JP2002131500A - Radiation image conversion plate and radiation image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiation image conversion plate and panel capable of preventing scattering of excited light occurring during reading radiation image and obtaining an image with high contrast. SOLUTION: The radiation image conversion plate consisting of a phosphor sheet provided with a stimulable phosphor layer on a support body and a protection layer provided to cover the fluorescent sheet and a panel where they are fixed. They have a function absorbing a reading light (excited light) in the periphery of the radiation image conversion plate and panel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation image conversion plate and a radiation image conversion panel using a stimulable phosphor, and more particularly to a radiation image conversion plate and a radiation image conversion having high image sharpness and contrast. It is about panels.

[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, X-rays that have passed through the subject are irradiated on a phosphor layer (fluorescent intensifying screen), thereby generating visible light and using the visible light as in the case of taking a normal photograph. A so-called radiograph, which is obtained by irradiating a film using a silver salt and developing the film, is used. 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 accumulated by the phosphor is absorbed by the phosphor. There is a method of detecting and imaging this fluorescence.

Specifically, for example, US Pat.
There is known a radiation image conversion method using a stimulable phosphor as described in JP-A No. 527 and JP-A-55-12144.

In this method, a radiation image conversion plate or a radiation image conversion panel containing a stimulable phosphor is used, and a radiation transmitted through a subject is applied to the stimulable phosphor layer to transmit radiation of each part of the subject. By accumulating radiation energy corresponding to the density, and subsequently exciting the stimulable phosphor with electromagnetic waves (excitation light) such as visible light and infrared light in a time series manner, the stimulable phosphor is accumulated in the stimulable phosphor. The emitted radiation energy is emitted as stimulated emission, and a signal depending on the intensity of the light is photoelectrically converted, for example, to obtain an electric signal, and the signal is converted into a visible image on a recording material such as a photosensitive film or a display device such as a CRT. Is to be played as

According to the above radiation image recording / reproducing method,
Compared with the conventional radiographic method using a combination of a radiographic film and an intensifying screen, there is an advantage that a radiographic image rich in information can be obtained with a much smaller exposure dose.

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.

The following are examples of stimulable phosphors conventionally used for radiation image conversion.

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

(A) X ', BeX ", M (III) X'" ₃ described in JP-A-56-74175, wherein
X ', X "and X""are each at least one of Cl, Br and I, and M (III) is a trivalent metal; (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; (h) Na described in JP-A-59-56479.
X ', wherein X' is at least one of Cl, Br and I; (i) 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 member 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
1, at least one trivalent metal selected from the group consisting of Ga, In, and Tl; A is a metal oxide; X ', X ", and X'" are F, Cl, B
at least one halogen selected from the group consisting of r and I; (j) 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; (k) 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) M (II) X ₂ · aM (II) X ′ ₂ : xEu ^{2+ described in} JP-A-60-84381 (where M (II) is Ba, Sr and Ca X and X 'are at least one halogen selected from the group consisting of Cl, Br and I, and X ≠ X'; and a Is 0.1 ≦ a ≦ 10.0, x is 0 <x ≦
0.2) divalent europium-activated alkaline earth metal halide phosphor represented by the following composition formula; and the phosphor may contain the following additives; ) M described in JP-A-60-166379
(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; (b) K described in JP-A-60-22143.
X ″, MgX ′ ″ ₂ , M (III) X ″ ″ ₃ , wherein M (II
I) is at least one trivalent metal selected from the group consisting of Sc, Y, La, Gd and Lu;
X ′ ″ and X ″ ″ are each F, Cl, Br and I
At least one halogen selected from the group consisting of: (c) B described in JP-A-60-228592 and Si described in JP-A-60-228593.
Oxides such as O ₂ and P ₂ O ₅ , LiX ″ and NaX ″ described in JP-A-61-120882, wherein X ″ is at least one selected from the group consisting of F, Cl, Br and I. (D) S described in JP-A-61-120883.
iO: S described in JP-A-61-120885
nX ″ ₂ , wherein X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I; (e) C described in JP-A-61-235486.
sX ″, SnX ′ ″ ₂ , wherein X ″ and X ′ ″ are each at least one halogen selected from the group consisting of F, Cl, Br and I;
35487, CsX ″, Ln ³⁺ , wherein X ″ is at least one halogen selected from the group consisting of F, Cl, Br and I; Ln is Sc,
Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, H
at least one rare earth element 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 Lu
X is at least one of Cl, Br, and I; A is at least one of Ce and Tb; x is 0 <x <0.1) Rare earth element activated rare earth oxyhalide phosphor; (4) M described in JP-A-58-69281.
(II) OX: xCe (where M (II) is Pr, Nd, P
m, Sm, Eu, Tb, Dy, Ho, Er, Tm, Y
b, and at least one metal oxide selected from the group consisting of Bi; X is at least one of Cl, Br, and I; and x is 0 <x <0.1). A cerium-activated trivalent metal oxyhalide phosphor represented by the following formula: (5) M (I) X: xBi described in JP-A-62-25189 (where M (I) is Rb and C
X is at least one alkali metal selected from the group consisting of Cl, Br and I; and x is 0 <
a bismuth-activated alkali metal halide phosphor represented by a composition formula of (x ≦ 0.2); (6) M described in JP-A-60-141783.
(II) ₅ (PO ₄ ) ₃ X: xEu ²⁺ (where M (II) is C
a is 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 (2) a divalent europium-activated alkaline earth metal halophosphate phosphor represented by the following composition formula: (7) M described in JP-A-60-157099.
(II) ₂ BO ₃ X: xEu ²⁺ (where M (II) is Ca, S
X is at least one alkaline earth metal selected from the group consisting of r and 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) divalent europium-activated alkaline earth metal haloborate phosphor represented by a composition formula; (8) described in JP-A-60-157100 M
(II) ₂ (PO ₄ ) ₃ X: xEu ²⁺ (where M (II) is C
a is at least one alkaline earth metal selected from the group consisting of a, 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 halophosphate phosphor represented by a composition formula: (9) M described in JP-A-60-217354
(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) X is a numerical value in the range of 0 <x ≦ 0.2), and a divalent europium-activated alkaline earth metal hydride halide phosphor represented by the following composition formula: L described in JP-A-61-21173
nX ₃ · aLn′X ′ ₃ : xCe ³⁺ (where Ln and L
n 'is 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 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). Active rare earth composite halide phosphor; (11) L described in JP-A-61-21182
nX ₃ · aM (I) X′3: 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, N
X and X 'are each at least one halogen selected from the group consisting of Cl, Br and I; and a is 0 < a ≦ 10.0
And x is a numerical value in the range of 0 <x ≦ 0.2). (12) JP-A-61-40390 L described in the number
nPO ₄ .aLnX ₃ : xCe ³⁺ (where Ln is Y, L
a is at least one rare earth element selected from the group consisting of a, Gd and Lu; X is F, Cl, Br and I
At least one halogen selected from the group consisting of: a is a number in the range of 0.1 ≦ a ≦ 10.0 and x is a number in the range of 0 <x ≦ 0.2) cerium activated rare earth halophosphate phosphor represented by the formula; (13) CsX described in 61-236888 Pat JP: aRbX ': xEu ²⁺ (wherein, X and X' are each A is at least one halogen selected from the group consisting of Cl, Br and I; and a is 0 <
a is a numerical value in a range of 10.0 and x is 0 <x ≦ 0.2
(14) a divalent europium-activated cesium rubidium halide phosphor represented by the following composition formula: (14) M (II) X ₂ .aM described in JP-A-61-236890. (I) X ′: xEu ²⁺ (where M (I
I) is at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca; M (I) is L
i is at least one alkali metal selected from the group consisting of Rb and Cs;
a is at least one halogen selected from the group consisting of l, Br and I; and a is 0.1 ≦ a ≦ 20.0
Wherein x is a numerical value in the range of 0 <x ≦ 0.2); a divalent europium-activated composite halide phosphor represented by a composition formula; In, iodine-containing divalent europium activated alkaline earth metal fluoride halide-based phosphor, iodine-containing divalent europium activated alkaline earth metal halide-based phosphor,
A rare earth element-activated rare earth oxyhalide-based phosphor containing iodine and a bismuth-activated alkali metal halide-based phosphor containing iodine exhibit high-luminance photostimulated emission.

A radiation image conversion plate or panel using these stimulable phosphors emits stored energy by scanning with excitation light after accumulating radiation image information, and thus accumulates a radiation image again after scanning. It can be used repeatedly. In other words, while the conventional radiographic method consumes radiographic film for each single photographing, this radiographic image conversion method uses a radiographic image conversion plate or panel repeatedly,
It is also advantageous in terms of resource conservation and economic efficiency.

A laser beam having high beam convergence is generally used as a light source of the excitation light of the radiation image conversion plate or panel. However, when scanning with a laser beam through a protective layer made of a polymer film such as PET, Scattering of the excitation laser light inside the protective layer film, the periphery of the radiation image conversion plate or panel, or a support plate provided to support the radiation image conversion plate,
Further, irregular reflection of the excitation laser light may occur in a radiation image reading apparatus provided to transport and read a radiation image conversion plate or panel. The excitation light that has been irregularly reflected is irradiated on the radiation image conversion panel surface sequentially while scanning with the excitation light, and when reading, the stimulability of a place away from the place where the excitation light was irradiated and the stimulated emission was emitted. Since the phosphor surface is also excited to emit stimulated emission, there has been a problem that the resulting image has reduced sharpness and contrast.

Particularly, a stretched film such as a polyethylene terephthalate film or a polyethylene naphthalate film has a large refractive index despite having excellent physical properties as a protective layer in terms of transparency, barrier properties and strength. Therefore, a part of the excitation light incident on the inside of the film for the protective layer is repeatedly reflected at the upper and lower interfaces of the film and propagates to a place away from the scanned location, emits stimulated emission, sharpens sharpness, And the contrast is reduced. Excitation light that has propagated inside the protective layer and at the interface between the protective layers is reflected and scattered by the radiation image conversion plate and the periphery of the panel to emit stimulated emission, resulting in a reduction in sharpness and contrast. Furthermore, the excitation light reflected in the opposite direction to the phosphor surface at the upper and lower interfaces of the protective layer is also re-reflected between the photodetectors and peripheral members, and the stimulable phosphor surface at a location farther from the scanned location is also reflected. To excite and emit photostimulated luminescence,
Further, sharpness and contrast are reduced. Since the excitation light is red to infrared long-wavelength coherent light,
As long as the scattered light and the reflected light are not actively absorbed, the amount absorbed in the space inside the protective layer film or the inside of the reading device propagates to a distant place and deteriorates sharpness and contrast.

In order to prevent sharpness and deterioration of contrast, a method of thinning the protective layer film and shortening the propagation distance of the excitation light inside the protective layer film can be considered. There is a problem in that the moisture resistance and the scratch resistance are reduced by the thinning of the protective layer. Regarding the improvement of sharpness and contrast, Japanese Patent Publication No. 59-23400 discloses a radiation image conversion panel comprising a support, an undercoat layer, a phosphor layer,
A method of coloring any one of the intermediate layer and the protective layer with a color that absorbs excitation light, and JP-A-60-200200 discloses a method of coloring the adhesive layer between the phosphor layer and the protective layer.
When sharpness and contrast are increased by these methods, there is a problem that the above-mentioned image unevenness and linear noise become more remarkable.

When the sharpness and contrast are deteriorated, and the image unevenness and the linear noise are severe, it is a fatal defect for a radiation image conversion plate or panel used for disease diagnosis.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of a decrease in contrast caused by scattering of an excitation laser beam which occurs at the time of reading a radiographic image, and to convert a radiographic image capable of obtaining a clear radiographic image. It is to provide a plate and a panel.

[0018]

The above objects of the present invention have been attained by the following constitutions.

(1) A radiation image conversion plate comprising: a phosphor sheet having a stimulable phosphor layer provided on a support; and a protective layer provided so as to cover the phosphor sheet. A radiation image conversion plate having a reading light (excitation light) absorption function at a peripheral portion of the radiation image conversion plate.

(2) The radiation image conversion plate according to (1), wherein the protective layer is provided so as to cover the upper surface and the lower surface of the phosphor sheet.

(3) The peripheral edge of the radiation image conversion plate is a protective layer peripheral edge (1) or (2).
The radiation image conversion plate according to the above.

(4) The periphery of the protective layer is a surface of the upper protective layer,
The radiation image conversion plate according to any one of (1) to (3), wherein the radiation image conversion plate is at least one selected from an end surface of the upper protective layer, an inner surface of the upper protective layer, and an inner surface of the lower protective layer.

(5) The radiation image conversion plate according to (1), wherein the periphery of the radiation image conversion plate is the periphery of the phosphor sheet.

(6) The radiation image conversion plate according to (5), wherein the peripheral edge of the phosphor sheet is at least one selected from the surface of the phosphor layer, the inside of the phosphor layer and the cross section of the phosphor sheet. .

(7) A radiation image conversion plate comprising a phosphor sheet having a stimulable phosphor layer provided on a support and a protective layer provided to cover the phosphor sheet is a support plate ( A radiation image conversion panel fixed to a tray plate), and reading light (excitation light) is read on a support plate (tray plate).
A radiation image conversion panel having an absorption function.

(8) The radiation image conversion plate is (1)-
The radiation image conversion panel according to (7), which is the radiation image conversion plate according to any one of (6) and (7).

(9) The method according to (7) or (8), wherein the support plate is larger than the radiation image conversion plate, and has a reading light (excitation light) absorption function on the surface of the offset (protruding) portion of the support plate. Radiation image conversion panel.

Hereinafter, the present invention will be described in more detail. The radiation image conversion plate referred to in the present invention is a phosphor sheet in which a stimulable phosphor layer (hereinafter, also simply referred to as a phosphor layer) is provided on a support, and is provided so as to cover the phosphor sheet. The radiation image conversion panel is a panel in which the radiation image conversion plate is fixed to a support plate (tray plate).

In the radiation image conversion panel, the support plate (tray plate) and the radiation image conversion plate may be of the same size, but the support plate (tray plate) is made larger and an offset (protruding) portion is provided. May be used.

The peripheral part of the radiation image conversion plate or the radiation image conversion panel is the peripheral part of the phosphor sheet in which the stimulable phosphor layer is provided on the support, or the protective layer portion, and It refers to the area including the sheet peripheral portion and the outer peripheral portion of the phosphor sheet provided for forming the phosphor sheet and the protective layer.

As the peripheral portion having the excitation light absorbing function,
It covers the end face or the peripheral edge of the phosphor sheet, and in the case of the cover, it reduces the effective reading area. However, when the amount is too small, the excitation light absorbing function cannot be sufficiently exhibited, and the effect of improving the contrast becomes insufficient. The peripheral portion is preferably 20% or less of one side from the side (only the end face) of the phosphor sheet, more preferably 0.1% or more and 5% or less.

The protective layer of the present invention comprises ASTM D-100
The haze ratio measured by the method described in 3 is 5 or more and 60%
Less than, 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 has transparency. In particular, a vapor-deposited film obtained by vapor-depositing a thin film of a metal oxide, silicon nitride, or the like on a polyethylene terephthalate film or a polyethylene naphthalate film is more preferable in terms of moisture resistance.

In the present invention, having a function of absorbing a reading light (hereinafter, also simply referred to as excitation light) means a portion having a colorant that selectively absorbs the excitation light, The film may be coated on one side of the film, may be coated on both sides, or may be colored inside the protective layer film. These may be used for multiple sites.

The film for the protective layer 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 vapor-depositing a metal oxide or the like on the resin film in accordance with the required moisture-proof property. But at least 50 g / m2 in consideration of the moisture absorption deterioration of the stimulable phosphor.
It is preferably set to ² · day or less. As a method of laminating the resin film, any generally known method may be used.

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

Preferably, a moisture-proof protective layer is disposed above and below the phosphor sheet, and the upper and lower films for the moisture-proof protective layer are fused in a region where the periphery is outside the periphery of the phosphor sheet. With the sealing structure, it is possible to prevent moisture from entering from the outer peripheral portion of the phosphor sheet. Further, the infiltration of moisture can be reduced more reliably by forming a laminated moisture-proof film formed by laminating one or more aluminum films as the film for the moisture-proof protective layer on the support surface side. 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 of the film for the moisture-proof protective layer which is in contact with the phosphor surface may or may not be adhered.

The state of not adhering means that the phosphor surface and the film for the moisture-proof protective layer are optically and mechanically almost completely in contact with the moisture-proof protective layer even though the phosphor surface and the film for the moisture-proof protective layer are microscopically contacted. Film can be handled as a discontinuous body.

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

The haze ratio of the protective layer film can be easily adjusted by selecting the haze ratio of the resin film to be used. A resin film having an arbitrary haze ratio is industrially easily available.

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

JP-A-59-42500 and JP-B-1-5
No. 7759 discloses a method for increasing the haze ratio of the protective layer to eliminate image unevenness and linear noise, but the sharpness and contrast are 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 effect of improving the contrast of the present invention is small.

The method for coloring the radiation image conversion plate or the protective layer film of the panel to improve the sharpness and the contrast is described in JP-B-59-23400. It is described as an example of various embodiments in which the respective layers of the phosphor layer, the intermediate layer, and the protective layer are colored, but there is no description or suggestion of a specific protective layer film.

The colorant used for imparting a light absorbing function to the periphery of the radiation image conversion plate or panel and the support plate of the present invention includes a wavelength region of excitation light of the radiation image conversion plate or panel. A material having a characteristic of absorbing the excitation light is used.

Preferably, the film for protective layer has an excitation light absorbing function such that the light transmittance in the excitation light wavelength region is equal to or less than 60% for a film for protective layer having no excitation light absorbing layer. It is desirable to provide. When the light transmittance is 60% or more, the effect of improving the contrast of the present invention is small.

The kind of colorant to be used is determined by the type of stimulable phosphor used in the radiation image conversion panel.
Usually, a phosphor is used which exhibits stimulated emission in a wavelength range of 300 to 500 nm by excitation light having a wavelength in the range of 400 to 900 nm. For this reason, as a coloring agent, usually
Blue or green organic or inorganic coloring agents are used.

Examples of blue-green organic colorants 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, but are not limited to, ultramarine blue, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—CoO—NiO pigments.

As the support of the phosphor sheet used in the present invention, various polymer materials are used. Particularly, those which can be processed into a flexible sheet or web in handling as an information recording material are preferable, and in this regard, a cellulose acetate film, a polyester film,
Plastic films such as polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide film, triacetate film, and polycarbonate film are 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, an undercoat layer may be provided on the surface on which the stimulable phosphor layer is provided for the purpose of improving the adhesion to the stimulable phosphor layer.

Examples of the binder used in the stimulable phosphor layer in the present invention include proteins such as gelatin, polysaccharides such as dextran, and natural high molecular substances such as gum arabic; and polyvinyl butyral, Vinyl acetate, nitrocellulose, ethylcellulose,
A binder represented by a synthetic polymer such as vinylidene chloride-vinyl chloride copolymer, polyalkyl (meth) acrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol, linear polyester, etc. Can be mentioned.

Particularly preferred among such binders are nitrocellulose, linear polyester, polyalkyl (meth) acrylate, a mixture of nitrocellulose and linear polyester, nitrocellulose and polyalkyl (meth) acrylate. And a mixture of polyurethane and polyvinyl butyral. In addition, these binders may be cross-linked by a cross-linking agent. The stimulable phosphor layer can be formed on the undercoat layer by the following method, for example.

First, a stimulable phosphor and a binder are added to an appropriate solvent, and these are sufficiently mixed to prepare a coating solution in which phosphor particles and particles of the compound are uniformly dispersed in a binder solution. I do.

In general, the binder is used in an amount of 0.01 to 1 part by mass per 1 part by mass of the stimulable phosphor. However, in terms of the sensitivity, sharpness, and contrast of the obtained radiation image conversion plate or panel, it is preferable that the amount of the binder is small.
The range is more preferably from 3 to 0.2 parts by mass.

Examples of the solvent used for preparing the coating solution for the stimulable phosphor layer include lower alcohols such as methanol, ethanol, isopropanol and n-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, and the like.
Ketones such as cyclohexanone, esters of lower fatty acids such as methyl acetate, ethyl acetate and n-butyl acetate with lower alcohols, dioxane, ethers such as ethylene glycol monoethyl ether and ethylene glycol monomethyl ether, aromatic compounds such as triols and xylol And halogenated hydrocarbons such as methylene chloride and ethylene chloride, and mixtures thereof.

The coating solution contains a dispersant for improving the dispersibility of the phosphor in the coating solution, and a dispersant between the binder and the phosphor in the stimulable phosphor layer after formation. Various additives such as a plasticizer for improving the bonding strength may be mixed. Examples of dispersants used for such purposes include phthalic acid, stearic acid, caproic acid, and lipophilic surfactants. Examples of the plasticizer include phosphoric esters such as triphenyl phosphate, tricresyl phosphate, and diphenyl phosphate; phthalic esters such as diethyl phthalate and dimethoxyethyl phthalate; ethylphthalylethyl glycolate and butylphthalylbutyl glycolate; Glycolic acid esters of
And polyester of polyethylene glycol and aliphatic dibasic acid, such as polyester of triethylene glycol and adipic acid, polyester of diethylene glycol and succinic acid, etc. can be mentioned.

The preparation of the coating solution for the stimulable phosphor layer is performed using a dispersing device such as a ball mill, a sand mill, an attritor, a three-roll mill, a high-speed impeller disperser, a Kady mill, and an ultrasonic disperser. The prepared coating solution is coated on a support using a coating solution such as a doctor blade, a roll coater, or a knife coater, and dried to form a stimulable phosphor layer.

The thickness of the stimulable phosphor layer of the radiation image conversion plate or panel of the present invention depends on the desired properties of the radiation image conversion plate or panel, the type of stimulable phosphor, the binder and the stimulable phosphor. Depending on the mixing ratio with the body, etc.
It is preferably selected from the range of μm to 1000 μm,
More preferably, it is selected from the range of 10 μm to 500 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 layer film. A method in which the peripheral portion is sandwiched and heated and fused with an impulse sealer, or a laminating method in which pressure is applied and heated between two heated rollers is used.

In the above-mentioned method of heat-sealing with the impulse sealer, heat-sealing under a reduced pressure environment prevents displacement of the phosphor sheet in the film for the moisture-proof protective layer and eliminates moisture in the air. More preferred in a sense.

Hereinafter, the radiation image conversion plate and the panel of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows a phosphor sheet used in the present invention,
1 shows a cross-sectional view of a radiation image conversion plate and a panel. FIG. 1A is a cross-sectional view of the phosphor sheet 3, wherein 1 is a phosphor layer, and 2 is a support. FIG. 2B shows a protective layer 4 on the upper surface of a phosphor sheet 3 having a phosphor layer 1 on a support 2.
It is sectional drawing of the radiation image conversion plate 5 provided with. FIG. 2C is a cross-sectional view of a radiation image conversion plate 8 in which the upper surface protective layer 6 and the lower surface protective layer 7 are provided on the upper surface of the phosphor sheet 3 having the phosphor layer 1 on the support 2. It is. FIG. 4D shows the radiation image conversion plate 5.
Is a cross-sectional view of a radiation image conversion panel 12 fixed to a support plate 9 via a lead foil 10 having an adhesive layer 11 on both sides. (E) shows the radiation image conversion plate 8,
FIG. 1 shows a cross-sectional view of a radiation image conversion panel 12 fixed to a support plate 9 via a lead foil 10 having adhesive layers 11 on both sides.

FIG. 2 is a cross-sectional view of a radiation image conversion plate and a panel having an excitation light absorbing function at the periphery of the present invention. FIG. 2A shows a radiation image conversion plate end portion 14 on a protective layer peripheral portion 13 as a portion having an excitation light absorbing function.
2 shows a radiation image conversion plate in which an excitation light absorbing function is provided to each of the phosphor layer end portions 15. FIG. 6B shows the portions having the excitation light absorbing function on the upper surface side protective layer surface peripheral portion 16, the lower surface side protective layer inner surface peripheral portion 17, and the upper surface side protective layer inner peripheral portion 18 as the portions having the excitation light absorbing function. 2 shows a radiation image conversion panel to which is added. FIG. 3C shows a radiation image conversion plate and a panel in which the support plate offset portion upper surface 19 is provided with an excitation light absorbing function.

[0068]

The present invention will now be illustrated by way of examples.

Example 1 In order to synthesize a stimulable phosphor precursor of europium-activated barium fluoroiodide, an aqueous BaI ₂ solution (3.6 mol) was used.
/ L) 2780 ml and EuI ₃ aqueous solution (0.2 mol /
L) 27 ml were placed in the reactor. The reaction mother liquor in the reactor was kept at 83 ° C. while stirring. 322 ml of an aqueous solution of ammonium fluoride (8 mol / L) was injected into the reaction mother liquor using a roller pump to generate a precipitate. After completion of the injection, the temperature and the stirring were continued for 2 hours to ripen the precipitate. Next, the precipitate was separated by filtration, washed with ethanol, and dried under vacuum 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 inter-particle fusion, 0.2% by mass of ultrafine alumina powder is added, and the mixture is sufficiently stirred with a mixer. Ultrafine alumina powder was uniformly adhered to the surface. This was filled in a quartz boat and calcined at 850 ° C. for 2 hours in a hydrogen gas atmosphere using a tube furnace to obtain europium-activated barium fluoroiodide phosphor particles. Next, particles having an average particle diameter of 7 μm were obtained by classifying the phosphor particles.

As the phosphor layer forming material, 427 g of the europium-activated barium fluoroiodide phosphor obtained above, 15.8 g of polyurethane resin (Desmolac 4125, manufactured by Sumitomo Bayer Urethane Co., Ltd.), and bisphenol A type epoxy resin 0 g of methyl ethyl ketone-toluene (1:
1) The mixture was added to a mixed solvent and dispersed by a propeller mixer to prepare a coating solution having a viscosity of 25 to 30 Pa · s. This coating solution was applied on a 100-μm-thick black PET support using a doctor blade, and then dried at 100 ° C. for 15 minutes to form a 270-μm-thick phosphor layer.
The resulting phosphor sheet is shown in FIG.

<Preparation of Protective Layer-Adhesive Type Radiation Image Conversion Plate and Panel> The phosphor sheet obtained above was cut into a square of 20 cm × 20 cm, and PET having a polyester-based adhesive layer provided on the phosphor layer was used. A film (thickness: 12 μm) was laminated so that the adhesive layer was on the phosphor layer surface, and heated and pressed using a heat roll at 80 to 100 ° C. to produce a radiation image conversion plate having an unsealed structure (FIG. 1 (b)).

Next, using the obtained radiation image conversion plate, a radiation image conversion panel fixed to a support plate via a lead foil having adhesive layers on both surfaces was produced (see FIG. 1 (d)).

<Production of Radiation Image Conversion Plate and Panel of Protective Layer Four-side Sealed (with Mimi) Type> The film for the protective layer on the upper surface (phosphor surface) side had the structure shown in the following (A). . (A) VMPET12 // VMPET12 // PET1
2 // Sealant film PET: Polyethylene terephthalate Sealant film: CPP (casting polypropylene) is used as a heat-sealable film VMPET: Alumina-deposited PET (commercial product: manufactured by Toyo Metallizing Co., Ltd.) Film thickness (μm)
Is shown.

The above “//” means that the dry lamination adhesive layer has a thickness of 2.5 μm. The adhesive used for dry lamination is a two-component reaction type urethane adhesive.

The protective layer film on the lower surface (support surface) side
A dry laminate film having a structure of sealant film // aluminum foil film 9 μm // polyethylene terephthalate (PET) 188 μm was used. The above “//” is a dry lamination adhesive layer, and the thickness of the adhesive layer is 1.5 μm.
m, a two-component reaction type urethane adhesive was used.

The above-mentioned phosphor sheet is cut into a square of 20 cm × 20 cm, and the peripheral portion is fused using an impulse sealer under reduced pressure using the above-mentioned film for the upper protective layer and the film for the lower protective layer. Thus, a radiation image conversion plate of a protective layer with four sides sealed (with a dent) was produced (see FIG. 1C).

Next, using the obtained radiation image conversion plate, a radiation image conversion panel fixed to a support plate via a lead foil having an adhesive layer on both surfaces was produced (see FIG. 1 (e)).

In order to impart the excitation light absorbing function to the portion corresponding to the peripheral portion of the phosphor sheet of each protective layer film and the phosphor layer, coloring was performed by the following method. (1) Coloring method of upper surface side protective layer surface A portion corresponding to the peripheral portion of the phosphor sheet (inner frame 19.8c
A frame-shaped printing plate having a size of mx 19.8 cm and an outer frame of 21 cm x 21 cm) was prepared, and an ink containing an organic blue colorant (Zavon Fast Blue 3G, manufactured by Hoechst) dispersed and dissolved in methyl ethyl ketone was used. Printing was carried out on the surface of the film for the upper protective layer so as to have the degree of coloring shown in Table 1 (see FIG. 2B). (2) Coloring method inside protective layer The intermediate layer of the protective layer film having a multilayer structure is printed using the printing plate used in the above (1) so as to have the degree of coloring shown in Table 1, and then the multilayer structure is formed by dry lamination. (See FIGS. 2 (a) and 2 (b)). (3) Method for Coloring Inner Surface of Lower Protective Layer Using the printing plate used in the above (1), printing was performed on the surface of the lower protective layer film so as to have the degree of coloring shown in Table 1 (FIG. 2B). reference). (4) Coloring method of phosphor layer surface and end face The phosphor layer surface (20 cm × 20 cm) is 19.8 cm ×
Masking is performed with a 19.8 cm mask at the center, and an organic blue colorant (Zapon Fast Blue 3) dispersed and dissolved in methyl ethyl ketone from the peripheral edge and end.
G, manufactured by Hoechst Co., Ltd.) to color the periphery. (5) Coloring Method Inside Phosphor Layer 19.8 cm × 20 cm × 20 cm
Masking is performed with a 19.8 cm mask at the center, and an organic blue colorant (Zapon Fast Blue 3) dispersed and dissolved in methyl ethyl ketone from the peripheral edge and end.
G, manufactured by Hoechst) to color the inside of the phosphor layer (see FIG. 2A). (6) Method for coloring peripheral edge and end of radiation image conversion plate of protective layer adhesion type 19.8 cm × 19.8 to radiation image conversion plate (20 cm × 20 cm) of protection layer adhesion type obtained above.
Masking was performed with a mask having a size of about 10 cm, and an organic blue colorant (Zavon Fast Blue 3G, manufactured by Hoechst) dispersed and dissolved in methyl ethyl ketone was applied from the peripheral edge and the edge to color the peripheral edge (FIG. 2 (a)
reference). (7) Method of coloring the surface of the support plate The offset (protruding) portion of the support plate (aluminum plate) (FIG. 2)
(D), the object of the present invention can be sufficiently achieved, but a black paint is applied to the entire surface of the support plate so that the reflectance at 690 nm is 5%.

The reflectance was expressed as a relative value of the amount of light when the reflectance on the aluminum mirror surface was taken as 100%.

The light transmittance of the peripheral portion having the excitation light absorbing function was a value of the light transmittance in a light wavelength region of 690 nm.

Table 1 shows the form of the protective layer, the presence or absence of the support plate, the coloring site, and the degree of coloring of each sample of the radiation image conversion plate and panel manufactured as described above.

(Evaluation of Contrast) Using each radiation image conversion plate and panel obtained above, uniform X-ray exposure (solid) (tube voltage: 80 kV) was performed using a lead disk (thickness: 2 mm) for contrast evaluation. After that, readout was performed using a semiconductor laser (690 nm) as excitation light, the obtained image information was output to a film, and the contrast was evaluated on a 5-point scale according to the following criteria.

5: Peripheral edge of lead disk and brightness difference between black and white are clearly confirmed. 4: Peripheral edge of lead disk is slightly blurred, but brightness difference between black and white is almost clearly recognized. 3: Peripheral portion of lead disk. The brightness difference between black and white is slightly unclear. 2: The periphery of the lead disk and the brightness difference between black and white are not clear and the lead disk is not reproduced. 1: The shape of the lead disk and the brightness difference between black and white are not clear. Clear and low whiteness at the center. Evaluations of 3 or less are not practically suitable for diagnosis. Table 1 shows the obtained results.

[0084]

[Table 1]

From Table 1, it can be seen that the sample of the present invention shows better contrast than the comparison.

[0086]

According to the present invention, a radiation image conversion plate and a panel having a high contrast can be provided by imparting an excitation light absorbing function to a peripheral portion.

[Brief description of the drawings]

FIG. 1 is a sectional view of a phosphor sheet, a radiation image conversion plate, and a panel used in the present invention.

FIG. 2 is a cross-sectional view of a radiation image conversion plate and a panel having an excitation light absorbing function at a peripheral portion of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Phosphor layer 2 Support body 3 Phosphor sheet 4 Protective layer 5, 8 Radiation image conversion plate 6 Upper side protective layer 7 Lower side protective layer 9 Support plate 10 Lead foil 11 Adhesive layer 12 Radiation image conversion panel 13 Peripheral part of protective layer 14 Radiation image conversion plate edge 15 Phosphor layer edge 16 Upper surface side protective layer surface peripheral edge 17 Lower surface side protective layer inner surface peripheral edge 18 Upper surface side protective layer inner peripheral edge 19 Support plate offset portion upper surface 20 Support plate offset portion upper surface coloring Department

Claims (9)

[Claims] 1. A radiation image conversion plate comprising: a phosphor sheet provided with a stimulable phosphor layer on a support; and a protective layer provided so as to cover the phosphor sheet. A radiation image conversion plate having a reading light (excitation light) absorption function at a peripheral portion of the radiation image conversion plate. 2. The radiation image conversion plate according to claim 1, wherein the protective layer is provided so as to cover the upper surface and the lower surface of the phosphor sheet. 3. The radiation image conversion plate according to claim 1, wherein the periphery of the radiation image conversion plate is a periphery of the protective layer. 4. The protective layer according to claim 1, wherein the periphery of the protective layer is at least one selected from the surface of the upper protective layer, the end surface of the upper protective layer, the inside of the upper protective layer and the inner surface of the lower protective layer. The radiation image conversion plate according to any one of claims 1 to 3. 5. The radiation image conversion plate according to claim 1, wherein the periphery of the radiation image conversion plate is the periphery of the phosphor sheet. 6. The phosphor sheet according to claim 6, wherein a peripheral portion of the phosphor sheet is a phosphor layer surface,
6. The radiation image conversion plate according to claim 5, wherein at least one is selected from the inside of the phosphor layer and the cross section of the phosphor sheet. 7. A radiation image conversion plate comprising a phosphor sheet provided with a stimulable phosphor layer on a support and a protective layer provided so as to cover the phosphor sheet is a support plate (tray). A radiation image conversion panel fixed to a plate, wherein the support plate (tray plate) has a reading light (excitation light) absorption function. 8. The radiation image conversion plate according to claim 1, wherein
8. The radiation image conversion panel according to claim 7, wherein the radiation image conversion plate is the radiation image conversion plate according to any one of the above. 9. The radiation image according to claim 7, wherein the support plate is larger than the radiation image conversion plate, and has a reading light (excitation light) absorption function on a surface of an offset (protruding) portion of the support plate. Conversion panel.