JP2002296398A - Method for manufacturing radiographic image conversion panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a radiographic image conversion panel whose sensitivity is high and which produces radiation images of high image quality. SOLUTION: The method for manufacturing the radiographic image conversion panel, which includes a process of forming a phosphor layer, by evaporating onto a substrate the substance generated by heating an evaporation source containing stimulable phosphors of a europium activation alkali metal halide base or their material has the evaporation source, where the concentration of an ingredient of Europium activation agent is higher than that of the Europium activation agent for the phosphors, in the phosphors layer to be formed is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art When irradiated with radiation such as X-rays, 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 reduced. By utilizing a stimulable phosphor (accumulating phosphor) having a property of exhibiting stimulable luminescence in response to a stimulable phosphor-containing sheet-like radiation image conversion panel, the stimulable phosphor is transmitted or covered by a subject. After radiating the radiation emitted from the specimen to once accumulate and record radiation image information of the subject or the subject, the panel is scanned with excitation light such as laser light to emit sequentially as stimulating light, and the stimulating light is emitted. A radiation image recording / reproducing method, which comprises obtaining an image signal by photoelectrically reading emitted light, is widely used in practice. After the reading of the panel is completed, the remaining radiation energy is erased, and then the panel is prepared for the next imaging and used repeatedly.

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. is there. However, when the stimulable phosphor layer is self-supporting, a support is not necessarily required. Also, a protective layer is usually provided on the upper surface of the stimulable phosphor layer (the side not facing the support) to protect the phosphor layer from chemical alteration or physical impact. ing.

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 do not include a binder formed by a vapor deposition method or a sintering method and are composed only of aggregates of a stimulable phosphor,
It is also known that a gap between aggregates of stimulable phosphors is impregnated with a polymer substance.

As another method of the above-mentioned radiation image recording / reproducing method, Japanese Patent Application No. 11-372978 filed by the present applicant discloses that the radiation absorbing function and the energy storage function of the conventional stimulable phosphor are separated. A radiation image conversion panel containing at least a stimulable phosphor (phosphor for energy storage) and a phosphor containing a phosphor (radiation absorbing phosphor) that absorbs radiation and emits light in the ultraviolet to visible region. A radiation image forming method using a combination with a screen has been proposed. In this method, radiation transmitted through a subject is first converted into light in the ultraviolet to visible region by a radiation absorbing phosphor of the screen or panel, and the light is then converted to a radiation image by an energy storage phosphor of the panel. Store and record as information. Next, the panel is scanned with excitation light to emit stimulated emission light, and the stimulated emission light is photoelectrically read to obtain an image signal. Such a radiation image conversion panel and a fluorescent screen are also included in the present invention.

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

For the purpose of improving sensitivity and image quality, as described in, for example, Japanese Patent Publication No. Hei 6-77079, as a method of manufacturing a radiation image conversion panel, a stimulable phosphor layer is formed by a vapor deposition method. Methods of forming have been proposed. The vapor deposition method includes a vapor deposition method and a sputtering method.For example, in the vapor deposition method, an evaporation source made of a stimulable phosphor or its raw material is heated by irradiating a resistance heater or an electron beam to evaporate the evaporation source. By scattering and depositing the evaporated substance on the surface of a substrate such as a metal sheet, a phosphor layer composed of a columnar crystal of a stimulable phosphor is formed.

[0008] The phosphor layer formed by the vapor deposition method
It does not contain a binder and consists only of a stimulable phosphor. Voids (cracks) exist between the columnar crystals of the stimulable phosphor.
Exists. For this reason, the entrance efficiency of the excitation light and the extraction efficiency of the emission light can be increased, so that the sensitivity is high, and the scattering of the excitation light in the plane direction can be prevented, so that an image with high sharpness can be obtained. . However, in the above-described evaporation method using a resistance heater, a substance having a high vapor pressure among evaporation sources evaporates preferentially (for example, the activator of the phosphor evaporates earlier than the base material). There is a problem that the composition of the phosphor charged as the evaporation source does not match the composition of the phosphor in the formed phosphor layer.

[0009] Japanese Patent Publication No. Hei 6-77079 discloses a stimulable phosphor (specifically, RbB) as an evaporation source.
r: using a Tl stimulable phosphor), there is disclosed a method in which the activator concentration of the phosphor in the evaporation source and the activator concentration of the intended phosphor or the actual activator concentration are determined. No description is given of the relationship between the phosphor and the activator concentration in the obtained deposited film. The temperature at which the vapor pressure is 1.333 Pa is 894 K for RbBr and 53 K for TlBr.
3K.

On the other hand, Japanese Patent Publication No. 7-84588 discloses that
A radiation image conversion method and a radiation image conversion panel using an alkali metal halide-based stimulable phosphor activated by europium are disclosed. However, as a method of forming a phosphor layer of a radiation image conversion panel, a method of forming the phosphor layer by applying the phosphor particles and a binder is described.

[0011]

As a result of repeated studies on a method for forming a phosphor layer of a radiation image conversion panel using the above-described vapor deposition method, the present inventors have found that the evaporation source is locally irradiated with an electron beam. Even in the electron beam evaporation method of heating and instantaneously evaporating, there is a large difference in the temperature at which the base component and the activator component have a constant vapor pressure, such as a CsBr: Eu phosphor. In the case (temperature at which the vapor pressure becomes 1.333 Pa, CsBr: 556 K, EuBr ₂ : 1013 K),
That is, if there is a large difference in the vapor pressure at the same temperature, in the unified vapor deposition using the phosphor itself as the evaporation source, the base component having a high vapor pressure (in this case, CsBr) is likely to evaporate first, As a result, the composition of the phosphor charged as the evaporation source does not match the composition of the phosphor in the formed phosphor layer, and the activator concentration in the phosphor layer may be lower than a desired concentration. I understand. It has also been found that if a vapor deposition film containing an excess of the base component is formed first, the activator component to be doped on the surface is likely to be rejected. Then, as a result, the sensitivity is significantly reduced because the activator concentration of the phosphor in the obtained phosphor layer is low.

Accordingly, the present invention provides a method for manufacturing a radiation image conversion panel with high sensitivity. The present invention also provides
An object of the present invention is to provide a method for manufacturing a radiation image conversion panel that provides a high-sensitivity and high-quality radiation image.

[0013]

The present invention is achieved by heating a europium-activated alkali metal halide stimulable phosphor having the following basic composition formula (I) or an evaporation source containing the raw material thereof. In a method for manufacturing a radiation image conversion panel, comprising a step of forming a phosphor layer by evaporating a substance on a substrate, the concentration of a europium activator component as a source of the europium activator of the intended phosphor is used as the evaporation source. A method of manufacturing a radiation image conversion panel, characterized in that an evaporation source having a higher concentration is used.

[0014] The basic formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zEu ‥‥ (I) [ However, M ^I is the group consisting of Li, Na, K, Rb and Cs represents at least one alkali metal more selected; M ^II is be, Mg, Ca, Sr, Ba, Ni, C
u, represents at least one alkaline earth element or trivalent metal selected from the group consisting of 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; and a, b and z each represent 0 ≦ a <0.5, 0 ≦ b <0.5, 0
<Represents a numerical value within the range of z <0.2]

Preferred embodiments of the method for manufacturing a radiation image storage panel of the present invention will be described below. (1) The concentration of the europium activator component in the evaporation source is 150 times or less the europium activator concentration of the phosphor in the phosphor layer to be formed. (2) The concentration of the europium activator component in the evaporation source is 1.5 to 10 times the europium activator concentration of the phosphor in the phosphor layer to be formed. (3) The concentration α of the europium activator component in the evaporation source satisfies the following relational expression. 10 ⁻⁵ ≦ α ≦ 10 ⁻¹

According to the present invention, there is further provided a method of heating an evaporation source containing a base component raw material and an activator component raw material of a europium-activated alkali metal halide stimulable phosphor having the above basic composition formula (I). In a method for manufacturing a radiation image conversion panel comprising a step of forming a phosphor layer by vapor-depositing a substance generated on a substrate, the concentration of the base component raw material, and the europium activator component in the target phosphor layer In addition, there is also a method for manufacturing a radiation image conversion panel, wherein activator component raw materials having a concentration higher than the europium activator concentration of the phosphor are co-evaporated by using evaporation sources arranged separately from each other.

Preferred embodiments of the method for producing a radiation image storage panel utilizing co-evaporation of the present invention are described below. (1) The concentration of the europium activator component in the activator component raw material of the evaporation source is 150 times or less the europium activator concentration of the phosphor in the phosphor layer formed. (2) The concentration of the europium activator component in the activator component raw material of the evaporation source is 1.5 to 10 times the europium activator concentration of the phosphor in the phosphor layer to be formed. (3) The concentration α of the europium activator component in the activator component raw material of the evaporation source satisfies the following relational expression. 10 ⁻⁵ ≦ α ≦ 10 ⁻¹

[0018] In the present invention, the concentration of europium activator component or europium activator, the molar ratio of the activator Eu relative to the central element M ^I maternal phosphor having the above basic composition formula (I) Eu / M ^I.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, it is preferable to use electron beam irradiation when heating an evaporation source.

Hereinafter, the method of manufacturing the radiation image conversion panel of the present invention will be described in detail by taking as an example a case where the phosphor layer is formed by an electron beam evaporation method which is a kind of evaporation method.
A substrate for forming a vapor-deposited film usually serves also as a support of the radiation image conversion panel, and can be arbitrarily selected from materials known as a support of the conventional radiation image conversion panel. A quartz glass sheet; a metal sheet made of aluminum, iron, tin, chromium and the like; and a resin sheet made of aramid and the like. In a known radiation image conversion panel, in order to improve sensitivity or image quality (sharpness, granularity) as the radiation image conversion panel,
It is known to provide a light reflecting layer made of a light reflecting substance such as titanium dioxide or a light absorbing layer made of a light absorbing substance such as carbon black. The substrate used in the production of the radiation image storage panel of the present invention can also be provided with these various layers, and their configuration can be arbitrarily selected according to the desired purpose, use, etc. of the radiation image storage panel. Can be. Further, JP-A-58-2002
As described in Japanese Patent Publication No. 00, a surface of the substrate on the side of the phosphor layer (an undercoat layer (adhesion-imparting layer) is formed on the surface of the substrate on the side of the phosphor layer) in order to improve the sharpness of the obtained image. When an auxiliary layer such as a light reflecting layer or a light absorbing layer is provided, the surface of the auxiliary layer may be formed.

[0021] As the phosphor, the basic formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zEu ‥‥ (I) europium activated alkali metal halide stimulable having phosphor is used. However, M ^I is Li, N
a represents at least one alkali metal selected from the group consisting of a, K, Rb and Cs; M ^II represents Be, Mg, C
a, Sr, Ba, Ni, Cu, Zn and Cd represent at least one kind of alkaline earth metal or divalent metal selected from the group consisting of Cd; M ^III represents Sc, Y, La, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, E
r, Tm, Yb, Lu, Al, Ga, and In represent at least one rare earth element or trivalent metal selected from the group consisting of In; X, X ′, and X ″ represent F, Cl, Br, respectively.
And I represents at least one halogen selected from the group consisting of; and a, b and z each represent 0 ≦ a <
0.5, 0 ≦ b <0.5, and 0 ≦ z <0.2.

It is preferable that M ^I in the above basic composition formula (I) contains at least Cs. It is preferable that X contains at least Br. In the basic composition formula (I), a metal oxide such as aluminum oxide, silicon dioxide, or zirconium oxide may be added as an additive, if necessary, in an amount of 0.5 mol or less based on 1 mol of M ^I. May be added.

In the present invention, the phosphor layer can be formed on the substrate by, for example, an electron beam evaporation method as follows. By using the electron beam evaporation method, a columnar crystal having a particularly good shape and a well-arranged array can be obtained. First,
Prepare an evaporation source. In the present invention, the evaporation source basically comprises a europium-activated alkali metal halide-based stimulable phosphor having the above basic composition formula (I). However, a phosphor is used in which the concentration of europium as an activator is higher than the concentration of europium in the phosphor in the phosphor layer to be formed.

In the present invention, if the activator concentration Eu / M ^I in the evaporation source is made slightly higher than the activator concentration of the phosphor in the phosphor layer to be formed, the resulting phosphor layer will Can be made higher than before, and an effect of improving sensitivity can be obtained. Therefore, the activator concentration Eu / M ^I in the evaporation source is preferably set to be higher than 1 time and 150 times or less of the target activator concentration of the phosphor. Particularly preferably, it is 1.5 times or more and 10 times or less.

In order to form the vapor-deposited film (phosphor layer) to have the desired activator concentration, not only the high activator concentration in the evaporation source but also the desired phosphor composition and activator concentration are required. Since there are various factors such as the concentration of the activator (absolute value) and the evaporation conditions such as the form of the evaporation source and the evaporation rate, the optimum activator concentration of the evaporation source cannot be determined unconditionally. However, for example, CsBr having an Eu concentration (Eu / Cs) of about 0.01:
In order to form a phosphor layer composed of a Eu phosphor, it is desirable to make the Eu concentration in the evaporation source about 2 to 50 times.

The activator concentration α in the evaporation source (Eu / M
^I , absolute value) generally satisfies the relational expression: 10 ⁻⁵ ≦ α ≦ 10 ⁻¹ .

Alternatively, the evaporation source may be a mixture of the phosphor and the activator component, or may be a mixture of a base component of the phosphor and an activator component. The activator component is generally a compound containing the activator element Eu, and for example, a halide or oxide of Eu is used. The parent component may be the compound itself that constitutes the parent, or may be a mixture of two or more raw materials that can react with each other to form the parent compound. In any case, the concentration of the activator and / or activator component of the phosphor should be higher than the target activator concentration of the target phosphor as a whole evaporation source.

The evaporation source is preferably processed into a tablet (tablet) by compression under pressure. The compression under pressure is generally performed by applying a pressure in the range of 800 to 1000 kg / cm ² . During the compression, the mixture may be heated to a temperature in the range of 50 to 200C. After compression under pressure, it is preferable to subject the obtained tablet to a degassing treatment. The relative density of the tablet is preferably 80% or more and 98% or less,
Particularly preferably, it is 90% or more and 96% or less. If the relative density of the tablet is low, the phosphor does not evaporate uniformly from the tablet surface, resulting in non-uniform film thickness of the deposited film, bumping substances adhering to the substrate, and the phosphor itself evaporating unevenly. As a result, a phosphor activator or additive is segregated in the deposited film.

When the phosphor of the present invention or its raw material component is deposited, the base component raw material and the activator component raw material are separated and arranged, and they are simultaneously heated by a known co-deposition method or the like. Co-evaporation can also be performed.

Next, the evaporation source and the substrate to be deposited are placed in a deposition apparatus, and the inside of the apparatus is evacuated to 1.33 × 10 ⁻⁴ to 1.33 × 10 ^-4 .
The degree of vacuum is set to about 6.67 × 10 ⁻² Pa. At this time,
While maintaining the degree of vacuum at this level, an inert gas such as an Ar gas or a Ne gas may be introduced. Next, an electron beam is generated from a plurality of electron guns and irradiated to each of the evaporation sources. It is desirable that the acceleration voltage of the electron beam be set to 1.5 kV or more and 5.0 kV or less. If the acceleration voltage is lower than 1.5 kV, the voltage becomes unstable, the beam position of the electron beam fluctuates, or the shape of the scanning surface by the electron beam of the evaporation source changes to keep the evaporation surface flat. It becomes difficult. On the other hand, when the acceleration voltage is higher than 5.0 kV, the columnar crystals of the phosphor that grows in vapor phase by evaporation become uneven.

The irradiation of the electron beam causes the stimulable phosphor or the like of the evaporation source to be heated, evaporated, scattered, and deposited on the substrate surface.
The deposition rate of the phosphor, that is, the deposition rate, is generally in the range of 0.1 to 1000 μm / min, preferably 1 to 1000 μm / min.
〜100 μm / min. When the evaporation source includes an activator component of the phosphor, the phosphor is synthesized on the substrate and a phosphor layer is formed at the same time. Note that two or more phosphor layers can be formed by performing the electron beam irradiation a plurality of times. In that case, another phosphor layer, another phosphor,
For example, various known stimulable phosphors and Japanese Patent Application No. Hei 11-3
It may be composed of a radiation absorbing phosphor described in Japanese Patent No. 72978. Furthermore, the object to be deposited (substrate) may be cooled or heated as necessary at the time of vapor deposition, or the phosphor layer may be subjected to a heat treatment (annealing treatment) after the vapor deposition.

In this way, a phosphor layer in which the columnar crystals of the stimulable phosphor have grown substantially in the thickness direction is obtained. The phosphor layer is composed of only the stimulable phosphor, and voids (cracks) exist between the columnar crystals of the stimulable phosphor.
The thickness of the phosphor layer is usually in the range of 100 μm to 1 mm, preferably in the range of 200 μm to 700 mm.

The distribution of the composition of the stimulable phosphor in the obtained phosphor layer was analyzed by a cathodoluminescence method (CL), an electron spectroscopy method (ESCA), and an electron microanalyzer method (E
PMA), secondary ion mass spectrometry (SIMS) and the like. Alternatively, the measurement can be performed by shaving off a portion to be measured in the phosphor layer and subjecting the portion to a fluorescent X-ray method, an atomic absorption method, an inductively coupled high frequency plasma spectroscopy (ICP) or the like.

In the present invention, the vapor deposition method is not limited to the above-mentioned electron beam vapor deposition method. For example, other methods such as a resistance heating method in which an evaporation source is heated and evaporated using a resistance heater instead of an electron gun are used. Can also be used.

In the above-mentioned vapor deposition operation, the substrate does not necessarily have to serve also as a support of the radiation image conversion panel. After forming the vapor deposition film, the vapor deposition film is peeled off from the substrate, and an adhesive is used on a separately prepared support. Then, a method of providing a phosphor layer by joining together may be used.

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 to avoid a change in characteristics. The protective layer is desirably transparent so that it hardly affects the incidence of excitation light and the emission of stimulated emission light, and the radiation image conversion panel is sufficiently protected from external physical and chemical impacts. It is desirable that it is chemically stable, has high moisture resistance, and has high physical strength so that it can be protected.
As the protective layer, a solution prepared by dissolving a transparent organic polymer substance such as a cellulose derivative, polymethyl methacrylate, or an organic solvent-soluble fluororesin in an appropriate solvent is applied on the stimulable phosphor layer. Or a sheet for forming a protective layer such as an organic polymer film such as polyethylene terephthalate or a transparent glass plate, and provided on the surface of the phosphor layer using an appropriate adhesive. Alternatively, an inorganic compound formed on the phosphor layer by vapor deposition or the like is used. In the protective layer, various additives such as light scattering fine particles such as magnesium oxide, zinc oxide, titanium dioxide, and alumina; slip agents such as perfluoroolefin resin powder and silicone resin powder; and cross-linking agents such as polyisocyanate. May be dispersedly contained. The thickness of the protective layer is generally in the range of about 0.1 to 20 μm when composed of a polymer substance, and 100 to 1 μm when composed of an inorganic compound such as glass.
000 μm.

Further, a fluororesin coating layer may be provided on the surface of the protective layer in order to enhance the contamination 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 on the surface of the protective layer and drying.
The fluororesin may be used alone, but is usually used as a mixture of the fluororesin and a resin having a high film forming property. Also, an oligomer having a polysiloxane skeleton or an oligomer having a perfluoroalkyl group can be used in combination. The fluororesin coating layer may be filled with a particulate filler in order to reduce interference unevenness and further improve the quality of a radiographic image. The thickness of the fluororesin coating layer is usually in the range of 0.5 μm to 20 μm. In forming the fluororesin coating layer, additional components such as a crosslinking agent, a hardening agent, an anti-yellowing agent and the like can be used. In particular, the addition of a crosslinking agent is advantageous for improving the durability of the fluororesin coating layer.

As described above, a radiation image conversion panel according to the method of the present invention is obtained. The configuration of the panel according to 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,
It may be colored by a colorant that absorbs the excitation light and does not absorb the stimulating light (see Japanese Patent Publication No. 59-23400).

[0039]

EXAMPLES [Example 1] (1) Preparation of evaporation source 100 g of cesium bromide (CsBr, 0.47 mol) and 5.5212 g of europium bromide (EuBr _2.2 ,
(1.7 × 10 ⁻² mol) was pulverized and mixed in a mortar, and then further mixed by stirring with a stirring vibrator for 15 minutes. The resulting mixture was placed in a furnace, evacuated for 3 minutes, and then heated to a temperature of 5 in a nitrogen atmosphere.
It was baked at 25 ° C. for 2 hours. After firing, the furnace was evacuated for 15 minutes to cool the fired product. Then, the obtained CsBr:
After crushing the Eu stimulable phosphor in a mortar, pressure 800 kg
/ Cm ² to produce tablets. The tablet was further evacuated at a temperature of 150 ° C. for 2 hours to perform a degassing treatment.

(2) Formation of Phosphor Layer An aluminum substrate was placed in a vapor deposition apparatus as a support. After the above evaporation source was placed at a predetermined position in the apparatus, the inside of the apparatus was evacuated to a degree of vacuum of 6.7 × 10 ⁻³ Pa. Next, the evaporation source was irradiated with an electron beam having an accelerating voltage of 2.3 kV for 20 minutes using an electron gun, and CsBr:
The Eu stimulable phosphor was deposited at a rate of 25 μm / min.
After that, the irradiation of the electron beam was stopped, the inside of the device was returned to atmospheric pressure,
The aluminum substrate was taken out of the apparatus. On the board,
A phosphor layer having a structure in which columnar crystals of a phosphor having a width of about 3 μm and a length of about 450 μm densely stand in a substantially vertical direction (layer thickness:
450 μm). Thus, the radiation image storage panel of the present invention comprising the support and the stimulable phosphor layer was manufactured.

[Embodiment 2] In the embodiment 1, EuBr
A radiation image storage panel of the present invention was produced in the same manner as in Example 1 except that the amount of _2.2 was changed to 18.404 g (5.6 × 10 ^-2 mol).

[Embodiment 3] In the embodiment 1, EuBr
A radiation image storage panel of the present invention was produced in the same manner as in Example 1 except that the amount of _2.2 was changed to 184.04 g (5.6 × 10 ^-1 mol).

Comparative Example 1 In Example 1, EuBr was used.
A radiation image conversion panel for comparison was manufactured in the same manner as in Example 1 except that the amount of _2.2 was changed to 1.8404 g (5.6 × 10 ⁻³ mol).

Example 4 (1) Production of Evaporation Source A powder of 100 g of cesium bromide (CsBr, 0.47 mol) was compressed under a pressure of 800 kg / cm ² to produce a tablet. Tablet at 150 ° C and 2
It was evacuated for a time and degassed. Separately, 5.5212 g of europium bromide (EuBr _2.2 , 1.7 × 10 ^-2 mol) was press-compressed at a pressure of 800 kg / cm ² to produce a tablet. Tablet at 150 ° C
And degassed for 2 hours.

(2) Formation of phosphor layer (co-deposition) An aluminum substrate was placed in a vapor deposition apparatus as a support. After placing the cesium bromide tablet and the europium bromide tablet at predetermined positions in the apparatus, the inside of the apparatus was evacuated to a degree of vacuum of 6.7 × 10 ⁻³ Pa. Then
A cesium bromide tablet and a europium bromide tablet are irradiated with an electron beam having an accelerating voltage of 2.3 kV for 20 minutes using an electron gun, and a CsBr: Eu stimulable phosphor is deposited on an aluminum substrate at a rate of 25 μm / min. I let it. Thereafter, the irradiation of the electron beam was stopped, the inside of the apparatus was returned to the atmospheric pressure, and the aluminum substrate was taken out of the apparatus. On the substrate, the width is about 3μ
m, a phosphor layer having a structure in which columnar crystals of a phosphor having a length of about 300 μm densely stand in a substantially vertical direction (layer thickness: 450 μm)
m) had been formed. Thus, the radiation image conversion panel of the present invention comprising the support and the stimulable phosphor layer was manufactured by the co-evaporation method.

Fifth Embodiment In the fourth embodiment, EuBr
A radiation image storage panel of the present invention was produced in the same manner as in Example 4, except that the amount of _2.2 was changed to 18.404 g (5.6 × 10 ^-2 mol).

[Evaluation of Performance of Radiation Image Conversion Panel] The sensitivity of each obtained radiation image conversion panel was evaluated by the following method. Tube voltage 4 for radiation image conversion panel
After irradiating X-rays at 0 kVp and a tube current of 30 mA, He-
Scanning was performed with Ne laser light, photostimulated light was detected by a photomultiplier, and sensitivity was evaluated based on the light emission intensity. It was represented by a relative value based on Comparative Example 1. The Eu concentration (Eu / Cs molar ratio) of the phosphor layer was determined by X-ray fluorescence measurement. Table 1 summarizes the obtained results.

[0048]

Table 1 ──────────────────────────────── Sensitivity Eu concentration of evaporation source Eu concentration of phosphor layer ──────────────────────────────── Example 1 2 0.036 (3 times) 0.0005 Example 2 11 0.12 (10 times) 0.0015 Example 3 45 1.2 (100 times) 0.0102 ────────────────────────── {Example 4 25 0.036 (3 times) 0.0300 Example 5 30 0.12 (10 times) 0.1000} ──────────────── Comparative Example 1 1 0.01 0.0002 ──────────────────────── ────────

As is clear from the results shown in Table 1, all the radiation image conversion panels (Examples 1 to 3) manufactured by using the evaporation source having a higher activator concentration than the conventional one according to the method of the present invention were obtained. CsBr: Eu in the phosphor layer more than the radiation image conversion panel manufactured according to the conventional method (Comparative Example 1)
The activator concentration of the stimulable phosphor was high, and as a result, the sensitivity was significantly improved. In particular, in the panel of Example 3 in which the target activator concentration was achieved, extremely high sensitivity was obtained.

[0050]

According to the present invention, the phosphor layer is formed by an evaporation method, particularly an electron beam evaporation method, using an evaporation source in which the concentration of the europium activator component is higher than the concentration of the activator of the target phosphor. By the formation, the activator concentration in the phosphor layer can be higher than before and at or near the target concentration, and a radiation image conversion panel with significantly improved sensitivity can be obtained. Further, the radiation image conversion panel of the present invention has good shape and arrangement of columnar crystals of the phosphor in the phosphor layer, surface properties, good adhesion to the support, and excellent radiation image quality such as sharpness. Can be given.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 11/85 CPF C09K 11/85 CPF G01T 1/00 G01T 1/00 B F-term (Reference) 2G083 AA03 BB01 CC03 DD02 DD12 EE02 EE03 4H001 CA08 XA00 XA03 XA04 XA09 XA11 XA12 XA13 XA17 XA19 XA20 XA21 XA28 XA29 XA30 XA31 XA35 XA37 XA38 XA39 XA48 XA49 XA53 XA55 XA56 YA63

Claims (9)

[Claims] 1. A fluorescent substance obtained by heating a europium-activated alkali metal halide-based stimulable phosphor having the basic composition formula (I) or an evaporation source containing a raw material thereof on a substrate. In a method for manufacturing a radiation image conversion panel including a step of forming a body layer,
A method for producing a radiation image conversion panel, wherein an evaporation source having a concentration of a europium activator component higher than a concentration of a europium activator of a phosphor in a target phosphor layer is used as the evaporation source. Basic formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zEu ‥‥ (I) [ However, M ^I is selected from the group consisting of Li, Na, K, Rb and Cs Represents at least one alkali metal; M ^II is Be, Mg, Ca, Sr, Ba, Ni, C
u, represents at least one alkaline earth element or trivalent metal selected from the group consisting of 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; and a, b and z each represent 0 ≦ a <0.5, 0 ≦ b <0.5, 0
<Represents a numerical value within the range of z <0.2] 2. The radiation image conversion panel according to claim 1, wherein the concentration of the europium activator component in the evaporation source is not more than 150 times the europium activator concentration of the phosphor in the phosphor layer to be formed. Manufacturing method. 3. The method according to claim 2, wherein the concentration of the europium activator component in the evaporation source is 1.5 to 10 times the europium activator concentration of the phosphor in the phosphor layer to be formed. Method for manufacturing a radiation image conversion panel. 4. The radiation according to claim 1, wherein the concentration α of the europium activator component in the evaporation source satisfies the relational expression: 10 ⁻⁵ ≦ α ≦ 10 ^−1. A method for manufacturing an image conversion panel. 5. A substance generated by heating an evaporation source containing a base component raw material and an activator component raw material of a europium-activated alkali metal halide-based stimulable phosphor having the basic composition formula (I). In a method for manufacturing a radiation image conversion panel including a step of forming a phosphor layer by vapor deposition on a substrate, the concentration of the base component raw material and the europium activator component is determined by adjusting the concentration of the europium phosphor in the target phosphor layer. A method for manufacturing a radiation image conversion panel, wherein activator component raw materials having a higher activator concentration are co-evaporated by using evaporation sources separated from each other. Basic formula ^{(I): M I X ·} aM II X '2 · bM III X "3: zEu ‥‥ (I) [ However, M ^I is selected from the group consisting of Li, Na, K, Rb and Cs Represents at least one alkali metal; M ^II is Be, Mg, Ca, Sr, Ba, Ni, C
u, represents at least one alkaline earth element or trivalent metal selected from the group consisting of 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; and a, b and z each represent 0 ≦ a <0.5, 0 ≦ b <0.5, 0
<Represents a numerical value within the range of z <0.2] 6. The method according to claim 5, wherein the concentration of the europium activator component in the activator component raw material of the evaporation source is not more than 150 times the europium activator concentration of the phosphor in the phosphor layer formed. A method for producing the radiation image storage panel according to the above. 7. The concentration of the europium activator component in the activator component raw material of the evaporation source is 1.5 to 10 times the europium activator concentration of the phosphor in the phosphor layer to be formed. A method for manufacturing a radiation image conversion panel according to claim 6. 8. The method according to claim ⁵ , wherein the concentration α of the europium activator component in the activator component raw material of the evaporation source satisfies the relational expression: 10 ⁻⁵ ≦ α ≦ 10 ⁻¹ . 13. The method for manufacturing a radiation image conversion panel according to the paragraph. 9. The method of manufacturing a radiation image conversion panel according to claim 1, wherein the heating of the evaporation source is performed by irradiation with an electron beam.