JPH0562719B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a radiation image conversion panel used in a radiation image conversion method using a stimulable phosphor.

[Technical Background of the Invention] As a method of obtaining a radiation image as an image, so-called radiography has conventionally been used, which uses a combination of a radiographic film having an emulsion layer made of a silver salt photosensitive material and an intensifying screen. There is. Recently, a radiation image conversion method using a stimulable phosphor, as described in Japanese Patent Application Laid-open No. 55-12145, has been attracting attention as an alternative to the above-mentioned radiographic method. Summer. This radiation image conversion method uses a radiation image conversion panel (stimulable phosphor sheet) containing a stimulable phosphor. Accumulated in the stimulable phosphor by absorbing it into the stimulable phosphor and then exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light or infrared rays in a time-series manner. Radiation energy is emitted as fluorescence (stimulated luminescence), this fluorescence is read photoelectrically to obtain an electrical signal, and the obtained electrical signal is converted into an image.

The above-mentioned radiation image conversion method has the advantage that a radiation image rich in information can be obtained with a much lower exposure dose than conventional radiography methods. Therefore, this radiation image conversion method has a very high utility value especially in direct medical radiography such as X-ray photography for the purpose of medical diagnosis.

The radiation image conversion panel used in the above radiation image conversion method has a basic structure consisting of a support and a phosphor layer provided on one side of the support. Note that the surface of this phosphor layer opposite to the support (the surface not facing the support) is generally provided with a transparent protective film made of a polymeric substance.
Protects the phosphor layer from chemical deterioration or physical impact.

The phosphor layer usually consists of a stimulable phosphor and a binder that contains and supports the stimulable phosphor in a dispersed state.The stimulable phosphor absorbs radiation such as X-rays and then becomes visible. It has the property of emitting light (stimulated luminescence) when irradiated with electromagnetic (excitation light) such as light and infrared rays. Therefore, the radiation transmitted through the subject or emitted from the subject is absorbed by the phosphor layer of the radiation image conversion panel in proportion to the amount of radiation, and the radiation of the subject or subject is absorbed on the radiation image conversion panel. An image is formed as a cumulative image of radiation energy. This accumulated image can be emitted as stimulated luminescence by time-series excitation with the electromagnetic waves mentioned above, and by reading this stimulated luminescence photoelectrically and converting it into an electrical signal, the accumulated image of radiation energy can be imaged. It becomes possible to convert into

The radiation image conversion method described above is a very advantageous image forming method as described above, but the radiation image conversion panel used in this method is also highly sensitive, similar to the intensifying screen used in conventional radiography. It is desired that the image quality is high and that it provides an image with excellent image quality (sharpness, graininess, etc.). In particular, when applying a radiation image conversion method to medical radiography, it is necessary to reduce the radiation dose to the human body and obtain more information, so the radiation image conversion panel used in the method must have as high a sensitivity as possible. It is desirable that

The sensitivity of a radiation image storage panel is basically determined by the amount of stimulated luminescence of the stimulable phosphor contained in the panel, and this amount of luminescence not only depends on the luminescent properties of the phosphor itself, but also In cases where the excitation light for exhaustion emission does not have sufficient intensity, the intensity also varies depending on the intensity.

In the radiation image conversion method, the radiation image conversion panel is read out by scanning the panel with excitation light such as a laser beam.
A part of the excitation light is reflected by the panel surface and therefore does not reach the phosphor layer, resulting in the problem that the excitation light is not used efficiently. In particular, when using semiconductor lasers, which are considered for practical use as excitation light sources, the output of the laser light is small, so it is desirable to increase the efficiency of excitation light use and improve panel sensitivity. .

In addition, if the light reflection on the panel surface is large,
The excitation light reflected on the panel surface is re-reflected by a readout system and enters the panel, thereby exciting parts other than the irradiation target (flare phenomenon).
As a result, image information of other parts will also be read out together, resulting in inaccurate image information. From this point of view as well, it is desired to reduce the surface reflection of the panel as much as possible.

[Summary of the Invention] An object of the present invention is to provide a radiation image conversion panel with improved sensitivity.

Another object of the present invention is to provide a radiation image conversion panel that is highly sensitive and provides images with excellent image quality.

The present invention provides a radiation image storage panel having a support, a phosphor layer containing a stimulable phosphor, and a protective film in this order, in which 400 to
An inorganic substance having an optical film thickness corresponding to an odd multiple of 1/4 of the wavelength of excitation light in the range of 900 nm (nλ/4: n = 1, 3, 5, ~ ~ ~, λ = wavelength of excitation light) A radiation image conversion panel characterized in that it is provided with an excitation light antireflection film consisting of:

Note that in the present invention, the "panel surface" means the surface on the side that is irradiated with excitation light. in general,
In implementing a radiation image conversion method using a radiation image conversion panel, excitation light is irradiated from the protective film side, and the panel surface usually refers to the surface of the protective film.

The present invention provides an antireflection film on the excitation light irradiation side surface of a radiation image conversion panel, thereby increasing the utilization efficiency of excitation light and improving the sensitivity of the panel. That is, by providing a layer made of a material with a suitable thickness on the panel surface with respect to excitation light for causing the stimulable phosphor contained in the radiation image conversion panel to stimulate luminescence, the panel surface can be improved. The absorption of the excitation light in the phosphor layer can be increased by reducing the reflection of the excitation light at the phosphor layer. This makes it possible to maintain a high amount of stimulated luminescence of the phosphor in the phosphor layer even when irradiated with weak-intensity excitation light, making it possible to increase the sensitivity of the panel.

In particular, when the excitation light has a low output such as a semiconductor laser beam, or when the intensity of the excitation light cannot be increased due to readout setting conditions, etc., the utilization efficiency of the excitation light of the radiation image conversion panel increases. This can be said to be a big advantage.

Further, it is possible to prevent the flare phenomenon caused by the excitation light reflected on the panel surface being re-reflected by another object as described above, thereby making it possible to obtain accurate image information.

Therefore, by using the panel of the present invention, restrictions on the excitation light source and the readout system can be relaxed, so improvements such as miniaturization and speeding up of the radiation image conversion device used for panel readout can be made. This makes it easier, and in turn, it becomes possible to widen the range of application of the radiation image conversion method.

Furthermore, when a fluoride such as magnesium fluoride is used as a material for the antireflection film, the hardness of the panel surface can be increased at the same time, and its scratch resistance can be improved. Fluorescence (i.e., image information) typically emitted from a radiation image conversion panel
The readout is performed from the same side as the excitation light irradiation, and therefore, the scratch resistance of the panel surface is improved, making it possible to prevent image deterioration due to scratches on the panel surface.

[Structure of the Invention] The radiation image conversion panel of the present invention having the preferable characteristics as described above can be manufactured, for example, by the method described below.

The support used in the present invention can be arbitrarily selected from various materials used as supports for intensifying screens in conventional radiography methods or materials known as supports for radiation image conversion panels. . Examples of such materials include films of plastic materials such as cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate, metal sheets such as aluminum foil, aluminum alloy foil, regular paper, Paraiter paper, resins, etc. Examples include coated paper, pigment paper containing pigments such as titanium dioxide, and paper sized with polyvinyl alcohol. However, when considering the characteristics and handling of the radiation image conversion panel as an information recording material,
A particularly preferred material for the support in the present invention is plastic film. This plastic film may be kneaded with a light-absorbing substance such as carbon black, or may be kneaded with a light-reflecting substance such as titanium dioxide.
The former is a support suitable for a high sharpness type radiation image conversion panel, and the latter is a support suitable for a high sensitivity type radiation image conversion panel.

In known radiation image conversion panels, a phosphor layer is provided in order to strengthen 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 polymeric substance such as gelatin is coated on the surface of the support on the side to be coated to form an adhesion imparting layer, or a light reflective layer made of a light reflective material such as titanium dioxide, or a light absorbing material such as carbon black. Providing a light absorption layer is also practiced. The support used in the present invention can also be provided with these various layers.

Furthermore, as described in Japanese Patent Application Laid-Open No. 58-200200, in order to improve the sharpness of the obtained image, the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side) When an adhesion-imparting layer, a light-reflecting layer, a light-absorbing layer, etc. are provided, fine irregularities may be uniformly formed on the surface (meaning the surface thereof).

Next, a phosphor layer is formed on the support.
The phosphor layer is basically a layer consisting of a binder containing and supporting particles of stimulable phosphor in a dispersed state.

As mentioned above, a stimulable phosphor is a phosphor that exhibits stimulated luminescence when irradiated with radiation and then with excitation light, but from a practical standpoint, the waveform is
300-500nm with excitation light in the 900nm range
It is desirable that the phosphor exhibits stimulated luminescence in the wavelength range of . Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include those described in U.S. Pat. No. 3,859,527.
SrS: Ce, Sm, SrS: Eu, Sm, ThO ₂ : Er, and La ₂ O ₂ S: Eu, Sm, described in JP-A-55-12142.
ZnS: Cu, Pb, BaO・xAl ₂ O ₃ : Eu (however, 0.8
<x≦10), and M〓O・xSiO ₂ :A (however,
M〓 is Mg, Ca, Sr, Zn, Cd, or Ba,
A is Ce, Tb, Eu, Tm, Pb, Tl, Bi, or
(Ba _1-Xy , Mg _x , Ca _y )FX: aEu ²⁺ (where X
is at least one of Cl and Br,
x and Y are 0<x+y≦0.6 and xy≠0, and a is ^10-6 ≦a≦5× ^10-2 ), as described in JP-A-55-12144.
LnOX:xA (Ln is La, Y, Gd, and
At least one of Lu, X is at least one of Cl and Br, A is at least one of Ce and Tb, and x is 0<x<0.1
(Ba _1-x , M ²⁺ _x ) FX:yA (where M ²⁺ is Mg,
At least one of Ca, Sr, Zn, and Cd, or at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy, Pr, Ho,
at least one of Nd, Yb, and Er; x is 0≦x≦0.6; y is 0≦y≦0.2);
FX・xA: yLn [However, M〓 is Ba, Ca, Sr,
At least one of Mg, Zn, and Cd, A
are BeO, MgO, CaO, SrO, BaO, ZnO,
Al ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , TlO ₂ ,
ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , and
At least one of ThO ₂ , Ln is Eu, Tb,
Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sm,
and at least one of Gd, X is Cl,
At least one of Br, and I,
x and y are respectively 5×10 ^-5 ≦x≦0.5 and 0<y≦0.2] A phosphor is described in JP-A-56-116777 (Ba _{1- x} , M〓x(F ₂・aBaX ₂ :yEu, zA [however,
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium; X is at least one of chlorine, bromine, and iodine; A is at least one of zirconium and scandium;
a, x, y, and z are each 0.5≦a≦1.25,
0≦x≦1, 10 ^-6 ≦y≦2×10 ^-1 , and 0<z
≦10 ^-2 ], described in Japanese Patent Application Laid-Open No. 57-23673, (Ba _1-x , M〓x)F ₂・aBaX ₂ :yEu, zB [However, ,
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium;
10 ^-6 ≦y≦2×10 ^-1 and 0<z≦2×10 ^-1 ] A phosphor is described in JP-A-57-23675 (Ba _{1 -x} , M〓x)F ₂・aBaX ₂ :yEu, zA [However,
M〓 is beryllium, magnesium, calcium,
at least one of strontium, zinc, and cadmium; X is at least one of chlorine, bromine, and iodine; A is at least one of arsenic and silicon; a, x, y, and z are each 0.5 ≦a≦1.25, 0≦x≦1, 10 ^-6
≦y≦2×10 ⁻¹ and 0<y≦5×10 ¹ ]
A phosphor represented by the composition formula is described in JP-A-58-69281.
MOX: xCe [However, M〓 is Pr, Nd, Pm, Sm,
At least one trivalent metal selected from the group consisting of Eu, Tb, Dy, Ho, Er, Tm, Yb, and Bi, X is one or both of Cl and Br, and x is 0<x<0.1] A phosphor is described in JP-A-58-206678.
Ba _1-x M _x/2 L _x/2 FX:yEu ²⁺ [However, M is Li, Na,
Represents at least one alkali metal selected from the group consisting of K, Rb, and Cs; L is Sc,
Y, La, Ce, Pr, Nd, Pm, Sm, Gd, Tb,
represents at least one trivalent metal selected from the group consisting of Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In, and Tl;
and x is 10 ^-2 ≦x≦0.5, and y is 0<y≦0.1]; JP-A-59-27980 stated in the issue
BaFX・xA:yEu ²⁺ [wherein, 10 ^-6 ≦x≦
0.1, y is 0<y≦0.1], which is described in JP-A-59-47289.
BaFX・xA:yEu ²⁺ [However, X is at least one halogen selected from the group consisting of Cl, Br, and I; A is hexafluorosilicic acid,
x is a fired product of at least one compound selected from the hexafluoro compound group consisting of monovalent or divalent metal salts of hexafluorotitanic acid and hexafluorozirconic acid;
10 ^-6 ≦x≦0.1, y is 0<y≦0.1] A phosphor described in JP-A No. 59-56479
BaFX・xNaX′: aEu ²⁺ [However, X and X′ are
Phosphor, each of which is at least one of Cl, Br, and I, and x and a are 0<x≦2 and 0<a≦0.2, respectively] JP-A-59- M described in Publication No. 56480〓
FX・xNaX′: yEu ²⁺ : zA [However, M〓 is Ba,
at least one alkaline earth metal selected from the group consisting of Sr, and Ca;
X′ is at least one kind of halogen selected from the group consisting of Cl, Br, and I;
is at least one transition metal selected from V, Cr, Mn, Fe, Co, and Ni; and
A phosphor ^represented by the composition formula: There M〓
FX・aM〓X′・bM′〓X″ ₂・cM〓X ₃・xA：
yEu ²⁺ [where M〓 is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; M〓 is Li, Na, K, Rb, and Cs
is at least one kind of alkali metal selected from the group consisting of; M′〓 is at least one divalent metal selected from the group consisting of Be and Mg;
M〓 is at least one kind of trivalent metal selected from the group consisting of Al, Ga, In, and Tl; A is a metal oxide; X is at least one kind selected from the group consisting of Cl, Br, and I. X′, X″, and X″ are at least one kind of halogen selected from the group consisting of F, Cl, Br, and I; and a is 0≦a≦2, and b is 0 ≦
b≦10 ^-2 , c is 0≦c≦10 ^-2 , and a+b+c≧
10 ^-6 ; x is 0<x≦0.5, y is 0<y≦0.2
A phosphor _represented by the composition ^formula M〓X ₂・aM〓
M〓 is at least one kind of alkaline earth metal selected from the group consisting of Ba, Sr, and Ca; X and X' are at least one kind of halogen selected from the group consisting of Cl, Br, and I, and ≠
X′; and a is 0.1≦a≦10.0, and x is 0<
x < 0.2], and the like.

In addition, the M〓X _{2 ・}aM〓X′ ₂ :xEu ² ₊ phosphor described in the above-mentioned Japanese Patent Application No. 58-193161 contains additives as shown below. It may be contained in the following proportions per 1 mole of 〓X′ ₂ .

bM〓X″ (however, M〓 is Rb and Cs
X″ is at least one halogen selected from the group consisting of F, Cl, Br and I, and b satisfies 0<b≦10.0); Gansho 59
−bKX″/cMgX described in specification No. 77225
₂・dM〓X′′′′′ ₃ (However, M〓 is Sc, Y, La, Gd
and at least one kind of trivalent metal selected from the group consisting of Lu, and X'', and b, c and d are 0≦b≦2.0, 0≦
c≦2.0, 0≦d≦2.0, and 2×10 ^-5 ≦
b+c+d); yB described in the specification of Japanese Patent Application No. 59-84356 (however, y is 2×10 ^-4 ≦y≦
2×10 ^-1 ); and bA described in Japanese Patent Application No. 59-84358 (where A is SiO ₂ and
(at least one kind of oxide selected from the group consisting of P ₂ O ₅ , and b is 10 ^-4 ≦b≦2×10 ^-1 ) Among the above stimulable phosphors, divalent europium activation Alkaline earth metal fluorohalide phosphors, divalent europium-activated alkaline earth metal halide phosphors, and rare earth element-activated rare earth oxyhalide phosphors are particularly preferred because they exhibit high-intensity stimulated luminescence. However, the stimulable phosphor used in the present invention is not limited to the above-mentioned phosphors, but any phosphor that exhibits stimulated luminescence when irradiated with radiation and then irradiated with excitation light. It may be.

Examples of binders for the phosphor layer include proteins such as gelatin, polysaccharides such as dextran, or natural polymeric substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethylcellulose, and vinylidene chloride. Binders represented by synthetic polymeric substances such as vinyl chloride copolymers, polyalkyl (meth)acrylates, vinyl chloride/vinyl acetate copolymers, polyurethanes, cellulose acetate butyrate, polyvinyl alcohol, linear polyesters, etc. can. Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl(meth)
acrylates, mixtures of nitrocellulose and linear polyesters and mixtures of nitrocellulose and polyalkyl (meth)acrylates.
Note that some of these binders may be crosslinked with a crosslinking agent.

The phosphor layer can be formed on the support, for example, by the following method.

First, the above-mentioned stimulable phosphor and binder are added to a suitable solvent and thoroughly mixed to prepare a coating solution in which phosphor particles are uniformly dispersed in the binder solution.

Examples of solvents for preparing coating solutions include lower alcohols such as methanol, ethanol, n-propanol, and n-butanol; chlorine-containing hydrocarbons such as methylene chloride and ethylene chloride; and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate; Ethers such as dioxane, ethylene glycol monoethyl ether and ethylene glycol monomethyl ether; and mixtures thereof.

The mixing ratio of the binder and the stimulable phosphor in the coating solution varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, etc., but in general, the mixing ratio of the binder and the stimulable phosphor is , 1:1 to 1:100 (weight ratio), and particularly preferably 1:8 to 1:40 (weight ratio).

The coating liquid also contains a dispersant to improve the dispersibility of the phosphor in the coating liquid, and a dispersant to improve the bonding force between the binder and the phosphor in the phosphor layer after formation. Various additives such as plasticizers may be mixed. Examples of dispersants used for such purposes include phthalic acid, stearic acid, caproic acid, lipophilic surfactants, and the like. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; and ethyl phthalyl ethyl glycolate and butyl phthalyl butyl glycolate. Glycolic acid esters; and polyesters of polyethylene glycol and aliphatic dibasic acids, such as polyesters of triethylene glycol and adipic acid and polyesters of diethylene glycol and succinic acid.

The coating solution containing the phosphor and binder prepared as described above is then uniformly applied to the surface of the support to form a coating film of the coating solution. This coating operation can be carried out using conventional coating means such as a doctor blade, roll coater, knife coater, etc.

The formed coating film is then dried by gradually heating to complete the formation of the phosphor layer on the support. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of phosphor, the mixing ratio of binder and phosphor, etc., but usually
The thickness should be 20 μm to 1 mm. However, the thickness of this layer is preferably 50 to 500 μm.

Note that the phosphor layer does not necessarily need to be formed by directly applying a coating liquid onto the support as described above.
For example, a phosphor layer is formed by separately applying a coating liquid onto a sheet such as a glass plate, metal plate, or plastic sheet and drying, and then this is pressed onto a support, or by using an adhesive. The support and the phosphor layer may be bonded together.

Next, a transparent protective film is provided on the surface of the phosphor layer opposite to the side in contact with the support for the purpose of physically and chemically protecting the phosphor layer.

The transparent protective film may be made of a transparent material such as a cellulose derivative such as cellulose acetate or nitrocellulose; or a synthetic polymer material such as polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride/vinyl acetate copolymer. It can be formed by coating the surface of the phosphor layer with a solution prepared by dissolving a polymeric substance in an appropriate solvent. Alternatively, it can also be formed by a method such as adhering a transparent thin film separately formed from polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide, etc. to the surface of the phosphor layer using a suitable adhesive. The thickness of the transparent protective film formed in this way is approximately 3 to 20 μm.
It is desirable to set it to m.

An antireflection film, which is a characteristic feature of the present invention, is provided on this transparent protective film.

The material used for the antireflection film in the radiation image storage panel of the present invention has low reflection characteristics with respect to excitation light for causing the stimulable phosphor contained in the panel to stimulate luminescence. That is, it has a small reflectance to electromagnetic waves in the excitation wavelength region of the stimulable phosphor. At the same time, the material needs to have low absorption characteristics for excitation light, in other words, it needs to have excellent transmission characteristics. Examples of such materials include inorganic fluorides such as magnesium fluoride, calcium fluoride, cryolite; and aluminum oxide,
Inorganic oxides such as zirconium dioxide, titanium dioxide, silicon monoxide, and silicon dioxide can be mentioned. Since antireflection films obtained using these fluorides have high surface hardness, they can improve the scratch resistance of the panel surface (ie, the fluorescent readout side surface), which is also preferable from the viewpoint of image quality.

The antireflection film can be provided, for example, by forming a thin film made of the above-mentioned material on the surface of the protective film by a method such as vacuum deposition or sputtering. From the viewpoint of reflection characteristics, the thickness of the antireflection film is preferably on the order of the wavelength of the excitation light. In particular, the optical thickness is an odd multiple of 1/4 of the wavelength of the excitation light (where the wavelength is λ, the thickness of the film is on the order of the wavelength of the excitation light). Thickness = nλ/4, n = 1, 3, 5
) is preferable because the reflectance becomes low. Further, by forming the antireflection film into a multilayer film, the reflectance can be further reduced. Generally, it is desirable that the thickness of the antireflection film be approximately 0.1 to 10 μm.

In the present invention, by attaching an antireflection film to the surface of the protective film of the radiation image conversion panel as described above, it is possible to improve the utilization efficiency of excitation light. Further, even when the intensity of excitation light is low, the sensitivity of the panel can be maintained at high sensitivity. Furthermore, it is possible to reduce the reflection of the excitation light on the panel surface, thereby preventing a reduction in readout accuracy due to re-reflection of the excitation light.

Note that the radiation image conversion panel of the present invention is disclosed in Japanese Patent Application Laid-open No.
55-163500, Japanese Patent Application Laid-open No. 57-96300, etc., it may be colored with a coloring agent, and this coloring can improve the sharpness of the image obtained. can. Further, in the radiation image conversion panel of the present invention, white powder may be dispersed in the phosphor layer for the same purpose as described in Japanese Patent Application Laid-Open No. 146447/1983.

Next, Examples and Comparative Examples of the present invention will be described.
However, these examples do not limit the invention.

[Example] Methyl ethyl ketone was added to a mixture of powdered divalent europium-activated barium fluoride bromide phosphor (BaFBr: 0.001Eu ²⁺ ) and linear polyester resin, and further nitrocellulose with a nitrification degree of 11.5% was added. A dispersion liquid containing the phosphor in a dispersed state was prepared. Next, tricresyl phosphate, n
- After adding butanol and methyl el ketone, thoroughly stir and mix using a propeller mixer to ensure that the phosphor is uniformly dispersed, and the mixing ratio of binder and phosphor is 1:10, and the viscosity is 25~25. 35PS (25℃)
A coating solution was prepared. Next, the coating solution was uniformly applied using a doctor blade onto a titanium dioxide-mixed polyethylene terephthalate sheet (support, thickness: 250 μm) placed horizontally on a glass plate. After coating, the support on which the coating film has been formed is placed in a dryer, and the temperature inside the dryer is adjusted to 25°C.
The coating film was dried by gradually increasing the temperature from °C to 100 °C. In this way, a layer film is formed on the support.
A phosphor layer of 250 μm was formed.

A transparent protective film is formed by placing and adhering a polyethylene terephthalate transparent film (thickness: 12 μm, coated with a polyester adhesive) with the adhesive layer facing down on top of this phosphor layer. did.

Next, magnesium fluoride (MgF ₂ ) was deposited on this transparent protective film to a thickness of about 1580 Å (He
An anti-reflection film was provided by depositing the anti-reflection film to a thickness of 1/4 of the wavelength of -Ne laser light, 632.8 nm.

In this way, a radiation image storage panel was produced, which consisted of a support, a phosphor layer, a transparent protective film, and an antireflection film.

[Comparative Example] A radiation image composed of a support, a phosphor layer, and a transparent protective film was prepared by performing the same procedure as in the example except that an antireflection film was not provided on the protective film. A conversion panel was manufactured.

Next, the surface reflectance of each radiation image conversion panel on the protective film side surface was measured using a He--Ne laser (632.8 nm). As a result, the surface reflectance of the conventional radiation image conversion panel (comparative example) was about 4%, but the surface reflectance of the radiation image conversion panel of the present invention (example) was about 1.5%, and the panel surface The light reflection was significantly reduced.

Claims (1)

[Scope of Claims] 1. A radiation image conversion panel having a support, a phosphor layer containing a stimulable phosphor, and a protective film in this order, in which excitation light in the range of 400 to 900 nm is applied to the surface of the panel. Odd multiple of 1/4 of wavelength (nλ/4:
A radiation image conversion panel characterized by being provided with an excitation light antireflection film made of an inorganic substance and having an optical thickness corresponding to n=1, 3, 5, ~~~, λ = wavelength of excitation light. . 2. The radiation image conversion panel according to claim 1, wherein the excitation light antireflection film is made of an inorganic fluoride. 3. The radiation image conversion panel according to claim 1, wherein the excitation light antireflection film is made of magnesium fluoride. 4. The radiation image conversion panel according to claim 1, wherein the excitation light antireflection film has a thickness in the range of 0.1 to 10 μm.