EP0577027A1 - Combinaison de matériau photographique à l'halogénure d'argent et d'écrans renforçateurs radiographiques - Google Patents

Combinaison de matériau photographique à l'halogénure d'argent et d'écrans renforçateurs radiographiques Download PDF

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Publication number
EP0577027A1
EP0577027A1 EP93110212A EP93110212A EP0577027A1 EP 0577027 A1 EP0577027 A1 EP 0577027A1 EP 93110212 A EP93110212 A EP 93110212A EP 93110212 A EP93110212 A EP 93110212A EP 0577027 A1 EP0577027 A1 EP 0577027A1
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EP
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Prior art keywords
photographic material
silver halide
layer
combination
halide photographic
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EP93110212A
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German (de)
English (en)
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EP0577027B1 (fr
Inventor
Yuichi c/o Fuji Photo Film Co. Ltd. Hosoi
Terumi c/o Fuji Photo Film Co. Ltd. Matsuda
Nobuyuki c/o Fuji Photo Film Co. Ltd. Iwasaki
Kazuhiko c/o Fuji Photo Film Co. Ltd. Takeuchi
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Fujifilm Holdings Corp
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Fuji Photo Film Co Ltd
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Priority claimed from JP04193432A external-priority patent/JP3083647B2/ja
Priority claimed from JP04193433A external-priority patent/JP3083648B2/ja
Application filed by Fuji Photo Film Co Ltd filed Critical Fuji Photo Film Co Ltd
Publication of EP0577027A1 publication Critical patent/EP0577027A1/fr
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/16—X-ray, infrared, or ultraviolet ray processes
    • G03C5/17—X-ray, infrared, or ultraviolet ray processes using screens to intensify X-ray images
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C2200/00—Details
    • G03C2200/58—Sensitometric characteristics
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21K—TECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K4/00—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens
    • G21K2004/04—Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens with an intermediate layer

Definitions

  • the present invention relates to a novel combination of a silver halide photographic material and radiographic intensifying screens, and the invention also relates to a novel radiographic intensifying screen and a novel silver halide photographic material employable for the combination. Particularly, the present invention relates to a novel combination of a silver halide photographic material and radiographic intensifying screens showing excellent characteristics in balance between the sensitivity and the image quality.
  • a radiographic image of the organ of patient is obtained by recording a pattern of X-rays having passed through the patient on a photographic material (silver halide photographic material) in which at least one photosensitive silver halide emulsion layer is provided on a transparent support by coating.
  • a radiographic intensifying screen is usually employed in combination with the photographic material so as to avoid exposure of the objective human body to a large dose of X-rays.
  • a radiographic intensifying screen provided on a support is a phosphor layer which absorbs X-rays and then converts them into the visible light to which the photographic material is sensitive. Therefore, the sensitivity of the system for X-ray photography can be remarkably improved by the use of a radiographic intensifying screen.
  • the photographic material placed in contact with said intensifying screen receives very diffuse visible light emitted by said screen because the visible light converted within the phosphor layer is scattered and reflected in the phosphor layer having an increased thickness which is caused by the increase of the phosphor.
  • the visible light converted within the deep area of the thick phosphor layer hardly comes out of the phosphor layer. Therefore immoderate increase of the phosphor content does not further increase the effective visible light emitted by the intensifying screen.
  • the total absorption of X-rays can be increased and the visible light converted in the intensifying screen can be efficiently used.
  • radiographic intensifying screens having different sensitivities in a wide range; for example, from the type of low sensitivity such as a screen that emits weak luminescence and gives an image of high sharpness (such screen has a relatively thin phosphor layer) to the type of high sensitivity such as a screen that emits high luminescence and gives an image of low sharpness (such screen has a relatively thick phosphor layer).
  • a silver halide photographic material having photographic emulsion layers provided on both sides has a defect that the image quality is likely deteriorated by "cross-over light".
  • the word “cross-over light” means the visible light which is emitted by each intensifying screen placed on each side of the photographic material and then passes through the support of the photographic material (thickness of the generally used support is 170-180 ⁇ m) and finally reaches the photosensitive layer provided on the opposite side to deteriorate the image quality (particularly, in sharpness).
  • U.S. Patent Nos. 4,425,425 and 4,425,426 disclose inventions in which a spectral sensitized emulsion including tabular silver halide grains having a high aspect ratio is used as a silver halide photographic emulsion. According to these patented inventions, the cross-over light can be reduced to 15-22 % level.
  • U.S. Patent No. 4,803,150 discloses an invention in which a dye layer comprising fine crystalline dye particles and being decolorizable by the developing process is provided between the support and the photosensitive layers in the silver halide photographic material. It is described that cross-over light can be reduced to 10 % level or less by the invention.
  • 4,803,150 disclose an X-ray photographic system: in which the light property (sensitivity) of the front side combination (consisting of an intensifying screen placed on the side to be exposed [i.e., front screen] and a photosensitive layer [i.e., front photosensitive layer]) is made to differ from that of the back combination (consisting of an intensifying screen placed on the opposite side [i.e., back screen] and a photosensitive layer [i.e., back photosensitive layer]), and the contrast given by the former combination is made to differ from that given by the latter.
  • Photographic Science and Engineering, vol. 26 (1982), No. 1, pp. 40 describes experiments about the combinations of intensifying screens and a silver halide photographic material each of which is available from 3M Co.
  • a radiographic image of high quality can be obtained by a combination of a silver halide photographic material of low sensitivity and radiographic intensifying screens of low sensitivity.
  • the exposure (dose) of X-rays applied to human body should be naturally increased. Therefore, such combination is not practically applicable, and particularly, in the case of group examination in which it is required to reduce the dose of X-rays to be applied as much as possible.
  • An object of the present invention is to provide a novel X-ray photographic system, that is, a combination of a silver halide photographic material and radiographic intensifying screens, which exhibits excellent characteristics in balance between the sensitivity and the image quality obtained by the combination.
  • an object of the invention is to provide a novel combination of a silver halide photographic material and radiographic intensifying screens which has practically satisfactory sensitivity and gives radiographic images having practically satisfactory image quality.
  • a further object of the invention is to provide a novel radiographic intensifying screen advantageously employable for the above novel X-ray photographic system.
  • a still further object of the invention is to provide a novel silver halide photographic material advantageously employable for the above novel X-ray photographic system.
  • the present invention resides in a combination for forming a radiographic image comprising a silver halide photographic material and two radiographic intensifying screens, one of which is placed on the front of said photographic material and the other of which is on the back; wherein 1) at least one of said intensifying screens absorbs X-rays of 80 KV p in an amount of not less than 25 % and shows contrast transfer function values of at least 0.79 and at least 0.36 at spatial frequencies of 1 lp/mm and of 3 lp/mm, respectively; and 2) said photographic material has silver halide photosensitive layers one of which is provided on the front of its support and another of which is on the back; and at least one of said photosensitive layers has such a sensitivity that 0.010-0.035 lux ⁇ second of exposure dose is required to obtain an image having a density of 0.5 more than the minimum density thereon, said density being determined by the steps of: exposing the photosensitive layer of the photographic material to monochromatic light of which wavelength is the same as the main emission wavelength of the intensifying screen defined in the
  • the invention also resides in a combination for forming a radiographic image comprising a silver halide photographic material and two radiographic intensifying screens, one of which is placed on the front of said photographic material and the other of which is on the back; wherein 1) at least one of said intensifying screens absorbs X-rays of 80 KV p in an amount of not less than 25 %; 2) said photographic material has silver halide photosensitive layers one of which is provided on the front of its support and another of which is on the back; and at least one of said photosensitive layers has such a sensitivity that 0.010-0.035 lux ⁇ second of exposure dose is required to obtain an image having a density of 0.5 more than the minimum density thereon, said density being determined by the steps of: exposing the photosensitive layer of the photographic material to monochromatic light of which wavelength is the same as the main emission wavelength of the intensifying screen defined in the above 1) and of which half width is 15 ⁇ 5 nm, developing at 35°C for 25 seconds in the developing solution comprising the following: potassium hydroxide 21
  • the former combination of the invention (COMBINATION I) comprises an intensifying screen having high sensitivity and showing contrast transfer function (CTF) in the specific range and a photographic material having sensitivity in the specific range. Owing to such a specific combination, the former combination of the invention provides an X-ray photographic system which shows excellent characteristics in balance between the sensitivity and the image quality.
  • CTF contrast transfer function
  • the latter combination of the invention (COMBINATION II) comprises an intensifying screen having high sensitivity and the photographic material having sensitivity in the specific range and prominently decreased cross-over. Owing to such a specific combination, the latter combination of the invention provides an X-ray photographic system which shows excellent characteristics in balance between the sensitivity and the image quality.
  • the sensitivity of each of the silver halide photographic material and the radiographic intensifying screen of the combination is independently defined.
  • the obtained radiographic image exhibits poor sharpness while their graininess is excellent.
  • the photographic material is replaced with a low sensitive photographic material showing high sharpness (which can be accomplished by reducing the cross-over)
  • the obtained radiographic image still exhibits unsatisfactory sharpness, which is unfavorably accepted in clinical diagnosis.
  • a radiographic image obtainable by a combination of a low sensitive intensifying screen absorbing a small amount of X-rays and a medium sensitive (i.e., standard) or high sensitive photographic material exhibit poor graininess while their sharpness is excellent.
  • the suitable sensitivity of each of the silver halide photographic material and the radiographic intensifying screens of the combination depends upon various conditions such as the sensitivity level of the combination and the size of the object.
  • the further study has revealed that a radiographic image of high quality can be obtained with high sensitivity using a combination of a photograpic material of a specific sensitivity and a radiographic intensifying screen which exhibits high contrast transfer function (CTF) and of which phosphor contents are increased to enhance the absorption of X-rays, while maintaining the required sharpness.
  • CTF contrast transfer function
  • a radiographic image of high quality is also obtainable with high sensitivity using a combination of a photograpic material having a high sensitivity and a reduced cross-over and a radiographic intensifying screen of which phosphor contents are increased to enhance the absorption of X-rays, while maintaining the required sharpness.
  • Preferred sharpness level depends on the size of the object.
  • the values of modulation transfer function (MTF) at spatial frequencies of 0.5 lp/mm to 3 lp/mm are important, and preferred values are not less than 0.65 and not less than 0.22 at 1 lp/mm and 2 lp/mm, respectively.
  • MTF modulation transfer function
  • Figure 1 shows the relation between spatial frequency (lp/mm) and contrast transfer function (CTF) with respect to the radiographic intensifying screen applied for the combination of the invention of silver halide photographic material and radiographic intensifying screens.
  • Figure 2 shows the characteristic curve of the green filter used in combination with tungsten light source for measuring the sensitivity of silver halide photographic material.
  • Figure 3 shows the relations between the sensitivity and the image quality of the radiographic image of chest, with respect to the combinations of the invention of silver halide photographic material and radiographic intensifying screens, and a combination of radiographic intensifying screens and silver halide photographic material generally used for X-ray photography.
  • the combination of the present invention of silver halide photographic material and radiographic intensifying screens is very sensitive and gives an image having excellent quality. Therefore, using the combination of the invention, a radiographic image having high recognizability can be obtained without increasing the dose of X-rays to which a human boy is exposed. Consequently, the combination of the invention of silver halide photographic material and radiographic intensifying screens is very advantageous for improving the precision of medical diagnosis.
  • the radiographic intensifying screen consists essentially of a support and a phosphor layer provided thereon.
  • the phosphor layer comprises a binder and phosphor particles dispersed therein.
  • a transparent film is generally provided on the free surface (surface which is not in contact with the support) of the phosphor layer to keep the phosphor layer from chemical deterioration and physical shock.
  • a preferred phosphor for the radiographic intensifying screen of the invention is a phosphor represented by the following formula: M (w-n) M' n O w X in which M is at least one metal selected from the group consisting of Y, La, Gd and Lu; M' is at least one rare earth element, preferably one rare earth element being selected from the group consisting of Dy, Er, Eu, Ho, Nd, Pr, Sm, Ce, Tb, Tm and Yb; X is an intermediate chalcogen (i.e., S, Se or Te) or a halogen; "n” is a number satisfying the condition of 0.0002 ⁇ n ⁇ 0.2; and "w” is 1 when "X” is a halogen, or is 2 when "X” is a chalcogen.
  • M is at least one metal selected from the group consisting of Y, La, Gd and Lu
  • M' is at least one rare earth element, preferably one rare earth element being selected from the group consisting of Dy,
  • phosphor preferably used for the radiographic intensifying screen of the invention are given below: terbium activated rare earth oxysulfide phosphors such as Y2O2S:Tb, Gd2O2S:Tb, La2O2S:Tb, (Y,Gd)2O2S:Tb, and (Y,Gd)2O2S:Tb,Tm; terbium activated rare earth oxyhalide phosphors such as LaOBr:Tb, LaOBr:Tb,Tm, LaOCl:Tb, LaOCl:Tb,Tm, GdOBr:Tb, and GdOCl:Tb; and thulium activated rare earth oxyhalide phosphors such as LaOBr:Tm and LaOCl:Tm.
  • terbium activated rare earth oxysulfide phosphors such as Y2O2S:Tb, Gd2O2S:Tb, La2O2S:Tb,
  • a particularly preferred phosphor for the radiographic intensifying screen of the invention is the terbium activated gadolinium oxysulfide phosphor.
  • terbium activated gadolinium oxysulfide phosphors there are detailed descriptions about terbium activated gadolinium oxysulfide phosphors in U.S. Patent No. 3,725,704.
  • the phosphor layer comprises a binder and phosphor particles dispersed therein.
  • the phosphor layer is generally provided on a support under an atmospheric pressure utilizing the following coating procedure.
  • the phosphor particles and the binder are mixed in an appropriate solvent to prepare a coating dispersion.
  • the coating dispersion is directly applied onto a surface of a support for radiographic intensifying screen under an atmospheric pressure using a doctor blade, roll coater, knife coater or the like, and the solvent contained in the coating dispersion is removed to form a phosphor layer.
  • the phosphor layer is placed on the support by the steps of applying the coating dispersion on a false support under an atmospheric pressure to form a phosphor sheet, peeling off the sheet from the false support, and then causing the sheet to adhere to a genuine support.
  • Preferably used for the invention is a radiographic intensifying screen in which the phosphor density is increased (that is, void volume of the phosphor layer is lowered) by compressing the phosphor layer containing the below-described thermoplastic elastomer as a binder.
  • the sensitivity of the radiographic intensifying screen is essentially determined by the total amount of emission given by the phosphor contained therein, and the total amount of emission varies depending upon not only the emission luminance of the phosphor per se but also the content (i.e., amount) of the phosphor in the phosphor layer.
  • the large content of the phosphor also results in increase of absorption of a radiation such as X-rays, so that the screen shows high sensitivity and provides an image of improved quality, especially in graininess.
  • an intensifying screen utilizing such a phosphor layer provides an image of high sharpness if the phosphor layer is densely packed with the phosphor, because such phosphor layer can be made thinner to reduce spread of stimulating rays which is caused by scattering within the phosphor layer.
  • radiographic intensifying screen is preferably prepared by a process comprising the steps of:
  • Step a) is described below.
  • a phosphor sheet for a phosphor layer of the radiographic intensifying screen can be prepared in the process which comprises applying the coating dispersion (i.e., binder solution in which the phosphor particles are uniformly dispersed) onto a false support, drying the coated film and peeling off the film to obtain the phosphor sheet (film).
  • the coating dispersion i.e., binder solution in which the phosphor particles are uniformly dispersed
  • the phosphor particles and the binder are mixed and stirred in an appropriate solvent to prepare a coating dispersion comprising the phosphor particles homogeneously dispersed in a binder solution.
  • thermoplastic elastomer of which softening point or melting point is in the range of 30-150°C is used alone or in combination with other binder polymers.
  • the destruction of the phosphor particles in a compression treatment can be avoided by the use of the thermoplastic elastomer, because it has elasticity at room temperature and has fluidity when it is heated.
  • thermoplastic elastomers include; polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, ethylene-vinyl acetate, polyvinyl chloride, natural rubber, fluorocarbon rubber, polyisoprene, chlorinated polyethylene, styrene-butadiene rubber and silicone rubber.
  • the binder preferably includes the thermoplastic elastomer as much as possible, and therefore it is most preferred that the binder comprises thermoplastic elastomer in its 100 wt.% content.
  • Examples of the solvents employable in the preparation of the dispersion include lower aliphatic alcohols such as methanol, ethanol, n-propanol and n-butanol; chlorinated hydrocarbons such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; esters of lower aliphatic alcohols with lower aliphatic acids such as methyl acetate, ethyl acetate and butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; and mixtures of the above-mentioned solvents.
  • lower aliphatic alcohols such as methanol, ethanol, n-propanol and n-butanol
  • chlorinated hydrocarbons such as methylene chloride and ethylene chloride
  • ketones such as acetone, methyl ethyl
  • the ratio between the binder and the phosphor in the coating solution may be determined according to the characteristics of the aimed radiographic intensifying screen and the nature of the employed phosphor. Generally, the ratio therebetween is in the range of 1:1 to 1:100 (binder: phosphor, by weight), preferably in the range of 1:8 to 1:40, by weight.
  • the coating solution may contain various additives such as a dispersing agent to improve dispersibility of the phosphor particles therein and a plasticiser to increase the bonding between the binder and the phosphor particles in the resulting phosphor layer.
  • a dispersing agent to improve dispersibility of the phosphor particles therein
  • a plasticiser to increase the bonding between the binder and the phosphor particles in the resulting phosphor layer.
  • the dispersing agent include phthalic acid, stearic acid, caproic acid and a hydrophobic surface active agent.
  • plasticizer examples include phosphates such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate; phthalates such as diethyl phthalate, and dimethoxyethyl phthalate; glycolates such as ethylphthalyl ethyl glycolate and butylphthalyl butyl glycolate; and polyesters of polyethylene glycols with aliphatic dicarboxylic acids such as polyester of triethylene glycol with adipic acid and polyester of diethylene glycol with succinic acid.
  • phosphates such as triphenyl phosphate, tricresyl phosphate and diphenyl phosphate
  • phthalates such as diethyl phthalate, and dimethoxyethyl phthalate
  • glycolates such as ethylphthalyl ethyl glycolate and butylphthalyl butyl glycolate
  • the coating dispersion containing the phosphor and the binder prepared as above is applied evenly onto a surface of a support to form a layer of the coating dispersion.
  • the coating procedure can be carried out by a conventional method such as a method using a doctor blade, a roll coater or a knife coater.
  • a false support material employable in the invention can be selected from those employed in the conventional radiographic intensifying screens such as glass plate and metal plate.
  • the support material include plastic films such as films of cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate and polycarbonate; metal sheets such as aluminum foil and aluminum alloy foil; ordinary papers; baryta paper; resin-coated papers; pigment papers containing titanium dioxide or the like; papers sized with polyvinyl alcohol or the like; and ceramic sheets such as sheets of alumina, zirconia, magnesia and titania.
  • the process for preparation of the phosphor sheet comprises the steps of applying the coating dispersion onto a false support, drying the coated film and peeling off the film to obtain the phosphor sheet for the phosphor layer of the radiographic intensifying screen. Therefore, the surface of the false support preferably is beforehand coated with a release agent so that the film may be easily peeled off.
  • Step b) is described below.
  • a support for a radiographic intensifying screen is prepared.
  • the support can be freely selected from the same materials as the material for the false support used in preparation of the phosphor sheet.
  • one or more additional layers are occasionally provided between the support and the phosphor layer, so as to enhance the adhesion between the support and the phosphor layer, or to improve the sensitivity of the screen or the quality of an image (sharpness and graininess) provide thereby.
  • a subbing layer or an adhesive layer may be provided by coating a polymer material such as gelatin over the surface of the support on the phosphor layer side.
  • a light-reflecting layer or a light-absorbing layer may be provided by forming a polymer material layer containing a light-reflecting material such as titanium dioxide or a light-absorbing material such as carbon black.
  • these additional layers may be provided on the support, and the constitution thereof can be optionally selected depending upon the purpose of the radiographic intensifying screen.
  • the phosphor sheet prepared in Step a) is placed on a support, and then compressed and affixed simultaneously on the support at a temperature of not lower than softening point or melting point of the binder.
  • the phosphor sheet is not beforehand fixed on a support but simultaneously compressed and affixed on the support. Therefore, the pressure extends throughout the sheet and the destruction of the phosphor particles can be avoided. Moreover, assuming that the pressure applied to the sheet is kept at the same level, the sheet simultaneously compressed and affixed on the support has higher packing ratio of the phosphor than that of the sheet which is beforehand fixed on the support and subjected to compression treatment.
  • Examples of the compressing apparatus for the compression treatment include known apparatus such as a calender roll and a hot press.
  • a compression treatment using a calender roll involves moving the phosphor sheet prepared in Step a) on a support to pass through between two rollers heated at a temperature not lower than softening point or melting point of the thermoplastic elastomer of the binder.
  • the compressing apparatus employable in the invention is not restricted to them. Any other apparatuses can be employed so long as they can compress a sheet such as the above-stated one under heating.
  • the pressure for compression preferably is not less than 50 kgw/cm2.
  • a radiographic intensifying screen generally has a transparent film on the free surface of the phosphor layer to physically and chemically protect the phosphor layer.
  • the transparent protective film generally has a thickness within the range of approximately 0.1 to 20 ⁇ m.
  • the transparent protective film can be formed on the phosphor layer by the steps of coating the surface of the phosphor layer with a solution of a transparent polymer such as a cellulose derivative (e.g., cellulose acetate or nitrocellulose), or a synthetic polymer (e.g. polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride-vinyl acetate copolymer), and drying the coated solution.
  • a transparent polymer such as a cellulose derivative (e.g., cellulose acetate or nitrocellulose), or a synthetic polymer (e.g. polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride-vinyl acetate copolymer
  • the transparent film can be provided on the phosphor layer by beforehand preparing a protective film from a plastic sheet of polyethylene terephthalate, polyethylene naphthalate, polyethylene, polyvinylidene chloride or polyamide; or transparent glass sheet, followed by placing and fixing it onto the phosphor layer with an appropriate adhesive agent.
  • the protective film for the radiographic intensifying screen preferably is a film formed from a solution containing fluoro-resin soluble in an organic solvent.
  • the fluoro-resin is a polymer of an olefin having fluorine (i.e., fluoroolefin) or a copolymer using an olefin monomer having fluorine as a copolymer component.
  • the film formed from the fluoro-resin solution may be cross-linked.
  • the protective film of fluoro-resin is advantageous because stain (caused by, for instance, the plasticizer and the like exuding from radiographic films or other materials in contact with the protective film) hardly permeates the film and the stain can be easily removed by wiping.
  • the film can be easily formed by the steps of applying a solution of the resin dissolved in a proper organic solvent and drying the coated solution in the same manner described above.
  • the protective film can be formed by the steps of evenly coating the surface of the phosphor layer with a solution for forming a protective film containing the fluoro-resin soluble in organic solvents by a doctor blade or the like, and drying the coated solution.
  • the protective film and the phosphor layer can be formed at the same time by simultaneous superposing coating method.
  • the fluoro-resin is a polymer of an olefin having fluorine (fluoroolefin) or a copolymer of an olefin having fluorine as a copolymer component.
  • fluoro-resins include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer and fluoroolefin-vinyl ether copolymer.
  • the fluoro-resin is generally insoluble in organic solvents, but the resin comprising a fluoroolefin as a copolymer component is soluble in organic solvents provided that other copolymer components (other than fluoroolefin) are appropriately selected. Therefore, by the steps of dissolving such resin into an appropriate solvent, applying the obtained solution onto the phosphor layer and drying the applied solution, the protective film can be easily formed.
  • An example of such copolymer is fluoroolefin-vinyl ether copolymer.
  • Polytetrafluoroethylene and its modified compounds are also employable for forming the protective film by application as well as the above-mentioned copolymer comprising fluoroolefin as a copolymer component, because they are soluble in a proper organic solvent of fluorine type such as a perfluoro-type solvent.
  • the protective film may contain a resin other than the fluoro-resin and may also contain additives such as a cross linking agent, a hardner and an anti-yellowing agent.
  • the amount of the fluoro-resin contained in the protective film is preferred to be not less than 30 wt.%, more preferably not less than 50 wt.%, and most preferably not less than 70 wt.%.
  • the resin employable in combination with the fluoro-resin include polyurethane resin, polyacryl resin, cellulose derivatives, polymethyl methacrylate, polyester resin and epoxy resin.
  • the protective film of the radiographic intensifying screen of the invention may comprise one or both of an oligomer having polysiloxane structure and an oligomer having perfluoroalkyl group.
  • the oligomer having polysiloxane structure has, for example, dimethylpolysiloxane structure, and it preferably has at least one functional group (e.g., hydroxyl group: -OH).
  • the molecular weight (average weight) preferably is within the range of 500-100,000, more preferably 1,000-100,000 and most preferably 3,000-100,000.
  • the oligomer having perfluoroalkyl group e.g., tetrafluoroethylene group
  • preferably has at least one functional group e.g., hydroxyl group: -OH
  • the molecular weight (average weight) of the oligomer preferably is within a range of 500-100,000, more preferably 1,000-100,000 and most preferably 10,000-100,000.
  • the oligomer having a functional group is very advantageous because of the following reason: namely, such oligomer is fastened to the structure of the resin for forming the protective film by cross-linking reaction between the oligomer and the resin during formtaion of the protective film, and so the oligomer is hardly removed by iterative use of the screen or by cleaning the film surface, and consequently the oligomer can effectively work for a long time.
  • the amount of the oligomer contained in the film preferably is within the range of 0.01-10 wt.%, more preferably 0.1-2 wt.%.
  • the protective film also may contain a powder of perfluoroolefin resin or a powder of silicone resin.
  • the average size of the powder of perfluoroolefin resin or silicone resin preferably is within the range of 0.1-10 ⁇ m, more preferably 0.3-5 ⁇ m.
  • the amount of the powder of perfluoroolefin resin or the powder of silicone resin contained in the protective film preferably is within the range of 0.5-30 wt.%, more preferably 2-20 wt.% and most preferably 5-15 wt.%, based on the total weight of the protective film.
  • the radiographic intensifying screen for invention preferably is highly sensitive and shows contrast transfer function (CTF) values of at least 0.79 and at least 0.36 at the spatial frequencies of 1 line/mm and of 3 lines/mm, respectively.
  • CTF contrast transfer function
  • the radiographic intensifying screen for invention shows CTF values higher, at any spatial frequency, than the following relation curve between spatial frequency plotted on horizontal axis (1p/mm or line/mm) and CTF values plotted on vertical axis.
  • 1p/mm CTF 0.00 1.00 0.25 0.950 0.50 0.905 0.75 0.840 1.00 0.790 1.25 0.720 1.50 0.655 1.75 0.595 2.00 0.535 2.50 0.430 3.00 0.360 3.50 0.300 4.00 0.255 5.00 0.180 6.00 0.130
  • the measurement and evaluation of the contrast transfer function of from a radiographic intensifying screen to a photographic material can be carried out using the MRE single face material specimen (available from Eastman Kodak) on which a rectangular chart is printed.
  • Figure 1 shows the above relation curve between spatial frequency (1p/mm) and CTF values.
  • the preferred radiographic intensifying screen having the above-mentioned characteristics can be easily prepared by the method in which the above-described thermoplastic elastomer is used as a binder and the phosphor layer is compressed.
  • the protective film of the radiographic intensifying screen is a transparent synthetic resin layer having the thickness of not more than 5 ⁇ m.
  • a thin protective layer contributes to improving the sharpness of the obtained radiographic image, because it shortens the distance between the silver halide photographic material and the phosphor on the radiographic intensifying screen.
  • the silver halide photographic material for the invention has the constitution: in which provided are silver halide photographic layers one of which is provided on the front of a support and another of which is on the back of the support; and at least one of said photosensitive layers has the sensitivity that 0.010-0.035 lux ⁇ second (preferably, 0.012-0.030 lux ⁇ second) of exposure dose is required to obtain an image having a density of 0.5 more than the minimum density thereon, said density being obtained by the steps of: exposing the photographic material to monochromatic light of which wavelength is the same as the main emission wavelength of the radiographic intensifying screen defined in the aforementioned 1) and of which half width is 15 ⁇ 5 nm, developing at 35°C for 25 seconds in the developing solution (which is referred to as "Standard developer” or “Developer A”, hereinafter) comprising the following: potassium hydroxide 21 g potassium sulfite 63 g boric acid 10 g hydroquinone 25 g triethylene glycol 20 g 5-nitroindazole
  • the silver halide photographic material is so produced that more than 15 %, more preferably not more than 10 %, most preferably 10 to 2 %, of the light emitted by the intensifying screen placed on the front of said photographic material, that is, cross-over light, may not reach the photosensitive layer provided on the back of said material.
  • the wavelength of exposing light should precisely or nearly correspond to the main emission wavelength of the radiographic intensifying screen used in combination.
  • the wavelength of the light used for measuring the sensitivity of the photographic material should be around 545 nm because the main emission wavelength of the phosphor is 545 nm.
  • the monochromatic light can be obtained by means of a filter system in which interference filters are combined. Using such filters system, a monochromatic light which has sufficient intensity to be used and of which half width is 15 ⁇ 5 nm can be easily obtained, though the intensity of the light depends upon the combination of the interference filters. Since the spectral sensitivity spectrum of photographic material is continuous independently of spectral sensitization, the sensitivity is practically constant within the half width of 15 ⁇ 5 nm.
  • An example of the exposure light source in the case that terbium activated gadolinium oxysulfide phosphor is used as the phosphor of the intensifying screen, is a system comprising a tungsten light (color temperature: 2,856 K) and a filter having the characteristics shown in Fig. 2.
  • Developing time 25 seconds (21 sec. in the solution + 4 sec. in air) Fixing time: 20 seconds (16 sec. in the solution + 4 sec. in air; The fixing solution has the below-described composition.) Washing: 12 seconds Squeege and drying: 26 seconds
  • Developing Apparatus a commercially available roller conveyor automatic developing machine (e.g., FPM-5000 automatic developing machine available from Fuji Photo Film Co., Ltd.); (Developing tank 22 liter [vol.],35°C [temp.]); (Fixing tank 15.5 liter [vol.], 25°C [temp.]); Another example of the commercially available roller conveyor automatic developing machine is M-6AW available from Eastman Kodak.
  • Fixing Solution F The composition of the fixing solution (hereinafter, referred to as Fixing Solution F) is as follows: ammonium thiosulfate (70 % wt./vol.) 200 ml sodium sulfite 20 g boric acid 8 g sodium ethylenediaminetetraacetate (dihydrates) 0.1 g aluminum sulfate 15 g sulfuric acid 2 g glacial acetic acid 22 g and water to adjust the volume to 1 liter, and then, if required, the value of pH is adjusted to 4.2 using sodium hydroxide or glacial acetic acid.
  • cross-over The measurement of the amount of the cross-over light (hereinafter simply referred to as "cross-over") is performed in the following manner: a photographic material having photosensitive layers provided on both sides is placed on the radiographic intensifying screen in contact with the front surface or the screen; and then a sheet of black paper is placed on the photographic material in contact with the front surface (i.e, the surface other than the surface contacting the screen) of said material; in this arrangement, the material is exposed to X-rays with various doses, which are adjusted by varying the distance between the intensifying screen and the focal spot of the X-ray generator; thereafter, the exposed material is developed and then divided into two sheets.
  • the photosensitive layer having been in contact with the intensifying screen (back side photosensitive layer) is peeled off, and from another sheet, the photosensitive layer on the other side (front side photosensitive layer) is peeled off.
  • the optical density is measured and plotted against the corresponding dose to draw a characteristic curve for each layer.
  • a typical silver halide photographic material for the invention comprises, for example, a subbing layer, a dye layer (which is provided to reduce the cross-over, if needed), at least one photosensitive silver halide emulsion layer, and a protective layer, superposed in this order on each side (i.e., on each of the front side and the back side) of a blue-colored transparent support.
  • a subbing layer a dye layer (which is provided to reduce the cross-over, if needed)
  • at least one photosensitive silver halide emulsion layer which is provided to reduce the cross-over, if needed
  • a protective layer superposed in this order on each side (i.e., on each of the front side and the back side) of a blue-colored transparent support.
  • each layer provided on one side is substantially the same as the corresponding layer provided on the other side.
  • the support is made of transparent material such as polyethylene terephthalate, and is colored with a blue dye.
  • Various blue dyes such as anthraquinone dye, which is known as a dye for radiographic film, are employable.
  • the thickness of the support is within the range of 160-200 ⁇ m.
  • a subbing layer of water-soluble polymer such as gelatin can be provided on the support in the same way as the conventional radiographic film.
  • a dye layer is provided on the subbing layer to reduce cross-over.
  • the dye layer is usually prepared in the form of a colloidal layer containing a dye, and the layer can be preferably decolorized in the developing process defined in the above. It is also preferred that the dye be fixed in the bottom part of the layer in order not to enter into the photosensitive silver halide emulsion layer or the protective layer provided thereon.
  • the above-mentioned dye layer effectively reduces the cross-over to 15 % or less, particularly 10 % or less.
  • a photosensitive silver halide emulsion layer is provided on the dye layer.
  • the photosensitive silver halide emulsion layer of the photographic material of the invention can be prepared in the known manner. However, since the silver halide emulsion used for the invention is relatively low-sensitive among the emulsions for known radiographic materials, it is preferred to comprise silver halide particles of a small size.
  • the preferred size of the particles is 0.3-0.8 ⁇ m (more preferably, 0.5-0.7 ⁇ m) in terms of the mean diameter of the circle corresponding to the projected area, when a non-tabular particle (of which aspect ratio is nearly 1) is used for the invention.
  • the size of the particles preferably is within the range of 0.4-1.4 ⁇ m (more preferably, 0.5-1.0 ⁇ m).
  • the sensitivity of the silver halide emulsion can be reduced by other methods such as the method in which dyes are added to the emulsion, and the method in which the degree of sensitization (spectral sensitization or chemical sensitization) is reduced.
  • the silver halide photographic material should be sensitive to the light emitted by the radiographic intensifying screen used in combination. Since an ordinary silver halide emulsion is sensitive to the light of which wavelength is within the range of blue to ultraviolet, it can be used in combination with an intensifying screen which emits the luminescence of which wavelength is within the range of blue to ultraviolet (example of such screen is a radiographic intensifying screen using calcium tungstate phosphor). However, the silver halide in the photographic material should be spectral sensitized to green light if an intensifying screen using terbium activated gadolinium oxysulfide phosphor, which emits luminescence having main wavelength of 545 nm, is used.
  • the silver halide emulsion for the silver halide photographic material of the invention comprises tabular silver halide particles.
  • the emulsion comprising tabular silver halide particles exhibits excellent characteristics in balance between the sensitivity and the image quality, and has excellent spectral-sensitizable characteristics and high ability to reduce the cross-over. Therefore, such emulsion is very advantageous.
  • Such methods are employable for preparing the tabular silver halide particle emulsion for the preparation of the photographic material of the invention.
  • improved methods include: the method in which reduction sensitization is performed in combination with addition of a mercapto compound or a certain dye to improve the pressure characteristics; the sensitization method using selenium compounds; the method in which the iodide content of the particle surface is lowered to reduce the pressure mark possibly produced in the transfer using rollers; and the method (which is applied for preparing two silver halide emulsions used for the photographic material having double photosensitive layers) in which the silver/gelatin ratio of each emulsion is optimized to improve the balance between drying ability and reduction of the pressure mark produced in the transfer using rollers.
  • the silver halide photographic material of the invention preferably has a dye layer which can be decolorized in the developing process performed under the aforementioned conditions. From this point of view, it is preferred to reduce the amount of the binder used in the photosensitive layer superposed on the dye layer.
  • the amount of the binder in the photosensitive layer preferably is not more than 5 g/cm2, more preferably not more than 3 g/cm2.
  • the amount of the silver contained in the photosensitive layer preferably is not more than 3 g/cm2, more preferably not more than 2 g/cm2.
  • the silver halide photographic material used in the invention is preferably prepared to give an exposure image having the following characteristic curve, after stepwise exposing the photographic material to X-rays and developing the material under the conditions described above: the characteristic curve having the mean gamma ( ⁇ ) between the point of the density higher than the minimum density by 0.1 (the point of D min + 0.1) and the point of the the density higher than the minimum density by 0.5 (the point of D min + 0.5) within the range of 0.5-0.9, and the mean gamma ( ⁇ ) between the point of D min + 1.2 and the point of D min + 1.6 within the range of 3.2-4.0; said characteristic curve being drawn on the rectangular coordinate in which the unit length of the axis of optical density (D) is the same as that of the axis of exposure (log E).
  • the silver halide photographic material giving the above-described characteristic curve is employed for the radiographic system of the invention, a radiographic image having excellent characteristics can be obtained.
  • the characteristic curve of such image shows an elongated toe and high gamma in the medium density region. Therefore, by the use of the photographic material having the above-described characteristics, radiographic images of a low density (such as a radiographic image of mediastinum or shadow of heart, through which only a small amount of X-rays can pass) can be made much clearer and the density of a radiographic image of the field of lung through which a large amount of X-rays can pass, can be more clearly visualized. Besides that, the contrast of the images are also improved.
  • the silver halide photographic material giving the above-described preferable characteristic curve can be a photographic material having two or more silver halide emulsion layers, provided on each side of which sensitivities differ from each other. With respect to such photographic material, it is particularly preferred that the upper layer be of high sensitive and the lower one be of low sensitivity and give high contrast.
  • the difference of sensitivity between the two layers generally is set to not less than 1.5 times, preferably not less than twice, as much as the sensitivity of the lower layer.
  • the ratio of the amounts of the emulsions used in each layer is determined according to the differences of sensitivity and covering power between the adopted emulsions.
  • the amount of the high sensitive emulsion to be used is reduced, when the difference of sensitivity is increased. For instance, if one emulsion is twice as sensitive as the other and that covering powers of them are nearly the same, the ratio of the high sensitive emulsion to the low-sensitive one is within the range of 1:20 to 1:5, in terms of the amount of silver.
  • a protective layer comprising a water-soluble polymer such as gelatin is provided in the known manner to finally prepare a silver halide photographic material of the invention.
  • Anti-fogging agent & stabilizer ibid. pp.10, col.L-B, 1.17 - pp.11, col.L-T, 1.7 3.
  • the combination of the invention can be constituted by a combination of a photographic material having the specific sensitivity and one or two high sensitive radiographic intensifying screens which absorb X-rays to give spatial frequencies in the specific range.
  • a preferred example of the combination comprises a radiographic intensifying screen which absorbs X-rays of 80 KV p in the ratio of 30 to 40 % and a photographic material whose sensitivity defined hereinbefore corresponds to 0.012-0.015 lux ⁇ second.
  • a further preferred example of the combination comprises a pair of a radiographic intensifying screen which absorbs X-rays of 80 KV p in the ratio of 30 to 40 % and a photographic material of which sensitivity defined above corresponds to 0.02-0.03 lux ⁇ second.
  • the latter can give an image having excellent image quality with a practical sensitivity (i.e., an acceptable dose of X-rays).
  • a silver halide photographic material in which each of the front and the back photosensitive layers satisfies the above-described conditions concerning the sensitivity, and the characteristics of corresponding layers are substantially the same.
  • a radiographic intensifying screen having the same characteristics as those of the intensifying screen on the other side is preferably provided.
  • the amount of the phosphor coated on the front intensifying screen can be made to be smaller than that of the phosphor coated on the back side screen, as is described in U.S. Patent No. 4,710,637.
  • the combination of the invention comprising a silver halide photographic material and two radiographic intensifying screens is selected so that the combination can have practically acceptable sensitivity and futher that excellent radiographic image quality can be obtained.
  • the total sensitivity of the combination gives the density of 1.0, the density being obtained by the steps of exposing the combination to X-rays of 80 KV p with a exposure dose in the range of 0.5-1.5 mR generated by a three-phase X-ray generator and developing in the above-defined developing solution under the aforementioned conditions.
  • the measurement of Detective Quantum Efficiency is generally utilized for measuring image formation efficiency of a combination comprising a silver halide photographic material and radiographic intensifying screens. Further, the measurement of Noise Equivalent Quanta (NEQ) is also used for totally evaluating both sharpness and graininess.
  • the value of DQE is calculated by dividing (Signal/Noise)2 value of the image finally formed on the photographic material of the combination by (Signal/Noise)2 value of the X-rays impinged onto the photographic material. If an ideal image is formed, the value of DQE is 1. However, the value is usually less than 1.
  • the value of NEQ is defined by (Signal/Noise)2 value of the finally obtained image.
  • DQE NEQ( ⁇ ) / O ⁇
  • NEQ( ⁇ ) ⁇ log e ⁇ ⁇ (MTF( ⁇ )) ⁇ 2 / NPS0( ⁇ )
  • ⁇ represents the contrast
  • MTF( ⁇ ) is the modulation transfer function of the image
  • NPS0( ⁇ ) is the output noise power spectrum
  • ⁇ represents spatial frequency
  • O is the number of the impinged X-ray quanta.
  • the relation between sensitivity and image quality can be evaluated by DQE.
  • DQE The relation between sensitivity and image quality.
  • the image quality of the finally obtained image can be evaluated by NEQ. In other words, if the combination has a higher NEQ, it gives better image quality.
  • NEQ gives physical evaluation of the image quality, it does not directly indicate clinical recognizability of the image. In fact, if the graininess and the sharpness of the image are extremely unbalanced, the image does not exhibit high visual recognizability for diagnosis. Therefore, from a clinical point of view, the image is preferably evaluated based on both NEQ and MTF.
  • radiographic intensifying screens were prepared in a pair (i.e, front screen and back screen).
  • Radiographic intensifying screen A (Sample A) Radiographic intensifying screen B (Sample B)
  • Binder A polyurethane, Desmolac TPKL-5-2625 (trade name); available from Sumitomo Bayer Urethane Co., Ltd. [solid content: 40 %]
  • Binder B nitrocellulose, nitration degree: 11.5 %)
  • the obtained dispersion was coated on a polyethylene terephthalate film (false support, thickness: 180 ⁇ m) which had been beforehand coated with a silicon release agent so that the thickness of the obtained phosphor layer would be 160 ⁇ m (this thickness was measured after the compression treatment described below was done). After being dried, the coated film was peeled off to give a phosphor sheet.
  • the obtained dispersion for a subbing layer was coated by a doctor blade on a polyethylene terephthalate film containing titanium dioxide (support, thickness: 250 ⁇ m) which was placed on a glass plate.
  • the coated layers were heated at temperatures gradually rising from 25°C to 100°C to prepare a subbing layer (thickness: 15 ⁇ m).
  • the phosphor sheet prepared above was superposed on the subbing layer, and then the prepared composite was compressed at a pressure of 400 kgw/cm2 and a temperature of 80°C using a calender roll.
  • fluoro-resin fluoroolefinvinyl ether co-polymer, Lumiflon LF100 (trade name); available from Asahi Glass Co., Ltd.
  • 25 g of a crosslinking agent isocyanate, Desmodul Z4370 (trade name); available from Sumitomo Bayer Urethane Co., Ltd.
  • 5 g of an epoxy resin of Bisphenol A type and 5 g of an alcohol modified silicone oligomer which had dimethylpolysiloxane structure and hydroxyl groups (carbinol groups) at both terminals, X-22-2809 (trade name); available from Shin-Etsu Chemical Co., Ltd.
  • solvent mixture of toluene and isopropyl alcohol (1:1, in volume) to prepare a dispersion for a protective film.
  • the obtained dispersion for a protective film was coated by a doctor blade on the phosphor layer having been compressed on the support.
  • the coated film was heated to 120°C for 30 minutes to prepare a transparent protective film having a thickness of 3 ⁇ m.
  • radiographic intensifying screen A consisting of a support, a subbing layer, a phosphor layer and a transparent protective film was prepared.
  • the obtained screen was named "Radiographic intensifying screen A”.
  • Radiographic intensifying screen A The procedure of the above-described preparation of Radiographic intensifying screen A was repeated except that the phosphor layer was prepared so that the thickness of the obtained layer would be 230 ⁇ m (this thickness was measured after the compression treatment was made) to prepare a radiographic intensifying screen consisting of a support, a subbing layer, a phosphor layer and a transparent protective film.
  • the obtained screen was named "Radiographic intensifying screen B".
  • An X-ray generator of tungsten target tube (80 KV p , three-phase) was set, and the sample screen was placed in front of the tungsten anode of the target tube at a distance of 200 cm. Thereafter, the sample screen was exposed to X-rays generated by the tube through an aluminium plate having the thickness of 3 mm. The amount of X-rays passing through the screen was measured by an ionization dosimeter placed behind the screen at a distance of 50 cm. Independently, as a blank test, the measurement without the screen was carried out to obtain the amount of X-rays directly reaching the dosimeter.
  • a photographic material (MRE single face type; available from Eastman Kodak) was placed in close contact with the sample screen, and then a radiographic image of a rectangular chart for measuring MTF (made of molybdenum, thickness: 80 ⁇ m, spatial frequency: 0-10 lp/mm) was obtained in the following manner.
  • the chart was placed in front of an X-ray tube at a distance of 2 m.
  • the photographic material was placed behind the chart (i.e., material faced the tube through the chart) and the sample intensifying screen was provided behind the photographic material in close contact.
  • the X-ray tube was DRX-3724HD (Trade name) available from Toshiba Corporation, in which X-rays were generated by tungsten target and a pulse generator (80 KV p , three-phase), and then passed through 3 mm thick aluminium equivalent material including aperture to make the focal spot size of 0.6 mm ⁇ 0.6 mm.
  • the X-rays generated from the tube were made to pass through a filter of water having a path of 7 cm (which absorbed X-rays in nearly the same amount as a human body) to obtain a radiographic image of the chart.
  • the exposed photographic material was developed by means of a roller conveyor automatic developing machine (FPM-5000) available from Fuji Photo Film Co., Ltd. in the manner described hereinbefore.
  • RD III developing solution available from Fuji Photo Film Co., Ltd. (of which composition was the same as that of above-described Developing Solution A) was used at 35°C
  • Fixing Solution F which was prepared in the following manner: 200 ml of ammonium thiosulfate [70 % wt./vol.], 20 g of sodium sulfite, 8 g of boric acid, 0.1 g of disodium ethylenediaminetetraacetate [dihydrates], 15 g of aluminum sulfate, 2 g of sulfuric acid, and 22 g of glacial acetic acid were added to water so that the volume would be 1 liter, and then the value of pH was adjusted to 4.2) was used at 25°C.
  • the density of the radiographic image of the developed sample was measured to obtain a density profile by means of a microdensitometer under the condition that the aperture was a slit of 30 ⁇ m ⁇ 500 ⁇ m (scanning direction ⁇ vertical direction) and the sampling distance was 30 ⁇ m. This procedure was repeated twenty times and the obtained values were averaged to obtain the density profile on which CTF was calculated. Thereafter, the peak corresponding to the pulse of each spatial frequency in the density profile was observed to calculate the density contrast of each frequency.
  • the dose was adjusted by varying the distance between the combination and the X-ray source, which was the same generator as used in the above-described CTF measurement.
  • the exposed material was developed in the same manner as described in the CTF measurement.
  • the sample for the measurement was prepared.
  • the density of the prepared sample was measured using visible light to obtain a characteristic curve. According to the obtained characteristic curve, the dose of X-rays required to give a density of D min + 1.0 was measured and the sensitivity was defined by the reciprocal number of said required dose. The calculated sensitivity of each sample was reduced to a relative value, based on the sensitivity of HR-4 (commercially available radiographic intensifying screen) on the back side being set at the value of 100 as the standard. The results are set forth in Table 1.
  • Table 1 screen X-ray absorption Sensitivity CTF (1 lp/mm) CTF (3 lp/mm) HR-3 (front) 18.2 % 48 0.890 0.660 HR-3 (back) 18.2 % 48 0.889 0.660 HR-4 (front) 22.3 % 89 0.850 0.510 HR-4 (back) 23.1 % 100 0.850 0.506 HR-8 (front) 31.3 % 155 0.775 0.340 HR-8 (back) 32.2 % 170 0.763 0.336 Screen A 32.8 % 200 0.869 0.494 Screen B 43.2 % 270 0.802 0.375
  • salts were removed by the precipitation method. After the emulsion was heated to 40°C, 30 g of gelatin, 2.35 g of phenoxyethanol and 0.8 g of sodium polystyrenesulfonate as a viscosity improver were added. The pH and pAg values of the resulting emulsion were adjusted to 5.90 and 8.25, respectively, with sodium hydroxide and aqueous silver nitrate solution.
  • the emulsion was chemically sensitized under stirring at 56°C in the following manner.
  • Silver bromide was added to the emulsion at a ratio of 0.1 mol %, and then 0.043 mg of thiourea dioxide was added. Subsequently, the emulsion was settled for 22 minutes for performing reduction sensitization.
  • 20 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene and 400 mg of the following sensitizing dye were added:
  • 0.83 g of calcium chloride was further added.
  • 1.3 mg of sodium thiosulfate, 2.7 mg of the following selenium sensitizer: 2.6 mg of chloroauric acid and 90 mg of potassium thiocyanate were added.
  • the emulsion was settled for 40 minutes and then cooled to 35°C. Thus, a fine tabular particle-monodispersed emulsion was obtained.
  • the hardening agent was added in such amount that the swelling ratio would be 230 %.
  • a coating dispersion containing the following components per 1 m2 was prepared:
  • the surface of a biaxially stretched polyethylene terephthalate film colored with a blue dye having a thickness of 175 ⁇ m was subjected to corona discharge treatment. Then, each surface was sequentially and superposingly coated with the coating dispersions having the following composition in the amounts described below (amount of each component was based on a dispersion for coating a single face) by a wire-bar coater to form a subbing layer consisting of two sub-layers on each surface.
  • the obtained emulsion was sensitized to prepare a coating dispersion in the same manner as described in the procedure for Silver halide photographic material I.
  • Silver halide photographic material II was prepared in the same manner as described in the procedure for Silver halide photographic material I.
  • the amount of the applied coating dispersion of silver halide emulsion was 1.64 g/m2 (amount in terms of silver metal) per one surface.
  • the obtained emulsion was sensitized to prepare a coating dispersion in the same manner as described in the procedure for Silver halide photographic material I.
  • Silver halide photographic material III was prepared in the same manner as described in the procedure for Silver halide photographic material I.
  • the amount of the applied coating dispersion of silver halide emulsion was 1.50 g/m2 (amount in terms of silver metal) per one surface.
  • the obtained emulsion was sensitized to prepare a coating dispersion in the same manner as described in the procedure for Silver halide photographic material I.
  • Silver halide photographic material IV was prepared in the same manner as described in the procedure for Silver halide photographic material I.
  • the amount of silver halide emulsion of the applied coating dispersion was 1.38 g/m2 (amount in terms of silver metal) per one surface.
  • the sensitivity of the sample material was measured using light emitted by a tungsten light source (color temperature: 2856 K) and then passing through the optical filter having the characteristic curve shown in Fig. 2 (by which the wavelength of the light was set to around 545 nm - corresponding to the main wavelength of the luminescence of the below-described radiographic intensifying screen used in combination).
  • the sample photographic material was exposed to the above light through a neutral step wedge for 1/20 second.
  • the exposed photographic material was developed in RD III developing solution available from Fuji Photo Film Co., Ltd. (of which composition was the same as those of the above-described developing solution A) at 35°C for 25 seconds (total processing time: 90 seconds) by means of an automatic developing machine (FPM-5000) available from Fuji Photo Film Co., Ltd.
  • FPM-5000 automatic developing machine
  • the exposure dose required to give the density of D min + 0.5 was calculated and the sensitivity was defined by the required exposure dose.
  • the results expressed by lux ⁇ second are set forth in Table 2.
  • the illuminance of the light emitted by the tungsten light source and then passing through the optical filter was measured by an compnsated illuminometer of PI-3F type (compensated).
  • the sample silver halide photographic material was placed between a sheet of black paper and Radiographic intensifying screen A (containing terbium activated gadolinium oxysulfide phosphor, the main emission wavelength: 545 nm, green light).
  • the black paper on this combination was placed to face an X-ray generator, and then exposed to X-rays.
  • the X-ray generator used in this measurement was the same as used for the evaluation of a radiographic intensifying screen.
  • the photographic material was exposed to X-rays in various doses, which were adjusted by varying the distance between the intensifying screen and the X-ray generator. After the exposing process was complete, the exposed material was developed in the same manner as stated in the measurement of sensitivity.
  • the developed photographic material was divided into two sheets.
  • the photosensitive layer on each sheet was independently peeled off.
  • the density of the photosensitive layer having been in contact with the intensifying screen was found higher than that of the photosensitive layer in the other side (black paper side).
  • Radiographic intensifying screen A was replaced with other intensifying screens.
  • the obtained values were nearly the same as obtained in the above measurement.
  • a photographic material to be measured was sandwiched between two radiographic intensifying screens to prepare a sample combination. With respect to the prepared combination, the exposing and developing processes were carried out in the same manner as described in the measurement of sensitivity of intensifying screens.
  • the dose of X-rays required to give the density of D min + 0.5 was measured and the sensitivity was defined by the reciprocal number of said required dose.
  • the calculated sensitivity of each sample was converted to a relative value, based on the sensitivity of the combination consisting of HR-4/Super HRS being set at the value of 100 as the standard.
  • the value of gamma was expressed by the average gamma between density of 0.8 and 1.2.
  • a sample photographic material was placed between two sample radiographic intensifying screens, and then a radiographic image of the rectangular chart for measuring MTF described above was formed.
  • the chart was placed in front of the aforementioned X-ray tube at a distance of 2 m.
  • the photographic material was placed behind the chart (i.e., the material faced the tube through the chart) and the sample intensifying screen was placed behind the photographic material in close contact.
  • the exposed photographic material was developed by means of a roller conveyor automatic developing machine available from Fuji Photo Film Co., Ltd. (FPM-5000) in the manner described above.
  • the dose of X-rays in exposing process was the same as described above.
  • the density of the radiographic image of the developed sample was measured by microdensitometer to obtain a density profile. This procedure was twenty times repeated and the obtained values were averaged to obtain the density profile on which CTF was calculated. Thereafter, the peak corresponding to the pulse of each spatial frequency in the density profile was detected to calculate the density contrast at each frequency.
  • the obtained density contrast was converted to the effective exposure rectangular contrast based on the independently obtained characteristic curve.
  • MTF( ⁇ ) b(1+(au)2) ⁇ 1 (each of "a” and "u” is a parameter).
  • the parameters were determined in the same manner as in the derivation of Coltman's formula.
  • the effective exposure rectangular contrast was expressed by MTF( ⁇ ) and its components at high frequencies such as MTF(3), MTF(5), ⁇ ⁇ ⁇ ⁇ ⁇ , MTF(111); and then the parameters were determined so that the calculated values might correspond to the observed values.
  • the measurement was carried out using the same X-ray generator as used in the measurement of MTF (in which the X-rays of 80 KV p were caused to pass through the 3 mm aluminum equivalent material and the filter of water having the path of 7 cm).
  • the combination was placed in front of the X-ray tube at a distance of 2 m, and exposed to the X-rays.
  • the dose of X-rays was so adjusted that the density of the image of the developed material might be 1.0.
  • the sample for measuring NPS0( ⁇ ) was prepared.
  • the density of the image of the sample was measured by the microdensitometer on condition that the aperture was a slit of 30 ⁇ m ⁇ 500 ⁇ m (scanning direction ⁇ vertical direction) and that the sampling distance was 20 ⁇ m.
  • the number of sampling points was 8192 points/line ⁇ 12 lines.
  • the results were divided at every 256 points, and FFT processing was performed.
  • the FFT treatment was 1320 (average) times repeated to obtain a noise power spectrum.
  • An image of the chest phantom (available from Kyoto Kagaku Co., Ltd.) was photographed in the following manner.
  • An X-ray generator three-phase; 12 pulse; 100 KV p ) equipped with a 3 mm aluminum equivalent material to make the focal spot size of the generated X-rays to be 0.6 mm ⁇ 0.6 mm was used.
  • the phantom was placed in front of the X-ray generator at a distance of 140 cm. Behind the phantom, a grid for inhibiting scattering (grid ratio: 8:1) and the combination of photographic material and intensifying screen were placed. In this arrangement, a radiographic image of the phantom was obtained.
  • the photographic material of the combination was developed in RD III developing solution and the aforementioned Fixing Solution F at 35°C for 25 seconds (total processing time: 90 seconds) by the automatic developing machine (FPM-5000) in the same manner as in the measurement of photographic characteristics.
  • the dose of X-rays was adjusted by varying the exposure time so that the density of the determined point on the image might be 1.6.
  • the quality of the obtained image of the chest phantom was visually estimated mainly from the viewpoint of clinical recognizability of veins in lung.
  • the results were expressed by the marks A, B, C and D which mean "excellent”, “good”, “recognizable” and “not recognizable", respectively. Further, more detailed estimation was expressed using small letters "a” and "z”. For instance, if two images each of which quality was assigned to the same mark A have slightly different qualities, the better one was expressed by Aa and the worse was by Az.
  • Example 1 The procedure of the preparation of Silver halide photographic material I in Example 1 was repeated except that the upper sub-layer of the subbing layer of the support was formed by coating the following dispersion of fine crystalline dye particles, to prepare four Silver halide photographic materials V, VI, VII and VIII.
  • the dye particles having the diameter of not less than 0.9 ⁇ m were removed by centrifugation to obtain the aimed dye dispersion.
  • the combination of the invention of silver halide photographic material and radiographic intensifying screen exhibits excellent characteristics in balance between the sensitivity and the image quality, as compared with the known combination of silver halide photographic material and radiographic intensifying screen generally used for radiography.
  • the combination of the invention gives a radiographic image of better quality, under the condition that the sensitivity is kept at the same level, and on the other hand, under the condition that the image quality is kept at the same level, the radiography can be carried out at a smaller dose of X-rays.
  • radiographic intensifying screens were prepared in a pair (i.e, front screen and back screen).
  • Radiographic intensifying screen A (Sample A, which was the same as Radiographic intensifying screen A prepared in Example 1)
  • Radiographic intensifying screen B (Sample B, which was the same as Radiographic intensifying screen B prepared in Example 1)
  • the X-ray absorption was measured in the manner as described in Example 1.
  • the contrast tansfer function was measured in the manner as described in Example 1.
  • the sensitivity was measured in the manner as described in Example 1.
  • Table 7 screen X-ray absorption Sensitivity CTF (1 lp/mm) CTF (3 lp/mm) HR-3 (front) 18.2 % 48 0.890 0.660 HR-3 (back) 18.2 % 48 0.889 0.660 HR-4 (front) 22.3 % 89 0.850 0.510 HR-4 (back) 23.1 % 100 0.850 0.506 HR-8 (front) 31.3 % 155 0.775 0.340 HR-8 (back) 32.2 % 170 0.763 0.336 HR-12 (front) 30.6 % 181 0.773 0.294 HR-12 (back) 42.7 % 275 0.681 0.213 Trimax 12 (front) 29.7 % 151 0.782 0.226 Trimax 12 (back) 47.3 % 245 0.643 0.191 Screen A 32.8 % 200 0.869 0.494 Screen B 43.2 % 270 0.802 0.375
  • the obtained reaction mixture was washed by the known flocculation method, and then in the mixture were dispersed at 40°C, gelatin, a viscosity increasing agent and antiseptic. The mixture was adjusted to pH 5.6 and pAg 8.9. To the mixture kept at 55°C were added 21 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene and 170 mg of the following sensitizing dye: The obtained mixture was ripened for 10 min. To the mixture were then added successively 9 g of sodium thiosulfate 5 hydrates, 77 mg of potassium thiocyanate, and 1.6 mg of chloroauric acid. The mixture was ripened for 50 min. The ripened mixture was chilled after addition of 70 mg of 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene emulsion, to obtain a fine non-tabular particle-monodispersed emulsion A.
  • the silver halide particles of the obtained silver halide emulsion were in the form of potatoes and had a mean diameter of the circle corresponding to the projected area of 0.60 ⁇ m and variation coefficient of 18 %.
  • a coating dispersion containing the following components per 1 m2 was prepared:
  • the surface of a biaxially stretched polyethylene terephthalate film colored with blue dye having a thickness of 175 ⁇ m was subjected to corona discharge treatment. Then, each surface was sequentially and superposingly coated with the coating dispersions having the following components in the amounts described below (amount of each component was based on a dispersion for coating a single surface) by a wire-bar coater to form a subbing layer consisting of two sub-layers on each surface.
  • Magenta dye A The above magenta dye was added to the gelatin solution after it was prepared in the form of a dispersion of microcrystalline particles according to the following method.
  • the above-described coating dispersions for silver halide emulsion layer and for surface protective layer were simultaneously and superposingly applied on the support having subbing layers each of which had been provided on each surface.
  • Silver halide photographic material IX which had a silver halide emulsion layer and a surface protective layer both of which were provided on each side, was obtained.
  • the amount of silver halide emulsion of the applied coating dispersion was 2 g/m2 (amount in terms of silver metal) per one surface.
  • the amount of gelatin of the emulsion of the surface protective layer was 1 g/m2 per one surface.
  • salts were removed by the precipitation method. After the emulsion was heated to 40°C, 41 g of gelatin, 1.4 g of phenoxyethanol and 0.8 g of sodium polystyrenesulfonate as a viscosity improver were added. The pH and pAg values of the resulting emulsion were adjusted to 5.90 and 7.90, respectively, with sodium hydroxide and aqueous silver nitrate solution.
  • the emulsion was chemically sensitized under stirring at 56°C in the following manner.
  • Silver bromide was added to the emulsion at a ratio of 0.05 mol %, and then 0.1 mg of thiourea dioxide was added. Subsequently, the emulsion was settled for 10 minutes for performing reduction sensitization.
  • To the emulsion were added chlroroauric acid and potassium thiocyanate. The emulsion was cooled to 35°C, after 40 min. Thus, a fine tabular particle-monodispersed emulsion B was obtained.
  • the procedure for the preparation of the coating dispersion was performed using the above-obtained fine tabular particle-monodispersed emulsion B in place of the fine non-tabular particle-monodispersed emulsion A used for the preparation of Silver halide photographic material IX.
  • the coating dispersions for silver halide emulsion layer and for surface protective layer were then simultaneously and superposingly applied on the support having subbing layers each of which had been provided on each surface.
  • Silver halide photographic material X which had a silver halide emulsion layer and a surface protective layer both of which were provided on each side, was obtained.
  • the amount of silver halide emulsion of the applied coating dispersion was 1.5 g/m2 (amount in terms of silver metal) per one surface.
  • the obtained a silver halide emulsion C had the following characteristics: mean thickness: 0.200 ⁇ m, variation coefficient (standard deviation): 22.3 %, mean diameter of the circle corresponding to the projected area: 1.35 ⁇ m, aspect ratio: 6.8.
  • the procedure for the preparation of the coating dispersion was performed using the above-obtained tabular particle-monodispersed emulsion C in place of the fine non-tabular particle-monodispersed emulsion A used for the preparation of Silver halide photographic material IX.
  • the coating dispersions for silver halide emulsion layer and for surface protective layer were then simultaneously and superposingly applied on the support having subbing layers each of which had been provided on each surface.
  • Silver halide photographic material XI which had a silver halide emulsion layer and a surface protective layer both of which were provided on each side, was obtained.
  • the sensitivity of the sample material was measured in the manner as described in Example 1.
  • the noise power specturm was measured in the manner as described in Example 1.
  • NEQ was calculated in the manner as described in Example 1.
  • the quality of the obtained image of the chest phantom was visually estimated mainly from the viewpoint of clinical recognizability of veins in lung.
  • the results were expressed by the marks A, B, C and D which mean "excellent”, “good”, “recognizable” and “not recognizable”, respectively. Further, more detailed estimation was expressed using small letters "a” and "z”. For instance, if two images each of which quality was assigned to the same mark A have slightly different qualities, the better one was expressed by Aa and the worse was by Az.
  • Example 3 The procedure of the preparation of Silver halide photographic material in Example 3 was repeated except that the upper sub-layer (i.e., dye layer) of the subbing layer of the support was formed by coating the dispersion of fine crystalline dye particles in the combination of magenta dye B and mordant C set forth in the following Table 11, to prepare four Silver halide photographic materials XIII, XIV, XV and XVI.
  • the upper sub-layer i.e., dye layer
  • the subbing layer of the support was formed by coating the dispersion of fine crystalline dye particles in the combination of magenta dye B and mordant C set forth in the following Table 11, to prepare four Silver halide photographic materials XIII, XIV, XV and XVI.
  • the photosensitive layers on one side of the photographic mateirals IX, XIII, XIV, XV and XVI show almost the same sensitivity. Accordingly, the dyes employed are well fixed in the dye layer (upper sublayer).
  • the photographic material XV shows cross-over at almost the same level as the photographic mateial IX. Accordingly, the magenta dye B should be coated on one surface of the photographic material at the coating amount of 160 mg/m2 .
  • the photographic material was cut to give a sheet of 24 cm x 30 cm.
  • the photographic material having been not exposed was developed in the following two develping apparata of roller-conveyor type.
  • Deveoping Solution RDIII (Developing solution A) Development time 25 sec., Temperature 35°C Fixing Solution F Fixing time 20 sec., Temperature 25°C Washing Washing time 12 sec., Temperature 25°C Drying Drying time 26 sec., Temperature 55°C (Total time for processing: 90 sec.)
  • Example 3 The procedures of Example 3 were repeated except that the photosensitive emulsion A (fine non-tabular particle monodispersed emulsion A) and the photosensitive emulsion C (tabular particle emulsion C) were employed in the combination set forth in Table 14 to form a double coated photosensitive layer, to give three photographic materials, namely, Photographic materials XVII, XVIII and XIX.
  • Table 14 Photosensitive material Upper photo. layer (Emulsion C) Lower photo. layer (Emulsion A) Material IX -- 2,000 mg/m2 Material XVII 100 mg/m2 2,000 mg/m2 Material XVIII 200 mg/m2 2,000 mg/m2 Material XIX 400 mg/m2 2,000 mg/m2
  • the amount set forth in Table 14 indicates the amount of silver coated on one surface.
  • the obtained radiographic images were checked by observation.
  • the visual recognizability of the images on the shadow of veins and structure of mediastinum was marked in the following manner:

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Silver Salt Photography Or Processing Solution Therefor (AREA)
  • Conversion Of X-Rays Into Visible Images (AREA)
EP93110212A 1992-06-25 1993-06-25 Combinaison de matériau photographique à l'halogénure d'argent et d'écrans renforçateurs radiographiques Expired - Lifetime EP0577027B1 (fr)

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JP04193432A JP3083647B2 (ja) 1992-06-25 1992-06-25 ハロゲン化銀写真感光材料と放射線増感スクリーンとの組体
JP19343392 1992-06-25
JP04193433A JP3083648B2 (ja) 1992-06-25 1992-06-25 ハロゲン化銀写真感光材料と放射線増感スクリーンとの組体およびハロゲン化銀写真感光材料
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0690342A1 (fr) * 1994-06-28 1996-01-03 Konica Corporation Matériau composite constitué par un matériau photographique à l'halogénure d'argent sensible à la lumière et un écran renforçateur radiographique
EP0692735A1 (fr) * 1994-07-11 1996-01-17 Konica Corporation Composé de matériau photographique à l'halogénure d'argent sensible à la lumière et écran fluorescent au rayonnement
EP0740274A2 (fr) * 1995-04-28 1996-10-30 Toyota Jidosha Kabushiki Kaisha Procédé et dispositif de communication route/véhicule
EP0790526A1 (fr) * 1996-02-19 1997-08-20 Agfa-Gevaert N.V. Système pellicule-écran formant image radiographique
EP0579016B1 (fr) * 1992-07-08 1999-03-10 Fuji Photo Film Co., Ltd. Ecran intensificateur radiographique

Citations (4)

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EP0126644A2 (fr) * 1983-05-20 1984-11-28 Konica Corporation Matériel photosensible aux halogénures d'argent pour la photographie aux rayons X
EP0288038A1 (fr) * 1987-04-20 1988-10-26 Fuji Photo Film Co., Ltd. Ecran d'enregistrement d'une image obtenue par rayonnement et procédé de fabrication
EP0384753A2 (fr) * 1989-02-23 1990-08-29 Eastman Kodak Company Eléments radiographiques avec des relations de contrastes sélectionnées
US5108881A (en) * 1990-03-29 1992-04-28 Eastman Kodak Company Minimal crossover radiographic elements adapted for varied intensifying screen exposures

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DE69024409T2 (de) * 1989-06-05 1996-11-07 Fuji Photo Film Co Ltd Photographisches Röntgenmaterial

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Publication number Priority date Publication date Assignee Title
EP0126644A2 (fr) * 1983-05-20 1984-11-28 Konica Corporation Matériel photosensible aux halogénures d'argent pour la photographie aux rayons X
EP0288038A1 (fr) * 1987-04-20 1988-10-26 Fuji Photo Film Co., Ltd. Ecran d'enregistrement d'une image obtenue par rayonnement et procédé de fabrication
EP0384753A2 (fr) * 1989-02-23 1990-08-29 Eastman Kodak Company Eléments radiographiques avec des relations de contrastes sélectionnées
US5108881A (en) * 1990-03-29 1992-04-28 Eastman Kodak Company Minimal crossover radiographic elements adapted for varied intensifying screen exposures

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0579016B1 (fr) * 1992-07-08 1999-03-10 Fuji Photo Film Co., Ltd. Ecran intensificateur radiographique
EP0690342A1 (fr) * 1994-06-28 1996-01-03 Konica Corporation Matériau composite constitué par un matériau photographique à l'halogénure d'argent sensible à la lumière et un écran renforçateur radiographique
EP0692735A1 (fr) * 1994-07-11 1996-01-17 Konica Corporation Composé de matériau photographique à l'halogénure d'argent sensible à la lumière et écran fluorescent au rayonnement
US5576160A (en) * 1994-07-11 1996-11-19 Konica Corporation Composite of silver halide photographic light-sensitive material and radiation fluorescent screen
EP0740274A2 (fr) * 1995-04-28 1996-10-30 Toyota Jidosha Kabushiki Kaisha Procédé et dispositif de communication route/véhicule
EP0740274A3 (fr) * 1995-04-28 1999-04-14 Toyota Jidosha Kabushiki Kaisha Procédé et dispositif de communication route/véhicule
CN1085015C (zh) * 1995-04-28 2002-05-15 丰田自动车株式会社 公路/车辆通信方法及设备
EP0790526A1 (fr) * 1996-02-19 1997-08-20 Agfa-Gevaert N.V. Système pellicule-écran formant image radiographique

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EP0577027B1 (fr) 2000-08-23
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