JP2002277592A - Radiographic image conversion plate and radiographic image reader using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic image conversion plate having high image quality and high durability, and a radiographic image reader using it. SOLUTION: In this radiographic image conversion plate comprising an adhesive layer, a support body, a photostimulable phosphor layer and a protective layer on a support member, the distance A of the proximate part of a stimulated light reading member arranged opposite to the protective layer and the surface of the protective layer and the length B of the end non-adhered part of a radiographic conversion panel has the relation of 0<=B<=5A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to 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-described radiation image conversion method, the radiation image conversion panel is generally used repeatedly by transporting the imaging unit → reading unit → erasing unit → standby unit. Therefore, the size of the apparatus is inevitably increased and the price is inevitably increased. The panel must have flexibility, and since a flexible material such as PET is generally used for both the support and the protective layer, it has a drawback that it has high moisture permeability and lacks durability. Was. Further, there is a problem that the panel is easily damaged by the transport movement and the life is short.

On the other hand, 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. 06-5359, Japanese Patent Publication No.
No.-5360) is known.

As a result, the size and cost of the apparatus can be reduced, the cycle time from reading to erasing to photographing can be reduced, and the life of the panel can be prolonged. On the other hand, since it is necessary to perform reading from the side opposite to the X-ray incidence side, a special device is required in order to effectively utilize the image information. No. 61-73100), and the phosphor layer has an oblique columnar crystal structure (Japanese Patent Application No. 63-129996).
And Japanese Patent Application No. 03-121809, and a low refractive index layer is provided between the phosphor layer and the protective layer (Japanese Patent Application No. 62-206017).
No.) etc. are known.

In recent years, further miniaturization and lower price of the apparatus, higher image quality and longer life of the panel are required.
Particularly, from the viewpoint of improving the image quality, the distance between the surface of the radiation image conversion panel and the reading member provided in the reading device tends to be short.

By reducing the distance between the panel surface and the reading member, the light-collecting efficiency of stimulated emission is improved, and of course, the image quality is improved.

However, a radiation image conversion plate,
Due to the assembling accuracy of the reading member, and the change with time, in the peripheral portion of the radiation image conversion panel, the portion not adhered to the adhesive layer easily curls toward the protective layer side, and as a result, the contact with the reading member easily occurs, It has been found that durability deterioration such as image quality deterioration such as brightness reduction and brightness unevenness is likely to occur.

Therefore, a radiation image conversion plate exhibiting high image quality and high durability has been demanded.

[0013]

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

[0014]

The above objects of the present invention have been attained by the following items 1-4.

1. On a support member, a radiation image conversion plate having an adhesive layer, a support, a radiation image conversion panel having a stimulable phosphor layer and a protective layer in this order,
The distance A between the closest part of the photostimulated luminescence reading member arranged opposite to the protective layer and the surface of the protective layer, and the length B of the non-adhesive part at the end of the radiation image conversion panel are represented by the formula (1). A radiation image conversion plate characterized by satisfying the following.

2. 2. The radiation image conversion plate as described in 1 above, wherein the adhesive layer is a double-sided tape.

3. 3. The radiation image conversion plate according to 1 or 2, wherein the support member is a composite of carbon and foamed acrylic.

4. 4. The radiation image reading device according to claim 1, wherein the radiation image conversion plate according to any one of the above items 1 to 3 is disposed in a reading device, and a reading member is disposed facing the protective layer side of the plate. .

Hereinafter, the present invention will be described in detail. As a result of various studies, the present inventors have found that a radiation image conversion panel having an adhesive layer, a support, a stimulable phosphor layer and a protective layer on a support member as described in claim 1. In the radiation image conversion plate, the distance A between the closest part of the photostimulated luminescence reading device and the surface of the protective layer, which is disposed to face the protective layer, and the length B of the end portion of the radiation image conversion panel that is not adhered. Was adjusted so as to satisfy the above expression (1), whereby a radiation image conversion plate having both high image quality and high durability could be obtained.

According to a second aspect of the present invention, there is provided a radiation image conversion plate having, in this order, an adhesive layer, a support, a stimulable phosphor layer and a protective layer on a support member. In the above, when the length of the adhesive layer is longer than the length of the radiation image conversion panel, by installing a covering member on the non-adhesion portion with the radiation image conversion panel, a radiographic image having both high image quality and high durability A conversion plate could be obtained.

An embodiment of the stimulable luminescence reading member of the present invention which is disposed to face the radiation image conversion plate and the protective layer of the plate will be described with reference to FIG.

FIG. 1 is a schematic sectional view showing an example of a radiation image reading apparatus according to the present invention in which a radiation image conversion plate and a stimulated emission reading member of the present invention are arranged.

Here, an embodiment in which the length of the radiation image conversion panel 3 is longer than the length of the adhesive layer 2 is shown.

In FIG. 1, radiation R (specifically, X-rays) from a radiation generator (not shown) is irradiated from the support member 1 side, and the radiation image conversion panel 3 has a photostimulable property through an adhesive layer 2. The light arrives at the phosphor layer 3b, is absorbed, energy is accumulated, and an accumulation image of a radiation transmission image is formed.
Next, the accumulated image is excited by stimulating light T irradiated from a stimulating light source (not shown) and emitted as stimulating light.

The emitted stimulable luminescence is read by a stimulable luminescence reading member 4 and is read by a photoelectric conversion device 5 such as a photomultiplier.
The image is displayed on an image display device, and a radiation transmission image is observed.

In the radiation image conversion plate according to the first aspect of the present invention, the distance A between the closest part of the stimulable luminescence reading member 4 and the surface of the protective layer 3c of the radiation image conversion panel 3 is determined. By adjusting the length B of the unbonded end portion of the panel 3 so as to satisfy the expression (1), it is possible to provide a radiation image conversion plate that simultaneously satisfies both characteristics of high image quality and high durability. it can.

In the present invention, as the distance between the surface of the protective layer 3c of the radiation image conversion panel 3 and the stimulable luminescence reading member 4 becomes shorter, the luminous luminescence condensing efficiency is improved and the image quality is improved.

On the other hand, the unadhered portion curls toward the protective layer side in the peripheral portion of the panel due to the assembling accuracy of the plate and the apparatus, and changes with time, so that the non-adhered portion easily comes into contact with the stimulable luminescence reading member 4, so In order to prevent image quality deterioration such as uneven brightness, the distance A does not necessarily have to be short.

Therefore, from the viewpoint of maintaining high image quality and high durability, the distance A between the surface of the panel protective layer and the photostimulable luminescence reading member and the length B of the end portion of the radiation image conversion panel that is not adhered.
, It is necessary to maintain the relationship of 0 ≦ B ≦ 5A, but in order to maintain high image quality and high durability, 0 ≦ B ≦ 5A.
It is even more preferable to adjust B ≦ 3A.

Within the range satisfying the above expression (1),
Although the numerical values of A and B can be changed freely, from the viewpoint of obtaining a high-quality image, the distance A between the closest part of the stimulable luminescence reading member and the surface of the protective layer in the formula (1) is used.
Is preferably adjusted to a range of 0.5 mm to 5 mm, and more preferably 0.5 mm to 3 mm.

In order to avoid unnecessary contact between the reading member and the panel, it is essential to satisfy the above-mentioned expression (1). The length B of the end unbonded portion is 0 mm to 15 m
m, more preferably 0 mm
５5 mm.

In contrast to FIG. 1, when the length of the radiation image conversion panel 3 is shorter than the length of the adhesive layer 2, an adhesive layer covering member is provided on the surface of the adhesive layer protruding from the panel. It can satisfy both high image quality and high durability.

As the adhesive layer according to the present invention, it is preferable to use a double-sided tape from the viewpoints of work efficiency at the time of assembling the radiation image conversion plate and easy adjustment of the thickness of the adhesive layer. However, the type of the double-sided tape is not particularly limited, but it is preferable that the double-sided tape is made of a material having substantially no radiation absorption.

Here, "substantially no absorption of radiation" means that the radiation amount is 0.01% or less of the radiation amount irradiated on the radiation image conversion plate from the radiation generator.

The support member according to the present invention is preferably made of a material that has low radiation absorption (specifically, X-ray absorption), high strength, and good flatness. An acrylic composite is preferably used as the support member.

The stimulable phosphor layer and the stimulable phosphor according to the present invention will be described. Examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include the following.

(1) FX: yA (Ba _1-X , M (II) _{+ X} ) FX: described in JP-A-55-12145, wherein M (II) is Mg, Ca, Sr, At least one of Zn and Cd, X is at least one of Cl, Br, and I, A is Eu, Tb, Ce, Tm, Dy,
At least one of Pr, Ho, Nd, Yb, and Er, and 0 ≦ x ≦ 0.6, and y is 0 ≦ y ≦
0.2), a rare earth element-activated alkaline earth metal fluorohalide phosphor represented by the following composition formula: The phosphor may contain the following additives.

(A) X ', BeX ", M (III) X"" ₃ , wherein X', X" and X "" described in JP-A-56-74175 are Cl and Br respectively
And M (III) is a trivalent metal; and (b) B described in JP-A-55-160078.
eO, 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 ; (c) Z described in JP-A-56-116777.
r, Sc; (d) B described in JP-A-57-23667; (e) A described in JP-A-57-23675.
s, Si; (f) M described in JP-A-58-206678.
L, wherein M is at least one alkali metal selected from the group consisting of Li, Na, K, Rb, and Cs, and L is Sc, Y, La, Ce, Pr, Nd, Pm,
Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, L
at least one trivalent metal selected from the group consisting of u, Al, Ga, In, and Tl; (g) a calcined product of a tetrafluoroborate compound described in JP-A-59-27980; 59-272
No. 89, a calcined product of a salt of a monovalent or divalent metal of hexafluorosilicic acid, hexafluorotitanic acid and hexafluorozirconic acid;
No. 6479, wherein X 'is C
(h) V, described in JP-A-59-56480,
Transition metals such as Cr, Mn, Fe, Co and Ni; M (I) described in JP-A-59-75200
X ', M' (II) X " ₂ , M (III) X"' ₃ , A, wherein M (I) is at least one selected from the group consisting of Li, Na, K, Rb and Cs M ′ (II) represents at least one divalent metal selected from the group consisting of Be and Mg, and M (III) represents A
at least one trivalent metal selected from the group consisting of l, Ga, In, and Tl; A is a metal oxide; X ', X ", and X"' are F, Cl,
At least one halogen selected from the group consisting of Br and I; (i) M described in JP-A-60-101173.
(I) X ′, wherein 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; (j) M described in JP-A-61-23679.
(II) ′ X ′ ₂ .M (II) ′ X ″ ₂ , wherein M (II) ′ is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; X "is at least one halogen selected from the group consisting of Cl, Br and I, and X '≠ X"; and LnX "described in JP-A-61-264084. ₃ , where Ln is Sc, Y, La, C
e, Pr, Nd, Pm, Sm, Gd, Tb, Dy, H
at least one rare earth element selected from the group consisting of o, Er, Tm, Yb and Lu;
It is at least one halogen selected from the group consisting of l, Br and I.

(2) described in JP-A-60-84381
M (II) X_Two・ AM (II) X '_Two: XEu²⁺,
(Where M (II) is a group consisting of Ba, Sr and Ca
At least one alkaline earth metal selected;
X and X 'are selected from the group consisting of Cl, Br and I
At least one halogen and X ≠ X ′
And a is 0.1 ≦ a ≦ 10.0, x is 0 <x
≦ 0.2) divalent europium represented by the composition formula
Activated alkaline earth metal halide phosphor;
The following additives may be contained in the phosphor: (a) M described in JP-A-60-166379.
(I) X ′, wherein M (I) is composed of Rb and Cs
At least one alkali metal selected from the group;
X 'is selected from the group consisting of F, Cl, Br and I
(B) K described in JP-A-60-221483.
X ", MgX" "_Two, M (III) X ""_Three, Where M (I
II) is from the group consisting of Sc, Y, La, Gd and Lu
At least one trivalent metal selected; X ″,
X ′ ″ and X ″ ″ are both F, Cl, Br and
At least one halogen selected from the group consisting of
(C) It is described in JP-A-60-228592.
B, Si described in JP-A-60-228593.
O_Two, P_TwoO_FiveOxides such as JP-A-61-208882
LiX ″, NaX ″, wherein X ″ is
At least one selected from the group consisting of F, Cl, Br and I
And (d) S described in JP-A-61-220883.
iO: S described in JP-A-61-120885
nX "_TwoWherein X ″ is F, Cl, Br and I.
At least one halogen selected from the group consisting of: (e) C described in JP-A-61-235486;
sX ", SnX" "" _TwoWhere X ″ and X ′ ″ are
Each selected from the group consisting of F, Cl, Br and I
At least one halogen;
CsX ″, Ln described in US Pat.³⁺,
Wherein X ″ is selected from the group consisting of F, Cl, Br and I.
At least one halogen; Ln is Sc;
Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, H
selected from the group consisting of o, Er, Tm, Yb and Lu
(3) Ln described in JP-A-55-12144.
OX: xA, where Ln is La, Y, Gd, and L
at least one of u; X is Cl, Br, and I
At least one of them; A is less of Ce and Tb
X is 0 <x <0.1).
Rare earth element activated rare earth oxyhalide phosphor to be used; (4) M described in JP-A-58-69281.
(II) OX: xCe, wherein M (II) is Pr, Nd,
Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y
at least one selected from the group consisting of b and Bi
X is Cl, Br, and I
At least one; x is 0 <x <0.1) tuple
Cerium-activated trivalent metal oxyhalide fire represented by the formula
(5) described in JP-A-62-25189.
M (I) X: xBi, wherein M (I) is Rb and
At least one alkali selected from the group consisting of Cs
X is selected from the group consisting of Cl, Br and I
At least one halogen; and x is 0
<X ≦ 0.2).
Bismuth-activated alkali metal halide phosphor; (6) M described in JP-A-60-141783
(II)_Five(PO_Four)_ThreeX: xEu²⁺, (Where M (II) is
At least selected from the group consisting of Ca, Sr and Ba
Is also a kind of alkaline earth metal; X is F, Cl, Br
At least one halo selected from the group consisting of
X is a number in the range of 0 <x ≦ 0.2)
-Activated europium-activated alkaline earth represented by the composition formula:
(7) M described in JP-A-60-157 099
(II)_TwoBO_ThreeX: xEu²⁺, (Where M (II) is Ca,
At least one selected from the group consisting of Sr and Ba
X is Cl, Br and I
At least one halogen selected from the group consisting of
X is a numerical value in the range of 0 <x ≦ 0.2)
Divalent europium-activated alkaline earth metal halo
(8) M described in JP-A-60-157100
(II)_Two(PO_Four)_ThreeX: xEu²⁺, (Where M (II) is
At least selected from the group consisting of Ca, Sr and Ba
Is also a kind of alkaline earth metal; X is Cl, Br and
At least one halogen selected from the group consisting of
Yes; x is a numerical value in the range of 0 <x ≦ 0.2)
Bivalent europium-activated alkaline earth metal represented by the formula
(9) M described in JP-A-60-217354
(II) HX: xEu²⁺, (Where M (II) is Ca, Sr
At least one member selected from the group consisting of
X is from Cl, Br and I
At least one halogen selected from the group consisting of
Is a numerical value in the range of 0 <x ≦ 0.2).
Divalent europium activated halo hydrides of alkaline earth metals
Genide phosphor; (10) L described in JP-A-61-21173.
nX_Three・ ALn'X '_Three: XCe³⁺, (Where Ln and
Ln 'is a group consisting of Y, La, Gd and Lu, respectively.
At least one rare earth element selected from
And X ′ are each a group consisting of F, Cl, Br and I
At least one halogen selected from the group consisting of
X ≠ X ′; and a is in the range of 0.1 <a ≦ 10.0.
X is a numerical value in the range of 0 <x ≦ 0.2.
Activated rare earth composite halide represented by the composition formula
(11) L described in JP-A-61-21182
nX_ThreeAM (I) X'3: xCe³⁺, (Where Ln is
A small number selected from the group consisting of Y, La, Gd and Lu
At least a kind of rare earth element; M (I) is Li, N
a selected from the group consisting of a, K, Cs and Rb
X and X 'are each a kind of alkali metal.
At least selected from the group consisting of Cl, Br and I
Is also a kind of halogen; and a is 0 <a ≦ 10.0
X is a numerical value in the range of 0 <x ≦ 0.2
Cerium-activated rare earth composite represented by the composition formula
(12) L described in JP-A-61-40390.
nPO_Four・ ALnX_Three: XCe³⁺, (Where Ln is Y, L
at least one selected from the group consisting of a, Gd and Lu
X is a rare earth element; X is F, Cl, Br and I
At least one halogen selected from the group consisting of
And a is a numerical value in the range of 0.1 ≦ a ≦ 10.0.
Where x is a numerical value in the range of 0 <x ≦ 0.2)
A cerium-activated rare earth halophosphate phosphor represented by the formula: (13) described in JP-A-61-236888.
CsX: aRbX ': xEu²⁺, (Where X and
And X 'are selected from the group consisting of Cl, Br and I, respectively.
At least one halogen; and a is 0
<A ≦ 10.0 and x is 0 <x ≦ 0.
Divalent euro represented by the composition formula of 2)
Pium-activated cesium rubidium halide phosphor; (14) described in JP-A-61-236890
M (II) X_TwoAM (I) X ': xEu²⁺, (Where M
(II) is selected from the group consisting of Ba, Sr and Ca
At least one alkaline earth metal; M (I)
At least selected from the group consisting of Li, Rb and Cs
Is also a kind of alkali metal; X and X ′ are each
At least selected from the group consisting of Cl, Br and I
A is a kind of halogen; and a is 0.1 ≦ a ≦ 20.
X is a number in the range 0 <x ≦ 0.2
Activated bivalent europium represented by the composition formula
Radiation image conversion panel using these stimulable phosphors
Scans the excitation light after accumulating radiation image information.
Release the stored energy, so that the radiation
Images can be stored and used repeatedly.
You. In other words, in conventional radiography,
This radiographic image consumes radiographic film.
In the image conversion method, the radiation image conversion panel is used repeatedly.
Therefore, it is also advantageous in terms of resource protection and economic efficiency.

As described above, the stimulable phosphor is a phosphor that emits stimulable light when irradiated with radiation and then with excitation light. However, in practice, excitation light having a wavelength in the range of 400 to 900 nm is used. In general, phosphors exhibiting stimulated emission in the wavelength range of 300 to 500 nm are used.

Among the stimulable phosphors described above, iodine-containing divalent europium-activated alkaline earth metal fluorohalide-based phosphors, iodine-containing divalent europium-activated alkaline earth metal halides Phosphor, a rare earth element-activated rare earth oxyhalide phosphor containing iodine, and a bismuth activated alkali metal halide phosphor containing iodine are preferably used. From the viewpoint shown, the iodine-containing divalent europium-activated alkaline earth metal fluorinated halide-based phosphor (Eu-activated BaFI) according to claim 4 is particularly preferably used.

The stimulable phosphor according to the present invention is desirably dispersed in a resin in the stimulable phosphor layer. 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.

Examples of the solvent 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.

In the stimulable phosphor coating, a dispersing agent for improving the dispersibility of the stimulable phosphor in the coating, or a binder in the stimulable phosphor layer after formation and a stimulable phosphor, are used. Various additives such as a plasticizer for improving the bonding force with the phosphor may be mixed.

Examples of the dispersant 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 support (including the temporary support for sheet formation) according to the present invention will be described. As the support according to the present invention, for example, those made of various materials such as glass, wool, cotton, paper, and metal can be used. What can be processed into is preferred. From this point, for example, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, plastic film such as polycarbonate film, metal sheet such as aluminum foil and aluminum alloy foil, general paper and photographic base paper Base paper for printing, such as coated paper or art paper, baryta paper, resin coated paper, paper sized with polysaccharides as described in Belgian Patent 784,615, pigments such as titanium dioxide Pigmented paper containing, and processed paper such as paper sized with polyvinyl alcohol are particularly preferred.

The thickness of the support varies depending on the material of the support to be used and the like.
The thickness is more preferably 80 μm to 500 μm from the viewpoint of handling.

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 is provided on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesion to the stimulable phosphor layer.

Further, from the viewpoint of improving 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 the above-mentioned bubbles is prepared by incorporating bubbles into the polyethylene terephthalate according to the method described in JP-A-3-76727 and JP-A-6-226894 to reflect the stimulable fluorescence. And a support with improved luminance of the radiation image conversion panel can be produced. As a commercial product, Toray Industries, Inc.
A polyethylene terephthalate containing air bubbles such as E60L manufactured by the company can be obtained.

The layer thickness of the polyethylene terephthalate support containing air bubbles varies depending on the material of the support used, etc., but is generally 80 μm to 1000 μm, and preferably 80 μm to 500 μm from the viewpoint of handling.
μm.

The surface of these supports 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 radiation image conversion panel of the present invention will be described. ASTM D-1 as a protective layer
The haze ratio measured by the method described in 003 is 5 or more and 6
Less than 0%, a polyester film having an excitation light absorbing layer, a polymethacrylate film, a nitrocellulose film, a cellulose acetate film and the like can be used, but a stretched film such as a polyethylene terephthalate film or a polyethylene naphthalate film can be used. It is preferable as a protective layer in terms of transparency and strength. In particular, these polyethylene terephthalate films, polyethylene terephthalate films, and vapor-deposited films on which thin films such as metal oxides and silicon nitride are vapor-deposited are more preferable in terms of moisture-proof properties.

The protective film used in the present invention has an optimum moisture-proof property by laminating a resin film or a plurality of vapor-deposited films obtained by depositing a metal oxide or the like on the resin film in accordance with the required moisture-proof property. However, in consideration of deterioration due to moisture absorption of the stimulable phosphor, at least 50 g / m ^2.
It is preferably equal to or less than day. As a method for laminating the resin film, any generally known method may be used. Further, in this case, by providing the excitation light absorbing layer between the laminated resin films, the excitation light absorbing layer is protected from physical impact and chemical deterioration, and stable plate performance can be maintained for a long time. The excitation light absorbing layer may be provided at a plurality of locations, or the adhesive layer for lamination may contain a coloring agent to form the excitation light absorbing layer.

The protective film 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). The sealing of the phosphor plate may be performed by any known method, but the moisture proofing is performed by forming the outermost resin layer of the moisture-proof protective film on the side in contact with the phosphor sheet with a resin film having a heat-fusing property. Since the protective film can be fused, the sealing work of the phosphor sheet is made more efficient.

Preferably, a sealing film is provided in which the moisture-proof protective films are arranged above and below the phosphor sheet, and the upper and lower moisture-proof protective films are fused in a region where the periphery is outside the periphery of the phosphor sheet. With this structure, it is possible to prevent moisture from entering from the outer peripheral portion of the phosphor sheet. Further, by forming the moisture-proof protective film on the support surface side into a laminated moisture-proof film formed by laminating one or more aluminum films (see FIG. 2), the ingress of moisture can be reduced more reliably. This sealing method is also easy in terms of work.

In this case, the outermost layer of the heat-fusible resin layer on the side in contact with the phosphor surface of the moisture-proof protective film may or may not be adhered.

The state of non-adhesion means that even if the phosphor surface and the moisture-proof protective film are microscopically point-contacted, the phosphor surface and the moisture-proof protective film are almost optically and mechanically incompatible. It can be treated as a continuum.

The term "heat-fusible film" as used herein refers to a resin film which can be fused by a generally used impulse sealer, such as ethylene-vinyl acetate copolymer (EVA), polypropylene (PP) film, polyethylene PE) film and the like, but are not limited thereto.

The haze ratio of the protective film can be easily adjusted by selecting the haze ratio of the resin film used. Resin films of any haze ratio are readily available industrially.

It is assumed that the protective film of the radiation image conversion panel of the present invention has a very high optical transparency. As such a highly transparent protective film material, various plastic films having a haze value in the range of 2 to 3% are commercially available.

JP-A-59-42500 and Japanese Patent Publication No. 1-57
No. 759 discloses means for increasing the haze ratio of the protective layer to eliminate image unevenness and linear noise, but the sharpness is reduced. 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. The thickness of the stimulable phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the type of the stimulable phosphor, the mixing ratio between the binder and the phosphor, and the like.
0 μm to 1 mm. However, this layer thickness is preferably 50 to 300 μm.

The thickness of the stimulable phosphor layer of the radiation image conversion panel of the present invention depends on the characteristics of the intended radiation image conversion panel, the type of stimulable phosphor, and the mixture of the binder and the stimulable phosphor. Although it depends on the ratio and the like, it is preferably selected from the range of 10 μm to 1000 μm, more preferably from the range of 10 μm to 250 μm.

A phosphor sheet having a phosphor layer coated on a support is cut into a predetermined size. Any general method can be used for cutting, but a cosmetic cutting machine, a punching machine, or the like is desirable in terms of workability and accuracy.

Any known method can be used to seal the phosphor sheet cut to a predetermined size with the moisture-proof protective film. For example, the phosphor sheet is sandwiched between the upper and lower moisture-proof protective films. And a method in which the peripheral edge portion is heated and fused by an impulse sealer, or a laminating method in which pressure is applied between two heated rollers.

In the method of heat-sealing with the impulse sealer, the heat-sealing under a reduced-pressure environment is intended to prevent the phosphor sheet from being displaced in the moisture-proof protective film and to eliminate moisture in the atmosphere. More preferred.

An undercoat layer as described below may be provided between the support layer and the phosphor layer of the radiation image conversion panel of the present invention. Here, the undercoat layer will be described.

The undercoat layer used in the present invention is preferably formed by applying a resin dissolved in a solvent and drying it.
As the resin, specifically, polyurethane, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer , Polyamide resin, polyvinyl butyral, polyester, cellulose derivative (nitrocellulose etc.),
Styrene-butadiene copolymer, 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.

Examples of the solvent used for forming the undercoat layer include lower alcohols such as methanol, ethanol, n-propanol and n-butanol; hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride; acetone;
Ketones such as methyl ethyl ketone and methyl isobutyl ketone, aromatic compounds such as toluene, benzene, cyclohexane, cyclohexanone and xylene, methyl acetate,
Examples thereof include esters of lower fatty acids and lower alcohols such as ethyl acetate and butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ester, and ethylene glycol monomethyl ester, and mixtures thereof.

The undercoat layer used in the present invention preferably has a function of absorbing stimulating excitation light from the viewpoint of preventing sharpness deterioration caused by the excitation laser. here,
The function of absorbing the stimulating light is to absorb the exciting light of the stimulable phosphor. Specifically, the function of containing a coloring agent such as a dye or a pigment that selectively absorbs the exciting light is included. Is preferred.

The colorant such as the dye or pigment is determined by the type of the stimulable phosphor used in the radiation image conversion panel, and the stimulable phosphor for the radiation image conversion panel usually has a wavelength of 400. Since a phosphor that shows stimulated emission in a wavelength range of 300 to 500 nm by excitation light in the range of 900 to 900 nm is used, the colorant is usually
Blue to green organic or inorganic coloring agents are preferably used.

Examples of the blue to green organic colorant include:
Pomelo Fast Blue 3G (manufactured by Hoechst), Estrol Brill Blue N-3RL (manufactured by Sumitomo Chemical Co., Ltd.),
Sumiacryl Blue F-GSL (Sumitomo Chemical Co., Ltd.),
D & C Blue No1 (National Aniline Co., Ltd.), Spirit Blue (Hodogaya Chemical Co., Ltd.), Oil Blue No. 603 (Orient Co., Ltd.), Kitten Blue A
(Manufactured by Ciba-Geigy), Eisenkatilon Blue GL
H (made by Hodogaya Chemical Co., Ltd.), Lake Blue A, F, H
(Kyowa Sangyo Co., Ltd.), Rhodaline Blue 6GX (Kyowa Sangyo Co., Ltd.), Brimocyanin 6GX (Inabata Sangyo Co., Ltd.), Brill Acid Green 6BH (Hodogaya Chemical Co., Ltd.), Cyanine Blue BNRS (Toyo Ink Co., Ltd.), Lionor Blue SL (Toyo Ink Co., Ltd.)
Manufactured). Examples of blue to green inorganic colorants include ultramarine blue, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—CoO—NiO pigments, but the invention is not limited thereto.

The undercoat layer used in the present invention has a reflection absorbance of the peak wavelength of stimulating excitation light in the undercoat layer, from the viewpoint of the effects described in the present invention, particularly, from the viewpoint of maintaining good luminance of the radiation image conversion panel. The reflection absorbance ratio of the stimulated emission peak wavelength is preferably 2 or more, and more preferably 2 to 2.
10, particularly preferably 2 to 8.

Specifically, in the undercoat layer containing copper phthalocyanine used as a pigment for absorbing the stimulating excitation light, the excitation light absorbance / stimulated luminescence absorption is 6, and
5.5 for Pomelo Fast Blue 3G.

Here, the reflection absorbance at the excitation light peak wavelength of the undercoat layer is determined by exposing a colored portion and using a spectrophotometer (for example, U-3300 manufactured by Hitachi, Ltd.) using an integrating sphere. Can be measured. In the measurement of the undercoat layer, the stimulable phosphor layer is removed, the undercoat layer is exposed, and the measurement is performed. Then, the absorbance ratio at the excitation light peak wavelength / absorbance ratio of the stimulated emission peak wavelength in the absorbance measurement value is measured. Ask.

When a phosphor having a plurality of peaks in the stimulating emission wavelength is used, the peak having the highest emission intensity is selected, and the peak wavelength is used.

The following two methods can be considered for the method of manufacturing the radiation image conversion panel of the present invention. 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 composed of 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 required 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. 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 paint 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 providing 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, the stimulable phosphor sheet can be spread thinly by utilizing the method of pressing the stimulable phosphor sheet on the support without fixing it in advance.

Normally, the radiation image conversion panel is provided with a protective film for physically and chemically protecting the surface of the stimulable phosphor layer on the side opposite to the side in contact with the support.
Such a protective film is preferably provided also in the present invention.

[0096]

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

Example 1 << Synthesis of Phosphor >> In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, 2780 ml of a BaI ₂ aqueous solution (3.6 mol / L) and an EuI ₃ aqueous solution (3.6 mol / L) were used. (0.15 mol / L) was placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. while stirring.

An aqueous solution of ammonium fluoride (8 mol / L)
322 ml were injected into the reaction mother liquor using a roller pump to produce a precipitate. Keep warm and stir even after pouring
The sediment was aged continuously over time. Next, the precipitate was separated by filtration, washed with ethanol, and dried in vacuo to obtain europium-activated barium fluoroiodide crystals.

In order to prevent a change in particle shape due to sintering during firing and a change in particle size distribution due to fusion between particles,
0.2% by mass of the ultrafine alumina powder was added, and the mixture was sufficiently stirred with a mixer to uniformly adhere the ultrafine alumina powder to the crystal surface. This was filled in a quartz boat, and calcined at 870 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace to obtain europium-activated barium fluoroiodide phosphor particles. Next, the phosphor particles were classified to obtain a phosphor having an average particle size of 4 μm.

<< Preparation of Radiation Image Conversion Panel >> As a phosphor layer forming material, 427 g of the above-obtained europium-activated barium fluoroiodide phosphor was prepared, and a polyurethane resin (Desmolac 4125, manufactured by Sumitomo Bayer Urethane Co., Ltd.) was prepared.
15.8 g, bisphenol A type epoxy resin 2.0 g
Was added to a mixed solvent of methyl ethyl ketone-toluene (1: 1), and dispersed with a propeller mixer.
A coating solution of 0 Pa · s was prepared.

[0101] The above-mentioned coating solution was applied using a doctor blade.
On an E-60L (manufactured by Toray Industries, Inc.) support having a thickness of 188 μm, an undercoat layer having the following formulation was applied, and then a stimulable phosphor layer was formed so as to have a dry film thickness of 100 μm. An image conversion panel was manufactured.

E-60L: Foamed (bubble-containing) polyethylene terephthalate manufactured by Toray Industries, Inc. (Formulation of undercoat layer) Byron 630 100 parts by mass Copper phthalocyanine 0.1 part by mass Methyl ethyl ketone (MEK) 100 parts by mass Toluene 100 parts by mass The formulations were mixed and dispersed in a bead mill for 15 hours to obtain a coating solution for forming an undercoat layer. This coating solution was applied to the above-mentioned support with a bar coater so as to have a dry film thickness of 10 μm.

<< Preparation of Radiation Image Conversion Plate Samples 1 to 5 >> The radiation image conversion panel obtained above and the supporting member were adhered to each other using a double-sided tape. Length is 15mm, 9mm, 6mm, 2
mm and 0.5 mm plates were prepared.

Each of the obtained plate samples was placed in a reading device as shown in FIG. 1, and the stimulable luminescence reading member was set so that the distance between the closest portion to the protective layer of each panel was 2 mm. It was adjusted to become.

Next, the photographing, reading, erasing, and photographing are performed continuously, and as shown in Table 1, until the deterioration of the image unevenness and the linear noise as described below becomes 3 (impractical). A continuous test was performed.

(Evaluation of Image Unevenness and Linear Noise) After irradiating the radiation image conversion panel with X-rays having a tube voltage of 80 kVp,
The panel is scanned and excited by a He-Ne laser beam (633 nm), and stimulated emission emitted from the phosphor layer is received by a photodetector (photoelectron image multiplier with a spectral sensitivity of S-5) and converted into an electric signal. Then, the image was reproduced as an image by an image reproducing apparatus, printed out at twice the size of the output apparatus, and the obtained printed image was visually observed to evaluate the appearance of image unevenness and linear noise. For each of the image unevenness and the linear noise, six ranks from 0 to 5 are set as described below, and a level of 3 or less is impractical.

0: No image unevenness or linear noise 1: Light image unevenness or linear noise in one or two places in the plane 2: Light image unevenness or linear noise in three to four places in the plane Some (practicable) 3: Image unevenness or linear noise is seen in 3 to 4 places in the plane, and dark image unevenness or linear noise is found in 1 to 2 places in it (impractical) 4: In-plane 5: There are image unevenness and linear noise at 5 or more places 5: Dark image unevenness and linear noise at 5 or more places in the plane The obtained results are shown in Table 1.

[0108]

[Table 1]

From Table 1, it can be seen that, compared to the comparative sample, the sample of the present invention withstands a continuous test of 1,000,000 times or more before image unevenness and linear noise occur, and satisfies both high image quality and high durability. It is clear that this is a conversion plate.

[0110]

As described above, a radiation image conversion plate having high image quality and high durability, and a radiation image reading apparatus using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a combination of a radiation image conversion plate of the present invention and a photostimulable emission reading member.

FIG. 2 is a cross-sectional view of the radiation image conversion panel according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support member 2 Adhesive layer 3 Radiation image conversion panel 3a Support 3b Stimulable phosphor layer 3c Protective layer 11 Phosphor 12 Support 13 Laminated protective film 14 Aluminum laminated film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G083 AA03 CC01 CC04 DD16 EE07 5B047 AA17 BB08 BC14 5C072 AA01 BA16 VA01

Claims (4)

[Claims] 1. A radiation image conversion plate having, in this order, a radiation image conversion panel having an adhesive layer, a support, a stimulable phosphor layer and a protective layer on a support member, wherein the radiation image conversion plate faces the protective layer. The distance A between the closest portion of the photostimulated luminescence reading member to be arranged and the surface of the protective layer and the length B of the non-adhesive portion at the end of the radiation image conversion panel satisfies the following expression (1). Radiation image conversion plate. Formula (1) 0 ≦ B ≦ 5A 2. The radiation image conversion plate according to claim 1, wherein the adhesive layer is a double-sided tape. 3. The radiation image conversion plate according to claim 1, wherein the support member is a composite of carbon and foamed acrylic. 4. The radiation image conversion plate according to claim 1, wherein the radiation image conversion plate is disposed in a reading device, and a reading member is disposed facing the protective layer side of the plate. Radiation image reading device.