JP2002303698A - Radiation image conversion panel, radiation image conversion plate and radiation image reader using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation image conversion panel whose durability is high, a radiation image conversion plate and a radiation image reader using it. SOLUTION: The radiation image conversion panel which has a stimulable phosphor layer and a protective layer on a support is characterized in that the permeability of the support stipulated by JIS Z 0208 is 0.1 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a radiation image conversion panel, a radiation image conversion plate, and a radiation image reading apparatus using the same.

[0002]

2. Description of the Related Art Radiation images such as X-ray images are widely used for diagnosis of diseases. In order to obtain this X-ray image, the X-rays that have passed through the subject are applied to a phosphor layer (fluorescent screen).
Thus, a so-called radiograph is used, in which a visible light is generated by this, and this visible light is irradiated and developed on a film using a silver salt in the same manner as when a normal photograph is taken. However, in recent years, a method has been devised for directly taking out an image from the phosphor layer without using a film coated with a silver salt.

In this method, radiation transmitted through a subject is absorbed by a phosphor, and then the phosphor is excited by, for example, light or heat energy, so that the radiation energy stored by the phosphor is absorbed by the phosphor. There is a method of detecting and imaging this fluorescence.

[0004] Specifically, for example, US Pat.
A radiation image conversion method using a stimulable phosphor as described in JP-A-9-527 and JP-A-55-12144 is known.

The above-mentioned method uses a radiation image conversion panel containing a stimulable phosphor, and the radiation transmitted through the object is applied to the stimulable phosphor layer of the radiation image conversion panel, and each part of the object is irradiated with the radiation. By accumulating radiation energy corresponding to the radiation transmission density, and then stimulating the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared light in a time series manner, The stored radiation energy is emitted as stimulated emission, and a signal based on the intensity of the light is photoelectrically converted, for example, to obtain an electric signal, and the signal is applied to a recording material such as a photosensitive film or a display device such as a CRT. It is reproduced as a visual image.

In the above radiation image conversion method, generally, the radiation image conversion panel is repeatedly used by being conveyed and moved from a photographing section → a reading section → an erasing section → a standby section. Therefore, the size of the apparatus is inevitably increased and the price is inevitably increased. The panel needs to have flexibility, and since a flexible material such as PET is generally used for both the support and the protective layer, the panel has a drawback that it has high moisture permeability and lacks durability. I was In addition, there is a disadvantage that the panel is easily damaged by the transport movement and the life is short.

On the other hand, the applicant assigns a method in which the radiation image conversion panel is fixed in the apparatus and the reading / erasing unit moves integrally with the panel (Japanese Patent Publication No. 6-5359).
No. 6-5360).

As a result, it is possible to reduce the size and cost of the apparatus, shorten the cycle time for reading, erasing, and photographing, and extend the life of the panel. On the other hand, since it is necessary to read from the side opposite to the X-ray incidence side, a special device is required to make effective use of the image information, and a phosphor layer containing no binder is required. No. 61-73100),
The phosphor layer has an oblique columnar crystal structure (Japanese Patent Application No. 63-12 / 1988)
No. 9996, JP-A-4-326100), a low refractive index layer is provided between a phosphor layer and a protective layer (Japanese Patent Application No. 62-2060).
17) are known.

As described above, a flexible material such as PET has been used as a support for a conventional radiation image conversion panel. The use of a flexible material such as polyethylene terephthalate as the support is preferable in terms of flexibility, light weight, and low X-ray absorption, but does not reduce the durability of the radiation image conversion panel. It is necessary that the moisture permeability be low as described above, but in particular, europium-activated BaF having high X-ray absorption efficiency is used.
In the case of a stimulable phosphor having high water solubility (also referred to as high deliquescent) such as I, a material such as polyethylene terephthalate generally has a high water permeability, and thus a conventional radiation image conversion panel is used. In this case, improvement in durability remained as a problem to be solved.

Under the above circumstances, in recent years, there has been a demand for further miniaturization and lower cost of the apparatus, higher image quality and higher durability (longer life) of the panel.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a radiation image conversion panel, a radiation image conversion plate having high durability, and a radiation image reading apparatus using the same.

[0012]

The above objects of the present invention have been attained by the following items 1 to 6.

1. A radiation image conversion panel having a stimulable phosphor layer and a protective layer on a support,
When the moisture permeability defined by JIS Z 0208 is 0.
A radiation image conversion panel, wherein the number is 1 or less.

2. 2. The radiation image conversion panel according to the above item 1, wherein the support is a thin glass having a thickness of 50 μm to 500 μm.

[0015] 3. 3. The radiation image conversion panel according to 1 or 2, wherein the stimulable phosphor layer contains a stimulable phosphor represented by the general formula (1).

4. 4. A radiation image conversion plate having the radiation image conversion panel according to any one of the above 1 to 3 on a support member, wherein a moisture-proof layer is disposed between the support of the radiation image conversion panel and the support member. A radiation image conversion plate, wherein the moisture-proof layer has a moisture permeability defined by JIS Z 0208 of 0.1 or less.

5. The radiation image converter according to 4, wherein the support is an organic polymer film, the support member is carbon fiber or a composite material containing carbon fiber, and the moisture-proof layer is a thin glass of 50 μm to 500 μm. plate.

6. 6. A radiation image reading device, wherein the radiation image conversion plate according to 5 is fixed in a reading device, and a reading member is arranged facing the protective layer side of the plate.

Hereinafter, the present invention will be described in detail. The radiation image conversion panel of the present invention will be described.

As a result of various studies, the present inventors have made claim 1
As described in above, in a radiation image conversion panel having a stimulable phosphor layer and a protective layer on a support, the moisture permeability of the support specified by JIS Z 0208 is 0.1 or less. It has been found that by adjusting the thickness, a radiation image conversion panel having high durability can be obtained. From the viewpoint of further improving the durability, the moisture permeability of the support according to the present invention is preferably equal to or less than 0.08, and particularly preferably substantially zero. Here, the case where the moisture permeability is substantially 0 means that the moisture permeability is 0.001 or less.

In the case where glass is used as the support, thin glass whose thickness is adjusted to a range of 50 μm to 500 μm is used to suppress loss due to X-ray absorption and to increase photostimulability. It has been found that the phosphor can be effectively prevented from being deteriorated by moisture. In addition, from the viewpoint of more preferably achieving the effects described in the present invention, the thickness of the thin glass is preferably 80 μm to 400 μm.

The thin glass according to the present invention desirably has a high transmittance in a wide wavelength range and a spectral transmittance of 8 in order to efficiently transmit stimulated excitation light and stimulated emission.
0% or more is preferable. Examples of such glass include quartz glass and borosilicate glass. Borosilicate glass shows a transmittance of 80% or more in a wavelength range of 330 nm to 2.6 nm, and quartz glass shows a high transmittance even at a shorter wavelength, and is therefore preferably used in the present invention.

The radiation image conversion plate of the present invention will be described. According to a fourth aspect of the present invention, there is provided a radiation image conversion plate having the radiation image conversion panel according to any one of the first to third aspects on a support member, wherein the support of the radiation image conversion panel and the support are provided. By disposing a moisture-proof layer between members and adjusting the moisture permeability of the moisture-proof layer defined by JIS Z 0208 to 0.1 or less, a radiation image conversion that preferably exhibits the effects described in the present invention. A plate was obtained. The moisture permeability of the moisture-proof layer is preferably equal to or less than 0.08, and particularly preferably substantially zero. Here, the case where the moisture permeability is substantially 0 means that the moisture permeability is 0.001 or less.

The thickness of the moisture-proof layer is 50 μm to 500 μm.
μm is preferable, and more preferably 80 μm to 4 μm.
00 μm. Further, as the constituent material of the moisture-proof layer according to the present invention, the above-mentioned thin glass is preferably used similarly.

An organic polymer resin or an organic polymer film is preferably used as a support of the radiation image conversion panel used in the radiation image conversion plate according to the fourth aspect. , Carbon fiber or a composite material containing carbon fiber is preferably used.

Examples of the organic polymer film used for the support include a plastic film such as a cellulose acetate film, a polyester film, a polyethylene terephthalate film, a polyamide film, a polyimide film, a triacetate film, a polycarbonate film, a carbon composite material, and a general paper. And printing base paper such as photographic base paper, coated paper or art paper, baryta paper, resin coated paper, Belgian patent 78
Paper such as paper sized with polysaccharide or the like as described in US Pat. No. 4,615, pigment paper containing a pigment such as titanium dioxide, and processed paper such as paper sized with polyvinyl alcohol; Wool, cotton and the like are also included. Further, a composite of a plurality of materials including carbon and PET may be used. These supports preferably have moisture-proof properties.

The thickness of the support of the radiation image conversion plate according to claim 4 varies depending on the material used and the like.
50 μm to 1000 μm is preferable, and 5 μm is more preferable.
It is 0 μm to 500 μm.

The support according to the present invention includes a light-reflective layer made of a light-reflective substance such as titanium dioxide or a light-absorbing substance such as carbon black in order to improve sensitivity, image quality (sharpness, granularity) and the like. May be provided.

The surface of these supports may be a smooth surface or a mat surface for the purpose of improving the adhesion to the stimulable phosphor layer.

Further, in these supports, the undercoat layer described above may be provided on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesion to the stimulable phosphor layer.

In order to improve the image quality, for example, PET or the like into which a light-absorbing substance such as carbon is kneaded is preferable. preferable. Further, from the viewpoint of increasing the reflectivity of the support and improving the luminance of the radiation image conversion panel, polyethylene terephthalate containing bubbles is preferably used for the support according to the present invention.

Here, the polyethylene terephthalate containing air bubbles is disclosed in JP-A-3-76727 and JP-A-3-76727.
In the method described in U.S. Pat. No. 2,226,894, a support having improved luminance for a radiation image conversion panel can be produced by incorporating air bubbles in polyethylene terephthalate to increase the reflectivity for stimulated fluorescence. In addition, as a commercially available product, E
There is polyethylene terephthalate containing bubbles such as 60 L.

The thickness of the polyethylene terephthalate support containing bubbles is generally 80 μm to 10 μm.
00 μm, and preferably 50 μm from the viewpoint of handling.
μm to 500 μm.

The surface of the support may be a smooth surface, or may be a matte surface for the purpose of improving the adhesion to the reflective layer, the light absorbing layer and the stimulable phosphor layer.

The protective layer according to the present invention will be described. The protective layer according to the present invention preferably has a moisture permeability defined by JIS Z 0208 of 1.0 or less, more preferably 0.5 or less, and particularly preferably 0.1 or less. As a material used for the production of the protective layer, a thin glass or an organic polymer film used for the production of the support described above can be used, but from the viewpoint of using a material having low moisture permeability, a thin glass is preferable. . Also,
The thickness of the protective layer is preferably from 50 μm to 1000 μm, more preferably from 50 to 500 μm.

In a preferred embodiment of the present invention, the radiation image conversion panel of the present invention is used for a radiographic image capturing and reading method for reading from the side opposite to the side having the phosphor layer with respect to the X-ray incident side. Thus, the feature that the durability of the X-ray absorption radiation image conversion panel is improved is exhibited.

The protective layer desirably has a high transmittance in a wide wavelength range in order to transmit the stimulating light and the stimulating light efficiently, and the spectral transmittance is preferably 80% or more. Examples include quartz glass and borosilicate glass. Borosilicate glass shows a transmittance of 80% or more in a wavelength range of 330 nm to 2.6 nm, and quartz glass shows a high transmittance even at a shorter wavelength.

Further, it is preferable to provide an antireflection layer such as MgF _{2 on} the surface of the protective layer, because it has the effects of efficiently transmitting the stimulating excitation light and the stimulating light emission and reducing the decrease in sharpness. Although the refractive index of the protective layer is not particularly defined, many materials that can be used practically have a refractive index between 1.4 and 2.0.

The stimulable phosphor according to the present invention has a wavelength of 3 to 400 nm by excitation light having a wavelength of 400 to 900 nm.
Those exhibiting stimulated emission in the range of 00 to 500 nm can be used. Examples of stimulable phosphors conventionally used in radiation image conversion panels include rare earth-activated alkaline earth metal fluorinated halide-based phosphors. For example, JP-A-55-12145 and JP-A-55-16
No. 0078, No. 56-74175, No. 56-1167
No. 77, 57-23673, 57-23675
No. 58-206678, No. 59-27289,
Nos. 59-27980, 59-56479, 59
-56480 and the like, rare earth element activated alkaline earth metal fluorohalide-based phosphors;
No. 0, No. 60-84381, No. 60-106752
Nos., 60-166379 and 60-22483
No. 60-228592, No. 60-228593
No. 61-23679, No. 61-120882,
Nos. 61-120883, 61-120885, 61-235486, 61-235487, etc .; divalent europium-activated alkaline earth metal halide-based phosphors described in JP-A-55-12144; Rare earth element-activated oxyhalide phosphor described in JP-A-58-692
No. 81, cerium-activated trivalent metal oxyhalide phosphor; bismuth-activated alkali metal halide phosphor described in JP-A-60-70484; JP-A-60-141
No. 783 and No. 60-157100, divalent europium-activated alkaline earth metal halophosphate phosphors described in JP-A-60-157099, and divalent europium-activated alkaline earth metal haloborates described in JP-A-60-157099 Phosphor; JP-A-60-2
No. 17354, divalent europium-activated alkaline earth metal hydride halide phosphors;
Cerium-activated rare earth composite halide phosphors described in JP-A Nos. 173 and 61-21182;
Cerium-activated rare earth halophosphate phosphor described in No. 0; divalent europium-activated cerium rubidium halide phosphor described in JP-A-60-78151;
A divalent europium-activated composite halogen phosphor described in JP-A-78153; a tetrahedral rare-earth metal-activated alkaline earth metal fluorohalide phosphor precipitated from a liquid phase described in JP-A-7-233369, and the like. is there. Among them, a divalent europium-activated alkaline earth metal-activated halide phosphor containing iodine, a divalent europium-activated alkaline earth metal halide-based phosphor containing iodine, a rare earth element containing iodine The activated rare earth oxyhalide phosphor and the bismuth-activated alkali metal halide phosphor containing iodine preferably exhibit high luminance stimulable light emission.

Among the above stimulable phosphors, a divalent europium-activated alkaline earth metal fluorohalide-based phosphor containing iodine and a divalent europium-activated alkaline earth metal halide containing iodine Phosphors, rare earth element-activated rare earth oxyhalide phosphors containing iodine, and bismuth activated alkali metal halide phosphors containing iodine are preferably used. From the viewpoint shown, a divalent europium-activated alkaline earth metal fluorohalide-based phosphor containing iodine is particularly preferably used.

As divalent europium-activated alkaline earth metal fluorohalide-based stimulable phosphors containing iodine, JP-A-10-195431 and JP-A-10-23949.
No. 6, 10-239497 and the like, and a phosphor represented by the general formula (1) described in JP-A-11-1067.
No. 48 describes a phosphor represented by the general formula (2).

General formula (1) Ba _1-x M ² _x F _1-a I _{1 + a} : yM ¹ , zLn wherein M ² is Sr or Ca, M ¹ is Li, Na, K, Rb
Or, Cs and Ln are Ce, Pr, Sm, Eu, Gd, T
b, Tm or Yb, and 0 ≦ x ≦ 0.5, 0 ≦ y ≦
0.05, and 0 <z ≦ 0.2, −0.5 ≦ a ≦ 0.5
Represents

General formula (2) Ba _1-x Ca _x FBr _1-y I _y : aM ¹ , bM, cA In the formula, M ¹ is Ce, Pr, Sm, Eu, Gd, Tb, T
m or Yb, M is Li, Na, K, Rb or Cs, A is Al ₂ O ₃ or SiO ₂ , x, y, a, b and c are respectively 0 <x ≦ 0.03, 0 <y ≦ 0.30, 0.000
1 ≦ a ≦ 0.01, 0 <b ≦ 0.05, 0 <e ≦ 0.0
5 is represented.

The method for producing these stimulable phosphors is described in JP-A-10-195431 and JP-A-10-239496.
No. 10-239497 and the like,
Particularly preferred is a divalent europium-activated alkaline earth metal fluorinated iodide phosphor (E) represented by the general formula (1).
u-activated BaFI phosphor).

For the production of the stimulable phosphor represented by the general formula (1), a liquid phase synthesis method in which the particle shape can be easily controlled is preferable.
Note that the liquid phase method is also advantageous for uniformly containing the activator in the crystal. Hereinafter, an example of a method for producing the phosphor represented by the general formula (1) will be described.

(Production Method 1) a) A halide containing BaI ₂ and Ln is further contained, when x is not 0 in the above general formula (1), a halide of M ² is further added, and when y is not 0, a halide is further added. comprises a halide of M ^1, is BaI ₂ concentration after they were dissolved 2 mol /
A step of preparing an aqueous solution having a concentration of not less than L, preferably not less than 2.7 mol / L;
While maintaining the temperature at 0 ° C. or higher, the concentration was 5 mol / L.
A step of adding an aqueous solution of an inorganic fluoride (ammonium fluoride or alkali metal fluoride) of preferably 8 mol / L or more to obtain a precipitate of a precursor crystal of a stimulable phosphor; A production method comprising the steps of: separating a body crystal precipitate from an aqueous solution; and d) firing the separated precursor crystal precipitate while avoiding sintering.

After the phosphor precursor crystals have been dried, a sintering inhibitor such as alumina fine powder or silica fine powder is added thereto and mixed.
It is preferable that the sintering inhibitor fine powder is uniformly attached to the crystal surface. Incidentally, the sintering inhibitor may not be used by selecting the firing conditions.

Next, the phosphor precursor crystal is charged into a heat-resistant container such as a quartz boat, an alumina crucible, a quartz crucible, or the like.
The sintering is performed while avoiding sintering in the core of an electric furnace. The firing temperature is about 700-1300 ° C, 800-1000 ° C
Is preferred. Firing time varies depending on the filling amount of the phosphor raw material mixture, the firing temperature, the temperature of taking out from the furnace, and the like.
Generally, 0.5 to 12 hours is appropriate. As the firing atmosphere, a neutral atmosphere such as a nitrogen gas atmosphere, an argon gas atmosphere, a nitrogen gas atmosphere containing a small amount of hydrogen gas, a weak reducing atmosphere such as a carbon dioxide atmosphere containing carbon monoxide, or a trace oxygen introducing atmosphere. Can be used. By this firing, the desired stimulable phosphor is obtained.

(Production Method 2) a) When ammonium halide and a halide of Ln are contained and x is not 0 in the general formula (1), M is further added.
The ^second halide, y comprises a further halide of M ¹ if non-zero, it ammonium halide concentration was dissolved 3 mol / L or more, preferably prepared 4 mol / L or more aqueous Step b) While maintaining the aqueous solution at a temperature of 50 ° C. or more, preferably 80 ° C. or more, the aqueous solution is added with an inorganic fluoride (concentration of 5 mol / L or more, preferably 8 mol / L or more) such as ammonium fluoride or alkali metal. (Fluoride) and an aqueous solution of BaI ₂ are added continuously or intermittently while maintaining the ratio of the former fluorine and the latter Ba constant, thereby precipitating the precursor crystals of the stimulable phosphor. And c) separating the precursor crystal precipitate from the aqueous solution, and d) firing the separated precursor crystal precipitate while avoiding sintering. The details will be described below.

First, a raw material compound excluding BaI ₂ and a fluorine compound and an ammonium halide (NH ₄ Br, NH ₄ Cl or NH ₄ I) are dissolved using an aqueous solvent. That is, an ammonium halide and a halide of Ln, and if necessary, a halide of M ^{2 or} a halide of M ¹ are sufficiently mixed in an aqueous medium in an amount such that the concentration of ammonium halide becomes 3 mol / L or more. And dissolve to prepare an aqueous solution. At this time, a small amount of acid, ammonia, alcohol, water-soluble polymer, water-insoluble metal oxide fine particles, or the like may be added. This aqueous solution (reaction mother liquor) is maintained at a constant temperature.

Then, an aqueous solution of inorganic fluoride and an aqueous solution of BaI ₂ are simultaneously added to the aqueous solution maintained at a constant temperature and stirred so that the ratio of fluorine of inorganic fluoride to BaI ₂ is kept constant. The mixture is continuously or intermittently injected using a roller pump or the like. This injection is preferably carried out in a particularly vigorously stirred area. As described above, by allowing the reaction to proceed while preventing the Ba ion from becoming excessive during the formation of the phosphor crystal, the general formula (1)
The precursor crystal of the stimulable phosphor represented by the formula (1) precipitates. Next, the target stimulable phosphor can be obtained by separating the precursor crystal of the stimulable phosphor from the solvent in the same manner as in the production method 2, drying and firing.

In the above two production methods, regardless of the timing of addition of the halide of Ln, it may be present in the reaction mother liquor or the like at the start of the addition, at the time of addition of the inorganic fluoride aqueous solution, or with the inorganic fluoride aqueous solution and BaI. _{(2) It} may be added simultaneously with or after the addition of the aqueous solution.

In the present invention, the stimulable phosphor particles are preferably monodisperse, and the coefficient of variation obtained by dividing the standard deviation by the average particle diameter and multiplying by 100 is 20% or less, and more preferably 15% or less.
% Or less is preferable. Here, the average particle diameter is an average value of 200 particles randomly selected from a micrograph of the particles and calculated by a volume particle diameter converted into a sphere volume.

The particle size of the stimulable phosphor represented by the general formula (1) is 1 to 10 μm, preferably 1 to 8 μm.

Further, the stimulable phosphor according to the present invention is desirably contained in the stimulable phosphor layer in a dispersed state in the resin. Here, as the binder that can be used, for example, polyurethane, polyester, vinyl chloride copolymer, vinyl chloride-
Vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (nitrocellulose etc.), styrene-butadiene copolymer And various synthetic rubber resins, phenol resins, epoxy resins, urea resins, melamine resins, phenoxy resins, silicone resins, acrylic resins, urea formamide resins, and the like.
Among them, it is preferable to use polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, and nitrocellulose.

That is, first, a binder and stimulable phosphor particles are added to an appropriate organic solvent, and the mixture is stirred and mixed using a disperser or a ball mill to uniformly disperse the stimulable phosphor in the binder. A stimulable phosphor coating is prepared.

Solvents for preparing the stimulable phosphor coating include:
Lower alcohols such as methanol, ethanol, n-propanol and n-butanol; hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; toluene, benzene, cyclohexane, cyclohexanone and xylene And esters of lower fatty acids such as methyl acetate, ethyl acetate and butyl acetate with lower alcohols, ethers such as dioxane, ethylene glycol monoethyl ester and ethylene glycol monomethyl ester, and mixtures thereof.

The stimulable phosphor paint has a dispersant for improving the dispersibility of the stimulable phosphor in the paint or a binder in the stimulable phosphor layer after formation and the stimulable phosphor layer. Various additives such as a plasticizer for improving the bonding force with the phosphor may be mixed.

Examples of dispersants include phthalic acid, stearic acid, caproic acid, lipophilic surfactants and the like.

Examples of the plasticizer include triphenyl phosphate,
Phosphoric acid esters such as tricresyl phosphate and diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; glycolic acid esters such as ethyl phthalylethyl glycolate and butyl phthalbutyl butylate; triethylene glycol and adipic acid Examples thereof include polyesters, polyesters of polyethylene glycol and aliphatic dibasic acids such as polyesters of diethylene glycol and succinic acid, and the like.

The phosphor coating containing the stimulable phosphor and the binder prepared as described above is uniformly applied to the surface of a support or a temporary support for forming a sheet, whereby the paint is applied. Form a film.

As the coating means, for example, a doctor blade, a roll coater, a knife coater, an extrusion coater or the like can be used.

The following two main methods are conceivable for manufacturing the radiation image conversion panel. As a first production method, a phosphor coating solution comprising a binder and a phosphor or a stimulable phosphor (hereinafter referred to as a stimulable phosphor paint) is applied on a support to form a stimulable phosphor layer. I do.

As a second production method, a stimulable phosphor coating comprising a binder and a stimulable phosphor is applied on a temporary support to form a stimulable phosphor sheet. The stimulable phosphor sheet is mounted on a support, and is bonded to the support at a temperature equal to or higher than the softening temperature or the melting point of the binder.

As the method for forming the stimulable phosphor layer on the support, the above two types are mainly considered. What is necessary is a method for uniformly forming the stimulable phosphor layer on the support. Or a method by spraying.

The stimulable phosphor layer of the first production method is prepared by applying a stimulable phosphor coating material in which a stimulable phosphor is uniformly dispersed in a binder solution onto a support and drying the stimulable phosphor coating. Can be manufactured.

The sheet to be the stimulable phosphor layer in the second production method was prepared by applying a stimulable phosphor coating on a temporary support for forming a stimulable phosphor sheet or on a temporary support. It can be manufactured by coating on a protective film, drying, and then peeling off from the temporary support. The protective layer itself can be used as a temporary support in the final product as it is.

In the second production method, a stimulable phosphor coating is applied on a temporary support or a protective film provided on the temporary support, dried, and then separated from the temporary support to obtain a stimulable phosphor. The sheet is to be a phosphor layer. Therefore, it is preferable that a release agent is applied to the surface of the temporary support in advance so that the formed stimulable phosphor sheet is easily released from the temporary support.

In order to strengthen the bond between the support and the stimulable phosphor layer, a high-molecular substance such as polyester or gelatin is applied to the surface of the support to provide an undercoat layer for imparting adhesiveness, or to improve the sensitivity and image quality (sharpness). Light-reflective layer made of a light-reflective material such as titanium dioxide to improve
Alternatively, a light absorbing layer made of a light absorbing substance such as carbon black may be provided. These configurations can be arbitrarily selected according to the purpose, use, and the like.

The stimulable phosphor layer of the present invention may be compressed. By compressing the stimulable phosphor layer, the packing density of the stimulable phosphor can be further improved, and the sharpness and granularity can be further improved. As a compression method, a press machine, a calender roll, or the like can be used.

In the case of the first production method, the stimulable phosphor layer and the support are compressed as they are. In the case of the second production method, a stimulable phosphor sheet is placed on a support, and the sheet is adhered to the support while being compressed at a temperature not lower than the softening temperature or melting point of the binder.

As described above, by utilizing the method of pressing the stimulable phosphor sheet on the support without fixing it in advance, the sheet can be spread thinly.

The thickness of the stimulable phosphor layer varies depending on the intended characteristics of the radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio between the binder and the phosphor, and the like.
μm to 1 mm is preferred, and more preferably 50 μm
３００300 μm.

The protective layer according to the present invention comprises ASTM D-10
The haze ratio measured by the method described in No. 03 is 5 or more and 60 or more.
% Is preferable from the viewpoint of moisture-proof property.

The protective layer can have an optimum moisture-proof property by adjusting the thickness or laminating a plurality of the protective layers in accordance with the required moisture-proof property. It is preferably at least 50 g / m ² · day or less.

In the case where an excitation light absorbing layer or the like is provided, the protective layer protects the excitation light absorbing layer from physical impact and chemical deterioration, and can maintain stable plate performance for a long period of time. The excitation light absorbing layer may be provided at a plurality of positions in the protective layer, or the adhesive layer for lamination may contain a coloring agent to form the excitation light absorbing layer.

The protective layer may be in close contact with the phosphor layer with an adhesive layer, but is more preferably a structure provided to cover the phosphor surface (hereinafter referred to as sealing or sealing structure). In sealing the phosphor layer, any known method may be used, but the phosphor sheet composed of the phosphor layer and the support is cut larger than the moisture-proof thin glass plate serving as the protective film. Adhesive is applied to a region where the peripheral edge of the glass plate serving as a protective layer is outside the peripheral edge of the phosphor sheet, a spacer is disposed for the thickness of the phosphor sheet, and another film described later is formed on this. To form a sealed structure, it is possible to prevent water from entering from the outer peripheral portion of the phosphor sheet.

The phosphor sheet having the phosphor layer coated on the support can be cut into a predetermined size by any general method. However, in view of workability and accuracy, a decorative cutting machine is used. And a punching machine.

Further, after a moisture-proof thin glass plate serving as a protective film is closely arranged, a phosphor sheet comprising a phosphor layer and a support and the outermost resin layer on the side of contacting the thin glass with the glass layer and the support are provided. May be sandwiched up and down with a resin film having heat-fusibility to seal the periphery. At this time, these operations may be carried out under reduced pressure in order to improve the adhesion between the thin glass of the protective layer and the phosphor layer, or between the resin film and the support.

Further, when the resin film on the side of the support is a laminated moisture-proof film formed by laminating, for example, one or more layers of aluminum films, the ingress of moisture can be reduced more reliably. This sealing method is also easy in terms of work.

The term “heat-fusible resin film” as used herein refers to a resin film that can be fused with a generally used impulse sealer, such as an ethylene vinyl acetate copolymer (EVA) or a polypropylene (PP) film. Examples include, but are not limited to, polyethylene (PE) films.

When heat-sealing with an impulse sealer, heat-sealing under reduced pressure is more effective in preventing displacement of the phosphor sheet in the moisture-proof protective film and eliminating moisture in the air. preferable.

FIG. 1 shows an example of the radiation image conversion panel of the present invention thus manufactured. In FIG. 1, reference numeral 1 denotes a protective layer made of thin glass, 2 denotes a stimulable phosphor layer, 3 denotes a support, 5 denotes a spacer, and 4 denotes a stimulable phosphor layer and a support which sandwich the spacer. It is a sealing film for sealing a body.

It is assumed that the protective layer of the radiation image conversion panel of the present invention has a very high optical transparency. As such a highly transparent protective layer material, the thin glass of the present invention is particularly preferred. According to the present invention, image unevenness and linear noise can be eliminated, and the sharpness can be further improved.

The haze ratio for obtaining the effect of the present invention is preferably 5% or more and less than 60%, more preferably 10% or more and less than 50%.

If the haze ratio is less than 5%, the effect of eliminating image unevenness and linear noise is small, and if it is 60% or more, the sharpness improving effect of the present invention is small.

Next, the formed coating film is dried by gradually heating to complete the formation of the stimulable phosphor layer on the undercoat layer.

FIG. 2 shows an example of a radiation image conversion method using the radiation image conversion panel of the present invention. The radiation image conversion conversion panel of the present invention is advantageously used in a radiation image conversion method schematically illustrated in FIG. That is, in FIG. 2, reference numeral 21 denotes a radiation generator, 22 denotes a subject, 23 denotes a radiation image conversion panel according to the present invention, 24 denotes a stimulating excitation light source, and 25 denotes a photoelectric detector for detecting stimulating light emitted from the conversion panel. A conversion device 26 is a radiation image reproducing device that reproduces a signal detected by the 25 photoelectric conversion devices as an image.
7 is a radiation image display device for displaying a reproduced image, 2
Reference numeral 8 denotes a filter that separates the photostimulated excitation light and the photostimulated fluorescence and transmits only the photostimulated fluorescence.

As shown in FIG.
The radiation R from 1 enters the radiation image conversion panel 23 through the subject 22 (RI). This incident radiation R
I is absorbed by the stimulable phosphor layer of the radiation image conversion panel 23, its energy is accumulated, and an accumulation image of a radiation transmission image is formed.

Next, the accumulated image is excited by stimulating light from the stimulating light source 24 and emitted as stimulating light.

Since the intensity of the stimulated emission emitted is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by, for example, a photoelectric conversion device 25 such as a photomultiplier tube.
By reproducing the image as an image by the radiation image reproducing device 26 and displaying the image by the radiation image display device 27, a radiation transmission image of the subject can be observed.

In the case of a system in which X-rays are incident from the phosphor layer side and reading is performed on the phosphor layer side, since a subject such as a human body exists on the phosphor layer side, reading is performed in another place using a cassette type. In general, the panel is transported and read at another place. However, according to these methods, it takes a long time between the photographing and the reading, and it is not possible to perform a group medical examination or the like in a short time. With the method of entering X-rays from the back side and reading from the front side as described above, without moving the panel,
Since it can be read immediately, there is an advantage that many subjects can be photographed in a short time.

X-ray irradiation is performed from the support side of the radiation image conversion panel, and laser scanning as a stimulating light source on the panel and reading of the stimulating light emission are performed on the side opposite to the stimulable phosphor support. In these methods performed from the viewpoint of the above, it is advantageous to use an organic polymer resin film having low X-ray absorption as a support and to use a material such as glass having low moisture permeability and optically small haze for the protective film. Thus, it is possible to obtain a high-quality, high-durability radiation image conversion panel using a stimulable phosphor that is lightweight and has little X-ray absorption.

[0094]

The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 << Preparation of BaFI: Eu Phosphor Particles >> To synthesize a precursor of a europium-activated barium fluoroiodide stimulable phosphor, 2500 ml of a 3.5 mol / L BaI ₂ aqueous solution was used. 125 ml of a 0.2 mol / L EuI ₃ aqueous solution was put into a reactor, and the reaction mother liquor was kept at 90 ° C. while stirring.
Next, 250 ml of 10 mol / L ammonium fluoride aqueous solution
Was poured into the reaction mother liquor using a roller pump to form a precipitate, and the mixture was kept warm and stirred for 2 hours to mature the precipitate.

After the precipitate was filtered off and washed with methanol,
The crystals were dried under vacuum to obtain europium-activated barium fluoroiodide crystals. To prevent the change in particle shape due to sintering during sintering and the change in particle size distribution due to fusion between particles, 1% by mass of ultrafine alumina powder is added and sufficiently stirred with a mixer. Fine particles of alumina were uniformly attached to the crystal surface. This was filled in a quartz boat, baked at 900 ° C. for 3 hours in a nitrogen gas atmosphere using a tube furnace, and europium-activated barium fluoroiodide (BaFI:
Eu) phosphor particles were obtained. Average crystal size is 3.1 μm
Met.

<< Production of Radiation Image Conversion Panel Sample 1 >> The obtained phosphor particles were classified and average crystal size was 3.0 μm.
342 g of the phosphor and 18 g of a polyester resin (manufactured by Toyobo Co., Ltd., Byron 200) were added to a mixed solvent of MEK and toluene (1: 1), dispersed by a propeller mixer, and a coating solution having a viscosity of 25 Pa · s was obtained. Prepared. The coating solution was applied on a support (PET having a thickness of 250 μm) shown in Table 1 using a doctor blade, and then heated at 100 ° C.
For 15 minutes to form a phosphor layer having a thickness of 249 μm.

Next, the protective layer material (thin glass having a thickness of 1 mm, made of borosilicate glass) was cut into a size of 10 cm × 10 cm, and the phosphor layer and the support were cut into a slightly larger area. The sheet was brought into close contact with the phosphor layer. An adhesive (Ciba Geigy Co., Ltd. epoxy adhesive ARALDI) is applied to the portion of the protective layer that protrudes from the phosphor sheet.
TE AW136H and HARDENER HY99
4) is applied, a spacer made of the same material as the protective layer having the same thickness as the phosphor layer and the support is adhered to each of the four sides, and the adhesive resin is further applied to the spacer. Similarly, a sealing resin film (polyethylene terephthalate transparent film thickness 30) coated with the adhesive resin.
μm) was adhered and thermally bonded. Under reduced pressure, the protective layer and the phosphor layer or between the support and the resin film for sealing were sufficiently adhered. A radiation image conversion panel sample 1 sealed in this manner was manufactured.

<< Manufacture of Radiation Image Conversion Panel Samples 2 to 4 >> In manufacturing the radiation image conversion panel sample 1, the support was changed as shown in Table 1, and the surface of the support opposite to the phosphor layer was changed. The radiation image conversion panel samples 2 to 4 were produced in the same manner except that a moisture-proof layer was provided.

The moisture permeability of each of the moisture-proof layer and the support shown in Table 1 was determined for the used film or glass plate in accordance with the method specified in JIS Z 0208.

<< Sensitivity measurement and durability evaluation using the same >>
For each of the radiation image conversion panel samples 1 to 4, FIG.
As described above, the radiation image conversion panel was irradiated with X-rays having a tube voltage of 80 kVp from the back surface through an aluminum wedge. Next, the panel was scanned and excited by a 200 mW semiconductor laser (780 nm), and the stimulated emission emitted from the phosphor layer was received using a photoelectron image tube (Hamamatsu Photonics R1305). , And their intensities were measured and used as initial sensitivities.

Each of the radiation image conversion panel samples 1 to 4 was left in an environment of 40 ° C. and 90% RH for 3 months, and the initial sensitivity and the sensitivity after 3 months were compared relatively. The initial sensitivity was set to 100, and the sensitivity after three months elapsed was represented by relative sensitivity, which was used as durability data.

Table 1 shows the obtained results. As the durability data, the lower the numerical value, the lower the durability.

[0104]

[Table 1]

From the results shown in Table 1, it is clear that the sample of the present invention exhibits better durability than the comparison.

Example 2 << Manufacture of Radiation Image Conversion Plate Samples 5-7 >> In manufacturing the radiation image conversion panel sample 1, as shown in Table 2, a trading member was used as a support member, and a double-sided tape was used. A radiation image conversion plate sample 5 was manufactured in the same manner except that a radiation image conversion panel sample as described in Table 2 above was adhered. Next, as shown in Table 2, by providing a support member and a moisture-proof layer, radiation image conversion plate samples 6 and 7 were respectively manufactured.

The obtained radiation image conversion plate sample 5
For each of No. 7, the sensitivity was measured in the same manner as described in Example 1, and the durability was evaluated using the same.

Table 2 shows the obtained results. As the durability data, the lower the numerical value, the lower the durability.

[0109]

[Table 2]

From the results shown in Table 2, it is clear that the sample of the present invention exhibits better durability than the comparison.

[0111]

According to the present invention, a radiation image conversion panel and a radiation image conversion plate having high durability and a radiation image reading apparatus using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a radiation image conversion panel according to the present invention.

FIG. 2 is a schematic view showing one embodiment of an image conversion method using the radiation image conversion panel according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 protective layer 2 stimulable phosphor layer 3 support 4 sealing film 5 spacer 21 radiation generator 22 subject 23 radiation image conversion panel 24 stimulating excitation light source 25 photoelectric conversion device 26 radiation image reproducing device 27 radiation image display Device 28 Filter R Radiation from radiation generator RI Radiation incident through subject

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 42/02 G03B 42/02 B F-term (Reference) 2G083 AA03 CC02 CC04 CC08 CC09 DD01 DD02 DD11 DD16 EE08 2H013 AC01 AC03 4H001 CA01 CA08 XA09 XA17 XA35 XA53 XA56 YA63

Claims (6)

[Claims] 1. A radiation image conversion panel having a stimulable phosphor layer and a protective layer on a support.
The moisture permeability defined by IS Z 0208 is 0.1
A radiation image conversion panel characterized by the following. 2. The radiation image conversion panel according to claim 1, wherein the support is a thin glass having a thickness of 50 μm to 500 μm. 3. The radiation image conversion panel according to claim 1, wherein the stimulable phosphor layer contains a stimulable phosphor represented by the following general formula (1). General formula (1) BaFX: Eu wherein X represents a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. ] 4. A radiation image conversion plate having the radiation image conversion panel according to claim 1 on a support member, wherein the radiation image conversion plate is provided between the support of the radiation image conversion panel and the support member. A radiation image conversion plate, wherein a moisture-proof layer is disposed on the substrate, and the moisture-proof layer has a moisture permeability defined by JIS Z0208 of 0.1 or less. 5. The support according to claim 4, wherein the support comprises an organic polymer film, the support member comprises carbon fiber or a composite material containing carbon fiber, and the moisture-proof layer is a thin glass of 50 μm to 500 μm. A radiation image conversion plate according to item 1. 6. A radiation image reading device, wherein the radiation image conversion plate according to claim 5 is fixed in a reading device, and a reading member is arranged facing the protective layer side of the plate.