JP3162094B2 - Radiation image conversion panel and method of using the same - Google Patents

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 panel having a stimulable phosphor layer, and more particularly to a radiation image conversion panel which can be used even when the stimulable phosphor layer is deteriorated by moisture. And how to use it.

[0002]

2. Description of the Related Art In the medical field, for example, radiation images such as X-ray images are often used for diagnosing diseases. Conventionally, as a method of forming a radiation image, X-rays transmitted through a subject are irradiated on a phosphor layer (fluorescent screen) to generate visible light, and this visible light is used in the same manner as when a normal photograph is taken. A so-called radiographic method of irradiating and developing a film using a silver salt has been generally used.

However, in recent years, as a method of directly taking out an image from a phosphor layer without using a film coated with a silver salt, radiation that has passed through a subject is absorbed by the phosphor, and then the phosphor is irradiated with light or heat, for example. A method has been proposed in which, by excitation with energy, radiation energy absorbed and accumulated in the phosphor is emitted as fluorescence, and the fluorescence is detected and imaged. For example, U.S. Pat. No. 3,859,527 and JP-A-55-12144 disclose a radiation image conversion method using a stimulable phosphor and using visible light or infrared light as stimulating excitation light. In this method, a radiation image conversion panel having a stimulable phosphor layer formed on a substrate is used. A latent image is formed by accumulating radiation energy corresponding to the radiation transmittance of each part, and then the radiation energy accumulated in each part is stimulated by scanning the stimulable phosphor layer with stimulating excitation light. The light is emitted as light emission, and an optical signal based on the intensity of the light is photoelectrically converted, for example, and is imaged by an image reproducing apparatus. This final image is reproduced as a hard copy or on a CRT.

A radiation image conversion panel having a stimulable phosphor layer used in such a radiation image conversion method emits stored energy by scanning with stimulating excitation light after accumulating radiation image information. The radiation image can be stored again later, and can be used repeatedly. However, the radiation image conversion panel is required to have durability that can be repeatedly used for a long period of time or many times without deteriorating the image quality of the obtained radiation image. In order to enhance the durability, the stimulable phosphor layer of the radiation image conversion panel needs to be sufficiently protected from external physical or chemical stimuli. In particular, since the properties of the stimulable phosphor layer are easily degraded by moisture, it is necessary to sufficiently protect the stimulable phosphor layer from moisture.

However, conventionally, in order to protect the stimulable phosphor layer, means for covering the surface of the stimulable phosphor layer with a protective layer has been proposed. This protective layer is formed by directly applying a coating solution for the protective layer on the stimulable phosphor layer as described in, for example, JP-A-59-42500, or separately formed in advance. It is provided by bonding a protective layer on the stimulable phosphor layer. As the protective layer, a thin layer made of an organic polymer and having a thickness of about 10 μm is generally used. However, a commonly used protective layer made of an organic polymer shows permeability to a certain degree of moisture and / or moisture, so that the stimulable phosphor layer absorbs moisture, and radiation sensitivity is reduced, There is a problem that the accumulated energy is greatly attenuated (fading) after irradiation with radiation and before irradiation with stimulating excitation light, and the quality of the obtained radiation image varies or deteriorates. In order to prevent permeation of moisture in the protective layer, it is effective to increase the thickness of the protective layer. However, simply increasing the thickness of the protective layer reduces the sharpness. Therefore, as described in JP-A-62-206017, providing a low refractive index layer is preferable in that a thick protective layer can be used without reducing sharpness. is there. The low refractive index layer is formed by fixing the protective layer and the support with an adhesive using a spacer. In order to further effectively prevent the permeation of moisture, a technique has been proposed in which a filler which also functions as a moisture-proof material is provided outside the spacer (Japanese Patent Application Laid-Open No. 2-77700).

[0006]

However, even in the prior art as described above, when the radiation image conversion panel is used repeatedly for a long period of time, moisture gradually permeates. For this reason, the stimulable phosphor layer is deteriorated, and the radiation sensitivity and the like still remain. Therefore, an object of the present invention is to provide a radiation image conversion panel which can be easily reproduced and used even when the stimulable phosphor layer is deteriorated by moisture, and a method of using the same.

[0007]

In order to achieve the above object, a radiation image conversion panel of the present invention comprises a support, a stimulable phosphor layer provided on the support, and a stimulable phosphor layer. A protective layer is provided on the phosphor layer, and a spacer is provided between the support and the protective layer so as to surround the periphery of the stimulable phosphor layer and seals the stimulable phosphor layer. In the radiation image conversion panel, at least one of the support, the protective layer, and the spacer is provided with a ventilation hole in a closed space defined by the support, the protection layer, and the spacer, and the hardness after curing is changed to the hardness after curing. Using 20-85 adhesives
Characterized by being sealed by a detachable sealing member fixed and fixed . Further, the method of using the radiation image conversion panel of the present invention uses the radiation image conversion panel having the above configuration.
After that, the sealing member of the ventilation hole is removed, the enclosed space is dried , and moisture is removed from the stimulable phosphor layer degraded by moisture.
The radiation image conversion panel is repeatedly used by removing the stimulable phosphor layer to remove the stimulable phosphor layer, and then sealing the air holes with a sealing member again .

Hereinafter, the configuration of the present invention will be specifically described.
1 and 2 show an example of the radiation image conversion panel of the present invention, wherein 1 is a stimulable phosphor layer, 2 is a protective layer, 3 is a support, 4 is a spacer, 5 is a low refractive index layer, 6 Is a ventilation hole, and 7 is a sealing member. A stimulable phosphor layer 1 is provided on a support 3, and a protective layer 2 is provided on the stimulable phosphor layer 1 via a low refractive index layer 5 made of an air layer. Support 3
A spacer 4 is fixed between the protective layer 2 and the protective layer 2 by an adhesive so as to surround the peripheral edge of the stimulable phosphor layer 1.
The stimulable phosphor layer 1 is sealed from the external space by the spacer 4. Support 3, protective layer 2, spacer 4
Are provided at the end of the protective layer 2 and are sealed by a detachable sealing member 7.

The number of the ventilation holes 6 is not particularly limited. At least 1
It is only necessary to be provided at three places. Practically, one or two places are preferable. The cross-sectional area of the ventilation hole 6 is preferably 0.05 to 1.5 cm ² per 100 cm ³ of the closed space. The position where the ventilation hole 6 is provided is not particularly limited as long as it does not hinder the formation of the radiation image. In addition to being provided on the protective layer 2 as shown in FIG.
4 and 4, it may be provided at the end of the support 3, or may be provided at a part of the spacer 4 as shown in FIGS.

The ventilation hole 6 is sealed by a detachable sealing member 7. Here, "removable" means that the sealed portion is destroyed at an appropriate time after the sealing member 7 is sealed. This means that the sealing member 7 can be peeled off without performing, and the sealing member 7 can be bonded to the sealed portion again. Specifically, the sealing member 7 is fixed to the portion to be sealed using an adhesive capable of detachably fixing the sealing member 7.

[0011] Examples of such adhesives, so that sufficient adhesive strength is obtained at the time it is not, moreover again sealed damage to be sealed portion when peeling the sealing member 7, the hardness after hardening 20 ~ 85 adhesives are used. Specifically, elastic epoxy resin (hardness 70), silicone rubber
(Hardness 50), silicone resin (hardness 40) and the like. Further, from the viewpoint of sufficiently preventing the permeation of moisture over time, the moisture permeability of the adhesive is preferably 30 g / m ² · 24 hr or less. Here, “hardness” refers to a value measured according to JIS A. In addition, "moisture permeability" refers to JIS
It refers to a value measured according to Z 0208-1976 (the same applies hereinafter).

Further, from the viewpoint of preventing the formation of the radiation image from being disturbed and ensuring sufficient moisture proofing, the minimum distance from the periphery of the ventilation hole 6 to the periphery of the sealing member 7, that is, the outside air The distance of the moisture permeation through the adhesive interface when entering the closed space is preferably 1 to 10 mm. As the material of the sealing member 7, it is preferable to select a material suitable for the portion to be sealed, and particularly preferably the same material as the portion to be sealed. Further, the moisture permeability of the sealing member 7 is preferably 30 g / m ² · 24 hr or less from the viewpoint of moisture proof.

The protective layer 2 is provided for physically or chemically protecting the stimulable phosphor layer 1.
When the protective layer 2 is provided via the low-refractive-index layer 5, a material having a good light-transmitting property and capable of being formed into a sheet is used as the constituent material of the protective layer 2. The protective layer 2 desirably has a high light transmittance in a wide wavelength range in order to efficiently transmit stimulated excitation light and stimulated emission, and the light transmittance is 80%.
The above is preferred. As a material of such a protective layer 2,
Examples thereof include sheet glass such as quartz, borosilicate glass, and chemically strengthened glass, and organic polymer compounds such as polyethylene terephthalate (PET), expanded polypropylene (OPP), and polyvinyl chloride. For example, borosilicate glass is 330
Shows light transmittance of 80% or more in the wavelength range of nm to 2.6 μm,
Quartz glass shows high light transmittance even at shorter wavelengths. In particular, a sheet glass is preferable because it exhibits high light transmittance and excellent moisture resistance.

When the protective layer 2 is provided with the low refractive index layer 5 interposed therebetween, the thickness of the protective layer 2 is determined in consideration of the moisture permeability, but is usually 50 μm to 5 mm, preferably 100 μm.
m to 3 mm. The moisture permeability of the protective layer 2 is 30 g / m.
² · 24 hr or less, particularly preferably 10g / m ² · 24hr. Further, the surface of the protective layer 2, by providing the anti-reflection layer of MgF ₂ or the like, a stimulating light and stimulated luminescence with good efficiency transmission, there is also the effect of reducing the deterioration of the sharpness preferred. The refractive index of the protective layer 2 is not particularly limited, but is practically preferably in the range of 1.4 to 2.0. The protective layer 2 may have a multilayer structure of two or more layers as necessary.

As the material of the support 3, various polymer materials, glass, ceramics, metals and the like are used. Examples of the polymer material include films of cellulose acetate, polyester, polyethylene terephthalate, polyamide, polyimide, triacetate, polycarbonate and the like. Aluminum, iron,
Examples include a metal sheet or metal plate of copper, chromium, or the like, or a metal sheet or metal plate having a coating layer of an oxide of these metals. Examples of the glass include chemically strengthened glass and crystallized glass. Examples of the ceramic include a sintered plate of alumina or zirconia.

The moisture permeability of the support 3 is determined from the viewpoint of moisture resistance.
It is preferable that the moisture permeability of the protective layer 2 is substantially the same. Specifically, it is preferably 30 g / m ² · 24 hr or less.
The thickness of the support 3 varies depending on its material and the like, but is generally preferably 80 μm to 5 mm.
In particular, the thickness is preferably 200 μm to 3 mm. The surface of the support 3 may be a smooth surface, or may be a mat surface for the purpose of enhancing the adhesiveness to the stimulable phosphor layer 1. Further, the surface of the support 3 may have an uneven surface, or may have a surface structure in which minute tile plates independent of each other are densely arranged. In addition, an undercoat layer may be provided on the surface of the support 3 in order to enhance the adhesiveness with the stimulable phosphor layer 1, and a light reflection layer, a light absorption layer, and the like may be provided as necessary. You may.

The spacer 4 is not particularly limited as long as it can hold the stimulable phosphor layer 1 in a state of being shielded from the external atmosphere. Specifically, glass, ceramics, metal, plastic, and the like are used. In particular, the material of the spacer 4 is preferably the same as the material of the support 3. The moisture permeability of the spacer 4 is preferably 30 g / m ² · 24 hr or less from the viewpoint of moisture resistance. The thickness of the spacer 4 is not less than the thickness of the stimulable phosphor layer 1 and 5 mm.
The following is preferred. The width of the spacer 4 is determined mainly in consideration of the moisture-proof property of the contact portion between the spacer 4 and the support 3 and the protective layer 2, and is specifically preferably 1 to 30 mm. Further, the spacer 4, the support 3, and the protective layer 2
Is preferably 30 g / m ² · 24 hr or less.

The spacer 4 is fixed to the support 3 and the protective layer 2 by, for example, an adhesive. As such an adhesive, one having moisture resistance is preferable, and specifically, an epoxy resin, a phenol resin, a cyanoacrylate resin, a vinyl acetate resin, a vinyl chloride resin, a urethane resin, an acrylic resin, Ethylene vinyl acetate resin,
Organic polymer-based adhesives such as olefin-based resins, chloroprene-based rubbers, and nitrile-based rubbers; silicone-based adhesives; and inorganic-based adhesives mainly composed of alumina, silica, and the like. Further, from the viewpoint of enhancing the adhesiveness of the contact portion between the spacer 4 and the support 3 and the protective layer 2, an undercoat layer may be provided on the contact surface between the spacer 4 and the support 3 and the protective layer 2,
A roughening treatment may be performed.

The low-refractive-index layer 5 plays a role in preventing sharpness from being reduced by the protective layer 2. The low-refractive-index layer 5 exists in a state where the low-refractive-index layer 5 is shielded from the external atmosphere by the spacer 4. By providing the low-refractive-index layer 5, the protective layer 2 can be made substantially thick, and the Properties can be further enhanced. As the low refractive index layer 5, in addition to the air layer, a layer made of an inert gas such as nitrogen or argon, a layer having a refractive index of substantially 1 such as a vacuum layer, an etalle (refractive index 1.36), a methanol (refractive index) It may be a layer made of a liquid such as 1.33) or diethyl ether (refractive index 1.35). In another embodiment, CaF ₂ (refractive index: 1.23 to 1.26), Na ₃ AlF ₆ (refractive index: 1.35), Mg
A low-refractive-index layer made of a material such as F ₂ (refractive index 1.38) or SiO ₂ (refractive index 1.46) may be directly laminated on the protective layer 2.
The thickness of the low refractive index layer 5 is practically 0.05 μm to 3 mm.

In order to sufficiently prevent the sharpness from being lowered by the low refractive index layer 5, the low refractive index layer 5 needs to be in close contact with the stimulable phosphor layer 1. When 5 is a gas layer such as air, a vacuum layer, or a liquid layer, a close contact state can be obtained as it is. However, when a low refractive index layer made of CaF ₂ or the like is directly laminated on the protective layer 2, the low refractive index is obtained. It is preferable that the rate layer and the stimulable phosphor layer 1 are adhered to each other with an adhesive or the like.

The stimulable phosphor layer 1 is formed by, for example, a vacuum evaporation method.
It can be formed by a vapor deposition method such as a sputtering method, a CVD method, or an ion plating method, or by applying a coating liquid in which a stimulable phosphor powder is dispersed in a polymer binder. From the viewpoints of radiation sensitivity and image sharpness, the vapor deposition method is more preferable.

Here, the "stimulable phosphor" refers to a stimulus (stimulation excitation) such as optical, thermal, mechanical, chemical or electrical after the first irradiation of light or high-energy radiation.
Refers to a phosphor that shows stimulated emission corresponding to the dose of the first light or high-energy radiation.However, from a practical point of view, a phosphor that emits stimulated emission with a wavelength of 500 nm or more Is preferred.

The following can be used as the stimulable phosphor constituting the stimulable phosphor layer. (1) JP 48- 80487 No. BaSO described in Japanese _4: phosphor represented by A _x. (However, A is Dy, Tb, Tm
And x represents a number satisfying 0.001 ≦ x <1 mol%. ) (2) JP 48- 80489 No. SrSO described in Japanese _4: phosphor represented by A _x. (However, A is Dy, Tb, Tm
And x represents a number satisfying 0.001 ≦ x <1 mol%. (3) Phosphors such as Li ₂ B ₄ O ₇ : Cu and Ag described in JP-A-53-39277.

(4) Li ₂ O · (B ₂ O ₂ ) _x : Cu Li ₂ O · (B ₂ O ₂ ) _x : A phosphor such as Cu or Ag described in JP-A-54-47883. (However, x represents a number satisfying 2 <x ≦ 3.) (5) SrS: Ce, Sm SrS: Eu, Sm La ₂ O ₂ S: Eu, Sm described in US Pat. No. 3,859,527 ( Zn, Cd) S: Phosphor represented by Mn, X. (However, X represents a halogen.) (6) Phosphors such as ZnS: Cu and Pb described in JP-A-55-12142.

(7) A barium aluminate phosphor represented by the general formula of BaO.xAl ₂ O ₃ : Eu described in JP-A-55-12142. (Where x is
Represents a number satisfying 0.8 ≦ x ≦ 10. ) (8) Same 55- general formula described in JP 12142 is M ^II O · xSiO _2: alkaline earth metal silicate-based phosphor represented by A. (However, M ^II represents Mg, Ca, Sr, Zn, Cd, Ba, and A represents Ce, Tb, Eu, Tm, Pb, Tl, B
i represents at least one of Mn, and x is 0.5 ≦ x <2.
Represents a number that satisfies 5. (9) A phosphor represented by the general formula (Ba _1-xy Mg _x C a _y ) FX: eEu ^{2+ described} in JP-A-55-12143. (Where X represents at least one of Br and Cl, and x, y, and e are 0 <x +
It represents a number satisfying y ≦ 0.6, x · y ≠ 0, 10 ⁻⁶ ≦ e ≦ 5 × 10 ⁻² . )

(10) A phosphor represented by the general formula LnOX: xA described in JP-A-55-12144. (However, Ln is La, Y, G
X represents at least one of Cl and Br, A represents at least one of Ce and Tb, and x represents a number satisfying 0 <x <0.1. (11) A phosphor represented by general formula (Ba _1-x (M ^II ) _x ) FX: yA described in JP-A-55-12145. (However, M ^II is Mg, Ca, S
X represents at least one of r, Zn, and Cd;
Represents at least one of Br and I, and A represents Eu, Tb,
Represents at least one of Ce, Tm, Dy, Pr, Ho, Nd, Yb, and Er, where x and y are 0 ≦ x ≦ 0.6 and 0 ≦ y
Represents a number that satisfies ≦ 0.2. (12) A phosphor represented by the general formula of BaFX: xCe, yA described in JP-A-55-84389. (Where X represents at least one of Cl, Br and I, and A represents In, Tl, Gd, S
represents at least one of m and Zr, wherein x and y are 0 <x ≦
It represents a number that satisfies 2 × 10 ⁻¹ and 0 <y ≦ 5 × 10 ⁻² . )

(13) A rare earth element-activated divalent metal fluorohalide phosphor represented by the general formula M ^II FX.xA: yLn described in JP-A-55-160078. (However, M ^II is Mg, Ca, Ba, Sr, Z
n represents at least one of Cd and A represents BeO, Mg
O, 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 , T
a ₂ O _5, represents at least one of ThO _2, Ln is
Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Y
X represents at least one of b, Er, Sm, and Gd;
Represents at least one of Cl, Br and I, wherein x and y are 5
It represents a number that satisfies × 10 ⁻⁵ ≦ x ≦ 0.5 and 0 <y ≦ 0.2. (14) Phosphor represented by the general formula described in JP-A-55-160078: ZnS: A, (Zn, Cd) S: A, CdS: A, ZnS: A, X, CdS: A, X . (However, A is Cu, Ag, A
X represents any of u and Mn, and X represents halogen. (15) A phosphor represented by the following general formula xM ₃ (PO ₄ ) ₂ · NX ₂ : yAM ₃ (PO ₄ ) ₂ · yA described in JP-A-59-38278. (Where M and N are respectively M
g, at least one of Ca, Sr, Ba, Zn, Cd; X, at least one of F, Cl, Br, I; A, Eu, Tb, Ce, Tm, Dy, Pr, H
o, Nd, Yb, Er, Sb, Tl, Mn, and Sn, wherein x and y are 0 <x ≦ 6, 0 ≦ y ≦ 1
Represents a number that satisfies )

[0028] (16) the following formula described in JP 59-155487 discloses _{nReX 3 · mAX '2: xEu} nReX 3 · mAX' 2: xEu, phosphor represented by YSM. (Where Re is La, Gd, Y,
Represents at least one kind of Lu, and A represents Ba, Sr, Ca
X, X 'represents at least one alkaline earth metal of
Represents at least one of F, Cl, and Br, and x, y
Is 1 × 10 ⁻⁴ <x <3 × 10 ⁻¹ , 1 × 10 ⁻⁴ <y <1 × 10 ⁻¹
Where n / m is 1 × 10 ⁻³ <n / m <7 ×
Represents a number that satisfies 10 ^-1 . ) (17) JP 61- 72087 No. formulas described in Japanese ^{M I X · aM II X '} 2 · bM III X''3: alkali halide phosphor represented by cA. (However, M
^I represents at least one alkali metal of Li, Na, K, Rb and Cs, and M ^II represents Be, Mg, Ca, S
represents at least one divalent metal of r, Ba, Zn, Cd, Cu, Ni, and M ^III represents Sc, Y, La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga, In represents at least one trivalent metal, and X, X ′, X ″ are
Represents at least one halogen of F, Cl, Br, I, and A represents Eu, Tb, Ce, Tm, Dy, Pr, H
o, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl,
Represents at least one metal of Na, Ag, Cu, and Mg, and a, b, and c are 0 ≦ a <0.5, 0 ≦ b <0.5, 0 <
represents a number satisfying c ≦ 0.2. )

[0029] (18) generally described in JP 60- 84381 JP formula _{^{M II X 2 · aM II X}} '2: xEu 2+ divalent europium activated alkaline earth metal halide phosphor represented. (However, M ^II is Ba, Sr, Ca
X and X ′ are at least one halogen of Cl, Br, I and X ≠ X ′, and a, x is 0.1 ≦ a ≦ 1
0.0, 0 <x ≦ 0.2. ) (19) JP 63- formula 27,588 No. described in Japanese MX ₂ · aMX _'2: bEu divalent europium activated alkaline earth represented by ²⁺ metal halide phosphor. (Where M is at least one alkaline earth metal of Ca, Sr, Ba, X and X ′ are at least one halogen of Cl, Br, I, and X ≠ X ′ A, b is 0.5 ≦ a ≦ 1.
8, a number that satisfies 10 ⁻⁴ ≦ b ≦ 10 ⁻² . (20) Proceedings of the 51st Annual Meeting of the Japan Society of Applied Physics (Autumn 1990) Divalent europium-activated barium halide represented by the general formula BaX ₂ : Eu (X is a halogen) described on page 1086 Phosphor.

Of the above, alkali halide phosphors are particularly preferred because they can easily form a stimulable phosphor layer by vacuum deposition, sputtering, or the like. However, in the present invention, the phosphor is not limited to the above, and other phosphors may be used as long as the phosphor exhibits stimulable fluorescence when irradiated with radiation and then irradiated with stimulating excitation light. it can.

In the present invention, the stimulable phosphor layer 1 comprises
It may be a stimulable phosphor layer group composed of one or more layers containing at least one kind of the stimulable phosphor. The stimulable phosphor contained in each stimulable phosphor layer may be the same or different.

The thickness of the stimulable phosphor layer 1 is preferably 10 to 10 when no binder is used from the viewpoint of enhancing radiation sensitivity.
It is preferably 1,000 μm, particularly preferably 20 to 800 μm. When a binder is used, the thickness is preferably 20 to 1000 μm, particularly 50 to 500 μm.
μm is preferred.

Next, a method of using the present invention will be described. In the method of use of the present invention, the sealing member 7 of the ventilation hole 6 is removed at an appropriate time after the use of the radiation image conversion panel, and the inside of the enclosed space is dried. Is sealed and the radiation image conversion panel is reproduced and used repeatedly. The drying in the closed space is preferably performed by heating at a temperature of 40 to 100 ° C. for 0.1 to 3 hours. Further, it is preferable to heat and dry under reduced pressure in order to surely remove moisture. In the case of drying under reduced pressure, after drying, the closed space is filled with dry air or the like constituting the low refractive index layer 5 so as to have the same pressure as the atmospheric pressure, and then the ventilation hole 6 is immediately sealed with the sealing member 7. Is preferred. The dry air filled in the closed space preferably has a water content of 50 ppm or less, particularly preferably 20 ppm or less.

FIG. 7 schematically shows a radiation image conversion apparatus constructed using the radiation image conversion panel of the present invention, wherein 8 is a radiation generator, 9 is a subject, 10 is a radiation image conversion panel, and 11 is stimulating excitation. A light source 12, a photoelectric conversion device 12 for detecting stimulated emission emitted from the radiation image conversion panel 10, a reproduction device 13 for reproducing a signal detected by the photoelectric conversion device 12 as an image, and a reproduction device 13 for reproduction. A display device 15 for displaying an image is a filter that separates stimulated excitation light and stimulated emission and transmits only stimulated emission. In the radiation image conversion apparatus shown in FIG. 7, the radiation R from the radiation generator 8 enters the radiation image conversion panel 10 through the subject 9. This incident radiation R
I is absorbed by the stimulable phosphor layer 1 of the radiation image conversion panel 10 and its energy is accumulated, so that an accumulation image of a radiation transmission image is formed. Next, this accumulated image is converted to a stimulating excitation light source 1.
It is excited by stimulating light from 1 and emitted as stimulating light. Since the intensity of the emitted stimulating luminescence is proportional to the amount of the accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 12 such as a photomultiplier tube, for example.
By reproducing as an image by 3 and displaying by the display device 14, a radiation transmission image of the subject 9 can be observed.

[0035]

EXAMPLES Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. Example 1 A radiation image conversion panel having the configuration shown in FIGS. 1 and 2 was manufactured according to the following steps. 1mm thick and 4 size
On a support made of a crystallized glass plate of 00 mm x 500 mm, R
bBr (stimulable phosphor) was deposited to form a stimulable phosphor layer having a thickness of 300 μm. As the protective layer, a borosilicate glass plate having a thickness of 1 mm was used.
A 10 mm square vent was provided. A 1 mm thick spacer made of glass was fixed with an epoxy adhesive so as to surround the periphery of the stimulable phosphor layer between the support and the protective layer. Under reduced pressure of 1 × 10 ^-2 mmHg,
After heating and drying at 80 ° C for 2 hours, water content 20pp
m ₂ of dry N ₂ (nitrogen) gas. Next, the ventilation holes are sealed with an elastic epoxy-based adhesive (hardness: 50) using a sealing member made of the same material as the protective layer and made of a 20 mm square borosilicate glass plate having a thickness of 1 mm. A closed space was formed. The minimum bonding width between the sealing member and the periphery of the vent was 5 mm.

The radiation image conversion panel obtained in this manner is left under environmental conditions of a temperature of 60 ° C. and a relative humidity of 85% to be forcibly deteriorated, and the sensitivity decrease rate and the fading decrease over time are determined by the following method. The rate was determined. Further, the stimulable phosphor layer on the support is sealed with a protective layer and a spacer,
When the radiation image conversion panel was manufactured according to the present invention by sealing (sealing), the rate of decrease in sensitivity and the rate of fading before and after sealing were examined, and the performance degradation during the manufacture of the radiation image conversion panel was evaluated. In addition, the performance of the plate before sealing was evaluated in a vacuum and used as a reference in order to remove the influence of moisture.

Sensitivity reduction rate: X-rays with a P tube voltage of 80 kV _P are irradiated for 10 mR, and after t seconds, stimulated by semiconductor laser light (780 nm, 20 mW), and stimulated emission is emitted from the stimulable phosphor layer. Was photoelectrically converted by a photodetector (photomultiplier tube), and the magnitude of the obtained electric signal was defined as the sensitivity Sst (sec) of the radiation image conversion panel. Five seconds after the X-ray irradiation, the sensitivity S ₀ ( ₅ sec) of the radiation image conversion panel before sealing, the sensitivity Sst ( ₅ sec) of the radiation image conversion panel before the forced degradation test after sealing, and the forced degradation test From the sensitivity S ₆₀ ( ₅ sec) of the subsequent radiation image conversion panel, the sensitivity reduction rate (P) was determined by the following equations (1) and (2).

Sensitivity reduction rate during production (Pm):

(Equation 1)

Sensitivity reduction rate (Pr) due to forced deterioration:

(Equation 2)

Fading reduction rate: Q The decay rate of stored energy between the irradiation of X-rays and the reading of a signal by laser light, ie, fading: F, can be obtained by the following equation (3).

[0041]

(Equation 3)

However, S ( ₁₂₀ sec) is 1
The sensitivity after 20 seconds, S ( ₅ sec) indicates the sensitivity after 5 seconds. Fading F of sealing prior to radiation image conversion panel _0, fading reduction ratio by the following Equation 4 and Equation 5 from the forced deterioration test before fading Fst and forced deterioration test fading F ₆₀ after after sealing (Q ).

Fading reduction rate during production (Qm):

(Equation 4)

The fading reduction rate (Q
r):

(Equation 5)

Further, after the production of the radiation image conversion panel,
At the end of the day, peel off the sealing member of the ventilation hole and
After drying by heating at 80 ° C. for 2 hours under reduced pressure of 10 ^-2 mmHg, the atmosphere was replaced with dry N ₂ (nitrogen) gas having a water content of 20 ppm, and then the vent was sealed again with the peeled sealing member. Then, the radiation image conversion panel was reproduced. The radiation image conversion panel after the reproduction was examined for the sensitivity reduction rate and the fading reduction rate in the same manner as described above.

Further, at 180 days after the production, the radiation image conversion panel was reproduced in the same manner as described above, and the sensitivity reduction rate and the fading reduction rate were examined in the same manner as described above.

Example 2 The structure shown in FIGS. 3 and 4 was carried out in the same manner as in Example 1 except that a vent was provided in the support and a crystallized glass plate made of the same material as the support was used as the sealing member. A radiation image conversion panel was produced. The radiation image conversion panel was examined for the sensitivity reduction rate and the fading reduction rate in the same manner as in Example 1.

Example 3 An air hole was provided in a part of the spacer, the width thereof was set to 10 mm, and glass (the thickness of 1
mm, width 3.0 mm, length 400 mm), except that a radiation image conversion panel having the configuration shown in FIGS. 5 and 6 was produced in the same manner as in Example 1. The radiation image conversion panel was examined for the sensitivity reduction rate and the fading reduction rate in the same manner as in Example 1.

Example 4 Example 1 was repeated except that stretched polypropylene (thickness 1 mm) was used for the protective layer, stretched polypropylene of the same material as the protective layer was used as the sealing member, and silicone rubber (hardness 50) was used. A radiation image conversion panel was produced in the same manner as in 1.
The radiation image conversion panel was examined for the sensitivity reduction rate and the fading reduction rate in the same manner as in Example 1.

Comparative Example 1 The same as Example 1 except that a 10 μm thick polyethylene terephthalate having no ventilation holes was used as a protective layer, and a vinyl chloride-vinyl acetate copolymer resin was used for fixing to a spacer. Thus, a radiation image conversion panel for comparison was produced. With respect to this radiation image conversion panel, the sensitivity reduction rate and the fading reduction rate were examined in the same manner as in Example 1 except that reproduction was not performed.

Comparative Example 2 A comparative radiation image conversion panel was prepared in the same manner as in Example 1 except that a borosilicate glass plate having a thickness of 1 mm without a vent was used as a protective layer. With respect to this radiation image conversion panel, the sensitivity reduction rate and the fading reduction rate were examined in the same manner as in Example 1 except that reproduction was not performed.

Comparative Example 3 A polyethylene terephthalate sheet having a thickness of 10 μm was used as a protective layer and a sealing member, and a vinyl chloride-vinyl acetate copolymer resin (having a hardness of 90) was used as an adhesive for sealing the sealing member to the air holes. A radiation image conversion panel for comparison was produced in the same manner as in Example 1 except that the above was used. With respect to this radiation image conversion panel, the sensitivity reduction rate and the fading reduction rate were examined in the same manner as in Example 1 except that reproduction was not performed.

Comparative Example 4 A comparative radiation image conversion panel was produced in the same manner as in Example 1 except that an epoxy-based adhesive (hardness 100) was used as an adhesive for sealing the sealing member to the air holes. did. The radiation image conversion panel was examined for the sensitivity reduction rate and the fading reduction rate in the same manner as in Example 1. In addition,
In this radiation image conversion panel, the sealing member could not be peeled off because the bonding strength of the sealing member was too large. The above results are summarized in Tables 1 and 2 below.

[0054]

[Table 1]

[0055]

[Table 2]

As can be seen from Table 2, according to the radiation image conversion panel of the embodiment, even if the stimulable phosphor layer is deteriorated by moisture, it can be easily reproduced to the initial state where the rate of decrease in sensitivity and the rate of decrease in fading are small. Can be used.

[0057]

As described above in detail, according to the radiation image conversion panel of the present invention, when the stimulable phosphor layer is degraded by moisture, the moisture is easily removed and the stimulable phosphor layer is removed. The layer can be regenerated to its original good condition. According to the method of using the radiation image conversion panel of the present invention, the service life of the radiation image conversion panel is significantly extended.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a radiation image conversion panel of the present invention.

FIG. 2 is a plan view showing an example of the radiation image conversion panel of the present invention.

FIG. 3 is a longitudinal sectional view showing another example of the radiation image conversion panel of the present invention.

FIG. 4 is a plan view showing another example of the radiation image conversion panel of the present invention.

FIG. 5 is a longitudinal sectional view showing still another example of the radiation image conversion panel of the present invention.

FIG. 6 is a plan view showing still another example of the radiation image conversion panel of the present invention.

FIG. 7 is an explanatory view schematically showing a radiation image conversion apparatus configured using the radiation image conversion panel of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photostimulable phosphor layer 2 protective layer 3 support 4 spacer 5 low refractive index layer 6 vent hole 7 sealing member 8 radiation generator 9 subject 10 radiation image conversion panel 11 photostimulation excitation light source 12 photoelectric conversion device 13 reproducing device 14 Display device 15 Filter

Claims (2)

(57) [Claims] 1. A support, a stimulable phosphor layer provided on the support, a protective layer provided on the stimulable phosphor layer,
A radiation image conversion panel comprising a spacer provided between the support and the protective layer so as to surround the periphery of the stimulable phosphor layer and sealing the stimulable phosphor layer; In at least one of the layers and spacers,
Providing a ventilation hole in a closed space defined by the support, the protective layer and the spacer, and using an adhesive having a hardness after curing of 20 to 85 for the ventilation hole .
A radiation image conversion panel sealed by a fixed detachable sealing member. 2. The radiation image conversion panel according to claim 1.
After using , remove the sealing member of the ventilation hole, dry the enclosed space, and remove the stimulable phosphor layer deteriorated by moisture.
To recover the stimulable phosphor layer and remove
A method for using a radiation image conversion panel, wherein the radiation image conversion panel is repeatedly used by sealing a ventilation hole with a sealing member.