JPH1082899A - Radiological image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reproduce a radiological image having high quality and no image irregularity by forming a protective membrane out of a plastic film and a fluororesin-containing resin composition-coated layer formed on it and containing light scattering fine grains. SOLUTION: This protective membrane is constituted of a plastic film and a fluororesin-containing resin composition-coated layer formed on it and containing light scattering fine grains. A material having sufficient strength and high transparency such as polyethylene telephthalate is used for the plastic film. The light scattering fine grains of 1-30wt.%, particularly 5-20wt.%, are preferably contained in the fluororesin-containing resin composition-coated layer. An olefin polymer containing fluorine is used for the fluororesin, and the fluororesin is dissolved, singularly or together with another membrane forming resin, in a solvent to form a coating liquid. This coating liquid is uniformly applied on the surface of the plastic film and dried to form the fluororesin-containing resin composition-coated layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image conversion panel used for a radiation image conversion method using a stimulable phosphor.

[0002]

2. Description of the Related Art As an alternative to the conventional radiographic method, there has been known a radiation image conversion method using a stimulable phosphor as described in, for example, JP-A-55-12145. This method uses a radiation image conversion panel (a stimulable phosphor sheet) containing a stimulable phosphor, and transmits radiation transmitted through a subject or emitted from a subject to the stimulable phosphor of the panel. The radiation energy stored in the stimulable phosphor is absorbed by the body in a time-series manner by exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared rays. This is emitted as fluorescence (stimulated emission light), this fluorescence is read photoelectrically to obtain an electric signal, and a radiation image of a subject or a subject is reproduced as a visible image based on the obtained electric signal. . After the reading of the conversion panel, the remaining image is erased, and is prepared for the next photographing.
That is, the radiation image conversion panel is used repeatedly.

[0003] In this radiographic image conversion method, a radiographic image rich in information can be obtained with a much smaller exposure dose compared to the conventional radiographic method using a combination of a radiographic film and an intensifying screen. There is an advantage that can be. Furthermore, while the conventional radiographic method consumes radiographic film for each photographing operation, this radiographic image conversion method uses a radiographic image conversion panel repeatedly, which also contributes to resource conservation and economic efficiency. It is advantageous.

The radiation image conversion panel used in the radiation image conversion method has, as a basic structure, a support and a stimulable phosphor layer provided on the surface of the support. However,
When the phosphor layer is self-supporting, a support is not necessarily required. The stimulable phosphor layer usually comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. However, there is also known a stimulable phosphor layer which does not include a binder formed by a vapor deposition method or a sintering method and is composed of only an aggregate of the stimulable phosphor. Further, there is known a radiation image conversion panel having a stimulable phosphor layer in which a polymer substance is impregnated in a gap between stimulable phosphor aggregates. In any of these phosphor layers, the stimulable phosphor is X
Since it has the property of exhibiting stimulated emission when irradiated with excitation light after absorbing radiation such as radiation, the radiation transmitted through the subject or emitted from the subject is proportional to the radiation dose. The radiation image is absorbed by the stimulable phosphor layer of the radiation image conversion panel, and a radiation image of the subject or the subject is formed on the panel as a radiation energy accumulation image. This accumulated image can be emitted as stimulated emission light by irradiating the excitation light, and the accumulated image of radiation energy is imaged by photoelectrically reading the stimulated emission light and converting it into an electric signal. Can be realized.

[0005] A protective film is usually provided on the surface of the stimulable phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact. doing. The protective film is formed by applying a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative or polymethyl methacrylate in an appropriate solvent onto the phosphor layer, or An organic polymer film such as polyethylene terephthalate or a protective film forming sheet such as a transparent glass plate is separately formed, and this is provided using a suitable adhesive on the surface of the phosphor layer,
Alternatively, an inorganic compound formed on a phosphor layer by vapor deposition or the like is known. Among them, the protective film formed by coating has advantages that it generally has a strong adhesive strength to the phosphor layer and can be manufactured by a relatively simple process.

In carrying out the radiation image conversion method, the radiation image conversion panel includes radiation irradiation (recording of a radiation image), irradiation of excitation light (reading of a recorded radiation image), irradiation of erasing light (remaining radiation image). Erasure). The transfer of the radiation image conversion panel to each step is performed by a conveying means such as a belt or a roller. After one cycle, the panels are usually stacked and stored. However, when the radiation image conversion panel having the protective film formed by coating as described above is repeatedly used in this manner, the radiation image conversion panel may be stained or scratched on the surface of the protective film, for example. The image quality of the radiation image formed by the image conversion panel tends to gradually decrease. As with the conventional radiographic method, it is desired that the radiation image conversion panel also provides an image having high sensitivity and good image quality (sharpness, granularity, etc.). Preventing abrasion is an important issue.

[0007] As a coating film capable of preventing the sensitivity of the radiation image conversion panel from lowering due to the above-mentioned repeated use, there is a "phosphor layer comprising a stimulable phosphor and a protective film, which have already been filed by the present applicant. A radiation image conversion panel in which the protective film is a film formed of a coating film containing an organic solvent-soluble fluorine-based resin ”(Japanese Patent Application Laid-Open No. 2-193100) is known.

Another example of a coating film that can prevent the sensitivity of the radiation image conversion panel from lowering in the same manner as described above includes:
Already filed by the applicant of the present invention, "a phosphor layer comprising a stimulable phosphor and a protective film, wherein the protective film comprises a film-forming resin, a polysiloxane skeleton-containing oligomer or a perfluoroalkyl group-containing oligomer. A radiation image conversion panel which is formed from a coating film containing either one or both of them has been known (JP-A-4-310900).

[0009]

As described above, the protective film of the radiation image conversion panel repeatedly contacts the surface of the protective film with the surface of another object due to repeated use of the panel. Scratches and stains tend to occur on the surface, and the abrasions and stains may deteriorate the finally obtained radiation image or the quality of image information related to the radiation image. It is desired to improve the performance. In this regard, the coating film containing the fluorine-based resin and the coating film containing one or both of the polysiloxane skeleton-containing oligomer and the perfluoroalkyl group-containing oligomer described in each of the above publications have antifouling properties and antifouling properties. Although extremely effective in improving scratch resistance, subsequent studies have shown that repeated use of a radiation image conversion panel may cause cracks in the coating film, and therefore may not always be sufficient in durability. There was found.

[0010] As an improvement for realizing a protective layer exhibiting the above-mentioned antifouling property, anti-scratch property and high durability, the protective layer is formed of a plastic film and a resin containing a fluororesin applied thereon. The invention of a composite structure with a composition layer has been completed, and a patent application has already been filed by the present applicant (Japanese Patent Application No. 7-15506). The invention described in this prior application is directed to a radiation image conversion panel having a phosphor layer composed of a stimulable phosphor and a protective film provided thereon, wherein the protective film comprises a plastic film, A radiation image storage panel comprising a resin composition layer containing a fluorine-based resin formed by coating.

The protective film composed of a plastic film and a resin composition coated layer containing a fluorine-based resin, which is provided in the radiation image conversion panel described in the specification of Japanese Patent Application No. 7-15506, is an object of the present invention. It shows excellent effects on the improvement of stain resistance, scratch resistance and durability. However, when the present inventor examined the characteristics of the radiation image conversion panel provided with the protective film in more detail, a partially unclear portion was generated in a radiation image obtained using the radiation image conversion panel (ie, It was found that there was a case where image density unevenness occurred. Such uneven shading of an image is particularly problematic when a radiation image is used for medical diagnosis.

[0012]

Therefore, the present inventor has further studied for the purpose of suppressing or reducing the above-mentioned unevenness in image quality of the radiation image. As a result, by uniformly dispersing the light-scattering fine particles in the resin composition coating layer containing the above-mentioned fluorine-based resin, the image quality unevenness can be reduced without substantially lowering the sensitivity and other characteristics of the radiation image conversion panel. The present inventors have found that the occurrence of odor can be effectively suppressed, and reached the present invention.

Accordingly, the present invention provides a radiation image conversion panel having a phosphor layer composed of a stimulable phosphor and a protective film provided thereon, wherein the protective film comprises a plastic film and a plastic film thereon. A radiation-image conversion panel comprising: a resin composition layer containing a fluorine-based resin containing light-scattering fine particles formed by coating.

The above light-scattering fine particles are preferably contained in the coating layer of the resin composition containing a fluororesin in an amount of 1 to 30% by weight, particularly 5 to 20% by weight, more preferably 10 to 20% by weight. Is preferred.

In the present invention, the fluorine-based resin refers to a polymer of an olefin containing fluorine (fluoroolefin) or a copolymer containing an olefin containing fluorine as a copolymer component. The resin composition layer containing the fluororesin may be crosslinked.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The radiation image conversion panel of the present invention will be described in detail below.

First, the stimulable phosphor constituting the phosphor layer of the radiation image storage panel of the present invention will be described. The stimulable phosphor is a phosphor that emits stimulable light when irradiated with radiation and then with excitation light as described above, but has a wavelength in the range of 400 to 900 nm from a practical viewpoint. It is desirable that the phosphor emits stimulated emission in the wavelength range of 300 to 500 nm by the excitation light. Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention are described in JP-A-2-193100 and JP-A-4-31.
No. 0900 is described in detail.

Among the known stimulable phosphors, europium- or cerium-activated alkaline earth metal halide-based phosphors and cerium-activated rare earth oxyhalide phosphors are particularly preferred because they exhibit high-luminance stimulable emission. . However, the stimulable phosphor used in the present invention is not limited to the above-described phosphor, and can store irradiated radiation, and when irradiated with excitation light at an arbitrary time thereafter, Any phosphor may be used as long as the phosphor exhibits stimulable light emission.

The stimulable phosphor layer of the radiation image storage panel of the present invention comprises not only a stimulable phosphor and a binder containing the stimulable phosphor in a dispersed state but also containing no stimulable phosphor. It may be composed of only a stimulable phosphor aggregate or a phosphor layer in which a polymer substance is impregnated in a gap between the stimulable phosphor aggregates.

Next, the method for producing the radiation image storage panel of the present invention will be described by taking, as an example, the case where the phosphor layer comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state.

The phosphor layer can be formed on a support by, for example, the following known method. First, a stimulable phosphor and a binder are added to a solvent and mixed well to prepare a coating solution in which the stimulable phosphor is uniformly dispersed in a binder solution. The mixing ratio of the binder and the stimulable phosphor in the coating solution is determined by the characteristics of the target radiation image conversion panel,
Generally, the mixing ratio between the binder and the phosphor is from 1: 1 to 1: 100 (weight ratio), although it depends on the kind of the phosphor.
And particularly preferably from the range of 1: 8 to 1:40 (weight ratio). The coating solution containing the phosphor and the binder prepared as described above is then uniformly applied to the surface of the support to form a coating film. This coating operation is performed by a normal coating means, for example,
It can be performed by a method using a doctor blade, a roll coater, a knife coater, or the like.

The support can be arbitrarily selected from materials known as supports for conventional radiation image conversion panels. In a known radiation image conversion panel, a phosphor layer is provided to enhance the bond between the support and the phosphor layer or to improve the sensitivity or image quality (sharpness, granularity) of the radiation image conversion panel. A polymer material such as gelatin is applied to the surface of the support on the side to form an adhesion imparting layer,
Alternatively, it is known to provide a light reflecting layer made of a light reflecting substance such as titanium dioxide or a light absorbing layer made of a light absorbing substance such as carbon black. The support used in the present invention can also be provided with these various layers, and the configuration thereof can be arbitrarily selected according to the desired purpose and application of the radiation image storage panel. Further, as described in JP-A-58-200200, in order to improve the sharpness of the obtained image, the surface of the support on the side of the phosphor layer (the surface of the support on the side of the phosphor layer is adhered to). When an auxiliary layer such as a property imparting layer, a light reflecting layer, or a light absorbing layer is provided, the surface of the auxiliary layer may be provided).

After forming the coating on the support as described above, the coating is dried to complete the formation of the stimulable phosphor layer on the support. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the kind of the phosphor, the mixing ratio of the binder to the phosphor, and the like.
mm. However, the thickness of the stimulable phosphor layer is preferably 50 to 500 μm. The stimulable phosphor layer does not necessarily need to be formed by directly applying the coating solution on the support as described above. For example, the stimulable phosphor layer may be separately applied on a sheet such as a glass plate, a metal plate, or a plastic sheet. After applying a liquid and drying to form a phosphor layer, the phosphor layer is pressed onto the support or an adhesive is used to join the phosphor layer to the support. May be.

Next, protection which is a characteristic requirement of the radiation image conversion panel of the present invention, which is composed of a plastic film and a fluorine resin-containing resin composition coating layer containing light scattering fine particles formed thereon. The film will be described.

The plastic film, which is one of the constituents of the protective film of the present invention, is arbitrarily selected from polyethylene terephthalate, polyethylene naphthalate, aramid resin, etc., which are conventionally known as protective film materials for radiation image storage panels. Can be used. Of course, it is not limited to these resin materials, but it is desirable to use a plastic film having sufficient strength and high transparency. It is desirable that the thickness of the plastic film is usually in the range of 1 to 10 μm.

The protective film of the present invention is produced by applying a resin composition solution containing a fluororesin containing light-reflective fine particles on the above-mentioned plastic film and drying. The application of the light-reflective fine particle-containing resin composition to the plastic film may be performed on the surface of a laminate obtained by previously bonding and fixing the plastic film on the phosphor layer with an adhesive, or a glass plate. It may be carried out on the surface of a plastic film for a protective film temporarily fixed and placed on a flat substrate such as the above. In the latter case, the plastic film having the coating film formed on the surface is peeled off from the substrate, and then arranged so that the surface of the plastic film is in contact with the phosphor layer and bonded with an adhesive.

The fluororesin-containing resin composition layer of the radiation image storage panel of the present invention may be a fluororesin alone, a fluororesin and another film-forming resin, or a fluororesin and a polysiloxane skeleton-containing oligomer or A coating solution is prepared by dissolving or dispersing a composition such as a perfluoroalkyl group-containing oligomer in a solvent, and the resin composition layer forming material coating solution is uniformly applied to the plastic film surface using a coating means such as a doctor blade. And apply
It can be formed by drying this. In addition, the polysiloxane skeleton-containing oligomer and the perfluoroalkyl group-containing oligomer may be used simultaneously with the fluorine-based resin.

Examples of the film-forming resin which may be used in combination with the fluorine-based resin in forming the resin composition layer containing the fluorine-based resin include known resins for forming a protective film, such as polyurethane resin and polyacrylic resin. Examples include cellulose derivatives, polymethyl methacrylate, polyester resins, and epoxy resins. The fluororesin is a polymer of a fluorine-containing olefin (fluoroolefin) or a copolymer containing a fluorine-containing olefin as a copolymer component. Examples thereof include polytetrafluoroethylene and polychlorotrifluoroethylene. , Polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer and fluoroolefin-vinyl ether copolymer.

Fluorine-based resins are generally insoluble in organic solvents. In particular, copolymers containing a fluoroolefin as a copolymer component are generally insoluble depending on other structural units to be copolymerized (ie, other than the fluoroolefin). Since the resin composition becomes soluble in a typical organic solvent, a solution prepared by dissolving the resin in an appropriate solvent is applied onto the phosphor layer and dried to easily form a resin composition layer containing a fluororesin. Can be membrane. Examples of such a copolymer include a fluoroolefin-vinyl ether copolymer.
In addition, polytetrafluoroethylene and its modified product are also soluble in a suitable fluorinated organic solvent such as a perfluoro solvent, and therefore, like the copolymer containing the above-mentioned fluoroolefin as a copolymer component, the coating is performed. Thereby, a resin composition layer containing a fluorine-based resin can be formed.

In forming the resin composition layer containing the fluororesin of the radiation image storage panel of the present invention, a crosslinking agent, a hardening agent, an anti-yellowing agent and the like may be used. Further, since the strength of the resin is increased and the durability of the resin composition layer containing the fluorine-based resin is increased, it is preferable that the resin is crosslinked when the fluorine-based resin is used in the present invention.

In the present invention, the oligomer containing a polysiloxane skeleton which may be contained in the resin composition layer containing a fluorine-based resin has, for example, a dimethylpolysiloxane skeleton, and has at least one functional group (eg, a hydroxyl group).
It is preferable that the compound has a molecular weight (weight average) of 500 to 100,000. In particular, the molecular weight is preferably in the range of 1,000 to 100,000, and more preferably in the range of 3,000 to 10,000. Further, a perfluoroalkyl group (eg, tetrafluoroethylene group) -containing oligomer is
At least one functional group (for example, a hydroxyl group:-
OH), and preferably has a molecular weight (weight average) of 500 to 100,000. In particular, the molecular weight is preferably in the range of 1,000 to 100,000, and more preferably in the range of 10,000 to 100,000.

If an oligomer containing a functional group is used in the oligomer, a cross-linking reaction occurs between the oligomer and the resin composition layer-forming resin containing the fluorine-based resin when the resin composition layer containing the fluorine-based resin is formed. Since the oligomer is incorporated into the molecular structure of the film-forming resin, the oligomer can convert the fluorine-based resin even through long-term repeated use of the radiation image conversion panel or an operation such as cleaning the surface of the resin composition layer containing the fluorine-based resin. It is preferable to use an oligomer having a functional group, since the oligomer is not removed from the containing resin composition layer and the effect of adding the oligomer is effective for a long time. The oligomer is preferably contained in the resin composition layer containing the fluorine-based resin in an amount of 0.01 to 10% by weight, more preferably 0.1 to 2% by weight. Is preferably contained in an amount of

The resin composition layer containing the fluororesin may contain a perfluoroolefin resin powder or a silicone resin powder. As perfluoroolefin resin powder or silicone resin powder,
Those having an average particle size in the range of 0.1 to 10 μm are preferred, and those having an average particle size in the range of 0.3 to 5 μm are particularly preferred. These perfluoroolefin resin powders or silicone resin powders are used in a resin composition layer containing a fluororesin in an amount of 0.1% per weight of the resin composition layer.
It is preferably contained in an amount of 5 to 30% by weight, particularly preferably in an amount of 2 to 20% by weight and more preferably in an amount of 5 to 15% by weight. The thickness of the fluororesin-containing resin composition layer is usually in the range of 0.5 to 10 μm,
It is desirable that the layer be thinner than the thickness of the plastic film to be formed.

Next, the light-scattering fine particles to be introduced into the above-mentioned fluororesin-containing resin composition layer will be described. The light-scattering fine particles should have a particle size smaller than the thickness of the fluororesin-containing resin composition layer, and more specifically, have a particle size in the range of 0.05 to 5 μm, particularly 0.1 to 1 μm. Those having a range of 0.0 μm are preferred. And in order to bring about an effective light scattering action to the fluorine-based resin-containing resin composition layer,
The light-scattering fine particles preferably have a higher refractive index than the fluororesin-containing resin composition. In addition, the light scattering effect achieved by the introduction of the light-scattering fine particles and the undesired characteristics of the coating layer, such as a decrease in the strength of the coating film and a decrease in the uniformity of the coating film, which are likely to occur due to the introduction of the light-scattering fine particles. Considering the balance with the decrease in the content, the content of the light-scattering fine particles in the fluororesin-containing resin composition layer is preferably in the range of 1 to 30% by weight, more preferably 5 to 20% by weight, and 10 to 10% by weight. It is particularly preferred that the content is 20% by weight.

The light-scattering fine particles introduced into the fluororesin-containing resin composition layer in the present invention have a refractive index higher than that of the resin composition in the fluororesin-containing resin composition layer. As far as it is concerned, it may be organic fine particles or inorganic fine particles. Preferred examples of such light scattering fine particles include benzoguanamine resin particles having a particle size of about 0.1 to 0.5 μm, melamine / formaldehyde condensed resin particles having a particle size of about 0.1 to 0.5 μm, and particles. Titanium dioxide particles having a diameter of about 0.1 to 0.5 μm can be mentioned. As described above, since the light-scattering fine particles are preferably uniformly dispersed in the fluororesin-containing resin composition layer, if necessary, the light-scattering fine particles may be dispersed in the light-scattering fine particles. Surface treatment,
Alternatively, a dispersant may be allowed to coexist in the fluorine-containing resin-containing resin composition solution containing the light scattering fine particles. Examples of the dispersant used include a cationic dispersant, an anionic dispersant, a nonionic dispersant, and a surfactant dispersant such as a betaine dispersant, and a silane coupling agent.
Coupling agent-based dispersants such as titanate-based coupling agents and aluminum-based coupling agents can be mentioned. Among these dispersants, coupling agents such as titanate coupling agents and aluminum coupling agents are preferable. The amount of the coupling agent added is preferably in the range of 0.2 to 10% by weight of the light scattering fine particles, and particularly preferably in the range of 0.5 to 5.0% by weight.

As a means for enhancing the light scattering property of the fluorine-containing resin composition layer in the protective film, a method of roughening the surface of the layer can be considered. When the surface layer is subjected to a surface roughening treatment, the excellent antifouling property of the surface of the fluororesin-containing resin composition layer (the difficulty of attaching dirt and the ease of wiping off the dirt once adhered) decreases. Such a treatment for improving the light scattering property by the surface roughening treatment is not preferable, or at least, the improvement of the light scattering property only by the surface roughening treatment is not an effective method.

As described above, the radiation image conversion panel of the present invention is obtained. The configuration of the radiation image conversion panel of the present invention may include various known variations. For example, in a radiation image conversion panel, at least one layer of the panel is colored with a colorant that absorbs excitation light and does not absorb photostimulated light for the purpose of improving the sharpness of an obtained image. (See Japanese Patent Publication No. 54-23400).
However, it goes without saying that the radiation image conversion panel of the present invention can also have such a configuration.

[0038]

【Example】

[Examples 1 to 3] The radiation image storage panel of the present invention was manufactured as follows. As the phosphor layer forming material, phosphor: BaFBr _0.9 I _0.1 : 0.001Eu ²⁺ 200 g, polyurethane resin (manufactured by Dainippon Ink and Chemicals, Inc., Pandex T-5265H) 8 g, and epoxy resin (oiled shell epoxy) Co., Ltd., Epicoat 1001)
2 g was added to methyl ethyl ketone and dispersed by a propeller mixer to prepare a coating solution having a viscosity of 25 to 30 PS (25 ° C.). This coating solution was applied on a polyethylene terephthalate temporary support coated with a silicone release agent, and dried at 100 ° C. for 15 minutes. Next, the dried coating solution was peeled off from the temporary support, and the thickness was 300 μm.
Was obtained. Next, this phosphor sheet is coated with an undercoated polyethylene terephthalate film (thickness: 300).
μm) and heated and compressed (load: 45 kgf / sample width: 20 cm) using a heating roll at 60 to 70 ° C. to obtain a compressed phosphor layer (thickness: 200 μm) on the support.

A transparent polyethylene terephthalate film (thickness: 9 μm, provided with a polyester-based adhesive layer on one side) is superposed on the above-mentioned phosphor layer with the adhesive layer on the lower side. Thermocompression bonding was performed using a heating roll at 100 ° C. Separately, as a resin composition layer forming material containing a fluororesin, 50 g of a fluororesin: fluoroolefin-vinyl ether copolymer (Lumiflon LF100, 50% by weight xylene solution manufactured by Asahi Glass Co., Ltd.), a crosslinking agent: isocyanate (Nippon Polyurethane) 5 g of Coronate HX manufactured by K.K., solid content: 100% by weight) and an alcohol-modified silicone oligomer (having a dimethylpolysiloxane skeleton and having hydroxyl groups (carbinol groups) at both ends, manufactured by Shin-Etsu Chemical Co., Ltd.) , X-22-2809,
(Solid content: 66% by weight) was added to a methyl ethyl ketone solvent to prepare a coating solution having a viscosity of 0.1 to 0.3 ps. Then, benzoguanamine resin fine particles (Eposter S, manufactured by Nippon Shokubai Co., Ltd.,
3 μm) was added in a predetermined amount (shown in Table 1 below as the amount added to the above fluororesin) to obtain a fluororesin coating liquid containing light-scattering fine particles. In addition, the refractive index of the resin composition containing this fluororesin as a main component was 1.45, and the refractive index of the benzoguanamine resin fine particles was 1.57.

The fluororesin coating solution containing the light-scattering fine particles is applied to the surface of the polyethylene terephthalate film on the phosphor layer using a doctor blade, and then heat-treated at 120 ° C. for 20 minutes for heat curing. It dried and provided the 1.5-micrometer-thick fluorinated resin containing resin composition protective layer containing light scattering fine particles, and obtained the radiation image conversion panel according to the present invention.

Examples 4 to 6 As light-scattering fine particles,
A predetermined amount of titanium dioxide fine particles (average particle size: 0.15 μm, A-220 manufactured by Ishihara Sangyo Co., Ltd., refractive index: 2.5) (shown in Table 1 below by the amount added to the above fluororesin)
A radiation image storage panel according to the present invention was obtained by performing the same operations as in Example 1 except for using the above. In addition, in order to enhance the dispersibility of the titanium dioxide fine particles in the fluororesin-containing resin composition solution, in the production of the coating solution,
A titanate-based coupling agent (Plenact KR-138S, manufactured by Ajinomoto Co., Inc.) was used in combination.

[Examples 7 to 9] 4.6 g of Sumidur N3500 manufactured by Sumitomo Bayer Urethane Co., Ltd. was used as the isocyanate of the crosslinking agent, and melamine / formaldehyde condensed resin fine particles (average particle size: 0. 6 μm, Nippon Shokubai Co., Ltd. eposter S6,
The radiation image conversion panel according to the present invention was obtained by performing the same operation as in Example 1 except that a predetermined amount (refraction index: 1.57) was used (shown in Table 1 below as an addition amount to the above-mentioned fluororesin). I got In addition, in order to enhance the dispersibility of the melamine / formaldehyde condensed resin fine particles in the fluororesin-containing resin composition solution, a titanate-based coupling agent (manufactured by Ajinomoto Co., Ltd.,
Prenact AL-M).

Comparative Example 1 The same operation as in Example 1 was carried out except that no light-scattering fine particles were used in preparing the fluorine-containing resin-containing resin composition coating solution for forming the protective layer. Was obtained.

[Performance evaluation of radiation image conversion panel] 1) Sensitivity test After irradiating the radiation image conversion panel of the sample with X-rays having a tube voltage of 80 kVp, a He-Ne laser beam (wavelength: 632.8) was used.
nm), the amount of stimulated emission from the radiation image conversion panel was measured, and the sensitivity was indicated by the relative value of the amount of emitted light.

2) Image Sharpness After irradiating a sample radiation image conversion panel with X-rays having a tube voltage of 80 kVp through an MTF chart, the sample was excited with He-Ne laser light (wavelength: 632.8 nm) to produce a radiation image. The stimulated emission from the conversion panel was received by a light receiver (a photomultiplier tube having a spectral sensitivity of S-5). The received light was converted into an electric signal, which was reproduced by an image reproducing device to obtain an image on a display device. The modulation transfer function (MTF) of the obtained image was measured, and this was calculated as a spatial frequency of 2 cycles / m.
It was indicated by the value of m.

3) Irregularity of interference The radiation image conversion panel of the sample was visually judged according to the following criteria. AA: The presence of interference unevenness cannot be confirmed. BB: Slight interference unevenness is observed. CC: Remarkable interference unevenness is observed.

4) Quality of Reconstructed Image A radiation-reconstructed image for medical diagnosis was obtained using a radiation image conversion panel of a sample, and the quality of the image was visually determined according to the following criteria. AA: No shading is observed on the image. BB: Slight shading is observed on the image, but does not cause any problem in diagnosis. CC: Shading unevenness occurs on the image, which hinders precise diagnosis.

Table 1 shows the results obtained by the above tests together with the amount of the light-scattering fine particles added.

[0050]

[Table 1] Table 1 添加 Particle addition amount Relative sensitivity Sharpness Interference Uneven Image Unevenness ──────────────────────────────────── Example 1 6.0% 97 35.9 % BB BB Example 2 18.0% 97 35.7% AA AA Example 3 24.0% 96 36.4% AA AA ───────────────── Example 4 6.0% 100 37.0% BB BB Example 5 12.0% 100 37.8% BB BB Example 6 0% 99 37.5% AA AA {Example 7 0% 98 36.0% BB BB Example 8 1 2.0% 97 36.4% AA AA Example 9 24.0% 97 36.6% AA AA ────────── Comparative Example 1 0.0% 98 36.0% CC CC ────────────────────────── ──────────

As is evident from the above results, the fluororesin-containing coating protective layer into which the light-scattering fine particles of the present invention have been introduced can produce image unevenness without substantially changing the sensitivity and sharpness of the radiation image storage panel. Can be effectively suppressed.

[0052]

The radiation image conversion panel of the present invention is resistant to cracks even after repeated transport operations in a general radiation image conversion apparatus, and the fluorine-based resin-containing film as the surface layer of the protective film has high scratch resistance. It has the advantage that the decrease in sensitivity is small even after repeated transport operations, and furthermore, the light scattering fine particles introduced into the fluorine-containing resin-containing film on the surface layer of the protective film. The use of the radiation image conversion panel of the present invention in a radiation image recording / reproducing method makes it possible to reproduce a radiation image of high image quality without image unevenness.

Claims (11)

[Claims] 1. A radiation image conversion panel having a phosphor layer composed of a stimulable phosphor and a protective film provided thereon, wherein the protective film is formed by coating a plastic film and a plastic film thereon. A radiation image conversion panel comprising a fluororesin-containing resin composition layer containing light scattering fine particles. 2. The radiation image conversion panel according to claim 1, wherein the fluororesin-containing resin composition layer contains 1 to 30% by weight of light scattering fine particles. 3. The radiation image conversion panel according to claim 1, wherein the refractive index of the light-scattering fine particles is larger than the refractive index of the resin composition of the fluorine-containing resin-containing resin composition layer. 4. The radiation image conversion panel according to claim 1, wherein the light scattering fine particles are organic fine particles. 5. The radiation image conversion panel according to claim 1, wherein the light scattering fine particles are inorganic fine particles. 6. The radiation image conversion panel according to claim 1, wherein the fluororesin-containing resin composition layer further contains a dispersant. 7. The radiation image storage panel according to claim 6, wherein the dispersant is an aluminum-based or titanate-based coupling agent. 8. The method according to claim 1, wherein the light-scattering fine particles have a particle diameter smaller than the thickness of the fluororesin-containing resin composition layer, and the particle diameter is in a range of 0.05 to 5 μm. The radiation image conversion panel according to any one of the above items. 9. The radiation image conversion panel according to claim 1, wherein the thickness of the fluororesin-containing resin composition layer is smaller than the thickness of the plastic film. 10. The radiation image conversion panel according to claim 1, wherein the plastic film is a polyethylene terephthalate film or a polyethylene naphthalate film. 11. The radiation image conversion panel according to claim 1, wherein a support is provided below the phosphor layer.