JP2003028996A - Manufacturing method for radiation image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a radiation image conversion panel, giving high sensitivity and radiation image of high image quality. SOLUTION: After forming a layer, consisting of a ground substance of phosphor by gas-phase deposition, dispersion liquid or solution containing an activator agent composition of phosphor is spread over the phosphor ground layer. Then, by thermally treating the phosphor ground layer, the activator agent composition is penetrated and diffused in the phosphor ground layer; and then by thermally treating the phosphor ground layer, a phosphor layer is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a radiation image conversion panel used in a radiation image recording / reproducing method using a stimulable phosphor.

[0002]

2. Description of the Related Art When radiation such as X-rays is irradiated, a part of the radiation energy is absorbed and accumulated, and then, when irradiated with electromagnetic waves (excitation light) such as visible light and infrared rays, the accumulated radiation energy is changed. A stimulable phosphor having a property of emitting light (such as a stimulable phosphor exhibiting stimulated luminescence) is used to apply a test object to a sheet-shaped radiation image conversion panel containing the stimulable phosphor. After the radiation image information of the subject is once stored and recorded by irradiating the transmitted or emitted radiation from the subject, the panel is scanned with excitation light such as laser light and sequentially emitted as emitted light, and the emitted light is emitted. A radiation image recording / reproducing method, which consists of photoelectrically reading and obtaining an image signal, has been widely put into practical use. The panel that has finished reading is erased of the remaining radiation energy, and then prepared and used repeatedly for the next imaging.

A radiation image conversion panel (also referred to as a stimulable phosphor sheet) used in a radiation image recording / reproducing method has, as a basic structure, a support and a stimulable phosphor layer provided thereon. . However, when the stimulable phosphor layer is self-supporting, a support is not always necessary. A protective layer is usually provided on the upper surface of the stimulable phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact. There is.

The stimulable phosphor layer usually comprises a stimulable phosphor and a binder containing and supporting the stimulable phosphor in a dispersed state. However, those that are composed only of aggregates of stimulable phosphors that do not contain a binder formed by vapor deposition or sintering,
It is also known that a polymer substance is impregnated in the gaps between the aggregates of the stimulable phosphor.

The radiation image recording / reproducing method (and the radiation image forming method) has a number of excellent advantages as described above, but the radiation image conversion panel used in this method has the highest sensitivity possible. It is desired to provide an image having good image quality (sharpness, graininess, etc.).

For the purpose of enhancing sensitivity and image quality, there is a method for producing a radiation image conversion panel by forming a phosphor layer by a vapor deposition method as described in, for example, Japanese Patent Publication No. 6-77079. Proposed. Vapor deposition methods include vapor deposition methods and sputtering methods. For example, the vapor deposition method heats an evaporation source made of a phosphor or its raw material by irradiation of a resistance heater or an electron beam to evaporate and scatter the evaporation source, By depositing the evaporation product on the surface of a substrate such as a metal sheet, a phosphor layer made of columnar crystals of the phosphor is formed.

The phosphor layer formed by the vapor deposition method is
It does not contain a binder and is composed only of the phosphor, and there are voids (cracks) between the columnar crystals of the phosphor.
Therefore, it is possible to improve the entrance efficiency of the excitation light and the extraction efficiency of the emitted light, so that the sensitivity is high, and since it is possible to prevent the excitation light from being scattered in the plane direction, it is possible to obtain an image with high sharpness. . However, in the above vapor deposition method or the like, a substance having a high vapor pressure in the evaporation source tends to preferentially evaporate (for example, the matrix of the phosphor evaporates prior to the activator), There is a problem that it is difficult to match the composition of the charged phosphor with the composition of the phosphor in the formed phosphor layer.

For the purpose of making the activator concentration of the phosphor uniform in the thickness direction of the phosphor layer, JP-B-6-54360.
The publication discloses a method of forming a stimulable phosphor layer by forming an stimulable phosphor matrix layer and then adding and diffusing an activator to the phosphor matrix layer. Specifically, a method in which a phosphor base layer and an activator layer are separately formed by a vapor deposition method such as a resistance heating method, and then heat treatment is performed to thermally diffuse the activator into the phosphor base layer. , And after forming a phosphor base layer by a vapor deposition method, an activator is added to the phosphor base layer by diffusion of an activator gas or atmosphere powder or by injecting activator ions, followed by heat treatment. The method is described. However, in these methods, the activator does not actually diffuse sufficiently in the thickness direction of the phosphor base layer, and it is difficult to obtain a phosphor layer having a uniform activator concentration.

[0009]

The present inventor has studied the formation of a phosphor layer by a vapor deposition method, and as a result, depending on the type of activator (for example, Eu), an activator may be used. It was found that when the activated phosphor or its raw material mixture is directly vapor-deposited by vapor deposition or the like, the shape of the columnar crystal is deteriorated due to the presence of the activator.

Therefore, after forming a phosphor base layer composed of columnar crystals by a vapor deposition method, an activator dispersion liquid (or solution) is applied onto the base layer to form the activator dispersion liquid into columnar crystals. A phosphor having a uniform activator concentration without impairing the shape of the columnar crystals is obtained by infiltrating the voids between the columnar crystals and then heat treating the base layer to thermally diffuse the activator into the base layer. The inventors have found that a layer can be obtained and have reached the present invention.

Therefore, the present invention is to provide a method of manufacturing a radiation image conversion panel having a phosphor layer having a good shape and comprising columnar crystals having a uniform phosphor composition. That is, the present invention is to provide a method of manufacturing a radiation image conversion panel that provides a radiation image with high sensitivity and high image quality.

[0012]

The present invention is a method of manufacturing a radiation image conversion panel having a phosphor layer, which comprises forming a layer composed of a matrix of the phosphor by a vapor deposition method and then forming the phosphor layer. A dispersion or a solution containing an activator component is applied onto the phosphor base layer, and then the phosphor base layer is heat-treated to permeate and diffuse the activator component into the phosphor base layer to form a phosphor. A method of manufacturing a radiation image storage panel, the method including the step of forming a layer.

The present invention also resides in a radiation image conversion panel manufactured by the above method.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of the present invention, it is preferable to form a vapor-deposited film composed of a phosphor matrix by an electron beam vapor deposition method. The heat treatment of the phosphor base layer is performed at 50 ° C. to 600 ° C.
It is preferable to carry out at a temperature in the range of 100 ° C, particularly 100 ° C to 300 ° C. The phosphor is preferably a stimulable phosphor, and particularly preferably an alkali metal halide stimulable phosphor having the following basic composition formula (I). In the following basic composition formula (I), A is preferably Eu.

[0015]

[Chemical formula 1] M ^I X · aM ^II X ′ ₂ · bM ^III X ″ ₃ : zA (I)

[Wherein M ^I represents at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs; M ^II represents Be, Mg, Ca, Sr, Ba, N
represents at least one alkaline earth metal or divalent metal selected from the group consisting of i, Cu, Zn and Cd; M
^III is Sc, Y, La, Ce, Pr, Nd, Pm, S
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
represents at least one rare earth element or trivalent metal selected from the group consisting of b, Lu, Al, Ga and In; X,
X ′ and X ″ each represent at least one halogen selected from the group consisting of F, Cl, Br and I; A
Is Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, D
y, Ho, Er, Tm, Yb, Lu, Na, Mg, C
represents at least one rare earth element or metal selected from the group consisting of u, Ag, Tl, and Bi; and a, b, and z are 0 ≦ a <0.5, 0 ≦ b <0.5, 0, respectively.
Represents a numerical value within the range of ≤z <0.2]

The method of manufacturing the radiation image storage panel of the present invention will be described below in detail by taking the case of forming a phosphor layer made of a stimulable phosphor as an example.

The substrate for forming the vapor-deposited film usually doubles as a support for the radiation image conversion panel, and can be arbitrarily selected from materials known as a support for conventional radiation image conversion panels. A preferred substrate is a quartz glass sheet; a metal sheet made of aluminum, iron, tin, chromium or the like; a resin sheet made of aramid or the like. In a known radiation image conversion panel, in order to improve the sensitivity and image quality (sharpness, graininess) of the panel, a light reflecting layer of a light reflecting material such as titanium dioxide or a light absorbing material such as carbon black is used. It is known to provide a light absorbing layer and the like. The substrate used in the present invention can also be provided with these various layers, and their configuration can be arbitrarily selected according to the desired purpose and application of the radiation image conversion panel. Further, as described in JP-A-58-200200, for the purpose of improving the sharpness of the obtained image, the surface of the substrate on the phosphor layer side (the surface of the support on the phosphor layer side is undercoated). When an auxiliary layer such as a layer (adhesion-imparting layer), a light-reflecting layer or a light-absorbing layer is provided, it may be the surface of these auxiliary layers). Good.

The storage phosphor has a wavelength of 400 to 9
300 to 500 by irradiation with excitation light in the range of 00 nm
A stimulable phosphor that exhibits stimulated emission in the wavelength range of nm is preferable. An example of such a stimulable phosphor is described in JP-B-7-845.
88, JP-A-2-193100 and JP-A-4-3100.
It is described in detail in each publication of No. 10900.

Of these, the basic composition formula (I):

[0021]

[Chemical Formula 2] M ^I X · aM ^II X ′ ₂ · bM ^III X ″ ₃ : zA (I)

Alkali metal halide stimulable phosphors represented by are particularly preferable. However, M ^I is L
i represents at least one alkali metal selected from the group consisting of Na, K, Rb and Cs, and M ^II represents Be and M
g, Ca, Sr, Ba, Ni, Cu, Zn and at least one alkaline earth metal selected from the group consisting of Cd, M ^III represents Sc, Y, La, Ce,
Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, H
o, Er, Tm, Yb, Lu, Al, Ga and In represents at least one rare earth element or trivalent metal selected from the group consisting of In, and A represents Y, Ce, Pr, Nd, S.
m, Eu, Gd, Tb, Dy, Ho, Er, Tm, Y
It represents at least one rare earth element or metal selected from the group consisting of b, Lu, Na, Mg, Cu, Ag, Tl and Bi. X, X ′ and X ″ are F, Cl and
It represents at least one halogen selected from the group consisting of Br and I. a, b and z are each 0 ≦ a <
It represents a numerical value within the range of 0.5, 0 ≦ b <0.5, 0 ≦ z <0.2.

It is preferable that M ^I in the above basic composition formula (I) contains at least Cs. X preferably contains at least Br. It is particularly preferable that A is Eu or Bi. Further, in the basic composition formula (I), if necessary, aluminum oxide,
A metal oxide such as silicon dioxide or zirconium oxide may be added as an additive in an amount of 0.5 mol or less with respect to 1 mol of M ^I. Also, the basic composition formula (II):

[0024]

Embedded image M ^II FX: zLn (II)

A rare earth activated alkaline earth metal fluorohalide stimulable phosphor represented by the following is also preferable. However,
M ^II represents at least one alkaline earth metal selected from the group consisting of Ba, Sr and Ca, and Ln represents Ce, P
r, Sm, Eu, Tb, Dy, Ho, Nd, Er, Tm
And at least one rare earth element selected from the group consisting of Yb. X represents at least one halogen selected from the group consisting of Cl, Br and I. z is 0 <
It represents a numerical value within the range of z ≦ 0.2.

As M ^II in the above basic composition formula (II),
It is preferable that Ba accounts for more than half. Ln is preferably Eu or Ce. Further, in the basic composition formula (II), it appears as F: X = 1: 1 in the notation, but this shows that it has a BaFX type crystal structure, and it is stoichiometric in the final composition. It does not indicate the composition. In general, a state in which a large number of F ⁺ (X ⁻ ) centers, which are vacancy points of X ⁻ ions, are generated in the BaFX crystal is preferable in order to enhance the photostimulation efficiency for light of 600 to 700 nm. At this time, F is often slightly over X.

Although omitted in the basic composition formula (II), one or more of the following additives may be added to the basic composition formula (II), if necessary. bA, wN ^I , xN ^II , yN ^III where A represents a metal oxide such as Al ₂ O ₃ , SiO ₂ and ZrO ₂ . In preventing sintering between M ^II FX particles, it is preferable to use an average particle size of the primary particles has low reactivity with M ^II FX in the following ultrafine particles 0.1 [mu] m. N ^I represents a compound of at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, N ^II represents a compound of an alkaline earth metal consisting of Mg and / or Be, and N ^III is Al, Ga, In,
It represents a compound of at least one trivalent metal selected from the group consisting of Tl, Sc, Y, La, Gd and Lu. As these metal compounds, it is preferable to use halides as described in JP-A-59-75200, but it is not limited thereto.

Further, b, w, x and y are respectively M ^II
It is the amount of addition when the number of moles of FX is 1, and is 0.
≦ b ≦ 0.5, 0 ≦ w ≦ 2, 0 ≦ x ≦ 0.3, 0 ≦ y ≦
It represents a numerical value within each range of 0.3. These figures do not represent the elemental ratios contained in the final composition with respect to additives that are reduced by firing and subsequent cleaning treatments. In addition, some of the above compounds may remain as the compounds just added in the final composition,
^Some react with or are incorporated into ^II FX.

In addition to the basic composition formula (II), Z may be described in JP-A-55-12145, if necessary.
n and Cd compounds; TiO ₂ , BeO, MgO, C which are metal oxides described in JP-A-55-160078.
aO, SrO, BaO, ZnO, Y ₂ O ₃ , La ₂ O ₃ , I
n ₂ O ₃ , GeO ₂ , SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , Th
O ₂ ; Zr and Sc compounds described in JP-A-56-116777; B compound described in JP-A-57-23673; As described in JP-A-57-23675.
And Si compounds; tetrafluoroboric acid compounds described in JP-A-59-27980; JP-A-59-4728.
Hexafluorosilicic acid, hexafluorotitanic acid, and hexafluorozirconic acid monovalent or divalent salts described in JP-A No. 9-58; V, Cr described in JP-A-59-56480; Mn, F
Compounds of transition metals such as e, Co and Ni may be added. Further, in the present invention, not only the phosphor containing the above-mentioned additive, but any substance having a composition which is basically regarded as a rare earth activated alkaline earth metal fluorohalide stimulable phosphor. May be

However, in the present invention, the phosphors are not limited to the above-mentioned stimulable phosphors, and other stimulable phosphors or X-rays may be absorbed to absorb light in the ultraviolet or visible region (instantaneous). ) It may be a phosphor that emits light. Examples of such phosphors, LnTaO _4:
(Nb, Gd) system, Ln ₂ SiO ₅ : Ce system, LnOX:
Tm type (Ln is a rare earth element), CsX type (X is a halogen), Gd ₂ O ₂ S: Tb, Gd ₂ O ₂ S: P
r, Ce, ZnWO ₄ , LuAlO ₃ : Ce, Gd ₃ Ga ₅
O ₁₂ : Cr, Ce, HfO _{2 and the} like can be mentioned.

First, a layer composed of a matrix of the above-mentioned stimulable phosphor is formed on a support as follows by using an electron beam evaporation method which is one of vapor deposition methods. According to the electron beam evaporation method, columnar crystals having a good shape and an ordered arrangement can be obtained.

A host compound of a stimulable phosphor that is an evaporation source,
Further, the substrate which is the object to be vapor-deposited is installed in the vapor deposition apparatus, and the inside of the apparatus is evacuated to a vacuum degree of about 1 × 10 ⁻² to 1 × 10 ⁻⁴ Pa. At this time, while maintaining the degree of vacuum at this level,
You may introduce inert gas, such as Ar gas and Ne gas.

The matrix compound of the stimulable phosphor is preferably processed into tablets (pellets) by compression under pressure. Pressure compression is generally 800-1000 kg / cm
Apply pressure in the range of ² . 50 to 20 during compression
It may be heated to a temperature in the range of 0 ° C., or the tablets obtained after compression may be subjected to degassing treatment. The relative density of the tablet is preferably 80% or more and 98% or less. Furthermore, it is also possible to use the raw material or raw material mixture instead of the phosphor host compound.

Next, an electron beam is generated from the electron gun and irradiated on the evaporation source. At this time, the acceleration voltage of the electron beam is 1.5
It is desirable to set it to be not less than kV and not more than 5.0 kV. By the irradiation of the electron beam, the stimulable phosphor, which is the evaporation source, is heated, evaporated and scattered, and deposited on the substrate surface. The phosphor deposition rate, that is, the vapor deposition rate is generally 0.1 to
It is in the range of 1000 μm / min, preferably 1-100
It is in the range of μm / min.

The electron beam irradiation may be divided into a plurality of times to form two or more phosphor base layers, or a plurality of electron guns may be used to co-evaporate different phosphor bases. Good. Further, it is also possible to form the phosphor host layer at the same time as synthesizing the phosphor host on the substrate using the phosphor host material. Furthermore, the object to be vapor-deposited (substrate) may be cooled or heated during vapor deposition, if necessary.

In this way, a layer is obtained in which the columnar crystals made of the stimulable phosphor matrix are grown substantially in the thickness direction. The phosphor base layer does not contain a binder and is composed only of the phosphor base, and voids (cracks) exist between the columnar crystals of the phosphor base. The layer thickness of the phosphor base layer is usually in the range of 50 to 1000 μm, preferably 200.
It is in the range of μm to 700 μm.

In the present invention, the vapor deposition method is not limited to the electron beam evaporation method described above, and other known methods such as a resistance heating method, a sputtering method and a chemical vapor deposition (CVD) method can be used. is there. Details of these other vapor deposition methods and vapor phase deposition methods are described in various known documents including publications, and these can be referred to.

Next, the activator for the stimulable phosphor is dispersed or dissolved in a suitable solvent to prepare a dispersion or solution of the activator. As the activator, a halide or oxide of the activator element is used. The solvent is preferably one having a low solubility in the phosphor matrix so as not to adversely affect the columnar crystals of the phosphor matrix, and examples of the solvent used include ethanol, isobutyl alcohol, acetone and hexane. . Particularly preferred are those having low solubility in the matrix and solubility in the activator, such as ethanol and isobutyl alcohol. The water content of the solvent is 50 ppm
The following is preferable. The concentration of the activator in the dispersion or solution is generally in the range of 0.1 to 20% by weight, and its viscosity is in the range of 0.1 to 10 cP.

The activator dispersion liquid or solution is uniformly applied on the surface of the phosphor base layer, and then dried, so that the dispersion liquid or solution penetrates into the gaps between the columnar crystals of the phosphor base layer. Then, the activator is dispersed and attached to the entire surface of each columnar crystal. Examples of the method for applying the dispersion or solution of the activator to the surface of the phosphor base layer include a doctor blade coating method, a roll coating method, a knife coating method,
A bar coating method, a dip coating method, a spin coating method, a spray coating method and the like can be mentioned.

Next, the phosphor base layer holding the activator on the surface is heat-treated. The heat treatment is generally performed in a nitrogen atmosphere or a nitrogen atmosphere containing a small amount of oxygen or hydrogen for 10 times.
It is carried out at a temperature in the range of 0 ° C to 300 ° C for 1 to 10 hours. By the heat treatment, the activator adhering to the surface of the columnar crystals of the phosphor matrix is thermally diffused into the columnar crystals to obtain a phosphor layer composed of columnar crystals having a uniform activator concentration. Further, this heat treatment can also serve as an annealing treatment for the phosphor layer.

The substrate does not necessarily have to serve also as a support for the radiation image conversion panel. After forming the phosphor layer, the phosphor layer is peeled off from the substrate, and an adhesive is used on a separately prepared support. You may utilize the method of joining and providing a fluorescent substance layer on a support body.

It is desirable to provide a protective layer on the surface of the phosphor layer for the convenience of transportation and handling of the radiation image storage panel and for avoiding a change in characteristics. The protective layer has almost no effect on the incidence of excitation light or the emission of emitted light,
It is desirable to be transparent, and it is chemically stable, highly moisture-proof, and has high physical strength so that the radiation image conversion panel can be sufficiently protected from external physical impact and chemical influences. It is desirable to have.

As the protective layer, a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative, polymethylmethacrylate, or an organic solvent-soluble fluororesin in an appropriate solvent is coated on the phosphor layer. Or a sheet formed by separately forming a protective layer forming sheet such as an organic polymer film such as polyethylene terephthalate or a transparent glass plate and providing it on the surface of the phosphor layer with an appropriate adhesive. Alternatively, an inorganic compound deposited on the phosphor layer by vapor deposition or the like is used. Further, in the protective layer, various additives such as light-scattering fine particles of magnesium oxide, zinc oxide, titanium dioxide, alumina, etc., sliding agents such as perfluoroolefin resin powder, silicone resin powder, etc., and crosslinking agents such as polyisocyanate etc. May be dispersedly contained. The thickness of the protective layer is generally in the range of about 0.1 to 20 μm when it is made of a polymeric substance, and 100 to 100 when it is made of an inorganic compound such as glass.
It is in the range of 1000 μm.

A fluororesin coating layer may be further provided on the surface of the protective layer in order to enhance the stain resistance of the protective layer. The fluororesin coating layer can be formed by applying a fluororesin solution prepared by dissolving (or dispersing) a fluororesin in an organic solvent onto the surface of the protective layer and drying.
Although the fluororesin may be used alone, it is usually used as a mixture of the fluororesin and a resin having high film forming property. Further, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used together. The fluororesin coating layer may be filled with a fine particle filler in order to reduce interference unevenness and further improve the quality of a radiation image. The layer thickness of the fluororesin coating layer is usually in the range of 0.5 μm to 20 μm. In forming the fluororesin coating layer, an additive component such as a cross-linking agent, a hardener, an anti-yellowing agent, etc. can be used. In particular, the addition of the crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

Although the radiation image conversion panel of the present invention is obtained as described above, the configuration of the panel of the present invention may include various known variations. For example, for the purpose of improving the sharpness of the obtained image, at least one of the above layers may be colored with a coloring agent that absorbs excitation light but not stimulated emission light (Japanese Patent Publication No. 59-23400).

[0046]

EXAMPLES [Example 1] (1) Preparation of evaporation source 100 g of cesium bromide (CsBr, 0.47 mol)
After evacuation at a temperature of 150 ° C. for 2 hours to perform degassing treatment, the tablets were produced by pressure compression at a pressure of 800 kg / cm ² . The tablet was further evacuated at a temperature of 150 ° C. for 2 hours for degassing.

(2) Formation of Phosphor Base Layer A quartz substrate was placed in a vapor deposition apparatus as a support. After the evaporation source was placed at a predetermined position in the apparatus, the inside of the apparatus was evacuated to a vacuum degree of 1 × 10 ⁻³ Pa. Then, the evaporation source was irradiated with an electron beam with an accelerating voltage of 4.0 kV for 20 minutes by an electron gun to deposit a CsBr phosphor matrix on a quartz substrate heated to 250 ° C. at a rate of 25 μm / min. Then, the irradiation of the electron beam was stopped, the inside of the apparatus was returned to atmospheric pressure, and the quartz substrate was taken out from the apparatus. On a quartz substrate, a phosphor base layer (layer thickness: 500 μm) having a structure in which columnar crystals of a phosphor base having a width of about 3 μm and a length of about 500 μm are densely erected in a substantially vertical direction.
m) had been formed.

(3) Addition of activator 5.0 g of europium bromide (EuBr ₂ , 1.3 × 10 5)
^-2 mol) and 125 mL of absolute ethanol were mixed in a mortar to obtain a suspension. After the suspension was uniformly applied to the surface of the phosphor base layer with a bar coater, the phosphor base layer on the quartz substrate was dried in vacuum at 80 ° C. for 1 hour. As a result of measuring the weight change of the phosphor base layer after drying, it was confirmed that EuBr ₂ was applied to the base layer at a weight of 32 g / m ² . Next, the phosphor base layer is placed in a nitrogen atmosphere for 2 hours.
It heat-processed at 00 degreeC for 2 hours, and formed the layer which consists of CsBr: Eu stimulable fluorescent substance. Thus, the radiation image storage panel of the present invention comprising the support and the phosphor layer was manufactured.

Comparative Example 1 (1) Preparation of evaporation source 100 g of cesium bromide (CsBr, 0.47 mol), and 1.8404 g of europium bromide (EuBr ₂ ,
(4.7 × 10 ⁻³ mol) of each was degassed by evacuation at a temperature of 150 ° C. for 2 hours. Then press each to 800
Two tablets were produced by pressure compression at kg / cm ² . Each tablet was further degassed by evacuation at a temperature of 150 ° C. for 2 hours.

(2) Formation of Phosphor Layer A quartz substrate was placed in a vapor deposition device as a support. After the two evaporation sources were placed at predetermined positions in the apparatus, the apparatus was evacuated to a vacuum degree of 4.0 × 10 ⁻⁹ kg / cm ² . Then, each evaporation source was sequentially irradiated with an electron beam with an accelerating voltage of 4.0 kV by an electron gun, and the quartz substrate heated to 250 ° C.
The EuBr ₂ activator was deposited at a rate of 25 μm / min, followed by the CsBr phosphor matrix. Then, the irradiation of the electron beam was stopped, the inside of the apparatus was returned to atmospheric pressure, and the quartz substrate was taken out from the apparatus. On the quartz substrate, an activator layer (layer thickness: 6 μm) and a phosphor base layer (layer thickness: 500 μm) in that order.
Had been formed. Next, the activator layer and the phosphor base layer on the quartz substrate were heat-treated in a reducing atmosphere at 200 ° C. for 64 hours to form a layer composed of CsBr: Eu stimulable phosphor. In this way, a comparative radiation image conversion panel comprising a support and a phosphor layer was produced.

Comparative Example 2 (1) Preparation of evaporation source 100 g of cesium bromide (CsBr, 0.47 mol) and 1.8404 g of europium bromide (EuBr ₂ , 4.7 ×)
(10 ⁻³ mol) was crushed and mixed in a mortar, and then further stirred and mixed for 15 minutes by a stirring vibrator. The obtained mixture was placed in a furnace and evacuated for 3 minutes, then under a nitrogen atmosphere, at a temperature of 525 ° C.
It was baked for 2 hours. After firing, the furnace was evacuated for 15 minutes to cool the fired product. Then, the obtained CsBr: Eu stimulable phosphor was crushed in a mortar, and the pressure was 800 kg / cm.
^A tablet was prepared by pressure compression at ² . The tablets were further degassed by evacuation for 2 hours at a temperature of 150 ° C.

(2) Formation of Phosphor Layer A column of the stimulable phosphor is formed on a quartz substrate in the same manner as in Example 1 except that the above-mentioned CsBr: Eu stimulable phosphor tablet is used as an evaporation source. A phosphor layer (layer thickness: 500 μm) made of crystals was formed. In this way, a comparative radiation image conversion panel comprising a support and a phosphor layer was produced.

[Evaluation of Performance of Radiation Image Conversion Panel] The sensitivity of each obtained radiation image conversion panel and the columnar structure of the phosphor layer were evaluated.

(1) Sensitivity A radiation image conversion panel has a tube voltage of 80 kVp and a tube current of 30 m.
After irradiating with the X-ray of A, scanning was performed with He-Ne laser light to detect stimulated emission light with a photomultiplier, and sensitivity was evaluated by the emission intensity. It was expressed as a relative value based on Example 1.

(2) Columnar structure of phosphor layer A laser beam having a beam diameter of 100 μm is made incident from the front surface (phosphor layer side) of the radiation image storage panel, and the back surface (support side).
The beam diameter emitted from was measured, and the columnar structure of the phosphor was evaluated by the spread of the beam diameter. The obtained results are summarized in Table 1.

[0056]

[Table 1]                                 Table 1           ─────────────────────────                             Relative sensitivity Beam diameter (μm)           ─────────────────────────               Example 1 100 210               Comparative Example 1 5 200               Comparative Example 2 105 450           ─────────────────────────

From the results in Table 1, according to the method of the present invention,
A radiation image conversion panel (Example 1) produced by applying an activator to a phosphor base layer and diffusing the activator to form a phosphor layer (Example 1) has high sensitivity and a small beam diameter spread and a columnar structure. It turns out that is good.

On the other hand, a radiation image conversion panel (Comparative Example 1) produced by forming an activator layer and a phosphor mother layer according to a known method and then thermally diffusing it to form a phosphor layer, The columnar structure was good, but the sensitivity was remarkably low due to insufficient diffusion of the activator. In addition, the radiation image storage panel (Comparative Example 2) manufactured by directly depositing the phosphor to form the phosphor layer according to the conventional vapor deposition method (Comparative Example 2) has high sensitivity, but columnar crystals are formed due to the presence of the activator. Due to the hindered growth, the columnar structure was not good, resulting in a large spread of the beam diameter.

[0059]

According to the method of the present invention, after a phosphor matrix layer having a columnar structure is formed by a vapor deposition method such as an evaporation method,
The activator dispersion liquid (or solution) is applied onto the base layer to allow the activator dispersion liquid to penetrate into the gaps of the columnar structure, and then the base layer is heat-treated to thermally diffuse the activator into the base layer. By doing so, a phosphor layer having a uniform phosphor composition can be formed without deteriorating the shape of the columnar structure. Therefore, the radiation image conversion panel manufactured according to the method of the present invention can provide a radiation image having high sensitivity and excellent image quality such as sharpness and graininess.

Continued front page    F term (reference) 2G083 AA03 BB01 CC03 EE02 EE03                 4H001 CA04 CA08 XA00 XA03 XA04                       XA09 XA11 XA12 XA13 XA17                       XA19 XA20 XA28 XA29 XA30                       XA31 XA35 XA37 XA38 XA39                       XA48 XA49 XA53 XA55 XA56                       YA63

Claims (7)

[Claims] 1. A method for producing a radiation image storage panel having a phosphor layer, which comprises forming a layer composed of a base material of the phosphor by a vapor deposition method and then forming a dispersion liquid containing an activator component of the phosphor. Alternatively, a radiation including a step of forming a phosphor layer by applying a solution onto the phosphor base layer and then heat treating the phosphor base layer to permeate and diffuse the activator component into the phosphor base layer. Image conversion panel manufacturing method. 2. The method of manufacturing a radiation image storage panel according to claim 1, wherein an electron beam evaporation method is used as the vapor deposition method. 3. The heat treatment of the phosphor base layer is performed at 50 ° C. to 600 ° C.
The method for producing a radiation image conversion panel according to claim 1, wherein the method is performed at a temperature in the range of ° C. 4. The method of manufacturing a radiation image storage panel according to claim 1, wherein the phosphor is a stimulable phosphor. 5. The stimulable phosphor has a basic composition formula (I): M ^I X.aM ^II X ' ₂ .bM ^III X " ₃ : zA (I) [wherein M ^I is Li, Na, Represents at least one alkali metal selected from the group consisting of K, Rb and Cs; M ^II is Be, Mg, Ca, Sr, Ba, Ni, C
represents at least one alkaline earth metal or divalent metal selected from the group consisting of u, Zn and Cd; M ^III is S
c, Y, La, Ce, Pr, Nd, Pm, Sm, Eu,
Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, A
represents at least one rare earth element or trivalent metal selected from the group consisting of 1, Ga and In; X, X ′ and X ″
Each represents at least one halogen selected from the group consisting of F, Cl, Br and I; A is Y, Ce,
Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu, Na, Mg, Cu, Ag, Tl
And at least one rare earth element or metal selected from the group consisting of Bi; and a, b and z are 0 ≦ a <0.5, 0 ≦ b <0.5 and 0 ≦ z <0.2, respectively.
The method for producing a radiation image storage panel according to claim 4, wherein the stimulable phosphor is an alkali metal halide-based phosphor having a value within the range of. 6. The method for producing a radiation image storage panel according to claim 5, wherein A in the basic composition formula (I) is Eu. 7. A radiation image conversion panel manufactured by the method according to any one of claims 1 to 6.