Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-05-22
2004-01-27
Yamnitzky, Marie (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S421000, C428S447000, C250S484300, C250S484400, C528S033000, C528S038000
Reexamination Certificate
active
06682830
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radiation image storage panel for use in radiation image recording and reproducing techniques, in which phosphors are utilized. This invention also relates to a process for producing the radiation image storage panel.
2. Description of the Related Art
As techniques for obtaining radiation images for medical diagnosis and radiation images of various objects in a non-destructive mode and utilizing the radiation images for making medical diagnosis, flaw detecting inspections, and a like, radiography utilizing a combination of a silver halide photographic material (hereinbelow referred to simply as the photographic material) and an intensifying screen has heretofore been used in practice. With the radiography, radiation carrying image information of an object is irradiated to the intensifying screen, and a phosphor contained in the intensifying screen is excited by the radiation to emit near ultraviolet light or visible light. The emitted light impinges upon the photographic material, and a radiation image of the object is recorded on the photographic material. The radiation image is utilized for making medical diagnosis, flaw detecting inspections, or the like. Specifically, the photographic material comprises a substrate and a silver halide emulsion layer, which is overlaid on one surface of the substrate, or silver halide emulsion layers, which are overlaid on opposite surfaces of the substrate. Also, an intensifying screen is brought into close contact with one surface of the photographic material, or intensifying screens are brought into close contact with opposite surfaces of the photographic material. The combination of the photographic material and at least one intensifying screen is exposed to radiation carrying image information of the object, and the radiation image is thereby formed.
In lieu of the conventional radiography described above, radiation image recording and reproducing techniques utilizing stimulable phosphors have heretofore been used in practice. The stimulable phosphors have the properties such that, when the stimulable phosphors having absorbed energy from radiation are exposed to an electromagnetic wave, such as visible light or infrared rays, the stimulable phosphors are stimulated to emit the energy as fluorescence. The radiation image recording and reproducing techniques are described in, for example, U.S. Pat. No. 4,239,968. The radiation image recording and reproducing techniques utilize a radiation image storage panel (referred to also as the stimulable phosphor sheet) provided with a stimulable phosphor. With the radiation image recording and reproducing techniques, the stimulable phosphor of the radiation image storage panel is caused to absorb radiation, which carries image information of an object or which has been radiated out from a sample, and thereafter the stimulable phosphor is exposed to an electromagnetic wave (stimulating rays), such as visible light or infrared rays, which causes the stimulable phosphor to produce the fluorescence (i.e., to emit light) in proportion to the amount of energy stored thereon during its exposure to the radiation. The produced fluorescence (the emitted light) is photoelectrically detected to obtain an electric signal. The electric signal is then processed, and the processed electric signal is utilized for reproducing a visible image of the object or the sample.
The radiation image recording and reproducing techniques have the advantages in that a radiation image containing a large amount of information can be obtained with a markedly lower dose of radiation than in the conventional radiography utilizing the radiation film and the intensifying screen. Therefore, the radiation image recording and reproducing techniques are efficient particularly for direct medical radiography, such as the X-ray image recording for medical diagnosis.
Basically, the radiation image storage panel utilized for the radiation image recording and reproducing techniques comprises a substrate and a stimulable phosphor layer overlaid on the surface of the substrate. In cases where the stimulable phosphor layer has self-supporting properties, the radiation image storage panel need not necessarily be provided with the substrate. Ordinarily, a protective film is formed on the surface of the stimulable phosphor layer, which surface is opposite to the surface that stands facing the substrate. The protective film protects the stimulable phosphor layer from chemical deterioration or physical shocks.
By way of example, the protective film may be formed by applying a solution, which contains a transparent, organic high-molecular weight material, such as a cellulose derivative or a polymethyl methacrylate, in an appropriate solvent, onto the phosphor layer. Alternatively, the protective film may be formed by preparing a sheet for the formation of the protective film, such as an organic polymer film constituted of, e.g., a polyethylene terephthalate, or a transparent glass plate, and adhering the sheet for the formation of the protective film to the surface of the phosphor layer by use of an appropriate adhesive agent. As another alternative, the protective film may be formed by forming a film of an inorganic compound on the phosphor layer with a vacuum evaporation process. Of the above-enumerated protective films, the protective film formed by applying the solution, which contains the transparent, organic high-molecular weight material in the appropriate solvent, onto the phosphor layer, has the advantages in that the strength of adhesion with the phosphor layer is ordinarily high, and the protective film is capable of being produced with a comparatively simple process.
With the radiation image recording and reproducing techniques, the radiation image storage panel is utilized repeatedly through an operation cycle comprising the step of the irradiation of the radiation to the radiation image storage panel (the recording of the radiation image on the radiation image storage panel), the step of the irradiation of the stimulating rays to the radiation image storage panel (the readout of the recorded radiation image from the radiation image storage panel), and the step of the irradiation of erasing light to the radiation image storage panel (erasing of energy remaining on the radiation image storage panel). Also, conveyance of the radiation image storage panel to each of the steps is performed with conveyance means, such as belts and rollers. Ordinarily, after one operation cycle is finished, the radiation image storage panel is laid upon a radiation image storage panel, which has previously been subjected to the operation cycle. However, in cases where the radiation image storage panel provided with the protective film, which has been formed by applying the solution, which contains the transparent, organic high-molecular weight material in the appropriate solvent, onto the phosphor layer, is utilized repeatedly in this manner, for example, stains cling to the surface of the protective film, or scratches occur on the surface of the protective film. Therefore, there is the tendency for the image quality of the radiation image formed by the radiation image storage panel to become bad little by little.
As a radiation image storage panel provided with a protective film, which is capable of preventing the sensitivity of the radiation image storage panel from becoming low due to repeated use of the radiation image storage panel, the applicant proposed a radiation image storage panel provided with a protective film, which is formed from a film-forming resin and a polysiloxane skeleton-containing oligomer or a perfluoro alkyl group-containing oligomer. The radiation image storage panel is disclosed in Japanese Patent No. 2715189.
The protective film of the radiation image storage panel disclosed in Japanese Patent No. 2715189 has sufficient effects with respect to repeated use of at most 1,000 times. However, recently, several thousands of times to more than 10,000 times of
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
Thompson Camie S
Yamnitzky Marie
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