JPH0631907B2 - Radiation image conversion panel - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a radiation image conversion panel used in a radiation image conversion method utilizing a stimulable phosphor. More specifically, the present invention relates to a radiation image conversion panel using a stimulable phosphor containing iodine.

[Technical Background of the Invention and Prior Art] As a method for obtaining a radiographic image as an image, a so-called radiographic method using a combination of a radiographic film having an emulsion layer made of a silver salt light-sensitive material and an intensifying screen has hitherto been used. It's being used. Recently, as one of the alternative methods to the radiographic method, a radiographic image conversion method using a stimulable phosphor as described in, for example, Japanese Patent Application Laid-Open No. 55-12145 has been attracting attention. became. This radiation image conversion method uses a radiation image conversion panel (stimulable phosphor sheet) having a stimulable phosphor, and the radiation transmitted through the subject or the radiation emitted from the subject is irradiated onto the panel. It is accumulated in the stimulable phosphor by absorbing it in the stimulable phosphor and then exciting the stimulable phosphor in time series with electromagnetic waves (excitation light) such as visible light and infrared rays. Radiation energy is emitted as fluorescence (stimulated luminescence), this fluorescence is photoelectrically read to obtain an electric signal, and the obtained electric signal is imaged.

This radiographic image conversion method has an advantage that a radiographic image having a large amount of information can be obtained with a much smaller exposure dose than in the case of the conventional radiographic method. Therefore, this radiographic image conversion method is extremely useful in direct medical radiography such as X-ray radiography for the purpose of medical diagnosis.

The radiation image conversion panel used in the radiation image conversion method has, as a basic structure, a support and a phosphor layer provided on one surface thereof. In addition, a transparent protective film is generally provided on the surface of the phosphor layer opposite to the support (the surface not facing the support), and the phosphor layer is chemically altered or Protects against physical shock.

The phosphor layer is composed of a stimulable phosphor and a binder which contains and supports the stimulable phosphor in a dispersed state. The stimulable phosphor absorbs radiation such as X-rays and then emits visible light and It has a property of emitting light (stimulated luminescence) when irradiated with electromagnetic waves (excitation light) such as infrared rays. Therefore,
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 image of the subject or subject is radiated on the radiation image conversion panel. It is formed as an accumulated image of energy. This accumulated image can be emitted as stimulated emission by being excited in time series by the electromagnetic wave, and the accumulated image of radiation energy can be imaged by photoelectrically reading this stimulated emission and converting it into an electric signal. Can be converted.

The radiographic image conversion method is a very advantageous image forming method as described above, but the radiographic image conversion panel used in this method has high sensitivity like the intensifying screen used in the conventional radiographic method. It is desired to provide an image having excellent image quality (sharpness, graininess, etc.). In particular,
When the human body is used as a subject, it is desired that the sensitivity of the panel be as high as possible in order to reduce the exposure dose as much as possible.

Hitherto, as a stimulable phosphor used in a radiation image conversion panel, a divalent europium-activated barium fluorohalide phosphor (BaFX: Eu ²⁺ ; where X is I, or I and Cl and / or Br , A divalent europium-activated barium halide phosphor (BaXX ′: E)
u ²⁺ ; provided that X and X ′ are at least one halogen selected from Cl, Br and I, and X ≠
X ′, and at least one of X and X ′ contains I), a cerium-activated rare earth oxyhalide phosphor (LnOX: Ce; where Ln is at least one rare earth element selected from Y, La and lanthanide) And
X is I, or I and Cl and / or Br),
And a bismuth-activated alkali metal halide phosphor (M ^I X: Bi; where M ^I is Rb and / or Cs
And X is I, or I and Cl and / or Br) and the like containing iodine as a phosphor component is proposed.

However, when these iodine-containing stimulable phosphors are used, iodine is liberated from the phosphors to form iodine molecules (I ₂ ), so that the phosphor layer tends to be gradually colored yellow. . The radiation image conversion panel in which the phosphor layer is yellowed as described above has a problem that the sensitivity is significantly lowered.

SUMMARY OF THE INVENTION An object of the present invention is to provide a radiation image conversion panel with improved sensitivity.

The above-mentioned object is a radiation image conversion panel having a support and a phosphor layer made of a binder which contains and supports the stimulable phosphor provided in a dispersed state on the support, wherein the stimulable phosphor is This can be achieved by the radiation image storage panel of the present invention, which is a phosphor containing iodine, and the phosphor layer contains a compound having an epoxy group.

That is, the present invention realizes a remarkable improvement in the sensitivity of the panel by including a compound having an epoxy group in the phosphor layer of the radiation image conversion panel using the stimulable phosphor containing iodine as the phosphor component. To do.

The present inventors have found that when a stimulable phosphor containing iodine is used in a radiation image conversion panel, the phosphor layer is easily discolored to yellow, and as a result, stimulated emission light emitted from the phosphor, particularly blue. It has been found that the sensitivity of the panel is significantly reduced because the light in the region is absorbed in the phosphor layer. The yellowing of the phosphor layer is caused by iodine from the phosphor in the coating liquid for forming the phosphor layer during the panel manufacturing process.
Or liberated becomes ₂ molecule, or a coating formed phosphor layer was found that due to the formation of the I ₂ molecule.

According to the radiation image storage panel of the present invention, the compound having an epoxy group is added to the coating liquid in advance, and the epoxy layer-containing compound is contained in the phosphor layer formed by coating. The iodine liberated from the body is not trapped by this epoxy group and forms an I ₂ molecule. As a result, yellowing of the phosphor layer can be prevented and a highly sensitive panel can be obtained.

In particular, when an epoxy resin is used as a compound having an epoxy group, it simultaneously functions as a binder, so that it is possible to enhance the adhesion between the support and the phosphor layer in addition to improving the sensitivity. It should be noted that a case where all the binders are epoxy resins without using other binders is also included in the present invention.

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

The support used in the present invention can be arbitrarily selected from various materials used as a support for intensifying screens in conventional radiography or various materials known as a support for radiographic image conversion panels. . Examples of such materials include cellulose acetate, polyester,
Films of plastic substances such as polyethylene terephthalate, polyamide, polyimide, triacetate and polycarbonate, metal sheets such as aluminum foil and aluminum alloy foil, ordinary paper, baryta paper, resin coated paper, pigment paper containing pigments such as titanium dioxide, Examples thereof include paper sized with polyvinyl alcohol and the like. However, in consideration of the characteristics and handling of the radiation image storage panel as an information recording material, a particularly preferable material for the support in the present invention is a 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 radiation image conversion panel of high sharpness type, and the latter is a support suitable for a radiation image conversion panel of high sensitivity type.

The surface of the support is coated with a high molecular substance such as gelatin to form an adhesion-imparting layer for the purpose of strengthening the bond between the support and the phosphor layer, or titanium dioxide, oxidized for the purpose of improving sensitivity or image quality. For the purpose of providing a light reflecting layer made of a light reflecting substance such as zirconium or a light absorbing layer made of a light absorbing substance such as carbon black, or for improving the antistatic performance of the panel, carbon black, In ₂
O _3, an antistatic layer comprising a conductive material such as SnO ₂ may be provided.

Further, as described in JP-A-58-200200, for the purpose of improving the sharpness of the image, the surface of the support on the phosphor layer side (the surface of the support on the phosphor layer side is provided with adhesiveness). When a layer, a light reflection layer, a light absorption layer or an antistatic layer is provided, it means the surface thereof), and minute irregularities may be provided.

Next, a phosphor layer is formed on the support.

The phosphor layer, which is a characteristic requirement of the present invention, is a layer composed of a binder that contains and supports a stimulable phosphor containing iodine and a compound having an epoxy group in a dispersed state. However,
The binder itself may be a compound having an epoxy group such as an epoxy resin.

The stimulable phosphor containing iodine used in the present invention,
The composition of the phosphor contains iodine. That is, it contains iodine as at least one of the matrix component, additive component and activator component of the phosphor.

This stimulable phosphor containing iodine is a phosphor that exhibits stimulated emission upon irradiation with excitation light after irradiation with radiation as described above, but from a practical standpoint, the wavelength is 400-
300 with excitation light (for example, laser such as He-Ne laser and semiconductor laser) in the range of 900 nm
A phosphor that exhibits stimulated emission in the wavelength range of up to 500 nm is desirable. Examples of the iodine-containing stimulable phosphor used in the radiation image storage panel of the present invention include (1) Japanese Patent Application Laid-Open No. 55-12145 (Ba1 _-X , M2 ⁺ _X ) FX. : YA (however, M ²⁺ is Mg,
At least one of Ca, Sr, Zn, and Cd, X is 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, and x is 0 ≦ x ≦ 0.6, y is 0 ≦ y ≦ 0.2), and the rare earth element-activated alkaline earth represented by the composition formula Metal Fluorohalide Phosphor; Further, the phosphor may contain the following additives: L described in Japanese Patent Application No. 54-150873.
iX ′, BeX ″ ₂ , M ^III X ₃ (provided that X ′, X ″
And X are respectively at least one of Cl, Br and I; M ^III is a trivalent metal); Be described in JP-A-55-160078.
O, MgO, CaO, SrO, BaO, ZnO, Al ₂
O ₃ , Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , Ti
O ₂ , ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅
And metal oxides such as ThO ₂ ; Z described in JP-A-56-116777.
r, Sc; B described in JP-A-57-23673, As described in JP-A-57-23675,
Si; M described in JP-A-58-206678
L (where M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs; L is Sc, Y, La, Ce, Pr, Nd, Pm,
Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
u, Al, Ga, In, and at least one trivalent metal selected from the group consisting of Tl); A baked product of a tetrafluoroboric acid compound described in JP-A-59-27980. Hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid monovalent or divalent metal salts described in JP-A-59-47289; Na
X '(wherein X'is at least one of Cl, Br and I); V and C described in JP-A-59-56480.
Transition metals such as r, Mn, Fe, Co and Ni; M described in JP-A-59-75200
^{I X ', M' II X} "2, M III X 3, A ( however, M ^I is Li, Na, K, is at least one alkali metal selected from the group consisting of Rb, and Cs; M ^'II Is B
at least one divalent metal selected from the group consisting of e and Mg; M ^III is Al, Ga, In, and T
is at least one trivalent metal selected from the group consisting of l; A is a metal oxide; X ′, X ″ and X are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively. M ^I described in JP-A-60-101173.
X '(provided that M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X'is at least one halogen selected from the group consisting of F, Cl, Br and I); M described in Japanese Patent Application No. 59-145385
^II ′ X ′ ₂ · M ^II ′ X ″ ₂ [where M ^II ′ is Ba, Sr
And at least one alkaline earth metal selected from the group consisting of Ca; X ′ and X ″ are each C
at least one halogen selected from the group consisting of 1, Br and I, and X '≠ X "); and L described in Japanese Patent Application No. 60-106752.
nX ″ ₃ [where Ln is Sc, Y, La, Ce, P
r, Nd, Pm, Sm, Gd, Tb, Dy, Ho, E
at least one rare earth element selected from the group consisting of r, Tm, Yb and Lu; X ″ is F, Cl, Br
And at least one halogen selected from the group consisting of I); and (2) M ^II X ₂ · aM ^II X ′ ₂ : xEu ²⁺ (provided that M is present in JP-A-60-84381 ^{). II} is B
at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; X and X ′ are Cl,
At least one halogen selected from the group consisting of Br and I, and X ≠ X '; and a is 0.1 ≦ a ≦ 10.0 and x is 0 <x ≦ 0.2) A divalent europium-activated alkaline earth metal halide phosphor represented by the following composition formula; Further, the phosphor may contain the following additives: JP-A-60-166379 Is M ^I
X ″ (where M ^I is at least one alkali metal selected from the group consisting of Rb and Cs; X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I); K described in JP-A-60-221483
X ″, MgX ₂ , M ^III X ′ ₃ (where M ^III is S
at least one trivalent metal selected from the group consisting of c, Y, La, Gd and Lu; X ″, X and X
'Is at least one halogen selected from the group consisting of F, Cl, Br and I); B described in Japanese Patent Application No. 59-84356; Japanese Patent Application No. 59-84358. Si described in
Oxides such as O ₂ and P ₂ O ₅ ; L described in Japanese Patent Application No. 59-240451
iX ″, NaX ″ (where X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I); S described in Japanese Patent Application No. 59-240452.
iO: S described in Japanese Patent Application No. 59-240454
nX " ₂ (where X" is at least one halogen selected from the group consisting of F, Cl, Br and I); Cs described in Japanese Patent Application No. 60-78033.
X ″, SnX ₂ (wherein X ″ and X are at least one halogen selected from the group consisting of F, Cl, Br and I); and Japanese Patent Application No. 60-78035. Cs
X ″, Ln ³⁺ (where X ″ is F, Cl, Br and I
Is at least one halogen selected from the group consisting of; Ln is Sc, Y, Ce, Pr, Nd, Sm, Gd,
It is at least one rare earth element selected from the group consisting of Tb, Dy, Ho, Er, Tm, Yb and Lu); (3) LnOX: xA described in JP-A-55-12144 (however, Ln is at least one of La, Y, Gd, and Lu; X is at least one of Cl, Br, and I; A is at least one of Ce and Tb; and x is 0. <X <0.1) A rare earth element-activated rare earth oxyhalide phosphor represented by the composition formula; (4) M ^III OX: xCe (provided that M ^{III is} disclosed in JP-A-58-69281). Is Pr, Nd, P
m, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y
b, and at least one trivalent metal selected from the group consisting of Bi; X is at least one of Cl, Br, and I; x is 0 <x <0.1) cerium activated trivalent metal oxyhalide phosphors represented by the formula; (5) are described in Japanese Patent Application No. Sho 60-70484 Pat M ^I X: xBi (However, M ^I is selected from the group consisting of Rb and Cs X is at least one halogen selected from the group consisting of Cl, Br and I; and x is 0 <x ≦
A bismuth-activated alkali metal halide phosphor represented by a composition formula of (0.2); (6) M ^II ₅ (PO ₄ ) ₃ described in Japanese Patent Application No. 58-247237. X: xEu ²⁺ (However, M ^II is C
at least one alkaline earth metal selected from the group consisting of a, Sr and Ba; X is at least one halogen selected from the group consisting of F, Cl, Br and I; x is 0 <x ≦ 0 ., Which is a numerical value in the range of 2), and a divalent europium-activated alkaline earth metal halophosphate phosphor represented by the composition formula; (7) M ^II ₂ BO described in Japanese Patent Application No. 59-13153. ₃ X: xEu ²⁺ (However, M ^II is Ca, Sr
And at least one alkaline earth metal selected from the group consisting of Ba; X is at least one halogen selected from the group consisting of Cl, Br, and I; x
Is a numerical value in the range of 0 <x ≦ 0.2), and is a divalent europium-activated alkaline earth metal haloboric acid phosphor represented by a composition formula; (8) described in Japanese Patent Application No. 59-13154. M ^II ₂ PO ₄ X: xEu ²⁺ (where M ^II is Ca, Sr
And at least one alkaline earth metal selected from the group consisting of Ba; and X is at least one halogen selected from the group consisting of Cl, Br, and I;
x is a numerical value in the range of 0 <x ≦ 0.2), and the divalent europium-activated alkaline earth metal halophosphate phosphor is represented by the composition formula; (9) described in Japanese Patent Application No. 59-74364. M ^II HX: xEu ²⁺ (wherein M ^II is at least one alkaline earth metal selected from the group consisting of Ca, Sr and Ba; X is selected from the group consisting of Cl, Br and I) At least one halogen; x is 0
<Divalent europium-activated alkaline earth metal hydrohalide phosphor represented by the composition formula of <x ≦ 0.2) (10) Described in Japanese Patent Application No. 59-142010. LnX ₃ · aLn′X ′ ₃ : xCe ³⁺ (where L
n and Ln ′ are at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X and X ′ are at least one halogen selected from the group consisting of F, Cl, Br and I, respectively. And X ≠ X ′; and a is 0.1 ≦ a ≦ 1
A numerical value in the range of 0.0, and x is a numerical value in the range of 0 <x ≦ 0.2), and a cerium-activated rare earth composite halide phosphor represented by the composition formula: (11) Japanese Patent Application No. 59-141489. LnX ₃ · aM ^I X ′: xCe ³⁺ (where Ln is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; M ^I is Li; Na,
At least one alkali metal selected from the group consisting of K, Cs and Rb; X and X ′ are each C
at least one halogen selected from the group consisting of 1, Br and I; and a is a numerical value in the range of 0 <a ≦ 10.0 and x is a numerical value in the range of 0 <x ≦ 0.2. cerium activated rare earth halide phosphor represented by a composition formula); (12) LnPO are described in Japanese Patent Application No. Sho 59-163361 Pat ₄ · _{aLnX 3:} xCe ³⁺ (However, Ln
Is at least one rare earth element selected from the group consisting of Y, La, Gd and Lu; X is F, Cl, Br
And at least one halogen selected from the group consisting of I and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 10.0 and x is a numerical value in the range of 0 <x ≦ 0.2)
(13) CsX · aRbX ′: xEu ²⁺ described in Japanese Patent Application No. 60-78151 (wherein X and X ′ are Cl respectively). , At least one halogen selected from the group consisting of Br and I; and a is 0 <
a is a numerical value in the range of 10.0, and x is 0 <x ≦ 0.2
Divalent europium activated cesium halide, rubidium phosphor represented by a composition formula in the range which is of numbers); and (14) M is described in Japanese Patent Application No. Sho 60-78153 Pat ^II X ₂ · aM ^I X ': xEu ²⁺ (However, M ^II is B
at least one alkaline earth metal selected from the group consisting of a, Sr and Ca; M ^I is at least one alkali metal selected from the group consisting of Li, Rb and Cs; X and X ′ are each Cl , At least one halogen selected from the group consisting of Br and I; and a is a numerical value in the range of 0.1 ≦ a ≦ 20.0 and x is a numerical value in the range of 0 <x ≦ 0.2. There is a divalent europium-activated composite halide phosphor represented by the composition formula (1);

Among the above stimulable phosphors, divalent europium-activated alkaline earth metal fluoride halide-based phosphors containing iodine, divalent europium-activated alkaline earth metal halide-based phosphors containing iodine, iodine Rare earth element-activated rare earth oxyhalide-based phosphors containing bismuth and bismuth activated alkali metal halide-based phosphors containing iodine are particularly preferable because they exhibit high-intensity stimulated emission. However, the stimulable phosphor containing iodine used in the present invention is not limited to the above-mentioned phosphor, and contains iodine as a phosphor composition, and when irradiated with excitation light after irradiation with radiation. Any phosphor may be used as long as it exhibits stimulated emission.

The compound having an epoxy group used in the present invention has at least one epoxy group in one molecule. Is to have. The epoxy group-containing compound may be a monomer or a polymer. Examples of monomers include 1,2-epoxypropane and 1,2-epoxybutane.
Examples of the polymer include bisphenol A type epoxy resin represented by the following general formula.

When the epoxy group-containing compound is a polymer, it is preferable since it can function as a binder as well as an additive for preventing yellowing. Note that all the binders may be epoxy group-containing compounds.

The iodine liberated from the stimulable phosphor is efficiently captured by this epoxy group, so that it does not form I ₂ molecules, and therefore the phosphor layer does not turn yellow.

The addition amount of the epoxy group-containing compound varies depending on the kind and amount of the stimulable phosphor, the kind of the binder, etc., but is generally in the range of 0.001 to 10% by weight with respect to the phosphor, preferably It is in the range of 0.03 to 3% by weight. When the addition amount of the epoxy group-containing compound is less than 0.001% by weight, the yellowing preventing effect is hardly obtained. On the other hand, when the amount is more than 10% by weight, even if all the binders are the compounds, there is an effect of preventing yellowing, but the luminescent properties of the phosphor, flexibility of the panel, durability, etc. It will have an adverse effect.

Examples of binders are proteins such as gelatin, polysaccharides such as dextran, or natural polymer substances such as gum arabic; and polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, vinylidene chloride / vinyl chloride copolymer, Examples thereof include binders represented by synthetic polymer substances such as polyalkyl (meth) acrylate, vinyl chloride / vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, and linear polyester. Particularly preferred among such binders are nitrocellulose, linear polyesters, polyalkyl (meth) acrylates, mixtures of nitrocellulose and linear polyesters, mixtures of nitrocellulose and polyalkyl (meth) acrylates. It is a mixture of polyurethane and polyvinyl butyral. Note that these binders may be crosslinked with a crosslinking agent.

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

First, the above-described stimulable phosphor, a compound having an epoxy group and a binder (in some cases, other binder may not be used) are added to an appropriate solvent, and the resulting mixture is thoroughly mixed to form a binder. A coating liquid in which the phosphor particles and the epoxy group-containing compound are uniformly dispersed in the solution is prepared.

Examples of the solvent for preparing the coating liquid include lower alcohols such as methanol, ethanol, 1-propanol, 2-propanol and n-butanol; chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride; acetone, methyl ethyl ketone and methyl isobutyl. Ketones such as ketones; esters of lower fatty acids with lower alcohols such as methyl acetate, ethyl acetate, butyl acetate; ethers such as dioxane, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether; toluene; and mixtures thereof. You can

The mixing ratio of the binder and the stimulable phosphor in the coating liquid (however, when all the binder is an epoxy group-containing compound, it is equal to the ratio of the compound and the phosphor) is the desired radiation image conversion. Although it depends on the characteristics of the panel, the type of phosphor, the amount of the epoxy group-containing compound added, etc., the mixing ratio of the binder and the phosphor is generally selected from the range of 1: 1 to 1: 100 (weight ratio). , And especially 1: 8 to 1:40
It is preferable to select from the range of (weight ratio).

The coating liquid contains a dispersant for improving the dispersibility of the phosphor in the coating liquid, and also for improving the binding force between the binder and the phosphor in the formed phosphor layer. Various additives such as plasticizers may be mixed. Examples of dispersants used for such purpose include:
Examples thereof include phthalic acid, stearic acid, caproic acid and lipophilic surfactants. Examples of plasticizers include phosphoric acid esters such as triphenyl phosphate, tricresyl phosphate, diphenyl phosphate; phthalic acid esters such as diethyl phthalate and dimethoxyethyl phthalate; ethyl phthalyl glycolate, butyl phthalyl butyl glycolate, etc. And a polyester of polyethylene glycol and an aliphatic dibasic acid, such as a polyester of triethylene glycol and adipic acid, a polyester of diethylene glycol and succinic acid, and the like.

The coating liquid prepared as described above is then uniformly applied to the surface of the support to form a coating film of the coating liquid. This coating operation can be performed by using an ordinary coating means such as a doctor blade, a roll coater or a knife coater.

Then, the formed coating film is gradually heated and dried to complete the formation of the phosphor layer on the support. The layer thickness of the phosphor layer is the characteristics of the intended radiation image conversion panel,
The thickness is usually 20 μm to 1 mm, although it varies depending on the type of phosphor, the mixing ratio of the binder and the phosphor, and the like. However, this layer thickness is preferably 50 to 500 μm.

The phosphor layer does not necessarily have to be formed by directly applying the coating liquid on the support as described above.For example, the coating liquid may be separately applied on a sheet such as a glass plate, a metal plate, or a plastic sheet. After the phosphor layer is formed by drying, the phosphor layer may be bonded to the support by pressing it on the support or by using an adhesive.

A transparent protective film may be 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, for example, a cellulose derivative such as cellulose acetate or nitrocellulose; or a transparent polymer material such as polymethylmethacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyvinyl acetate, or vinyl chloride / vinyl acetate copolymer. It can be formed by a method in which a solution prepared by dissolving a high-molecular substance in a suitable solvent is applied to the surface of the phosphor layer. Alternatively, it can also be formed by a method of adhering a transparent thin film separately formed from polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide or the like to the surface of the phosphor layer with an appropriate adhesive. The thickness of the transparent protective film thus formed is
It is preferably about 0.1 to 20 μm.

Incidentally, JP-A-55-163500, JP-A-57-
As described in Japanese Patent Publication No. 96300, the radiation image conversion panel of the present invention may be colored with a coloring agent, and the sharpness of an image obtained by coloring can be improved. Further, as described in JP-A-55-146447, in the radiation image storage panel of the present invention, white powder may be dispersed in the phosphor layer for the same purpose.

Next, examples and comparative examples of the present invention will be described. However,
Each of these examples does not limit the invention.

[Example 1] bivalent europium-activated barium phosphor of the stimulable: particles ^{_{(BaFBr 0.85 I 0.15 0.001Eu 2+)}} 12
0 g, acrylic resin methyl ethyl ketone solution (solid content: 10% by weight), nitrocellulose methyl ethyl ketone solution (solid content: 10% by weight) 6 g, and bisphenol A-type epoxy resin (average molecular weight: 900) methyl ethyl ketone solution (solid content: : 50% by weight) 2 g to 18 g of methyl ethyl ketone, and then sufficiently mixed by stirring with a propeller mixer to uniformly disperse the phosphor particles, and the mixing ratio of the binder and the phosphor is 1:40 (weight ratio. )
A coating solution having a viscosity of 25 to 30 PS (25 ° C) was prepared.

Carbon black kneaded polyethylene terephthalate film placed horizontally on a glass plate (support, thickness: 2
50 μm) was coated with this coating solution using a doctor blade while changing the diameter of the opening of the doctor blade. After the coating, the support on which the coating film is formed is placed in a dryer, and the temperature inside the dryer is set from 25 ° C to 100 ° C.
The coating film was dried by gradually raising the temperature to ℃. Thus, a phosphor layer having a layer thickness varied in the range of about 150 to 500 μm was formed on the support.

Next, a polyethylene terephthalate film (thickness: 12 μm, with a polyester-based adhesive applied) is placed on the phosphor layer with the adhesive layer side facing down to adhere the transparent protective film. Formed.

Thus, a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film was produced.

[Comparative Example 1] A support and a phosphor layer were prepared in the same manner as in Example 1, except that 20 g of methyl ethyl ketone was used without adding the bisphenol A type epoxy resin solution to the coating solution. A radiation image conversion panel composed of a transparent protective film and a transparent protective film was manufactured.

X of the tube voltage of 80 KVp was applied to each obtained radiation image conversion panel.
He-Ne laser light (wavelength: 63
The sensitivity was measured by exciting at 2.8 nm). The results are shown in FIG.

FIG. 1 is a graph in which the horizontal axis represents the layer thickness of the phosphor layer and the vertical axis represents the relative sensitivity. In FIG. 1, Curve 1: Radiation image conversion panel containing epoxy group-containing compound (Example 1) Curve 2: Radiation image conversion panel not containing epoxy group-containing compound (Comparative Example 1).

As is clear from FIG. 1, the radiation image storage panel of the present invention containing an epoxy group-containing compound in the phosphor layer (Example 1).
Has significantly improved sensitivity as compared with a conventionally known radiation image conversion panel (Comparative Example 1) containing no epoxy group-containing compound. Further, the conventional panel has significant yellowing of the phosphor layer, and the sensitivity did not change much even if the phosphor layer was thickened.However, the panel of the present invention has no yellowing of the phosphor layer, The sensitivity increased in proportion to the layer thickness.

[Example 2] In the same manner as in Example 1, except that 120 g of bismuth-activated cesium iodide phosphor (CsI: 0.001 Bi) was used as the stimulable phosphor, and 1 g of 1,2-epoxypropane was used as the compound having an epoxy group. Is treated in the same manner as in Example 1 to give a layer thickness of 250 on the support.
A μm phosphor layer was formed.

Then, the same treatment as in the method of Example 1 was performed to produce a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film.

[Comparative Example 2] In Example 2, by performing the same treatment as in Example 2 except that 1,2-epoxypropane was not added to the coating liquid, the support, the phosphor layer and the transparent protective film were removed. A constructed radiation image conversion panel was produced.

The sensitivity of each radiation image conversion panel obtained in Example 2 and Comparative Example 2 was measured in the same manner as above. The results are shown in Table 1. In addition, the sensitivity was represented by setting the sensitivity of the panel of Example 2 to 100.

Example 3 In Example 1, a divalent europium-activated barium chlorobromide-based phosphor (BaClBr _0.9 I) was used as the stimulable phosphor.
_0.1 : 0.001Eu ²⁺ ) 120 g was used, and 1 g of 1,2-epoxybutane was used as the compound having an epoxy group, except that 1 g of 1,2-epoxybutane was used. A 250 μm phosphor layer was formed.

Then, the same treatment as in the method of Example 1 was performed to produce a radiation image conversion panel composed of the support, the phosphor layer and the transparent protective film.

[Comparative Example 3] In Example 3, by performing the same treatment as in the method of Example 3 except that 1,2-epoxybutane was not added to the coating liquid, the support, the phosphor layer and the transparent protective film were removed. A constructed radiation image conversion panel was produced.

Each of the radiation image conversion panels obtained in Example 3 and Comparative Example 3 was irradiated with X-rays having a tube voltage of 80 KVp, and then excited with semiconductor laser light (wavelength: 780 nm) to measure the sensitivity. The results are shown in Table 2. In addition, the sensitivity was represented by setting the sensitivity of the panel of Example 3 to 100.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the layer thickness of the phosphor layer and the relative sensitivity for the radiation image storage panel containing the epoxy group-containing compound of the present invention (curve 1) and the conventional radiation image storage panel (curve 2). Is.

Claims (5)

[Claims] 1. A radiation image conversion panel comprising a support and a phosphor layer comprising a binder, which is provided on and supports the stimulable phosphor in a dispersed state, wherein the stimulable phosphor is A radiation image conversion panel, which is a phosphor containing iodine and in which the phosphor layer contains a compound having an epoxy group. 2. The compound having an epoxy group is contained in the phosphor layer in an amount of 0.001 to 10% by weight based on the stimulable phosphor. The radiation image conversion panel according to item 1. 3. The compound having an epoxy group is contained in the phosphor layer in an amount of 0.03 to 3% by weight based on the stimulable phosphor. The radiation image conversion panel according to item 2. 4. The compound having an epoxy group is 1, 2
The radiation image storage panel according to claim 1, wherein the radiation image storage panel is at least one compound selected from the group consisting of epoxypropane, 1,2-epoxybutane, and epoxy resin. 5. The stimulable phosphor is a divalent europium-activated alkaline earth metal fluoride halide phosphor containing iodine, or a divalent europium-activated alkaline earth metal halide phosphor containing iodine. , A rare earth element-activated rare earth oxyhalide-based phosphor containing iodine, and a bismuth-activated alkali metal halide-based phosphor containing iodine, wherein the phosphor is at least one phosphor selected from the group consisting of: A radiation image conversion panel according to claim 1.