invention may have a protective layer.

  The protective layer may be formed by directly applying a protective layer coating solution on the photostimulable phosphor layer, or a protective layer separately formed in advance may be adhered on the photostimulable phosphor layer. Alternatively, a means for forming a stimulable phosphor layer on a separately formed protective layer may be taken.

  Materials for the protective layer include cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polyvinylidene chloride, nylon, polytetrafluoroethylene, polytrifluoride-chloride. Usual protective layer materials such as ethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer are used. In addition, a transparent glass substrate can be used as a protective layer.

Further, this protective layer may be formed by laminating inorganic substances such as SiC, SiO ₂ , SiN, Al ₂ O ₃ by vapor deposition, sputtering, or the like.

  The thickness of these protective layers is preferably 0.1 to 2000 μm.

  FIG. 1 is a schematic view showing an example of a basic configuration of a radiation image conversion panel of the present invention. In order to more reliably reduce the ingress of moisture into a phosphor that is cut to a predetermined size and has a photostimulable phosphor layer on the support, the photostimulability deposited on the substrate is reduced. From the top of the phosphor layer. By adhering the protective film, moisture can be prevented from entering from the outer peripheral portion of the phosphor.

  In FIG. 1, 11 represents a stimulable phosphor layer (vapor deposition type), 12 is a substrate (support), 13 is a heat-resistant resin layer, and 14 is a moisture-proof protective film. Examples of the substrate (support) include crystallized glass.

  The sealing structure of the present invention is formed into a bag shape using two laminated protective films A (no heat fusion) described in the examples described later, and the stimulable phosphor plate is wrapped under reduced pressure, and on the phosphor layer surface side. In this structure, the substrate and the protective film are fused using a heat-fusible sheet in a region outside the peripheral edge of the phosphor, and then the protective film on the back surface is removed and sealed.

  The heat-fusible film here refers to a resin film that can be fused with a commonly used impulse sealer, such as ethylene vinyl acetate copolymer (EVA), polypropylene (PP) film, polyethylene (PE) film, and the like. The present invention is not limited to this.

  As the film preferably used for the protective layer of the present invention, when the fusion film is used, the optimum moisture resistance can be achieved by laminating a plurality of fusion films in accordance with the required moisture resistance. . As a laminating method in this case, any generally known method may be used, but preferably a dry laminating method is excellent in terms of workability.

  The outer surface on the opposite side of the phosphor layer having the protective layer is matted, and the average inclination angle Δa of the surface roughness of the protective layer is 0.01 to 0.1. In the image conversion panel, it is more preferable.

  Here, the average inclination angle Δa of the surface roughness is an arithmetic average inclination angle Δa according to JIS-B-0601 (1998).

  Further, in order to increase the average inclination angle Δa of the surface roughness of the protective layer film, a method of coating a fluororesin-containing resin composition layer liquid in which an inorganic substance such as silica is dispersed on the protective layer film surface In the method of laminating a plurality of the films, there is a method of selecting the outermost resin film type, but the present invention is not limited to this.

  Resin films with various surface shapes are widely available on the market, and it is easy to select a film having the required average inclination angle Δa.

  Films such as polypropylene film, polyethylene terephthalate film, and polyethylene naphthalate film have excellent physical properties as a protective film in terms of strength. A part of the light is repeatedly reflected at the upper and lower interfaces of the film and propagates to a place away from the scanned place, emitting a stimulated emission and reducing sharpness. In addition, the excitation light reflected in the opposite direction to the phosphor layer surface at the upper and lower interfaces of the protective film is re-reflected between the photodetection devices and the peripheral members, so that the photostimulability of the place further away from the scanned place is achieved. Since the phosphor layer is excited to emit stimulated light emission, this further reduces sharpness. Since the excitation light is coherent light with a long wavelength from red to infrared, unless it actively absorbs scattered light or reflected light, the amount absorbed in the space inside the protective film or inside the reader is small and far away. It propagates to a new place and sharpness deteriorates.

  For this reason, it is preferable to provide an excitation light absorption layer presumed to have an effect of suppressing the scattered light and reflected light.

  The excitation light absorbing layer is a layer containing a colorant that selectively absorbs excitation light. As described later, these layers are coated on one surface of the protective film. Alternatively, it may be coated on both surfaces, or the protective film itself may be colored to form an excitation light absorbing layer.

  In addition, when a film such as a polypropylene film, a polyethylene terephthalate film, or a polyethylene naphthalate film is used as a component of the protective layer according to the present invention, the density other than the radiographic image of the subject, that is, the image unevenness, or the manufacturing process of the protective film Then, the linear noise that seems to be reduced.

  This effect becomes remarkable when the average inclination angle Δa is 0.01 or more.

  It is presumed that the total reflection of excitation light at the protective layer (protective film) interface is prevented at an inclination angle Δa near this value, but this effect is small when the protective film is not provided with an excitation light absorbing layer. From the above, it is presumed that the above effect is a synergistic effect of the anti-scattering effect of the excitation light absorbing layer and the total reflection prevention of the average inclination angle Δa of the surface roughness.

  According to the present invention, a protective film having high heat resistance can be used at a necessary thickness without deteriorating the image quality without impairing water resistance, moisture resistance and solvent resistance required as a protective layer material. The radiation image conversion panel with excellent heat resistance can be realized.

  When using a resin film for a protective film, it can be set as the structure which laminated | stacked the vapor deposition film which vapor-deposited the metal oxide etc. on the resin film or the resin film according to the flaw resistance and moisture resistance required.

  In addition, when a plurality of films are laminated as described above, an excitation light absorption layer is further provided between the laminated resin films, so that the excitation light absorption layer is protected from physical impact and chemical alteration and stable. The plate performance is more preferable because it can be maintained for a long time. The excitation light absorption layer may be provided at a plurality of locations, or a colorant may be included in the adhesive layer for laminating the resin film to form the excitation light absorption layer.

  The surface shape of the protective film can be easily adjusted by selecting a resin film to be used or by applying a coating film containing an inorganic substance on the resin film surface. It is also possible to color this coating film to form an excitation light absorbing layer. Furthermore, in recent years, resin films having an arbitrary surface shape are easily available.

  As described above, Japanese Patent Publication No. 59-23400 discloses a radiation image conversion panel for coloring the protective film of the excitation light absorbing layer radiation image conversion panel, suppressing scattered light and reflected light, and improving sharpness. Are described as an example of various embodiments in which each of the support, the undercoat layer, the phosphor layer, the intermediate layer, and the protective layer constituting the substrate is colored.

  As the colorant preferably used in the protective layer of the radiation image conversion panel in the present invention, a colorant having a property of absorbing excitation light of the radiation image conversion panel is preferably used.

  Preferably, the light transmittance of the protective film at the excitation light wavelength is 98% to 50% of the light transmittance of the protective film which is different only in that the excitation light absorption layer is not provided (for example, He—Ne laser light (633 nm). )) To provide an excitation light absorption layer. When the light transmittance exceeds 98%, the effect of the present invention is small. When the light transmittance is less than 50%, the luminance of the radiation image conversion panel rapidly decreases.

  Which colorant is used depends on the type of stimulable phosphor used in the radiation image conversion panel, but as a stimulable phosphor for the radiation image conversion panel, the excitation is usually in the range of 400 to 900 nm. A phosphor exhibiting stimulated emission in the wavelength range of 300 to 500 nm by light is used. For this reason, a blue to green organic or inorganic colorant is usually used as the colorant.

Examples of blue to green organic colorants include Zavon First Blue 3G (Hoechst), Estrol Brill Blue N-3RL (Sumitomo Chemical), Sumiacryl Blue F-GSL (Sumitomo Chemical), D & C Blue No. 1 (National Aniline), Spirit Blue (Hodogaya Chemical), Oil Blue No. 1 603 (manufactured by Orient), Kitten Blue A (manufactured by Ciba-Geigy), Eisen Katyron Blue GLH (manufactured by Hodogaya Chemical Co., Ltd.), Lake Blue A, F, H (manufactured by Kyowa Sangyo Co., Ltd.), rhodarin blue 6GX ( Kyowa Sangyo Co., Ltd.), Brimocyanin 6GX (Inabata Sangyo Co., Ltd.), Brill Acid Green 6BH (Hodogaya Chemical Co., Ltd.), Cyanine Blue BNRS (Toyo Ink Co., Ltd.), Lionol Blue SL (Toyo Ink Co., Ltd.) . Examples of blue to green inorganic colorants include, but are not limited to, ultramarine blue, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—CoO—NiO pigments.

(Phosphor layer)
Next, the phosphor constituting the radiation image conversion panel by covering with the protective film will be described.

  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 usually set to 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 of evaporating the photostimulable phosphor from the evaporation source is usually performed by scanning an electron beam emitted from an electron gun, but it can 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, the film can be sufficiently doped even if the film is thick, and the crystal transfer hardly occurs, so that the modulation transfer function (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.

  FIG. 2 is a diagram showing an example of a vapor deposition (evaporation) apparatus used in the present invention and a state in which a photostimulable phosphor layer is formed on the substrate (support) 12 by vapor deposition using the vapor deposition apparatus. It is. 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 of the substrate surface is θ2, the angle of the columnar crystal formed 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 crystal 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 at the time of 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.

  The sealing structure of the present invention is formed into a bag shape using two laminated protective films A (no heat fusion) described in the examples described later, and the stimulable phosphor plate is wrapped under reduced pressure, and on the phosphor layer surface side. It is a structure in which a substrate and a protective film are fused using a heat-fusible sheet in a region outside the peripheral edge of the phosphor, and then the protective film on the back surface is removed and sealed. Make it.

The support = substrate, a carbon-containing fiber-reinforced resin plate.

  The thickness of these supports varies depending on the material of the support used, but is generally 80 μm to 5000 μm, and more preferably 250 μm to 4500 μm from the viewpoint of handling.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the embodiments of the present invention are not limited to these examples.

Example 1
<< Preparation of Radiation Image Conversion Panel 1 >>
A radiation image conversion panel 1 having a vapor deposition type phosphor layer was produced according to the method described below.

(Preparation of photostimulable phosphor plate)
A 2 mm thick, 500 mm square carbon fiber reinforced resin plate (CFRP # 167A manufactured by Toho Tenax Co., Ltd., impregnated resin cured epoxy resin) is coated with a fluorine resin solution (TC-7105GN manufactured by Daikin Co., Ltd.) using a spray coater. , 80 ° C., 30 minutes, 170 ° C., 90 minutes, and then dried in two stages to form a 20 μm-thick fluorine resin film. This was put in a vacuum chamber of a known vapor deposition apparatus, argon gas was introduced into the vacuum chamber, the degree of vacuum was set to 0.1 Pa, and then an alkali halide phosphor having CsBr: 0.001Eu was placed in a crucible, A phosphor having a columnar structure with a thickness of 300 μm by carrying out vapor deposition on the fluororesin layer side of the substrate while transporting the substrate in a direction parallel to the substrate using an aluminum slit at a distance of 60 cm from the vapor deposition source A plate was formed.

(Preparation of moisture-proof sealing film)
A laminated protective film A including an alumina-deposited polyethylene terephthalate resin layer represented by the following configuration was produced.

Laminated protective film A: VMPET12 /// VMPET12 /// PET
In the laminated protective film A, VMPET represents polyethylene terephthalate deposited on alumina (commercial product: manufactured by Toyo Metallizing Co., Ltd.), and PET represents polyethylene terephthalate. In addition, the above “///” indicates that the thickness of the two-component reaction type urethane adhesive layer in the dry lamination adhesive layer is 3.0 μm, and the number displayed after each resin film is the number of each film. Represents film thickness (μm).

  Two sheets of the above laminated protective film A (without heat fusion) are used to form a bag, and the stimulable phosphor plate is wrapped under reduced pressure to protect the substrate in a region outside the phosphor periphery on the phosphor layer surface side. The film was fused using a heat-fusible sheet, and then the protective film on the back surface was removed and sealed to prepare a radiation image conversion panel (sample) 1.

  Table 1 shows the results of the measurement of the residual solvent amount of the substrate provided with the heat-resistant resin layer and the evaluation of the characteristics and durability of the obtained panel.

Example 2
A fluororesin solution ((TC-7105GN manufactured by Daikin Co., Ltd.)) was applied with a spray coater and dried in two stages of 80 ° C., 30 minutes, 170 ° C. and 80 minutes, to obtain a fluorine resin film. The same operation as in Example 1 was performed to prepare a radiation image conversion panel (sample) 2.

Example 3
The radiation image conversion panel was operated in the same manner as in Example 1 except that the drying conditions of Example 1 were dried in two stages: 80 ° C., 30 minutes, 140 ° C., 30 minutes to obtain a 20 μm-thick fluororesin film. (Sample) 3 was produced.

Example 4
A radiation image conversion panel (sample) 4 was prepared in the same manner as in Example 1 except that the drying conditions of Example 1 were dried in two stages of 80 ° C., 30 minutes, 120 ° C., and 20 minutes.

Example 5
A radiation image conversion panel (sample) 5 was prepared in the same manner as in Example 1 except that the drying conditions of Example 1 were dry-dried in two stages of 80 ° C., 30 minutes, 110 ° C., and 15 minutes.

Example 6
The same operation as in Example 1 was performed except that the fluororesin of Example 1 was changed to polyamideimide (Vilomax HR13NX manufactured by Toyobo Co., Ltd.) and dried in two stages of 80 ° C., 30 minutes, 160 ° C., and 30 minutes. An image conversion panel (sample) 6 was produced.

Example 7
A radiation image conversion panel (sample) 7 was prepared in the same manner as in Example 6 except that the drying conditions of Example 6 were dried in two stages: 80 ° C., 30 minutes, 140 ° C., 30 minutes.

Comparative Example 1
A radiation image conversion panel (sample) 8 was prepared in the same manner as in Example 1 except that the drying conditions of Example 1 were dry-dried in two stages of 80 ° C., 30 minutes, 170 ° C., and 120 minutes.

Comparative Example 2
A radiation image conversion panel (sample) 9 was prepared in the same manner as in Example 1 except that drying in Example 1 was performed only once at 80 ° C. for 30 minutes.

  The obtained radiation image conversion panels (samples) 1 to 9 were evaluated as follows.

(Characteristic evaluation of radiation image conversion panel)
The sensitivity and sharpness are both better as the value is larger.

Evaluation of Sensitivity (Luminance) Sensitivity was measured by irradiating the radiation image conversion panel with X-rays having a tube voltage of 80 kVp at 10 mAs at a distance of 2 m between the bombardment source and the plate, and then setting the panel on the Regius 350 to read. Evaluation was performed based on the electrical signal from the obtained photomultiplier.

  The sensitivity in the table is an average value of the entire phosphor surface, and is a relative sensitivity when the sensitivity of the sample 1 is 1.00.

Evaluation of sharpness Sharpness was evaluated by obtaining a modulation transfer function.

  After attaching a CTF chart to the radiation image conversion radiation image conversion panel sample, the radiation image conversion panel sample was irradiated with 80 kVp X-rays at 10 mAs (distance to the subject: 1.5 m), and then a semiconductor laser having a diameter of 100 μmφ (680 nm) : The CTF chart image was scanned and read using a power of 40 mW on the panel). The values in the table showed an MTF value of 2.0 lp / mm. The higher the value, the better the sharpness.

(Durability evaluation of radiation image conversion panel)
○: The above-mentioned sharpness value after repeating a 120-hour constant temperature chamber at 0 ° C., 40%, 80 ° C., and 40% after the rectangular image conversion panel is sealed with a sealing film is repeated 120 times. And a value of 85% or more is shown compared to before the introduction.

○ △: The above-mentioned sharpness of the image obtained by sealing the radiation image conversion panel with a sealing film after leaving it in a thermostatic chamber at 0 ° C., 40%, 80 ° C. and 40% for 3 hours was repeated 120 times. Evaluate and show a value of more than 80% and less than 85% compared to before introduction. ×: Constant temperature of 0 ° C., 40% and 80 ° C., 40% when the radiation image conversion panel is sealed with a sealing film The sharpness evaluation is performed after 120 hours of standing in a thermostatic chamber for 120 hours, and the value is 80% or less compared with that before the charging.

(Measurement of residual solvent amount)
The substrate (100 cm ² ) provided with the heat-resistant resin layer of each radiation image conversion panel was extracted with 50 ml of methanol, and the residual solvent was quantified by GC / MS.

  The above results are shown below.

It is the schematic which shows an example of the fundamental structure of the radiographic image conversion panel of this invention. It is a figure which shows an example of the vapor phase deposition (vapor deposition) apparatus used for this invention.

Explanation of symbols

11 photostimulable phosphor layer 12 heat resistant resin layer 13 substrate (support)
14 Moisture-proof protective film

Claims (4)

A radiation image conversion panel having a heat resistant resin layer selected from a fluororesin or a poly (amide) imide resin and a phosphor layer formed by a vapor deposition method in this order on a carbon fiber reinforced resin substrate. A radiation image conversion panel, wherein the residual solvent amount is 0.05 to 10 g / m ² . 2. The radiation image conversion panel according to claim 1, wherein the stimulable phosphor contained in the phosphor layer is a compound represented by the following general formula (1).
  General formula (1)
  M ¹ X ・ aM ² X '· bM ³ X ″: eA
  [Where M ¹ Is at least one alkali metal atom selected from Li, Na, K, Rb and Cs atoms, and M ² Is at least one divalent metal atom selected from the atoms of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni, and M ³ Is at least one selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In atoms. A trivalent metal atom, wherein X, X ′, and X ″ are at least one halogen atom selected from F, Cl, Br, and I atoms, and A is Eu, Tb, In, Ce, Tm, Dy , Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu and Mg, and at least one metal atom, and a, b, e Are numerical values in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <e ≦ 0.2, respectively.] The radiation image conversion panel according to claim 2, wherein the photostimulable phosphor is represented by the following general formula (2).
  General formula (2)
  CsX: yA
[Wherein, X represents Cl, Br or I, and A represents Eu, Sm, In, Tl, Ga or Ce. y is 1 × 10 ^-7 ~ 1x10 ^-2 Represents numerical values up to. ] The residual solvent amount in the heat resistant resin layer of the radiation image conversion panel according to any one of claims 1 to 3 is 0.05 to 10 g / m. ² The manufacturing method of the radiographic image conversion panel characterized by making it become.

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