JP3034587B2 - Radiation image conversion panel - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a radiation image conversion panel using a stimulable phosphor layer, and more particularly to a radiation image having a high practical level in both sharpness and sensitivity. The present invention relates to a radiation image conversion panel that provides the following.

[Related Art] For example, in the field of medicine, 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 taking out an image directly from the phosphor layer without using a film coated with a silver salt, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited by, for example, light or heat energy. Then, a method has been proposed in which 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, JP-A-55-121
No. 44 discloses 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. Forming a latent image by accumulating radiation energy corresponding to the radiation transmittance of each part of
Thereafter, the stimulable phosphor layer is scanned with stimulating excitation light to emit radiation energy accumulated in each part as stimulating light, and an optical signal based on the intensity of the light is photoelectrically converted, for example, to perform image reproduction. The image is formed by This final image is played 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 has a radiation absorption rate and a light conversion rate (both of which are the same as in the case of the radiography method using a fluorescent screen described above). (Hereinafter referred to as “radiation sensitivity”), and the image must have good graininess and high sharpness.

By the way, it is well known that the sharpness of an image in the conventional radiographic method is determined by the spread of instantaneous light emission (light emission at the time of irradiation) of a phosphor in a fluorescent screen. The sharpness of an image in a radiation image conversion method using a stimulable phosphor is not determined by the spread of stimulable luminescence of the stimulable phosphor in the radiation image conversion panel, that is, as in radiography. Rather than being determined by the spread of the emission of the phosphor, it is determined by the spread of the stimulating excitation light within the panel. More specifically, in this radiation image conversion method, the radiation image information accumulated in the radiation image conversion panel is chronologically extracted and taken out, so that the stimulus by the stimulating excitation light irradiated at a certain time (t _i ) The luminescence is preferably recorded as an output from a pixel (x _i , y _i ) on the panel to which all light was collected and to which the stimulating excitation light was irradiated at that time. If the stimulable phosphor existing outside the illuminated pixel (x _i , y _i ) also excites due to scattering or the like in the inside and is excited, the pixel is output as an output from the illuminated pixel (x _i , y _i ) Output from a wider area is recorded. Therefore, the stimulating light emitted by the stimulating excitation light irradiated at a certain time (t _i ) is changed to the pixel (x _i , y) on the panel to which the stimulating excitation light is truly irradiated at the time (t _i ). The light emission from _i ) alone has no effect on the sharpness of the obtained image, regardless of the extent of the light emission.

Under such circumstances, some means for improving the sharpness of a radiographic image have been proposed.

For example, JP-A-62-133399 discloses that the radiation image conversion panel is formed by laminating a support, a light reflection layer, and a stimulable phosphor layer in this order, and the reflection surface of the light reflection layer is a metal surface. (Hereinafter referred to as “light reflecting metal layer”). According to this technology, since the stimulating excitation light does not pass through the light reflecting metal layer, there is no light scattering due to the light reflecting layer thickness as in the conventional light reflecting white pigment layer, and the support has The light does not penetrate through the support and is not scattered in the support, and the sharpness of the read image is not reduced.

[Problems to be solved by the invention]

However, in the technique disclosed in JP-A-62-133399, since the metal surface of the support, that is, the light-reflecting metal layer is in direct contact with the phosphor layer, the phosphor layer forming step or the subsequent step is performed. In the heat treatment step (annealing step) and in the course of time after formation, a chemical reaction occurs between the metal on the surface of the support and the phosphor layer, thereby deteriorating the phosphor layer, lowering the radiation sensitivity, A problem arises in that the light transmittance and reflectance characteristics of the layer fluctuate.

Accordingly, an object of the present invention is to provide a radiation image conversion panel having a structure capable of preventing deterioration of the metal surface of the support and the phosphor layer, and having both good radiation sensitivity and sharpness of an image.

[Means for solving the problem]

In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, by interposing a transparent thin film layer between a support having a metal surface and a phosphor layer, the metal surface of the support was The present inventors have found that the present invention can prevent the deterioration of the phosphor layer and have completed the present invention.

Therefore, the radiation image conversion panel of the present invention is a radiation image conversion panel comprising a support having a metal surface, a stimulable phosphor layer and a protective layer of the stimulable phosphor layer,
On the metal surface of the support, a transparent thin film layer having a light transmittance of 70% or more for light having a wavelength of 350 to 800 nm is provided, and a stimulable phosphor layer is provided on the transparent thin film layer. I do.

 Hereinafter, the present invention will be described specifically.

FIG. 1 shows an example of the radiation image conversion panel of the present invention, wherein 1 is a support, 2 is a transparent thin film layer, 3 is a stimulable phosphor layer, and 4 is a protective layer.

The support 1 includes a non-metallic substrate 1A and a metal layer 1B provided on one surface of the substrate 1A.
Constitute the metal surface of the support 1. This metal layer 1B
Has a function as a light reflection layer and a light shielding layer. The metal layer 1B may be formed by laminating separate layers each having the functions of a light reflection layer and a light shielding layer.

A transparent thin film layer 2 is provided on a metal layer 1B of a support 1,
The stimulable phosphor layer 3 is provided on the transparent thin film layer 2. That is, the transparent thin film layer 2 is provided between the metal layer 1B, which is the metal surface of the support 1, and the stimulable phosphor layer 3 to prevent contact between the two. Further, the protective layer 4 is provided on the stimulable phosphor layer 3 with a gap 4A interposed therebetween.
Dried nitrogen gas or the like is sealed in the gap 4A.

FIG. 2 shows another example of the radiation image conversion panel of the present invention, in which a transparent thin film layer 2 and a
A stimulable phosphor layer 3 and a protective layer 4 are provided. That is, in this example, the function of the metal layer 1B shown in FIG. 1 is provided in the metal support 1 'itself.

The transparent thin film layer 2 needs to be transparent and a thin film in order to prevent light scattering. Specifically, the transparent thin film layer 2
Has a light transmittance of 70% or more for light having a wavelength of 350 to 800 nm. Further, when a colored layer is provided on the incident side of the stimulating excitation light with respect to the metal surface of the support 1 described later, the wavelength 35
The light transmittance for light of 0 to 800 nm is preferably 80% or more. The thickness of the transparent thin film layer 2 is 10 to ³ × 10 ⁵ Å
Is preferred, and in the case of an inorganic compound, it is preferably 10 ³ to 10 ⁴ 、, and in the case of an organic compound, it is preferably 10 ⁴ to 10 ⁵ Å.

Further, the transparent thin film layer 2 needs to be chemically stable so as not to deteriorate the metal surfaces of the supports 1, 1 'and the stimulable phosphor layer 3.

Therefore, the constituent materials of the transparent thin film layer 2 include oxides,
Preferred are nitrides, fluorides, carbides, polymers, gelatin and the like. Specifically, oxides such as SiO ₂ , Al ₂ O ₃ and TiO ₂ , fluorides such as MgF ₂ and CaF ₂ , carbides such as SiC, S
Preferred are nitrides such as iN, polymers such as PET and vinyl alcohol films, and gelatin.

The means for forming the transparent thin film layer 2 is not particularly limited.
Various thin film forming methods can be used. Specific examples include a vacuum deposition method, a sputtering method, an ion plating method, and a coating method.

The metal layer 1B in FIG. 1 functions as a light reflecting layer and a light shielding layer, and has a different optical density at an interface with an adjacent layer, that is, a different reflectivity and a metal surface. is necessary.

This metal layer 1B may be formed by an evaporation method, a sputtering method, an ion plating method, a plating method,
It may be formed by laminating a metal foil. In particular, according to a vapor deposition method such as a vapor deposition method, the formation of the metal layer 1B is easy, and the light reflection layer 1B is easily formed regardless of the shape of the unevenness of the surface of the nonmetallic substrate 1A or the like. be able to.

As a metal constituting the metal layer 1B, aluminum,
Gold, silver, copper, chromium, nickel, platinum, rhodium, tin and the like can be mentioned.

The thickness of the metal layer 1B is preferably 0.01 to 50 μm, and preferably has an average reflectance of 50% or more, particularly 70% or more with respect to light in the photostimulated emission wavelength region. This average reflectance is
It can be measured by an integrating sphere spectrophotometer.

Further, the metal layer 1B preferably has a transmittance of 1% or less for light having a wavelength of 350 to 800 nm.

FIG. 1 shows an example in which a non-metallic substrate 1A is used. As the non-metallic material, glass, ceramics, various polymer materials, or the like can be used. Specifically, quartz glass, glass such as chemically strengthened glass, crystallized glass, ceramics such as a sintered plate of alumina or zirconia, or cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film And a plastic film such as a polycarbonate film.

FIG. 2 shows an example in which a metal support 1 'is used. As the metal support 1', a metal sheet made of aluminum, aluminum-magnesium alloy, iron, stainless steel, copper, chromium, lead or the like is used. Can be used.

The thickness of the substrate 1A or the support 1 'varies depending on the material and the like, but is generally preferably 100 μm to 5 mm, and particularly preferably 200 μm to 2 mm from the viewpoint of easy handling.

The stimulable phosphor layer 3 is formed by a vapor deposition method such as a vacuum evaporation method (hereinafter, simply referred to as an “evaporation method”), a sputtering method, a CVD method, an ion plating method, or a stimulable phosphor or dispersion. It is preferable to form the phosphor coating prepared by suspending and dissolving an agent or the like in a binder solution and coating the phosphor coating in a single layer or in multiple layers according to performance.

When the stimulable phosphor layer is formed by a vapor deposition method, a support having a metal surface is placed in a vapor deposition apparatus, and then the inside of the vapor deposition apparatus is evacuated to a degree of vacuum of about 10 ⁻⁶ Torr. Next, at least one kind of the stimulable phosphor is heated and evaporated by a method such as a resistance heating method or an electron beam method to deposit the stimulable phosphor to a predetermined thickness on the metal surface of the support.

As a result, the stimulable phosphor layer 3 containing no binder was used.
Is formed, but it is also possible to form the stimulable phosphor layer a plurality of times in the vapor deposition step. In the evaporation step, co-evaporation can be performed using a plurality of resistance heaters or electron beams.

After the vapor deposition, a radiation image conversion panel of the present invention is manufactured by providing a protective layer directly or via a gap on the surface of the stimulable phosphor layer opposite to the support side, if necessary. When the stimulable phosphor layer is provided directly on the protective layer, a procedure may be adopted in which the stimulable phosphor layer is formed on the protective layer and then provided on the support.

In the vapor deposition method, the stimulable phosphor raw material is co-evaporated using a plurality of resistance heaters or electron beams to synthesize the desired stimulable phosphor on the metal surface of the support, and at the same time to stimulate the stimulable phosphor. It is also possible to form a luminescent phosphor layer.

Further, in the vapor deposition method, at the time of vapor deposition, an object to be deposited (a support or a protective layer) may be cooled or heated as necessary. Further, the stimulable phosphor layer may be subjected to a heat treatment (annealing) after the deposition. In addition, in the vapor deposition method, reactive vapor deposition may be performed by introducing a gas such as O ₂ and H ₂ as necessary.

When forming the stimulable phosphor layer by the sputtering method, after arranging the support having a metal surface in the sputtering apparatus in the same manner as in the vapor deposition method, the inside of the apparatus is once evacuated.
The degree of vacuum is set to about 10 ⁻⁶ Torr, and then an inert gas such as Ar or Ne is introduced into the sputtering apparatus as a gas for sputtering, so that the gas pressure is set to about 10 ⁻³ Torr.

Next, a stimulable phosphor layer is deposited to a predetermined thickness on the metal surface of the support by sputtering using the stimulable phosphor as a target.

In this sputtering step, it is also possible to form the stimulable phosphor layer in a plurality of times as in the case of the vapor deposition method.
Further, it is also possible to form a stimulable phosphor layer by simultaneously or sequentially sputtering a plurality of targets each using a different stimulable phosphor.

After the sputtering is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer directly or through a gap on the side opposite to the support side of the stimulable phosphor layer as necessary similarly to the vapor deposition method. Is done. In the case where the stimulable phosphor layer is provided directly on the protective layer, a procedure of forming the stimulable phosphor layer on the protective layer and then providing a support may be employed.

In the sputtering method, a plurality of stimulable phosphor raw materials are used as a target, and these are simultaneously or sequentially sputtered to synthesize a desired stimulable phosphor on a metal surface of a support, and at the same time, a stimulable phosphor is used. It is also possible to form a phosphor layer. In the sputtering method, reactive sputtering may be performed by introducing a gas such as O ₂ or H ₂ as necessary.

Further, in the sputtering method, an object to be deposited (a support or a protective layer) may be cooled or heated as needed during sputtering. After the sputtering, the stimulable phosphor layer may be subjected to a heat treatment.

In the step of forming the stimulable phosphor layer 3 by the vapor deposition method, the deposition rate of the stimulable phosphor layer is preferably 0.1 to 50 μm / min. If the deposition rate is too low, the productivity will be low, and if the deposition rate is too high, it will be difficult to control the deposition rate.

In the step of forming the stimulable phosphor layer 3 by the vapor deposition method, the temperature of the support 1 is preferably 400 ° C. or lower. If the temperature is too high, the sharpness of the image tends to decrease due to the progress of crystallization.

When a panel is manufactured by a vapor deposition method, the effect of the present invention is great because the phosphor directly contacts the metal.

When the stimulable phosphor layer is formed by a coating method, examples of the binder used include proteins such as gelatin, polysaccharides such as dextran or gum arabic, polyvinyl butyral, polyvinyl acetate, nitrocellulose, ethyl cellulose, and vinylidene chloride. Binders which are usually used for layer constitution such as vinyl chloride copolymer, polymethyl methacrylate, vinyl chloride-vinyl acetate copolymer, polyurethane, cellulose acetate butyrate, polyvinyl alcohol and the like are used. Generally, the binder is used in an amount of 0.01 to 1 part by weight based on 1 part by weight of the stimulable phosphor. However, from the standpoint of sensitivity and sharpness of the obtained radiation image conversion panel, it is preferable that the amount of the binder is small, and the range of 0.03 to 0.2 part by weight is more preferable in consideration of the ease of application.

The preparation of the stimulable phosphor coating 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 material is applied on a support using a doctor blade, a roll coater, a knife coater, or the like, and dried to form a stimulable phosphor layer.
The stimulable phosphor layer may be adhered to the support after the paint is applied on the protective layer and dried.

In addition, in the stimulable phosphor layer paint, for the purpose of improving the dispersibility of the stimulable phosphor layer phosphor particles, stearic acid,
A dispersant such as phthalic acid, caproic acid, or a lipophilic surfactant may be mixed. If necessary, a plasticizer for the binder may be added.

Examples of the plasticizer include phthalic acid esters such as diethyl phthalate and dibutyl phthalate; phosphoric acid esters such as tricresyl phosphate and triphenyl phosphate; and aliphatic dibasic acid esters such as diisodecyl succinate and dioctyl adipate. And glycolic acid esters such as ethylphthalylethyl glycolate and butylphthalylbutyl glycolate.

Examples of the solvent used for preparing the paint in which the stimulable phosphor is suspended include methanol, ethanol, isopropanol, lower alcohols such as n-butanol, acetone,
Ketones such as methyl ethyl ketone, methyl isobutyl ketone and 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; triols and xylols And halogenated hydrocarbons such as methylene chloride and ethylene chloride, and mixtures thereof.

In any case of the vapor deposition method and the coating method, the thickness of the stimulable phosphor layer 3 varies depending on the radiation sensitivity of the intended radiation image conversion panel, the type of the stimulable phosphor, and the like. To 1000 μm, and particularly preferably 50 to 500 μm. When the thickness of the stimulable phosphor layer 3 is too small, the radiation absorptivity is reduced and the radiation sensitivity is deteriorated.

The protective layer 4 is provided to protect the stimulable phosphor layer 3 physically or chemically. The protective layer 4 may be provided with a gap 4A as shown in FIG. 1 or FIG. 2, or may be formed by directly applying a coating liquid for the protective layer on the stimulable phosphor layer. Good. Further, a protective layer separately formed in advance may be bonded onto the stimulable phosphor layer.

When the protective layer 4 is provided with the gap 4A interposed therebetween, as a constituent material of the protective layer, a material having good translucency and capable of being formed into a sheet is used. The protective layer desirably exhibits 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 preferably 80% or more.

Examples of such a material include plate glass such as quartz, borosilicate glass, and chemically strengthened glass, and organic polymer compounds such as PET, drawn polypropylene, and polyvinyl chloride. Borosilicate glass shows a light transmittance of 80% or more in a wavelength range of 330 nm to 2.6 μm, and quartz glass shows a high light transmittance even at a shorter wavelength.

Further, it is preferable to provide an anti-reflection layer such as MgF _{2 on} the surface of the protective layer 4 because it has the effects of efficiently transmitting stimulated excitation light and stimulated emission and reducing a decrease in sharpness.

When the protective layer 4 is provided directly on the stimulable phosphor layer 3, the constituent materials of the protective layer include cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate,
Polyester, polyethylene terephthalate, polyethylene, vinylidene chloride, nylon and the like can be used. The protective layer 4 may be formed by laminating inorganic substances such as SiC, SiO ₂ , SiN, and Al ₂ O ₃ by a vapor deposition method, a sputtering method, or the like. In this case, the thickness of the protective layer 4 is 0.1 to 100 μm when the protective layer is provided directly on the phosphor layer.
m is preferable, and when the space 4A is provided, it is 50 μm to 5 mm, preferably 100 μm to 3 mm.

The thickness of the protective layer 4 is 50 μm to 5 mm, and preferably 100 μm to 3 mm in order to obtain good moisture proofness.

In the radiation image conversion panel of the present invention, in order to further enhance the sharpness of the image, a colored layer may be provided on the incident side of the stimulating excitation light with respect to the metal surface of the support 1.

This colored layer may be provided over the entire stimulable phosphor layer 3 or may be provided on the surface layer of the stimulable phosphor layer 3 and the support 1.
May be provided on any one of the layer portion adjacent to the metal surface and the protective layer 4. Further, it may be provided in two or more layers. Also,
The transparent thin film layer according to the present invention may be colored.

The colored layer has a function of absorbing at least a part of the stimulating excitation light for causing the stimulable phosphor to emit stimulating light, and has an average reflectance to light in the stimulating excitation light wavelength region. It is preferable to have a light absorption characteristic that is smaller than the average reflectance for light in the emission wavelength region.

As the colorant, an organic or inorganic colorant can be used, and a blue or green colorant is preferable in terms of hue.

In the present invention, "stimulable phosphor" means, after being irradiated with the first light or high-energy radiation, optically, thermally,
Phosphor that emits photostimulated light corresponding to the amount of initial light or high-energy radiation when stimulated by mechanical, chemical, or electrical stimulation (stimulated excitation). Is preferably a phosphor that emits photostimulated light by photostimulated excitation light of 500 nm or more.

The following can be used as the stimulable phosphor constituting the stimulable phosphor layer.

(1) BaSO described in JP 48-80487 discloses _4: A _x (however, A is represented Dy, Tb, at least one Tm, x is 0.00
It represents a number satisfying 1 ≦ x <1 mol%. The phosphor represented by).

(2) SrSO described in JP 48-80489 discloses _4: A _x (however, A is represented Dy, Tb, at least one Tm, x is 0.00
It represents a number satisfying 1 ≦ x <1 mol%. The phosphor represented by).

(3) Na ₂ SO ₄ according to JP 51-29889 discloses, CaSO _4, Ba
A phosphor obtained by adding at least one of Mn, Dy, and Tb to SO ₄ or the like.

(4) BeO, LiF, MgSO ₄ , C described in JP-A-52-30487
phosphor such as aF _2.

(5) Phosphors such as Li ₂ B ₄ O ₇ : Cu and Ag described in JP-A-53-39277.

(6) Li ₂ O · described in JP 54-47883 JP (B
₂ O ₂ ) _x : Cu (where x represents a number satisfying 2 <x ≦ 3), Li ₂ O · (B ₂ O ₂ ) _x : Cu, Ag (where x is 2 <x
Represents a number satisfying ≦ 3. ) And other phosphors.

(7) SrS: Ce, S described in U.S. Pat. No. 3,859,527
m, SrS: Eu, Sm, La ₂ O ₂ S: Eu, Sm, (Zn, Cd) S: Mn, X (where X represents a halogen).

(8) ZnS: Cu, Pb phosphor described in JP-A-55-12142.

(9) The general formula described in JP-A-55-12142 is BaO.xAl
_A barium aluminate phosphor represented by ₂ O ₃ : Eu (where x represents a number satisfying 0.8 ≦ x ≦ 10).

(10) The general formula described in JP- _A -55-12142 is represented by M _A O.xSiO ₂ :
A (however, M _A represents Mg, Ca, Sr, Zn, Cd, and Ba, A is C
represents at least one of e, Tb, Eu, Tm, Pb, Tl, Bi, and Mu, and x
Represents a number satisfying 0.5 ≦ x <2.5. The alkaline earth metal silicate-based phosphor represented by).

(11) The general formula described in JP-A-55-12142 (Ba _1-xy Mg
_x Ca _y ) FX: eEu ²⁺ (where X is at least one of Br and Cl)
X, y, and e represent 0 <x + y ≦ 0.6 and xy そ れ ぞ れ, respectively.
0, a number that satisfies 10 ⁻⁶ ≦ e ≦ 5 × 10 ⁻² . The phosphor represented by).

(12) The general formula described in JP-A-55-12142 is LnOX: xA (where Ln represents at least one of La, Y, Gd, and Lu;
Represents at least one kind of Cl and Br, A represents at least one kind of Ce and Tb, and x represents a number satisfying 0 <x <0.1. The phosphor represented by).

(13) The general formula described in JP-A-55-12145 is (Ba _1-x
(M _A ) _x ) FX: yA (where M _A represents at least one of Mg, Ca, Sr, Zn, Cd, X represents at least one of Cl, Br, I, and A is Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, represents at least one kind of Er, x, y are 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.2
Represents a number that satisfies The phosphor represented by).

(14) The general formula described in JP-A-55-84389 is BaFX: xC
e, yA (where X represents at least one kind of Cl, Br, I, A represents at least one kind of In, Tl, Gd, Sm, Zr, x,
y represents a number satisfying 0 <x ≦ 2 × 10 ⁻¹ and 0 <y ≦ 5 × 10 ⁻² . The phosphor represented by).

(15) In formula described in JP 55-160078 Patent Publication No. · M _A FX
xA: yLn (where, M _A represents at least one of Mg, Ca, Ba, Sr, Zn, and Cd, and A is BeO, MgO, CaO, SrO, BaO, ZnO, Al ₂ O ₃ ,
Y ₂ O ₃ , La ₂ O ₃ , In ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta
₂ O _5, represents at least one of ThO _2, Ln is, Eu, Tb, Ce, Tm ,
X represents at least one of Dy, Pr, Ho, Nd, Yb, Er, Sm, and Gd;
Represents at least one of Cl, Br and I, and x and y represent 5 × 10 ⁻⁵
It represents a number that satisfies ≦ x ≦ 0.5 and 0 <y ≦ 0.2. A) a rare earth element-activated divalent metal fluorohalide phosphor represented by the formula:

(16) The general formula described in JP-A-55-160078 is ZnS: A, (Z
n, Cd) S: A, CdS: A, ZnS: A, X, CdS: A, X (where A is
Represents any of Cu, Ag, Au and Mn, and X represents halogen. The phosphor represented by).

(17) General formula [I] xM ₃ (PO ₄ ) ₂ · NX ₂ : yA described in JP-A-59-38278. General formula [II] M ₃ (PO ₄ ) ₂ · yA (wherein M , N represents at least one of Mg, Ca, Sr, Ba, Zn, and Cd, X represents at least one of F, Cl, Br, and I, and A represents Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sb, Tl, M
represents at least one of n and Sn, and x and y are 0 <x ≦ 6, 0
Represents a number satisfying ≦ y ≦ 1. The phosphor represented by).

(18) General formula [III] nReX ₃ · mAX ′ ₂ : xEu described in JP-A-59-155487 General formula [IV] nReX ₃ · mAX ′ ₂ : xEu, ySm (where Re is La , Gd, Y, Lu
Represents at least one alkaline earth metal of Ba, Sr, Ca, X, X 'represents at least one of F, Cl, Br, x, y
Is 1 × 10 ⁻⁴ <x <3 × 10 ⁻¹ , 1 × 10 ⁻⁴ <y <1 × 10 ⁻¹
And n / m represents a number satisfying 1 × 10 ⁻³ <n / m <7 × 10 ⁻¹ . The phosphor represented by).

(19) General formula aBaX ₂ · (1-a) BaY ₂ : bEu ²⁺ described in JP-A-2-58593 (wherein X and Y are at least one of F, Cl, Br and I, respectively) Represents a seed, X ≠ Y, and a and b are 0 <a <1, 10 ⁻⁵ <b
Represents a number satisfying <10 ^-1 . The phosphor represented by).

(20) The general formula described in Japanese Patent Application Laid-Open No. 61-72087, M _A X • a M _B X ′ ₂ • bM _C X ″ ₃ : cA (where M _A is Li, Na, K, Rb, Cs represents at least one alkali metal, M _B is, Be, Mg, Ca, Sr , Ba, Zn, Cd, Cu, Ni
Of represents at least one divalent metal, M _C is, Sc, Y, La,
Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In
X, X ′, X ″ represents at least one trivalent metal of
Represents at least one halogen of F, Cl, Br, I;
u, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, C
u, represents at least one metal of Mg, a, b, c is 0 ≦ a
<0.5, 0 ≦ b <0.5, and 0 <c ≦ 0.2. An alkali halide phosphor represented by).

In the present invention, this alkali halide phosphor can be particularly preferably used because it is suitable for a vapor deposition method.

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.

FIG. 3 schematically shows a radiation image conversion apparatus configured using the radiation image conversion panel of the present invention, 5 is a radiation generator, 6 is a subject, 7 is a radiation image conversion panel, 8 is a stimulating excitation light source, Reference numeral 9 denotes a photoelectric conversion device that detects stimulated emission emitted from the radiation image conversion panel 7, reference numeral 10 denotes a reproduction device that reproduces a signal detected by the photoelectric conversion device 9 as an image,
Reference numeral 11 denotes a display device for displaying an image reproduced by the reproducing device 10, and reference numeral 12 denotes a filter that separates stimulated excitation light and stimulated emission and transmits only the stimulated emission.

In the radiation image conversion apparatus shown in FIG. 3, the radiation R from the radiation generation apparatus 5 enters the radiation image conversion panel 7 through the subject 6. The incident radiation RI is absorbed by the stimulable phosphor layer 3 of the radiation image conversion panel 7, and its energy is accumulated, thereby forming an accumulated radiation transmission image. Next, this accumulated image is excited by stimulating light from the stimulating light source 8 and emitted as stimulating light.

Since the intensity of the emitted photostimulated luminescence is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 9 such as a photomultiplier tube, and reproduced as an image by a reproduction device 10, By displaying the image on the display device 11, a radiation transmission image of the subject 6 can be observed.

〔Example〕

Hereinafter, examples of the present invention will be described together with comparative examples, but the present invention is not limited to these embodiments.

Example 1 A metal layer made of a 2000-mm-thick aluminum vapor-deposited film was formed on a substrate made of a crystallized glass plate having a thickness of 1.0 mm by a vapor deposition method to obtain a support having a metal surface. .

On the metal surface of this support, a thickness of 20
A transparent thin film layer composed of a vapor-deposited SiO ₂ film (light transmittance at 350 to 800 nm (hereinafter simply referred to as “light transmittance”) of 90% or more) was formed.

For measuring the light transmittance of the transparent thin film layer, only a transparent thin film layer having a predetermined thickness is formed on a transparent quartz glass plate (1.0 mm thick) for transmittance measurement, and the transparent quartz glass plate (1.0 m thick) is formed.
m) as a reference sample and a spectrophotometer (Hitachi type 557)
Was used in the range of 190 to 900 nm. Further, the measurement of the light transmittance of the protective layer was similarly performed using a spectrophotometer.

The support provided with the transparent thin film layer was placed in an evaporation apparatus, the temperature of the support was set to 200 ° C, and the degree of vacuum in the evaporation apparatus was set to 10 ° C.
^-6 Torr, vapor deposition was performed under the condition that the deposition rate of the vapor deposition material on the transparent thin film layer was 5 μm / min, and the thickness was 300 μm.
Of a stimulable phosphor (RbBr: Tl) was formed on the transparent thin film layer.

Next, in order to enhance the crystallinity of the stimulable phosphor layer,
Annealing was performed at 400 ° C.

On the stimulable phosphor layer after the annealing, a protective layer of a glass sealing type was provided through a gap to obtain a radiation image conversion panel A of the present invention having a configuration shown in FIG. In addition,
The voids were filled with dry nitrogen gas.

[Example 2] In Example 1, the transparent thin film layer was formed of Mg having a thickness of 2000 mm.
Transparent thin film layer made of a deposited film of F ₂ (light transmittance: 90%)
The radiation image conversion panel B of the present invention was obtained in the same manner except that the above was changed.

[Example 3] In Example 1, the metal layer was made of chrome having a thickness of 2000.
蒸 着, except that the thickness of the transparent thin film layer was changed to 3000 Å.
I got

Example 4 In Example 1, the metal layer was made of chromium and had a thickness of 2000.
Change to a 蒸 着 deposited film and replace the transparent thin film layer with a 3000 Å thick Zr
A radiation image conversion panel D of the present invention was obtained in the same manner except that the transparent thin film layer was composed of a two-layer structure of a vapor deposition film of O and a vapor deposition film of SiO ₂ having a thickness of 1000 °.

[Example 5] In Example 1, the transparent thin film layer was replaced with a 2000-mm thick Si film.
A radiation image conversion panel E of the present invention was obtained in the same manner except that the transparent thin film layer (light transmittance: 80% or more) composed of a vapor deposition film of N was used.

Example 6 A radiation image conversion panel F of the present invention was obtained in the same manner as in Example 1, except that the support was changed to a support made of an aluminum plate having a thickness of 0.3 mm.

[Example 7] In Example 6, the transparent thin film layer was formed using Mg having a thickness of 2000 mm.
Transparent thin film layer made of a deposited film of F ₂ (light transmittance: 90%)
A radiation image conversion panel G of the invention was obtained in the same manner except that the above was changed.

[Example 8] In Example 6, the transparent thin film layer was replaced with a 2000 mm thick Si film.
A radiation image conversion panel H of the present invention was obtained in the same manner except that the transparent thin film layer (light transmittance: 90% or more) composed of a vapor deposition film of C was used.

Example 9 8 parts by weight of a RbBr: Tl stimulable phosphor having an average particle diameter of 8.5 μm and 1 part by weight of a polyvinyl butyral resin were mixed and dispersed by using 8 parts by weight of a solvent (cyclohexanone), and the mixture was stimulated. A coating solution for a luminescent phosphor layer was prepared.

Next, on a surface plate placed horizontally, the thickness is
A metal layer consisting of a deposited film of aluminum of 2000 mm is formed, and a crystallized glass of 1.0 mm thickness is further formed as a support by forming a transparent thin film layer of a deposited film of 2000 mm of SiO _{2 by} a vapor deposition method. A frame for stopping the flow of the coating solution was provided on the four peripheral edges of the support.

The coating solution was cast on the protective layer, and allowed to stand at 25 ° C. for 24 hours to precipitate and separate stimulable phosphor particles, thereby forming a stimulable phosphor layer. Thereafter, the stimulable phosphor layer was further dried, a glass sealing type protective layer was provided with a gap formed thereon to obtain a radiation image conversion panel I of the present invention having a structure shown in FIG. .

The thickness of the stimulable phosphor layer of the radiation image conversion panel I is 300 μm.

Example 10 8 parts by weight of a BaFBr: Eu stimulable phosphor having an average particle diameter of 8.5 μm and 1 part by weight of a polyvinyl butyral resin were mixed and dispersed by using 8 parts by weight of a solvent (cyclohexanone), and the resulting mixture was stimulated. A coating solution for a luminescent phosphor layer was prepared.

Next, a separately formed thickness of 5 on the surface plate placed horizontally.
A polyethylene film having a thickness of μm was placed as a protective layer, and a frame for stopping the flow of the coating solution was provided around the four edges of the protective layer.

The coating solution was cast on the protective layer, and allowed to stand at 25 ° C. for 24 hours to precipitate and separate stimulable phosphor particles, thereby forming a stimulable phosphor layer. Thereafter, the stimulable phosphor layer is further dried, and as a support, a metal layer made of an aluminum evaporated film having a thickness of 2000 mm is formed thereon by a vapor deposition method. A 200 μm-thick polyethylene terephthalate film kneaded with carbon black having a transparent thin film layer formed of an SiO ₂ vapor-deposited film was adhered to obtain a radiation image conversion panel J of the present invention.

The thickness of the stimulable phosphor layer of the radiation image conversion panel J is 300 μm.

Comparative Examples 1 to 10 Radiation image conversion panels a to j for comparison were obtained in the same manner as in Examples 1 to 10, except that the transparent thin film layer was not provided.

[Evaluation]

The radiation image conversion panels A to J according to the present invention obtained as described above and the radiation image conversion panels a to j for comparison are obtained.
Each was used to produce a radiation image conversion apparatus having the configuration shown in FIG. 3, and a test for actually forming an image was conducted, and radiation sensitivity and image sharpness were examined.

Further, each of the radiation image conversion panels A to J and a to j was left for 60 days under the condition of a temperature of 45 ° C. and a relative humidity of 85% to forcibly perform a time-dependent acceleration test. Radiation sensitivity and image sharpness were examined.

 The results are shown in Tables 1 and 2 below.

The radiation sensitivity and sharpness in Tables 1 and 2 are the same as those obtained in Examples 1 and 9, respectively.
This is a relative value when 00 is set. The radiation sensitivity is a light emission amount when excited by a semiconductor laser beam after X-ray irradiation.
The sharpness was evaluated by examining the modulation transfer function (MTF). However, the values are based on the sum of the resolutions (%) when the spatial frequency is 0.5, 1.0, 2.0 cycles / mm.

As is clear from Tables 1 and 2, according to the radiation image conversion panels A to J according to the present invention, good results can be obtained in both radiation sensitivity and sharpness.

Such good results can be obtained because, in the radiation image conversion panel of the present invention, a transparent thin film layer exists between the metal surface of the support and the stimulable phosphor layer, and the contact between the two is reduced. This is because the metal surface of the support and the stimulable phosphor layer are in a chemically extremely stable state even during deposition (at a temperature of 200 ° C.) and during annealing (at a temperature of 400 ° C.). it is conceivable that.

However, the radiation image conversion panels a to j for comparison are inferior to the radiation image conversion panels A to J of the present invention in radiation sensitivity and / or sharpness. This is because, in the comparative radiation image conversion panel, the transparent thin film layer is not provided, so that the metal surface of the support undergoes a chemical reaction with the stimulable phosphor of the stimulable phosphor layer in the annealing step to corrode. Therefore, it is considered that radiation sensitivity and image sharpness are inferior.

〔The invention's effect〕

As described above in detail, according to the radiation image conversion panel of the present invention, the light transmittance for light having a wavelength of 350 to 800 nm between the metal surface of the support and the stimulable phosphor layer is 70% or more. Since the transparent thin film layer is provided, the metal surface of the support is not corroded by the stimulable phosphor of the stimulable phosphor layer, and is physically and chemically stable for a long period of time. Radiation sensitivity and image sharpness are good from the beginning, and these good properties are stably exhibited over a long period of time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one example of the radiation image conversion panel of the present invention, FIG. 2 is a cross-sectional view showing another example of the radiation image conversion panel of the present invention, and FIG. FIG. DESCRIPTION OF SYMBOLS 1 ... Support, 1A ... Non-metallic substrate 1B ... Metal layer, 1 '... Metal support 2 ... Transparent thin film layer, 3 ... Stimulable phosphor layer 4 ... Protective layer 5, a radiation generating device 6, a subject 7, a radiation image conversion panel 8, a stimulating excitation light source, 9, a photoelectric conversion device 10, a reproducing device, 11, a display device 12, a filter

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G21K 4/00

Claims (1)

(57) [Claims] 1. A radiation image conversion panel comprising a support having a metal surface, a stimulable phosphor layer, and a protective layer for the stimulable phosphor layer, wherein: A radiation image conversion panel comprising: a transparent thin film layer having a light transmittance of 70% or more for light having a wavelength of 350 to 800 nm; and a stimulable phosphor layer provided on the transparent thin film layer.