JPH077115B2 - Radiation image conversion panel - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a radiation image conversion panel using a stimulable phosphor, and more particularly to a radiation image conversion panel which gives a high quality radiation image with little deterioration due to moisture and a method for producing the same.

BACKGROUND OF THE INVENTION

Radiation images such as X-ray images are often used for disease diagnosis. In order to obtain this X-ray image, X-rays transmitted through the subject are irradiated onto the phosphor layer (fluorescent screen) to generate visible light, and this visible light is used in the same manner as when taking a normal photograph. A so-called radiograph in which a film using salt is irradiated and developed is used. On the other hand, in recent years, a method of directly taking out an image from the phosphor layer without using a film coated with silver salt has been devised. As this method, the radiation that has passed through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or thermal energy so that the radiation energy accumulated by the absorption by the phosphor is emitted as fluorescence. A method of detecting this fluorescence and imaging. Specifically, for example, U.S. Pat. No. 3,859,527 and JP-A-55-12144 disclose a radiation image conversion method in which a stimulable phosphor is used and visible rays or infrared rays are used as stimulated excitation light. This method uses a radiation image conversion panel in which a stimulable phosphor layer is formed on a support, and the radiation that has passed through the subject is applied to the stimulable phosphor layer of this radiation image conversion panel to apply the radiation to each part of the subject. A latent image is formed by accumulating the radiation energy corresponding to the radiation transmittance, and thereafter, the stimulable phosphor layer is scanned with stimulable excitation light to radiate the accumulated radiation energy of each part to generate a latent image. The light is converted into light and an image is obtained by an optical signal depending on the intensity of the light. This final image may be played back as a hard copy or a CRT
You may play on. A radiation image conversion panel having a stimulable phosphor layer used in this radiation image conversion method has a radiation absorption rate and a light conversion rate (including both of them, as in the case of the radiographic method using the above-described fluorescent screen). It is required that the image has good graininess and high sharpness, not to mention high radiation sensitivity. However, in general, a radiation image conversion panel having a stimulable phosphor layer applies a dispersion containing a granular stimulable phosphor having a particle size of about 1 to 30 μm and an organic binder onto a support or a protective layer, Since it is produced by drying, the packing density of the stimulable phosphor is low (filling ratio 50%), and it was necessary to increase the layer thickness of the stimulable phosphor layer in order to sufficiently increase the radiation sensitivity. On the other hand, the sharpness of the image in the radiation image conversion method tends to be higher as the layer thickness of the stimulable phosphor layer of the radiation image conversion panel is smaller. It was necessary to thin the luminescent phosphor layer. Further, the graininess of the image in the radiation image conversion method is determined by the spatial fluctuation of the radiation quantum number (quantum mottle), the structural disorder of the stimulable phosphor layer of the radiation image conversion panel (structural mottle), or the like. Therefore, as the layer thickness of the stimulable phosphor layer becomes thinner, the number of radiation quantum absorbed in the stimulable phosphor layer decreases and the quantum mottle increases, or structural disorder becomes apparent and the structure mottle increases. As a result, the image quality is degraded. Therefore, in order to improve the graininess of the image, the stimulable phosphor layer needs to be thick. That is, as described above, in the conventional radiation image conversion panel, the sensitivity to radiation and the graininess of the image, and the sharpness of the image show the opposite tendency to the layer thickness of the stimulable phosphor layer. The radiation image conversion panels have been made at the trade-off between radiation sensitivity and some degree of graininess and sharpness. In view of the reciprocity between such properties, the present applicant proposes a radiation image conversion panel containing no binder in the stimulable phosphor layer and a method for producing the same in JP-A-61-73100. There is. According to this, the stimulable phosphor layer of the radiation image conversion panel is formed by a method such as vapor deposition, since it does not contain a binder, the filling rate of the stimulable phosphor layer is The sharpness of the image is improved at the same time that the directivity of the stimulated excitation light and stimulated emission in the stimulable phosphor layer is significantly improved and the sensitivity of the radiation image conversion panel to radiation and the graininess of the image are improved. The sex is also improved. Since the panel releases accumulated energy by scanning excitation light after accumulating radiation image information, the radiation image can be accumulated again after scanning and can be repeatedly used. Therefore, it is a matter of course that the radiation image conversion panel is desired to have a high image quality of the obtained image, but it is required that the radiation image conversion panel has a performance that can be used for a longer period of time. However, stimulable phosphors generally have a high hygroscopic property, and when left in a room under normal climatic conditions, they adsorb moisture in the air and their performance deteriorates over time. Specifically, development occurs in which the sensitivity to radiation decreases and the fading speed of the latent image generated by irradiation of radiation increases. Now, the stimulable phosphor layer provided by the vapor deposition method is
Despite having many excellent features as described above,
Since the stimulable phosphor is not protected by the binder, it has a drawback that it is easily affected by moisture. In the phosphor layer in which the stimulable phosphor particles are dispersed in the binder,
For example, as described in JP-A-61-20982, a method in which hydrophobic fine particles are contained in the phosphor layer in an amount of 0.005% by weight or more and 10% by weight or less based on the stimulable phosphor, Japanese Patent Application No.
-53269, a method of containing a silane coupling agent in the phosphor layer, and Japanese Patent Application No. 61-53.
A method for improving the moisture resistance of the stimulable phosphor layer itself, such as a method of encapsulating stimulable phosphor particles as described in No. 270, has been proposed. No such method was used in the stimulable phosphor layer of No.

[Object of the Invention]

The present invention has been made in view of the above-mentioned current situation in a radiation image conversion panel having a stimulable phosphor layer, and an object of the present invention is to provide a stimulable phosphor formed by a vapor deposition method. It is an object of the present invention to provide a radiation image conversion panel which has excellent characteristics in image quality in a layer and whose performance deterioration due to adsorption of moisture is small.

[Constitution of the invention]

The above-mentioned object of the present invention is a radiographic image panel having at least one stimulable phosphor layer provided by a vapor deposition method, wherein the stimulable phosphor layer has a crack, and the crack It is achieved by a radiation image conversion panel characterized by impregnating a hydrophobic polymer substance. Silicon oil and fluorine-containing organic compounds are particularly preferable as the hydrophobic polymer substance. Next, the present invention will be specifically described. FIG. 1 (a) is a sectional view in the thickness direction of an example of the radiation image conversion panel of the present invention (hereinafter sometimes simply referred to as a panel when the meaning is clear). In the figure, reference numeral 10 shows the form of the panel of the present invention. Reference numeral 11 is a support, and 12 is a stimulable phosphor layer provided on the support, which is a stimulable phosphor layer formed by a vapor deposition method. If necessary, an adhesive layer may be provided between the support 11 and the stimulable phosphor layer 12 to improve the adhesiveness between the layers, or stimulated excitation light and / or stimulated emission. You may provide the reflective layer or the absorption layer. Further, 13 is a protective layer which is preferably provided. In the panel of the present invention, any form may be used as a form of incorporating a hydrophobic polymer substance such as silicon oil or a fluorine-containing organic compound in the stimulable phosphor layer, but it is particularly effective and easy to manufacture. The reason is that, as shown in FIGS. 1 (b) and (c), the stimulable phosphor layer 12 has fine cracks 14 extending in a direction perpendicular to the support 11, and in the cracks 14, Silicon oil or a fluorine-containing organic compound (hereinafter referred to as a specific hydrophobic substance) 15 is filled. Here, the crack in the stimulable phosphor is a general term for fine cracks, grooves, dents, crevasses, etc. provided along the crystal grain boundaries of the stimulable phosphor. As the form of the cracks, for example, as shown in FIG. 1 (b), in the stimulable phosphor layer 12 having a fine columnar block structure extending in a direction substantially perpendicular to the support 11, each fine columnar block is formed. It may be the crevasse 14 for partitioning. The columnar block structure may have any pattern. Figure 2 (a),
Examples of the pattern are shown in (b) and (c) as a plan view of a cross section parallel to the stimulable phosphor layer. 21 in FIG.
Is a cross section of the stimulable phosphor layer, 22 is the fine columnar block, and 23 is the crevasse (hatched portion). Further, the panel of the present invention has a structure in which cracks 14 are formed from the surface side of the stimulable phosphor layer 12 as shown in FIG. 1 (c), and the specific hydrophobic substance 15 is filled in the cracks. May be. Further, as shown in FIG. 1D, a thin coating may be formed on the phosphor layer 12 at the same time that the specific hydrophobic substance 15 is filled in the cracks 14. The thickness of the coating is preferably 30 μm or more. In the above example, it is not necessary that the specific hydrophobic substance is filled in the cracks without any clearance, and it may be only attached to the inner surface of the cracks. The thickness of the stimulable phosphor layer of the panel of the present invention varies depending on the sensitivity of the panel to radiation, the type of the stimulable phosphor, etc., but is preferably in the range of 10 to 800 μm, and 50 to 500 μm.
The range of m is more preferable. In the panel of the present invention, the width of the crack 14 is preferably about 1 to 20 μm, and the distance between adjacent cracks is preferably about 1 to 400 μm. The specific hydrophobic substance in the present invention includes the following. (1) Silicone oil As a silicone oil, an organic polysiloxane compound is particularly preferable. Among them, methylhydrogenpolysiloxane, OH-terminated dimethylpolysiloxane, Dimethyl polysiloxane, Is preferred. In the above, n = 3 to 200. (2) Fluorine-containing organic organic compound As the title compound, especially fluorinated fatty acid amide, FCH ₂ nCO-NH-CHR-COOH (n = 3 to 20, R: C _{1 to} C ₈ alkyl group) perfluoromonocarboxylic acid Chromium complex salt, Acrylic acid fluorinated alkyl ester Is mentioned. (3) Others Polystyrene, polyvinyl chloride, vinyl chloride-vinylidene chloride copolymer and the like can be used. As a method for impregnating the phosphor layer with a specific hydrophobic material, acetone, methyl ethyl ketone, trichloroethylene, perchlorethylene, carbon tetrachloride, methylene chloride, 1,1,1-trichloroethane, a hydrocarbon solvent, etc. %
It is dissolved in a certain concentration and then applied or sprayed on the phosphor layer, or the phosphor layer is immersed in the solution, dried at room temperature to about 70 ° C., and the solvent is evaporated. 100 to 3 as required
You may heat-process at 00 degreeC. In particular, among the organic polysiloxane compounds and the fluorine-containing organic compounds, there are preferable ones in which molecules are polymerized by heat treatment to lengthen the molecular chain and enhance the moisture-proof effect. A catalyst may be added as necessary during the heat treatment. Examples of the catalyst include zinc caprylate, iron caprylate, dibutyltin dilaurate, stannous caprylate, sodium acetate, zinc naphthenate and the like. Besides the polymer impregnation as described above, the polymerization reaction may be carried out after impregnation with a suitable solvent solution of a monomer or an oligomer. The stimulable phosphor in the panel of the present invention is a stimulus (stimulant excitation) such as optical, thermal, mechanical, optical or electrical after being irradiated with the first light or high energy radiation.
According to the above, the phosphor is a phosphor exhibiting stimulated emission corresponding to the dose of the first light or high-energy radiation, but from a practical viewpoint, it is preferably a phosphor exhibiting stimulated emission by stimulated excitation light of 500 nm or more. . Specifically, for example, JP-A-48-80
BaCO are described in JP 487 _4: phosphor represented by Ax, MgSO described in JP 48-80488 _4: phosphor represented by Ax, are described in JP-A-48-80489 SrSO ₄ : Ax phosphor, Na ₂ SO described in JP-A-51-29889
_At least 1 of Mn, Dy and Tb in ₄ , CaSO ₄ and BaSO ₄ etc.
Species-doped phosphors, phosphors such as BeO, LiF, MgSO ₄ and CaF ₂ described in JP-A-52-30487, JP-A-53-392
No. 77, phosphors such as Li ₂ B ₄ O ₇ : Cu, Ag, Li ₂ O. (B ₂ O ₂ ) x: Cu and Li ₂ described in JP-A-54-47883. O ・ (B ₂ O ₂ ) x: phosphor such as Cu, Ag, US Pat. No. 3,859,5
SrS: Ce, Sm, SrS: Eu, Sm, La ₂ O ₂ S: E described in No. 27
Examples include phosphors represented by u, Sm and (Zn, Cd) S: Mn, X. Further, ZnS: Cu, described in JP-A-55-12142,
Pb phosphor general formula BaO · xAl ₂ O _3: barium aluminate phosphor represented by Eu, and the general formula M ^II O · xSiO _2: alkaline earth represented by A metal silicate phosphor Is mentioned. Further, the general formulas described in _{JP-A-55-12143 (Ba 1 -x-yMgxCay)} FX: eEu alkaline earth fluoride halide phosphor represented by ^2+, JP 55-12144 It is described in. A phosphor represented by LnOX: xA, a phosphor represented by the general formula (Ba ₁ -xM ^II x) FX: yA described in JP-A-55-12145, and JP-A-55-84389. Phosphor represented by the general formula BaFX: xCe, yA described, rare earth element-activated divalent metal represented by the general formula M ^II FX.xA: yLn described in JP-A-55-160078 Fluorohalide phosphors, phosphors represented by the general formulas ZnS: A, CdS: A, (Zn, Cd) S: A, ZnS: A, X and CdS: A, X, in JP-A-59-38278. A phosphor represented by any of the following general formulas xM ₃ (PO ₄ ) ₂ · NX ₂ : yA M ₃ (PO ₄ ) ₂ · yA, the general formula nReX described in JP-A-59-155487. ^{_{3 · mA ▲ X 1 2 ▼}} : xEu nReX 3 · mA ▲ X 1 2 ▼: xEu, phosphor represented by YSM, and general formula described in JP-a-61-72087 M ^I X · aM ^II ▲ Examples thereof include alkali halide phosphors represented by X ¹ ₂ ▼ · bM ^III ▲ X ¹¹ ₃ ▼: cA. In particular, an alkali halide phosphor is preferable because it facilitates formation of a stimulable phosphor layer by a method such as vapor deposition and sputtering. However, the stimulable phosphor used in the panel of the present invention is
The phosphor is not limited to the above-mentioned phosphor, and any phosphor may be used as long as it exhibits stimulated emission when irradiated with radiation and then stimulated with excitation light. The panel of the present invention may be a stimulable phosphor layer group composed of one or two or more stimulable phosphor layers containing at least one kind of the stimulable phosphor described above. The stimulable phosphor contained in each stimulable phosphor layer may be the same or different. Next, a method for providing a stimulable phosphor layer by vapor-depositing the stimulable phosphor will be described. The first method is a vapor deposition method. In the method,
First, the support is installed in the vapor deposition equipment and then the equipment is evacuated.
The degree of vacuum is about 10 ^-6 Torr. Then, at least one of the stimulable phosphor layers is heated and evaporated by a method such as a resistance heating method or an electron beam method to deposit the stimulable phosphor on the surface of the support to a desired thickness. As a result, a stimulable phosphor layer containing no binder is formed, but it is possible to form the stimulable phosphor layer in a plurality of times in the vapor deposition step. Further, in the vapor deposition step, co-evaporation can be performed using a plurality of resistance heaters or electron beams. In the vapor deposition method, the stimulable phosphor raw material is co-deposited by using a plurality of resistance heaters or electron beams to synthesize the target stimulable phosphor on the support and at the same time stimulable phosphor. It is also possible to form a body layer. Further, in the vapor deposition method, the vapor deposition target may be cooled or heated during vapor deposition, if necessary. In addition, the stimulable phosphor layer may be heat-treated after completion of vapor deposition. The second method is a sputtering method. In this method, as in the vapor deposition method, after the support is placed in the sputtering apparatus, the inside of the apparatus is temporarily evacuated to a vacuum degree of about 10 ^-6 Torr, and then an inert gas such as Ar or Ne is used as a gas for sputtering. The gas is introduced into the sputtering apparatus to a gas pressure of about 10 ^-3 Torr. Next, the stimulable phosphor is deposited on the surface of the support to a desired thickness by sputtering using the stimulable phosphor as a target. In the sputtering step, it is possible to form the stimulable phosphor layer in a plurality of times in the same manner as in the vapor deposition method, and it is also possible to simultaneously use a plurality of targets made of different stimulable phosphors. Alternatively, it is also possible to sequentially sputter the target to form a stimulable phosphor layer. In the sputtering method, a plurality of stimulable phosphor raw materials are used as targets, and these are simultaneously or sequentially sputtered to synthesize a target stimulable phosphor on a support and at the same time a stimulable phosphor layer. Can also be formed. In the sputtering method, if necessary
Reactive sputtering may be performed by introducing a gas such as O ₂ or H ₂ . Further, in the sputtering method, the material to be vapor-deposited may be cooled or heated during the sputtering, if necessary. Also,
After completion of sputtering, the stimulable phosphor layer may be heat-treated. The third method is the CVD method. In this method, a target stimulable phosphor or an organometallic compound containing a raw material for a stimulable phosphor is decomposed by energy such as heat or high-frequency power to give a binder containing no binder on the support. A fluorescent phosphor layer is obtained. As a method of forming the protective layer, the following method is used. As a first method, a solution prepared by dissolving a film-forming polymer substance in a suitable solvent as disclosed in Japanese Patent Application No. 59-42500 is applied to the surface on which a protective layer is to be placed, There is a method of forming a protective layer by drying. As a second method, as disclosed in Japanese Patent Laid-Open No. 59-42500, a suitable binder is applied to one side of a thin film made of a polymeric material and the protective layer is adhered to the side to be provided. There is. Examples of the material for the protective layer used in the first method and the second method include cellulose derivatives such as cellulose acetate, nitrocellulose, and ethyl cellulose, or polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, polyvinyl acetate. Acrylonitrile, polymethylallyl alcohol, polymethyl vinyl ketone, cellulose diacetate, cellulose triacetate, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyglycine, polyacrylamide, polyvinylpyrrolidone, polyvinylamine, polyethylene terephthalate, polyethylene, polyvinylidene chloride , Polyvinyl chloride, polyamide (nylon), polytetrafluoride ethylene, polytrifluoride monochloride ethylene, Polypropylene, tetrafluoroethylene -
Examples include hexafluoropropylene copolymer, polyvinyl isobutyl ether, polystyrene and the like. As a third method, as described in JP-A No. 61-176900, a coating solution containing at least one of a radiation curable resin and a thermosetting resin is applied to the surface on which the protective layer is to be provided. However, there is a method in which the coating liquid is cured by irradiating with radiation such as ultraviolet rays or electron beams and / or heating by using the installation as shown in JP-A-61-176900. The radiation curable resin may be a compound having an unsaturated double bond or a composition containing the same, and such a compound is preferably a prepolymer and / or an oligomer having two or more unsaturated double bonds. Further, a monomer having an unsaturated double bond (vinyl monomer) can be contained therein as a reactive diluent. A vinyl monomer, a non-reactive binder, a cross-linking agent, a photopolymerization initiator, a photosensitizer, which is a reactive diluent as required for the prepolymer and / or oligomer which is the radiation curable resin and / or the thermosetting resin, A storage stabilizer, an adhesion improver and other additives are mixed and dispersed to prepare a protective layer coating solution. The protective layer coating solution may contain a binder that is not cured by irradiation with radiation and heating, if necessary. Examples thereof include cellulose ester, polyvinyl butyral, polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, styrene and acrylic acid copolymer. The protective layer formed by the above method has a thickness of 1 μm to 10 μm.
It is preferably in the range of about 0 μm, more preferably about 2 μm to 50 μm. In the panel of the present invention, the protective layer is not limited to one layer, and a protective layer group of two or more layers, particularly two or more protective layer groups having different hygroscopicity as described in Japanese Patent Application No. 61-156346. May be As described in JP-A-62-15498, the protective layer has a moisture-proof coefficient of 1.5 m ² 24 hr / g.mm at 40 ° C. and 90% RH.
The above is preferable. Further, the panel of the present invention may have a protective layer provided by a vapor deposition method such as a vapor deposition method, a sputtering method or a CVD method as described in Japanese Patent Application No. 61-53276. Generally, the thickness of such a protective layer is preferably 0.1 to 50 μm. As the inorganic material used for the protective layer formed by the vapor deposition method, fluoride-based and oxide-based materials are preferred. Fluoride-based materials are CaF ₂ , MgF ₂ , CeF ₂ , BaF ₂ , SrF ₂ , and oxide materials are SiO ₃ , SiO ₂ , Al ₂ O ₃ , TiO ₂ , Y ₂ O ₃ , ZrO ₂ , Mg.
O, Gd ₂ O ₃ , Sc ₂ O ₃ , HfO ₂ , CeO ₂ and the like. As the support used in the radiation image conversion panel of the present invention, various polymer materials, glass, metal and the like are used. In particular, a material that can be processed into a flexible sheet or web for handling as an information recording material is preferable,
From this point, for example, a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyamide film, a polyimide film, a triacetate film, a plastic film such as a polycarbonate film, a metal sheet of aluminum, iron, copper, chromium or the like, or a coating of the metal oxide. Metal sheets with layers are preferred. The layer thickness of these supports varies depending on the material of the support used and the like, but is generally 80 μm to 1000 μm, and the handling point is more preferably 80 μm to 500 μm. The surface of these supports may be a smooth surface or may be a matte surface for the purpose of improving the adhesiveness with the stimulable phosphor layer. Further, the surface of the support may be an uneven surface, or may have a surface structure in which individual small tile-shaped plates are densely arranged. Further, these supports may be provided with an undercoat layer on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesiveness with the stimulable phosphor layer. The panel of the present invention considered as described above is used in the radiation image conversion method schematically shown in FIG. That is, in FIG. 3, 31 is a radiation generator, 32 is a subject, 33 is the panel of the present invention, 34 is a stimulated excitation light source, and 35 is a photoelectric conversion device for detecting stimulated emission emitted from the panel,
36 is a device that reproduces the signal detected in 35 as an image 37 is a device that displays the reproduced image, 38 is a filter that separates stimulated excitation light and stimulated emission, and transmits only stimulated emission . It should be noted that after 35, any optical information from 33 can be reproduced as an image in some form, and is not limited to the above. As shown in FIG. 3, the radiation from the radiation generator 31 enters the panel 33 of the present invention through the subject 32. The incident radiation is absorbed by the stimulable phosphor layer of the panel 33, the energy is accumulated, and an accumulated image of a radiation transmission image is formed. Next, this storage layer is excited by stimulated excitation light from the stimulated excitation light source 34 and emitted as stimulable luminescence.
The panel 33 of the present invention does not contain a binder in the stimulable phosphor layer and has high directivity of the stimulable phosphor layer. Diffusion of the photoexcitation light in the stimulable phosphor layer is suppressed. Since the intensity of the stimulated emission emitted is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by the photoelectric conversion device 35 such as a photomultiplier tube, and reproduced as an image by the image reproduction device 36. By displaying with the image display device 37, the radiation transmission image of the subject can be observed.

【Example】

Next, the present invention will be described with reference to examples. EXAMPLE A 0.5 mm thick aluminum plate was anodized, sealed and heat treated by the method disclosed in Japanese Patent Laid-Open No. 61-142498 so that tile-shaped plates were individually arranged with fine gaps. The substrate having the above-mentioned surface structure was placed in the vapor deposition device.
The average diameter of the tile plate was 65 μm. Next, a stimulable phosphor was placed in a tungsten boat for resistance heating.
RbBr: Tl was charged and set on the resistance heating electrode, and then the vapor deposition device was evacuated to a vacuum degree of 2 × 10 ⁻⁶ Torr. Next, an electric current was passed through the tungsten boat to evaporate the stimulable phosphor by a resistance heating method and deposit the stimulable phosphor layer on the aluminum plate until the layer thickness became 300 μm. Next, the panel was taken out by a vaporizer and placed in a nitrogen atmosphere.
After heating to 300 ° C and holding in this state for a sufficient period of time, remove the heating furnace and increase the nitrogen flow rate to cool rapidly.
A stimulable phosphor layer having a fine columnar block structure surrounded by a crevasse was formed and taken out into the atmosphere. In this way, a panel original material having a stimulable phosphor layer on the support was obtained. Then, the sufficiently dried panel raw material was immersed in a 2% trichloroethylene solution of methylhydrogenpolysiloxane (Toray silicone SH1107 oil; made by Toray Silicone) for 1 hour, and then the panel raw material was taken out and dried at 55 ° C. Next, it heat-processed at 150 degreeC for 15 minutes. The panel original material thus treated with silicone oil was placed in a protective polypropylene protective bag having a thickness of 15 μm, vacuum-sealed by the method described in JP-A-61-220492, and the protective layer was formed. To form panel A of the present invention. A tube voltage of 80 KV was applied to the panel A of the present invention thus obtained.
After irradiating 10mR of X-ray of p, semiconductor laser light (wavelength 780n
The photostimulated luminescence emitted from the stimulable phosphor layer was photoexcited by a photodetector (photomultiplier tube), and the sensitivity to X-rays was examined from the magnitude of this signal. Next, the panel A was left in a thermo-hygrostat at 50 ° C. and 90% RH for 48 hours for forced deterioration, and the X-ray sensitivity was measured again. The results are also shown in Table 1. Comparative Example A comparative panel B was manufactured in the same manner as in the example, except that the step of treating the raw panel material with silicone oil was omitted. The comparative panel B thus obtained was subjected to a forced deterioration test in the same manner as in the example, and the results are shown in Table 1.
In Table 1, the sensitivity is shown as a relative value with the sensitivity of the panel A before the forced deterioration being 100. As can be seen from Table 1, the panel of the present invention can withstand a humidity of 90% RH and the decrease in sensitivity is significantly small.

【The invention's effect】

A moisture-proof measure for phosphors such as an alkali halide phosphor having a columnar block structure, which is convenient for vapor-phase deposition and has high performance but is weak against humidity, can be provided, which could provide a basis for the technology in this field.

[Brief description of drawings]

FIG. 1 is a sectional view of the panel of the present invention. FIG. 2 is a cross-sectional plan view of the panel of the present invention. FIG. 3 is an explanatory diagram of a radiation image conversion method using the panel of the present invention. 11 ... Support, 12 ... Photostimulable phosphor layer, 13 ... Protective layer, 14 ... Crack, 15 ... Specific hydrophobic substance

Claims (1)

[Claims] 1. A radiation image conversion panel having at least one photostimulable phosphor layer provided by a vapor deposition method, wherein the photostimulable phosphor layer has a crack, and the crack has a hydrophobic polymer. A radiation image conversion panel characterized by being impregnated with a substance.