WO2010032504A1 - Radiation image conversion panel and method for producing the same - Google Patents

Abstract

Disclosed is a radiation image conversion panel having a phosphor layer formed by vapor deposition and containing a phosphor columnar crystal which is mainly composed of a caesium halide phosphor. A method for producing the radiation image conversion panel is also disclosed. The radiation image conversion panel is characterized in that the phosphor layer is formed under such conditions that the vacuum degree is kept within the range of 0.05-10 Pa and the mass deposition rate is kept within the range of 0.01-2.0 mg/cm² min. The radiation image conversion panel has high sensitivity (high luminance), high sharpness, and excellent storage stability.

Description

Radiation image conversion panel and manufacturing method thereof

The present invention relates to a radiation image conversion panel having high sensitivity (high luminance), high sharpness, and excellent storage stability, and a method for manufacturing the same.

Conventionally, radiographic images such as X-ray images have been widely used for diagnosis of medical conditions in the medical field. In particular, radiographic images using intensifying screens and film systems have been developed as an imaging system that combines high reliability and excellent cost performance as a result of high sensitivity and high image quality in a long history. Used in the medical field. However, these pieces of image information are so-called analog image information, and free image processing and instantaneous electric transmission cannot be performed like digital image information that has been developing in recent years.

In recent years, digital radiological image detection devices represented by computed radiography (CR), flat panel type radiation detectors (FPD), and the like have appeared. In these, since a digital radiographic image is directly obtained and an image can be directly displayed on an image display device such as a cathode tube or a liquid crystal panel, image formation on a photographic film is not necessarily required. As a result, these digital X-ray image detection devices reduce the need for image formation by the silver halide photography method, and greatly improve the convenience of diagnosis work in hospitals and clinics.

The flat plate X-ray detector (FPD) is characterized in that the device is smaller than CR and the image quality at high dose is excellent. In this case, a scintillator plate made of an X-ray phosphor having a characteristic of emitting light by radiation is used to convert the radiation into visible light.

The radiation image conversion panel used for the radiation image detection is composed of a support and a phosphor layer provided thereon as a basic structure. However, a support is not necessarily required when the phosphor layer is self-supporting.

Also, a protective layer is usually provided on the upper surface of the phosphor layer (the surface not facing the support) to protect the phosphor layer from chemical alteration or physical impact.

The phosphor layer is composed of a phosphor and a binder containing and supporting the phosphor in a dispersed state, and is composed only of an aggregate of phosphors without including a binder formed by vapor deposition or sintering. And those in which a polymer substance is impregnated in the gap between the phosphor and the aggregate of the phosphor are known.

As another method of the above radiographic image detection method, a radiation image conversion containing at least a stimulable phosphor (an energy storage phosphor) is performed by separating a radiation absorbing function and an energy storage function of a conventional stimulable phosphor. A radiation image forming method using a combination of a panel and a phosphor screen containing a phosphor (radiation absorbing phosphor) that absorbs radiation and emits light in an ultraviolet to visible region has been proposed (for example, Patent Document 1). reference.).

In this method, radiation that has passed through a subject is first converted into light in the ultraviolet or visible region by the screen or panel radiation absorbing phosphor, and then the radiation is imaged by the panel energy storage phosphor. Accumulate and record as information. Next, the panel is scanned with excitation light to emit emitted light, and the emitted light is read photoelectrically to obtain an image signal.

The radiological image detection method (and the radiographic image formation method) is a method having a number of excellent advantages as described above. However, even in the radiographic image conversion panel used in this method, it is as sensitive as possible and It is desired to provide an image with good image quality (sharpness, graininess, etc.).

For the purpose of improving sensitivity and image quality, a method of forming a phosphor layer of a radiation image conversion panel by a vapor deposition method has been proposed. The vapor deposition method includes a vapor deposition method and a sputtering method. For example, the vapor deposition method evaporates and scatters the evaporation source by heating the evaporation source made of the phosphor or its raw material by irradiation with a resistance heater or an electron beam. By depositing the evaporated material 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 does not contain a binder and is composed only of the phosphor, and there are voids between the columnar crystals of the phosphor. For this reason, since the entrance efficiency of excitation light and the extraction efficiency of emitted light can be increased, the sensitivity is high, and the scattering of the excitation light in the plane direction can be prevented, so that a high sharpness image can be obtained. .

Also disclosed is a method of forming a needle-like phosphor layer on a substrate by controlling vapor deposition so that the phosphor layer is deposited on the substrate at a lower density than the density of the phosphor as a solid, and Although it is described that vapor deposition is performed at a vapor deposition rate> 1 mg / cm ² · min (see, for example, Patent Document 2), the degree of vacuum and the substrate temperature are not described in detail.

On the other hand, in order to convert radiation into visible light, a scintillator made of an X-ray phosphor having a characteristic of emitting light by radiation is used. In order to improve the S / N ratio in low-dose imaging, light emission is used. It becomes necessary to use highly efficient scintillators. In general, the light emission efficiency of a scintillator is determined by the thickness of the phosphor layer and the X-ray absorption coefficient of the phosphor. The thicker the phosphor layer, the more scattered the emitted light in the phosphor layer. However, sharpness decreases. Therefore, when the sharpness necessary for the image quality is determined, the layer thickness is determined.

Among them, cesium iodide (CsI) has a relatively high change rate from X-rays to visible light, and phosphors can be easily formed into a columnar crystal structure by vapor deposition. Therefore, scattering of emitted light within the crystal by the light guide effect. And the thickness of the phosphor layer can be increased (see, for example, Patent Document 3).

However, since luminescence efficiency is low only with cesium iodide (CsI), a mixture of cesium iodide (CsI) and sodium iodide (NaI) mixed at an arbitrary molar ratio is used as a support (substrate). Deposited as sodium-activated cesium iodide (CsI: Na) on the top, and recently, a mixture of cesium iodide (CsI) and thallium iodide (TlI) mixed at an arbitrary molar ratio is used as a support. Visible conversion efficiency is improved by performing heat treatment at a temperature of 200 ° C. to 500 ° C. on what is deposited as thallium activated cesium iodide (CsI: Tl) on the (substrate), and used as an X-ray phosphor. (For example, refer to Patent Document 4).

Further, a phosphor layer (also referred to as “scintillator layer”) based on cesium iodide (CsI) has a deliquescent property and has a drawback that the characteristics deteriorate with time. In order to prevent such deterioration with time, it has been proposed to form a moisture-proof protective layer on the surface of the phosphor layer.

For example, a method is known in which the upper and side surfaces of the phosphor layer and the outer periphery of the scintillator layer of the support (substrate) are covered with polyparaxylylene resin (see, for example, Patent Document 5).

On the other hand, in the flat panel type radiation detector (FPD; also referred to as “radiation image conversion panel”) using cesium iodide (CsI), in recent years, an increase in the area of the panel and a portable cassette type have been required. Compared to computed radiography (CR) using photostimulable phosphors, the required level of moisture resistance and impact resistance has become much stricter. I wasn't satisfied.

In order to improve the moisture resistance and impact resistance of a flat panel radiation detector (FPD) using cesium iodide (CsI), a conventional protective layer, sealing with a protective film, Although buffering has been used between the bodies, the required level could not be met.
JP 2001-255610 A US Patent Application Publication No. 2001 / 0010831A1 JP-A-63-215987 Japanese Examined Patent Publication No. 54-35060 JP 2000-284053 A

The present invention has been made in view of the above-mentioned problems and situations, and the problem to be solved is a radiation image conversion panel having high sensitivity (high brightness), high sharpness, and excellent storage stability, and a method for producing the same. Is to provide.

As a result of repeated studies on the formation of a phosphor layer made of a cesium halide phosphor by a vapor deposition method, the present inventor has obtained a moderate vacuum (about 0.1 Pa to 10 Pa) such as vapor deposition by a resistance heating method. In the case of performing vapor deposition, it has been found that when a phosphor is vapor-deposited at a vapor deposition mass rate within a specific range, a phosphor layer with extremely good columnar crystallinity and a remarkably high light emission amount can be obtained, leading to the present invention.

That is, the above-mentioned problem according to the present invention is solved by the following means.

1. A radiation image conversion panel having a phosphor layer containing a phosphor columnar crystal composed mainly of a cesium halide phosphor formed by a vapor deposition method, wherein the phosphor layer has a degree of vacuum of 0. It is characterized in that it is formed under the condition that it is maintained within the range of 05 Pa to 10 Pa and the deposition mass rate is maintained within the range of 0.01 mg / cm ² · min to 2.0 mg / cm ² · min. Radiation image conversion panel.

2. The phosphor columnar crystal is (1) an additive containing at least one of cesium iodide (CsI) and cesium bromide (CsBr) and (2) at least one of thallium (Tl) and europium (Eu); 2. The radiation image conversion panel as described in 1 above, wherein the radiation image conversion panel is formed using as a raw material.

3. 3. A method for producing a radiation image conversion panel according to 1 or 2, wherein the radiation image conversion panel is produced by heating an evaporation source containing a cesium halide phosphor or its raw material in a vapor deposition apparatus. Having a step of forming a phosphor layer by vapor-depositing a substance on a support, and after introducing an inert gas into the vapor deposition apparatus, maintaining a degree of vacuum within a range of 0.05 Pa to 10 Pa; and A method for producing a radiation image conversion panel, characterized in that vapor deposition is performed at a vapor deposition mass rate of 0.01 mg / cm ² · min to 2.0 mg / cm ² · min.

4. 4. The manufacturing of the radiation image conversion panel according to 3 above, wherein the phosphor layer is formed by performing vapor deposition while changing the degree of vacuum in the vapor deposition apparatus within the range in the course of forming the phosphor layer. Method.

5. 5. The method for producing a radiation image conversion panel according to 3 or 4, wherein the phosphor layer is formed by performing vapor deposition while changing the vapor deposition mass rate within the range in the course of forming the phosphor layer. .

6. 6. The radiation image conversion panel according to any one of 3 to 5, wherein the phosphor layer is formed by performing vapor deposition while changing the temperature of the support in the course of forming the phosphor layer. Production method.

7. 7. The method for producing a radiation image conversion panel according to any one of 3 to 6, wherein the thickness of the support is in the range of 30 μm to 500 μm.

8. 8. The method for producing a radiation image conversion panel according to any one of the above 3 to 7, wherein a vapor deposition apparatus having an evaporation source and a support rotating mechanism is used in a vacuum vessel, and the support is rotated by the support rotating mechanism. A method for producing a radiation image conversion panel, comprising: forming a phosphor layer by a vapor deposition method including a step of vapor-depositing a phosphor material while rotating the support.

By the above means of the present invention, it is possible to provide a radiation image conversion panel having high sensitivity (high luminance), high sharpness, and excellent storage stability, and a method for producing the same.

Schematic diagram of radiation image conversion panel manufacturing equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus of radiation image conversion 2 Vacuum container 3 Vacuum pump 4 Support body 5 Support body holder 6 Support body rotation mechanism 7 Support body rotating shaft 8 Evaporation source 9 Shutter 10 Shielding plate

The radiation image conversion panel of the present invention is a radiation image conversion panel having a phosphor layer containing a phosphor columnar crystal mainly composed of a cesium halide phosphor formed by a vapor deposition method. Under the condition that the body layer maintains the degree of vacuum within the range of 0.05 Pa to 10 Pa and the deposition mass rate within the range of 0.01 mg / cm ² · min to 2.0 mg / cm ² · min. , Formed. This feature is a technical feature common to the inventions according to claims 1 to 9. Here, the degree of vacuum is more preferably in the range of 0.10 Pa to 2.0 Pa.

As an embodiment of the present invention, the phosphor columnar crystal is composed of (1) at least one of cesium iodide (CsI) and cesium bromide (CsBr), and (2) of thallium (Tl) and europium (Eu). It is preferable that the raw material is an additive containing at least one of the above.

As a method for producing a radiation image conversion panel of the present invention, a phosphor is produced by evaporating a substance generated by heating an evaporation source containing a cesium halide phosphor or its raw material on a support in a vapor deposition apparatus. A step of forming a layer, and after introducing an inert gas into the vapor deposition apparatus, the degree of vacuum is maintained within a range of 0.05 Pa to 10 Pa, and the vapor deposition mass rate is 0.01 mg / cm ² · min. It is preferable that the production method is an embodiment in which vapor deposition is carried out within a range of ˜2.0 mg / cm ² · min.

As an embodiment of the manufacturing method, it is preferable that the phosphor layer is formed by performing vapor deposition while changing the degree of vacuum in the vapor deposition apparatus within the range in the course of forming the phosphor layer. Moreover, it is also preferable to perform vapor deposition by changing the vapor deposition mass rate within the range in the course of forming the phosphor layer. Furthermore, it is also preferable to perform vapor deposition by changing the temperature of the support in the course of forming the phosphor layer. The thickness of the support is preferably in the range of 30 μm to 500 μm.

Further, as an embodiment of the manufacturing method of the radiation image conversion panel, a support is installed in the support rotating mechanism using a vapor deposition apparatus having an evaporation source and a support rotating mechanism in a vacuum vessel, and the support is supported. It is preferable that the method is a manufacturing method in which the phosphor layer is formed by a vapor deposition method including a step of vapor-depositing the phosphor material while rotating the body.

(Configuration of radiation image conversion panel)
The radiation image conversion panel of the present invention is characterized by having a phosphor layer containing a phosphor columnar crystal mainly composed of a cesium halide phosphor formed by a vapor deposition method. It is preferable that various functional layers as described later are provided in addition to the layers depending on the purpose.

The radiation image conversion panel of the present invention is a radiation image conversion panel in which a phosphor layer is provided on a first substrate by a vapor deposition method via a functional layer such as a reflective layer. Adhering or closely adhering a photoelectric conversion panel provided with a photoelectric conversion element section (“planar light receiving element”) in which pixels consisting of a photosensor and TFT (Thin Film Transistor) or CCD (Charge Coupled Devices) are two-dimensionally arranged. A radiation image conversion panel may be used, or after forming a planar light receiving element on a substrate, a radiation image conversion may be performed by providing a phosphor layer directly or through a functional layer such as a reflective layer or a protective layer by a vapor deposition method. It is good as a panel.

Hereinafter, as a typical example, various constituent layers and constituent elements in the case of forming a radiation image conversion panel will be mainly described. However, a phosphor layer is provided directly after forming a planar light receiving element on a substrate. The same applies to the radiation image conversion panel.

(Phosphor layer)
The phosphor layer according to the present invention is a phosphor layer containing a phosphor columnar crystal composed mainly of a cesium halide phosphor formed by a vapor deposition method.

As a material for forming the phosphor constituting the phosphor layer according to the present invention, various known phosphor materials can be used. In the present invention, in particular, cesium iodide (CsI) and cesium bromide are used. The phosphor layer is preferably formed using at least one of (CsBr) as a main component. These compounds have a relatively high rate of change from X-rays to visible light, and can easily form phosphors into a columnar crystal structure by vapor deposition. Therefore, scattering of emitted light within the crystal is suppressed by the light guide effect, and fluorescence is reduced. This is because the thickness of the body layer can be increased.

However, since only cesium iodide (CsI) or cesium bromide (CsBr) has low luminous efficiency, it is preferable to add various activators.

For example, as disclosed in JP-B-54-35060, a mixture of cesium iodide (CsI) and sodium iodide (NaI) at an arbitrary molar ratio can be mentioned. Further, for example, CsI as disclosed in Japanese Patent Application Laid-Open No. 2001-59899 is deposited, and thallium (Tl), europium (Eu), indium (In), lithium (Li), potassium (K), rubidium (Rb) ), CsI containing an activating substance such as sodium (Na) is preferred. In the present invention, thallium (Tl) and europium (Eu) are particularly preferable. Furthermore, thallium (Tl) is preferred.

In the phosphor layer according to the present invention, it is desirable that the content of the additive is an optimum amount according to the target performance, but 0.001 mol% to 50 mol with respect to the content of cesium iodide. %, And preferably 0.1 mol% to 10.0 mol%.

Here, when the additive is 0.001 mol% or more with respect to cesium iodide or cesium bromide, the emission luminance obtained by using cesium iodide or cesium bromide alone is improved, and the intended light emission is achieved. This is preferable in terms of obtaining luminance. Moreover, it is preferable that it is 50 mol% or less because the properties and functions of cesium iodide or cesium bromide can be maintained.

Note that the thickness of the phosphor layer is preferably 100 μm to 800 μm, and more preferably 120 μm to 700 μm from the viewpoint of obtaining a good balance between luminance and sharpness characteristics.

The phosphor columnar crystal according to the present invention needs to be formed by a vapor deposition method. As the vapor deposition method, a vapor deposition method, a sputtering method, a CVD method, an ion plating method, or the like can be used. In the present invention, the vapor deposition method is particularly preferable.

In the present invention, the cesium halide phosphor may be a phosphor represented by the following basic composition formula (I) or (II). In this case, in the basic composition formula (I), X is iodine (I), and z is preferably a numerical value within the range of 1 × 10 ⁻³ ≦ z ≦ 50, and 1 × 10 ⁻¹ ≦ z. A numerical value within the range of ≦ 10 is more preferable.

In the basic composition formula (II), X is bromine (Br), and z is preferably a numerical value in the range of 1 × 10 ⁻⁵ ≦ z ≦ 1 × 10 ^−2. A numerical value within the range of ⁻⁵ ≦ z ≦ 1 × 10 ⁻³ is more preferable.
Basic composition formula (I): CsX · aM ^I X _a · bM ^II X _b2 · cM ^III X _c3 : zTl
Basic composition formula (II): CsX · aM ^I X _a · bM ^II X _b2 · cM ^III X _c3 : zEu
Where M ^I represents at least one alkali metal selected from Li, Na, K and Rb; M ^II represents at least one selected from Be, Mg, Ca, Sr, Ba, Ni, Cu, Zn and Cd. M ^III represents Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Represents at least one rare earth element or trivalent metal selected from Al, Ga and In; X, X _a , X _b and X _c each represent at least one halogen selected from F, Cl, Br and I; A, b, c, and z represent numerical values in the ranges of 0 ≦ a <0.5, 0 ≦ b <0.5, 0 ≦ c <0.5, and 0 <z <1.0, respectively. .

(Reflective layer)
In the present invention, it is preferable to provide a reflective layer (also referred to as a “metal reflective layer”) on the support (substrate), in order to reflect light emitted from the phosphor and increase the light extraction efficiency. Is. The reflective layer is preferably formed of a material containing any element selected from the element group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au.

In particular, it is preferable to use a metal thin film composed of the above elements, for example, an Ag film, an Al film, or the like. Two or more such metal thin films may be formed.

When the metal thin film has two or more layers, the lower layer is preferably a layer containing Cr from the viewpoint of improving the adhesion to the substrate. Further, a layer made of a metal oxide such as SiO ₂ or TiO ₂ may be provided in this order on the metal thin film to further improve the reflectance.

It should be noted that the thickness of the reflective layer is preferably 0.005 μm to 0.3 μm, more preferably 0.01 μm to 0.2 μm from the viewpoint of emission light extraction efficiency.

The formation method of the reflective layer according to the present invention may be any known method, and examples thereof include a sputtering process using the above raw materials.

(Metal protective layer)
In the radiation image conversion panel according to the present invention, a metal protective layer may be provided on the reflective layer.

The metal protective layer is preferably formed by applying and drying a resin dissolved in a solvent. A polymer having a glass transition point of 30 ° C. to 100 ° C. is preferable from the viewpoint of forming a film with a deposited crystal and a support (substrate). Specifically, polyurethane resin, vinyl chloride copolymer, vinyl chloride-acetic acid Vinyl copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, polyester resin, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer Examples include polymers, various synthetic rubber resins, phenol resins, epoxy resins, urea resins, melamine resins, phenoxy resins, silicon resins, acrylic resins, urea formamide resins, and the like, and polyester resins are particularly preferable.

The thickness of the metal protective layer is preferably 0.1 μm or more in terms of adhesion, and preferably 3.0 μm or less in terms of ensuring the smoothness of the surface of the metal protective layer. More preferably, the thickness of the metal protective layer is in the range of 0.2 to 2.5 μm.

Solvents used for metal protective layer preparation include lower alcohols such as methanol, ethanol, n-propanol and n-butanol, chlorine atom-containing hydrocarbons such as methylene chloride and ethylene chloride, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, Aromatic compounds such as toluene, benzene, cyclohexane, cyclohexanone, xylene, esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate, butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ester, ethylene glycol monomethyl ester, And mixtures thereof.

(Undercoat layer)
In the present invention, it is preferable to provide an undercoat layer from the viewpoint of attaching a film between the support (substrate) and the phosphor layer or between the reflective layer and the phosphor layer. The undercoat layer preferably contains a polymer binder (binder), a dispersant and the like.

The thickness of the undercoat layer is 0.5 μm from the viewpoint of suppressing light scattering in the undercoat layer and preventing deterioration of sharpness and preventing disorder of columnar crystallinity by heat treatment. It is preferable to adjust to a range of ˜4 μm.

Hereinafter, the components of the undercoat layer will be described.

<Polymer binder>
The undercoat layer according to the present invention is preferably formed by applying and drying a polymer binder (hereinafter also referred to as “binder”) dissolved or dispersed in a solvent. Specific examples of the polymer binder include polyurethane, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer. Polymer, polyamide resin, polyvinyl butyral, polyester, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea resin, melamine resin, phenoxy resin, silicone resin , Acrylic resins, urea formamide resins, and the like. Of these, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, and nitrocellulose are preferably used.

As the polymer binder according to the present invention, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like are particularly preferable in terms of adhesion to the phosphor layer. Further, a polymer having a glass transition temperature (Tg) of 30 to 100 ° C. is preferable from the viewpoint of attaching a film between the deposited crystal and the support (substrate). From this viewpoint, a polyester resin is particularly preferable.

Solvents that can be used to prepare the undercoat layer include lower alcohols such as methanol, ethanol, n-propanol, and n-butanol, hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride, acetone, methyl ethyl ketone, and methyl isobutyl ketone. Such as ketones, toluene, benzene, cyclohexane, cyclohexanone, xylene and other aromatic compounds, methyl acetate, ethyl acetate, butyl acetate and other lower fatty acid and lower alcohol esters, dioxane, ethylene glycol monoethyl ester, ethylene glycol monomethyl ester And ethers thereof and mixtures thereof.

It should be noted that the undercoat layer according to the present invention may contain a pigment or a dye in order to prevent scattering of light emitted from the phosphor and improve sharpness.

(Protective layer)
The protective layer according to the present invention focuses on protecting the phosphor layer. That is, cesium iodide (CsI) or cesium bromide (CsBr) has high hygroscopicity, and if it is left exposed, it absorbs water vapor in the air and deliquesces. To do.

The protective layer can be formed using various materials. For example, a polyparaxylylene film is formed by a CVD method. That is, a polyparaxylylene film can be formed on the entire surface of the phosphor and the support (substrate) to form a protective layer.

Also, as another protective layer, a polymer film can be provided on the phosphor layer. In addition, as a material of the polymer film, a film similar to the polymer film as a support (substrate) material described later can be used.

The thickness of the polymer film is preferably 12 μm or more and 120 μm or less, more preferably 20 μm or more and 80 μm or less, taking into consideration the formation of voids, the protective properties of the phosphor layer, sharpness, moisture resistance, workability, etc. Is preferred. The haze ratio is preferably 3% or more and 40% or less, more preferably 3% or more and 10% or less in consideration of sharpness, radiation image unevenness, production stability, workability, and the like. The haze ratio can be measured, for example, by Nippon Denshoku Industries Co., Ltd. NDH5000W. The required haze ratio is appropriately selected from commercially available polymer films and can be easily obtained.

The light transmittance of the protective film is preferably 70% or more at 550 nm in consideration of the photoelectric conversion efficiency, the emission wavelength of the phosphor, etc., but a film having a light transmittance of 99% or more is difficult to obtain industrially. Therefore, it is preferably substantially 99% to 70%.

The moisture permeability of the protective film is preferably 50 g / m ² · day (40 ° C., 90% RH) (measured according to JIS Z0208) or less, more preferably 10 g / m ² taking into account the protective properties and deliquescence of the phosphor layer. m ² · day (40 ° C./90% RH) (measured in accordance with JIS Z0208) or less is preferable, but a film having a moisture permeability of 0.01 g / m ² · day (40 ° C./90% RH) or less is industrial. Is practically 0.01 g / m ² · day (40 ° C, 90% RH) or more, 50 g / m ² · day (40 ° C., 90% RH) (measured according to JIS Z0208) ) Or less, more preferably 0.1 g / m ² · day (40 ° C./90% RH) or more, 10 g / m ² · day (40 ° C./90% RH) (measured according to JIS Z0208) or less .

(Support: substrate)
In the present invention, the support (also referred to as “substrate”) is preferably a quartz glass sheet, a metal sheet made of aluminum, iron, tin, chrome, a carbon fiber reinforced sheet, a polymer film, or the like.

Polymer films such as cellulose acetate film, polyester film, polyethylene terephthalate (PEN) film, polyamide film, polyimide (PI) film, triacetate film, polycarbonate film, carbon fiber reinforced resin sheet, etc. Can be used. In particular, a polymer film containing polyimide or polyethylene naphthalate is suitable for forming phosphor columnar crystals by a vapor phase method using cesium iodide as a raw material.

The polymer film as the support (substrate) according to the present invention is preferably a polymer film having a thickness of 30 μm to 500 μm and further having flexibility.

Here, the "flexible support (substrate) having" means elastic modulus at 120 ° C. (E120) the support is ^{1000N / mm 2 ~ 6000N / mm} 2 (substrate), such supports As the (substrate), a polymer film containing polyimide or polyethylene naphthalate is preferable.

Note that the “elastic modulus” refers to the slope of the stress relative to the strain amount in a region where the strain indicated by the standard line of the sample conforming to JIS C 2318 and the corresponding stress have a linear relationship using a tensile tester. Is what we asked for. This is a value called Young's modulus, and in the present invention, this Young's modulus is defined as an elastic modulus.

Support for use in the present invention (substrate) is preferably an elastic modulus at the 120 ° C. as described above (E120) is ^{1000N / mm 2 ~ 6000N / mm} 2. More preferably, it is 1200 N / mm ² to 5000 N / mm ² .

Specifically, polyethylene naphthalate ^{(E120 = 4100N / mm 2)} , polyethylene terephthalate ^{(E120 = 1500N / mm 2)} , polybutylene naphthalate ^{(E120 = 1600N / mm 2)} , polycarbonate (E120 = 1700N / ^mm 2) , Syndiotactic polystyrene (E120 = 2200 N / mm ² ), polyetherimide (E120 = 1900 N / mm ² ), polyarylate (E120 = 1700 N / mm ² ), polysulfone (E120 = 1800 N / mm ² ), polyethersulfone Examples thereof include a polymer film made of (E120 = 1700 N / mm ² ).

These may be used singly or may be laminated or mixed. Among them, as a particularly preferable polymer film, a polymer film containing polyimide or polyethylene naphthalate is preferable as described above.

Note that when bonding the scintillator panel and the planar light receiving element surface, uniform image quality characteristics cannot be obtained within the light receiving surface of the flat panel detector due to the influence of deformation of the support (substrate) or warpage during vapor deposition. Regarding the point, the support (substrate) is a polymer film having a thickness of 30 μm to 500 μm, so that the scintillator panel is deformed into a shape that matches the shape of the planar light receiving element surface, and is uniform over the entire light receiving surface of the flat panel detector Sharpness is obtained.

Further, the support may have a resin layer in order to make the surface smooth. The resin layer preferably contains a compound such as polyimide, polyethylene phthalate, paraffin, graphite, and the film thickness is preferably about 5 μm to 50 μm. This resin layer may be provided on the surface of the support or on the back surface.

Moreover, means for providing an adhesive layer on the surface of the support include means such as a bonding method and a coating method. Of these, the bonding method is performed using heating and a pressure roller. The heating conditions are about 80 ° C. to 150 ° C., the pressing conditions are 4.90 × 10 N / cm to 2.94 × 10 ² N / cm, and the conveyance speed is 0.1 m / second to 2.0 m / second is preferable.

(Method for manufacturing radiation image conversion panel)
The manufacturing method of the radiation image conversion panel according to the present invention will be described in detail taking the case of vapor deposition by a resistance heating method as an example. The resistance heating method has an advantage that vapor deposition can be performed at a moderate degree of vacuum, and a vapor deposition film having a good columnar crystal can be obtained relatively easily.

In the case of forming a phosphor layer (deposition film) by multi-source deposition (co-evaporation), first, as an evaporation source, the phosphor containing the host cesium halide (CsX) component and the activator (Eu or Tl) component Prepare at least two evaporation sources comprising Multi-source deposition is preferable because the evaporation rate can be controlled when the vapor pressures of the matrix component and the activator component of the phosphor are greatly different. Each evaporation source may be composed of only a CsX component and an activator (Eu, Tl) component, or may be a mixture with additive components, depending on the desired phosphor composition. . Further, the number of evaporation sources is not limited to two, and for example, three or more evaporation sources may be added by separately adding evaporation sources composed of additive components.

The matrix CsX component of the phosphor may be the CsX compound itself, or may be a mixture of two or more raw materials that can react to form CsX.

Further, the activator Eu component is generally a compound containing Eu, and for example, Eu halides and oxides are used.

The molar ratio of Eu ²⁺ compound in the Eu compound is preferably 70% or more. In general, Eu compounds contain Eu ²⁺ and Eu ³⁺ in a mixture, but the desired stimulating luminescence (or even instantaneous light emission) is emitted from a phosphor using Eu ²⁺ as an activator. It is. The Eu compound is preferably EuOBr.

The Tl compound is preferably thallium iodide (TlI).

The evaporation source preferably has a water content of 0.5% by mass or less. In particular, when the CsX component and the activator component serving as the evaporation source are hygroscopic, it is important from the viewpoint of preventing bumping to suppress the water content to such a low value. The evaporation source is preferably dehydrated by subjecting each of the phosphor components to a heat treatment in a temperature range of 100 ° C. to 300 ° C. under reduced pressure. Alternatively, each phosphor component may be heated and melted in an atmosphere containing no moisture such as a nitrogen gas atmosphere at a temperature equal to or higher than the melting point of the component for several tens of minutes to several hours.

Further, in the present invention, the evaporation source, particularly the evaporation source containing the CsX component, has an alkali metal impurity (alkali metal other than the constituent elements of the phosphor) of 10 ppm or less, and an alkaline earth metal impurity (phosphor of the phosphor). The content of (alkaline earth metal other than constituent elements) is desirably 5 ppm (mass) or less.

Such an evaporation source can be prepared by using a raw material with a low impurity content such as alkali metal or alkaline earth metal.

A plurality of evaporation sources and a support are arranged in a vapor deposition apparatus, and the inside of the apparatus is evacuated to a medium vacuum degree of about 0.05 Pa to 10 Pa. The degree of vacuum is preferably 0.05 Pa to 3 Pa. Alternatively, the inside of the apparatus is evacuated to a high vacuum level of about 1 × 10 ⁻⁵ Pa to 1 × 10 ⁻² Pa, and then an inert gas such as Ar gas, Ne gas, or N ₂ gas is introduced to Apply vacuum.

This makes it possible to reduce the water pressure, oxygen partial pressure, etc. in the apparatus. As the exhaust device, a rotary pump, a turbo molecular pump, a cryopump, a diffusion pump, a mechanical booster, or the like can be used in appropriate combination.

In the present invention, it is preferable to perform the deposition by changing the degree of vacuum at least once. Preferably, vapor deposition is performed by setting the vacuum degree in the initial stage of growth including the nucleation part lower than the vacuum degree in the latter half of the growth period.

Next, the evaporation source is heated by passing an electric current through each resistance heater. The CsX component, the activator component, and the like, which are evaporation sources, are heated to evaporate and scatter, and cause a reaction to form a phosphor and deposit on the support surface.

The temperature of the support is generally in the range of 20 ° C to 350 ° C, more preferably in the range of 25 ° C to 250 ° C.

In the present invention, it is preferable to perform the deposition by changing the support temperature at least once. Preferably, the deposition is performed by setting the support temperature in the initial stage of growth including the nucleation part lower than the support temperature in the latter half of the growth.

Generally, in vapor deposition under medium vacuum, the mean free path of the component particles evaporated from the evaporation source by heating is short, and the evaporation component particles do not reach the support unless the distance between the evaporation source and the support is reduced.

However, when the distance between the evaporation source and the support is small, the support temperature tends to increase due to the influence of radiation from the evaporation source heated by the support. When the deposition mass rate exceeds 2 mg / cm ² · min, particularly in the case of a thin resin substrate, the temperature rise of the substrate is large, and the light emission amount deviates greatly from the optimum substrate temperature, thereby causing a decrease in light emission amount. I understood that. At the same time, it was also found that the pillars of the phosphors grown on the support were fused and it was difficult to obtain independent columnar crystals. As a result, a phosphor layer with reduced sensitivity and sharpness can be obtained.

On the other hand, when the vapor deposition mass rate is slower than 0.01 mg / cm ² · min, it is found that the vaporized component particles collide with the gas in the vapor deposition apparatus such as an inert gas, and a good columnar crystal cannot be obtained. It was. As a result, the obtained phosphor layer has a reduced amount of X-ray absorption, and it becomes difficult to extract emitted light from the deep part of the phosphor layer, so that the amount of emitted light is reduced. Therefore, the sensitivity and sharpness are similarly reduced.

In the present invention, the rate of deposition of the phosphor, i.e., the deposition mass rate, in terms of independent columnar crystalline and emission amount, in the range of 0.01 mg / cm ² · min ~ 2.0mg / cm ² · min More preferably, it is in the range of 0.03 mg / cm ² · min to 2.0 mg / cm ² · min.

In the present invention, the deposition rate of the phosphor, that is, the deposition mass rate is preferably changed at least once to perform the deposition. Preferably, vapor deposition is performed by setting the vapor deposition mass rate in the initial stage of growth including the nucleation part lower than the vapor deposition mass rate in the latter half of the growth.

The vapor deposition rate of each evaporation source can be controlled by adjusting the resistance current of the heater and the opening area of the crucible.

The distance (vertical distance) between each evaporation source and the support varies depending on the size of the support, but is preferably in the range of 50 mm to 500 mm. The distance between the evaporation sources is preferably in the range of 50 mm to 100 mm.

It should be noted that two or more phosphor layers can be formed by performing heating with a resistance heater in a plurality of times. The deposited film may be heat-treated (annealed) after the deposition.

Prior to forming the phosphor layer made of the phosphor, a phosphor layer (deposition film) made only of the phosphor matrix compound (CsX) may be formed. This CsX phosphor layer (deposition film) is generally composed of a columnar crystal structure or an aggregate of spherical crystals, and the columnar crystallinity of the phosphor layer (deposition film) formed thereon can be further improved. . Furthermore, when the relative density of the CsX vapor deposition film is in the range of 80% to 98%, it can also function as a stress relaxation layer and enhance the adhesion between the support and the phosphor layer. Depending on the heating of the support during vapor deposition and / or heat treatment after vapor deposition, additives such as an activator in the phosphor layer (deposition film) diffuse into the CsX phosphor layer (deposition film). The boundaries are not always clear.

In the case of single deposition, the phosphor itself or the phosphor raw material mixture is used as an evaporation source and heated with a single resistance heater. The evaporation source is prepared in advance to contain a desired concentration of activator. Alternatively, the vapor deposition can be performed while supplying the CsX component to the evaporation source in consideration of the vapor pressure difference between the CsX component and the Tl or Eu component.

By performing vapor deposition in this way, a phosphor layer in which the columnar crystals of the phosphor are grown in the thickness direction can be obtained. The phosphor layer does not contain a binder and is composed only of the phosphor, and there are voids between the columnar crystals of the phosphor. The thickness of the phosphor layer varies depending on the characteristics of the intended radiation image conversion panel, the means and conditions of the vapor deposition method, but is usually in the range of 50 μm to 1 mm, preferably in the range of 200 μm to 700 μm. .

The vapor deposition method used in the present invention is not limited to the resistance heating method described above, and any other vapor deposition method may be used as long as it is performed under a medium vacuum.

The support 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 bonded to the support prepared separately by using an adhesive, A method of providing a phosphor layer on a support may be used. Alternatively, the support (substrate) may not be attached to the phosphor layer.

The method for manufacturing a radiation image conversion panel according to the present invention uses a vapor deposition apparatus having an evaporation source and a support rotation mechanism in a vacuum vessel, and installs the support on the support rotation mechanism and rotates the support. However, it is preferable that the phosphor layer is formed by a vapor deposition method including a step of vapor-depositing the phosphor material.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.

<Radiological image conversion panel manufacturing equipment>
FIG. 1 is a schematic configuration diagram of a radiographic image conversion panel manufacturing apparatus 1 according to the present invention. As shown in FIG. 1, the radiation image conversion panel manufacturing apparatus 1 includes a vacuum container 2, and the vacuum container 2 includes a vacuum pump 3 that evacuates the inside of the vacuum container 2 and introduces the atmosphere. .

A support holder 5 that holds the support 4 is provided near the upper surface inside the vacuum vessel 2.

A phosphor layer is formed on the surface of the support 4 by a vapor deposition method. As the vapor deposition method, a vapor deposition method, a sputtering method, a CVD method, an ion plating method, or the like can be used. In the present invention, the vapor deposition method is particularly preferable.

The support holder 5 is configured to hold the support 4 so that the surface of the support 4 on which the phosphor layer is formed faces the bottom surface of the vacuum vessel 2 and is parallel to the bottom surface of the vacuum vessel 2. It has become.

The support holder 5 is preferably provided with a heater (not shown) for heating the support 4. By heating the support 4 with this heater, the adhesion of the support 4 to the support holder 5 is enhanced and the film quality of the phosphor layer is adjusted. Further, the adsorbate on the surface of the support 4 is removed and removed, and an impurity layer is prevented from being generated between the surface of the support 4 and the phosphor.

Also, a heating medium or a mechanism (not shown) for circulating the heating medium may be provided as heating means. This means is suitable for the case where vapor deposition is performed while maintaining the temperature of the support 4 at a relatively low temperature of 50 to 150 ° C. during the vapor deposition of the phosphor.

Further, a halogen lamp (not shown) may be provided as a heating means. This means is suitable for the case where vapor deposition is performed while maintaining the temperature of the support 4 at a relatively high temperature such as 150 ° C. or higher during the vapor deposition of the phosphor.

Furthermore, the support holder 5 is provided with a support rotating mechanism 6 that rotates the support 4 in the horizontal direction. The support rotating mechanism 6 supports the support holder 5 and rotates the support 4 and a motor (not shown) that is disposed outside the vacuum vessel 2 and serves as a drive source for the support rotating shaft 7. Z).

Further, near the bottom surface inside the vacuum vessel 2, evaporation sources 8 a and 8 b are arranged at positions facing each other on the circumference of a circle centering on a center line perpendicular to the support 4. In this case, the distance between the support 4 and the evaporation sources 8a and 8b is preferably 100 to 1500 mm, more preferably 200 to 1000 mm. In addition, the distance between the center line perpendicular to the support 4 and the evaporation sources 8a and 8b is preferably 100 to 1500 mm, more preferably 200 to 1000 mm.

In the radiation image conversion panel manufacturing apparatus according to the present invention, it is possible to provide a large number of three or more evaporation sources, and the respective evaporation sources may be arranged at equal intervals or at different intervals. May be. Further, the radius of a circle centered on the center line perpendicular to the support 4 can be arbitrarily determined.

The evaporation sources 8a and 8b contain the phosphor and heat it by a resistance heating method. Therefore, the evaporation sources 8a and 8b may be composed of an alumina crucible wound with a heater, or a boat or a heater made of a refractory metal. May be. Further, the method of heating the phosphor may be a method such as heating by an electron beam or heating by high frequency induction other than the resistance heating method, but in the present invention, it is relatively easy to handle, inexpensive, and In view of the fact that it can be applied to a large number of substances, a method in which a direct current is passed and resistance heating is performed, and a method in which a crucible is indirectly resistance heated with a surrounding heater is preferable. The evaporation sources 8a and 8b may be molecular beam sources by a molecular source epitaxial method.

Further, a shutter 9 that blocks a space from the evaporation sources 8a and 8b to the support 4 is provided between the evaporation sources 8a and 8b and the support 4 so as to be openable and closable in the horizontal direction. In the evaporation sources 8a and 8b, substances other than the target substance attached to the surface of the phosphor can be prevented from evaporating at the initial stage of vapor deposition and adhering to the support 4.

<Manufacturing method of radiation image conversion panel>
Next, the manufacturing method of the radiographic image conversion panel which concerns on this invention using the above-mentioned scintillator panel manufacturing apparatus 1 is demonstrated.

First, the support 4 is attached to the support holder 5. Further, in the vicinity of the bottom surface of the vacuum vessel 2, evaporation sources 8 a and 8 b are arranged on the circumference of a circle centered on a center line perpendicular to the support 4. In this case, the distance between the support 4 and the evaporation sources 8a and 8b is preferably 100 to 1500 mm, more preferably 200 to 1000 mm. In addition, the distance between the center line perpendicular to the support 4 and the evaporation sources 8a and 8b is preferably 100 to 1500 mm, more preferably 200 to 1000 mm.

Next, the inside of the vacuum vessel 2 is evacuated and adjusted to a desired degree of vacuum. Thereafter, the support holder 5 is rotated with respect to the evaporation sources 8a and 8b by the support rotation mechanism 6, and when the vacuum container 2 reaches a vacuum degree capable of vapor deposition, the phosphor is evaporated from the heated evaporation sources 8a and 8b. The phosphor is grown on the surface of the support 4 to a desired thickness.

Note that the phosphor layer can be formed by performing the process of growing the phosphor on the surface of the support 4 in a plurality of times.

In the vapor deposition method, the vapor deposition target (support 4, protective layer, or intermediate layer) may be cooled or heated as necessary during vapor deposition.

Further, after the vapor deposition, the phosphor layer may be heat-treated. In the vapor deposition method, reactive vapor deposition may be performed in which vapor deposition is performed by introducing a gas such as O ₂ or H ₂ as necessary.

The thickness of the phosphor layer to be formed is 50 μm to 2000 μm, preferably 50 μm to 1000 μm from the viewpoint of obtaining the effects of the present invention, although it varies depending on the purpose of use of the radiation image conversion panel and the type of the phosphor. More preferably, it is 100 μm to 800 μm.

The temperature of the support 4 on which the phosphor layer is formed is preferably set to room temperature (rt) to 300 ° C., more preferably 50 ° C. to 250 ° C.

After the phosphor layer is formed as described above, the phosphor layer is physically or chemically protected on the surface of the phosphor layer opposite to the support 4 as necessary. A protective layer may be provided. The protective layer may be formed by directly applying a coating solution for the protective layer to the surface of the phosphor layer, or a protective layer separately formed in advance may be adhered to the phosphor layer. The thickness of these protective layers is preferably 0.1 μm to 2000 μm.

The protective layer may be formed by laminating inorganic substances such as SiC, SiO ₂ , SiN, and Al ₂ O ₃ by vapor deposition, sputtering, or the like.

In the present invention, it is preferable to provide the above various functional layers in addition to the protective layer.

According to the radiographic image conversion panel manufacturing apparatus 1 or the manufacturing method described above, by providing the plurality of evaporation sources 8a and 8b, the overlapping portions of the vapor flows of the evaporation sources 8a and 8b are rectified, and the surface of the support 4 is rectified. The crystallinity of the phosphor to be deposited can be made uniform. At this time, as the number of evaporation sources is increased, the vapor flow is rectified at more locations, so that the crystallinity of the phosphor can be made uniform in a wider range. Further, by disposing the evaporation sources 8 a and 8 b on the circumference of a circle centering on the center line perpendicular to the support 4, the effect that the crystallinity becomes uniform due to the rectification of the vapor flow is provided. Can be obtained isotropically on the surface.

Further, the phosphor can be uniformly deposited on the surface of the support 4 by depositing the phosphor while rotating the support 4 by the support rotating mechanism 6.

As described above, according to the radiation image conversion panel manufacturing apparatus 1 or the manufacturing method of the present invention, the phosphor layer is grown on the surface of the support 4 so that the crystallinity of the phosphor is uniform. Thus, the sensitivity unevenness of the phosphor layer can be reduced, and the sharpness of the radiation image obtained from the radiation image conversion panel using the scintillator panel according to the present invention can be improved.

Further, by limiting the incident angle of the phosphor deposited on the support 4 to a predetermined range to prevent variations in the incident angle of the stimulable phosphor, the crystallinity of the phosphor is made more uniform, and the radiation image The sharpness of the radiation image obtained from the conversion panel can be improved.

In addition, although the case where the support body holder 5 was provided with the support body rotation mechanism 6 was demonstrated above, this invention is not necessarily restricted to this, It vapor-deposits in the state which the support body holder 5 hold | maintained the support body 4 and was still. The present invention is also applicable to the case where the phosphors from the evaporation sources 8a and 8b are deposited by moving the support 4 in the horizontal direction with respect to the evaporation sources 8a and 8b.

Hereinafter, the present invention will be specifically described with reference to examples, but the embodiment of the present invention is not limited thereto.

The radiation image conversion panel according to the present invention was obtained by the following method using the manufacturing apparatus shown in FIG.

[Comparative Example 1-1]
(Production of radiation image conversion panel)
Phosphor 1 (CsI only) and phosphor 2 (CsI: 0.003 Tl) were vapor-deposited on one side of a support made of a polyimide resin sheet having a thickness of 0.1 mm to form a phosphor layer. That is, first, a support was placed on a support holder provided with a support rotation mechanism. Next, the phosphor raw material is filled in the evaporation source crucible as an evaporation material, and the two evaporation source crucibles are in the vicinity of the bottom of the inside of the vacuum vessel and are circles centered on the center line perpendicular to the support Arranged on the circumference. At this time, the distance between the support and the evaporation source was adjusted to 400 mm, and the distance between the center line perpendicular to the support and the evaporation source was adjusted to 400 mm. Subsequently, the inside of the vacuum vessel was once evacuated, Ar gas was introduced and the degree of vacuum was adjusted to 0.05 Pa, and then the temperature of the support was maintained at 200 ° C. while rotating the support at a speed of 10 rpm. Subsequently, the phosphor 1 was deposited at a deposition mass rate of 0.008 mg / cm ² · min in a state where the inside of the crucible was raised to a predetermined temperature by resistance heating and the support was not rotated, and the film thickness of the phosphor layer was The vapor deposition was terminated when the thickness reached 40 μm. Next, the phosphor 2 was deposited under the same conditions, and the deposition was terminated when the thickness of the phosphor layer reached 400 μm.

Next, the phosphor layer was placed in a protective layer bag in dry air to obtain a comparative radiation image conversion panel 1-1 having a structure in which the phosphor layer was sealed.

[Comparative Example 1-2]
Among the production conditions of Comparative Example 1-1, the degree of vacuum was changed to 0.04 Pa and the vapor deposition mass rate was changed to 2.0 mg / cm ² · min to obtain a radiation image conversion panel 1-2 of Comparative Example. It was.

[Invention 1-1]
Among the production conditions of Comparative Example 1-1, the substrate temperature up to 40 μm was changed to 30 ° C., the deposition mass rate was changed to 1.8 mg / cm ² · min, and the radiation image conversion panel 1-1 according to the present invention was selected. Got.

[Invention 1-2]
Among the production conditions of the present invention 1-1, the degree of vacuum was changed to 0.10 Pa to obtain a radiation image conversion panel 1-2 according to the present invention.

[Invention 1-3]
Among the production conditions of the present invention 1-2, the vapor deposition mass rate up to 40 μm was changed to 0.01 mg / cm ² · min to obtain a radiation image conversion panel 1-3 according to the present invention.

[Invention 1-4]
Among the production conditions of the present invention 1-3, the degree of vacuum was changed to 0.05 Pa to obtain a radiation image conversion panel 1-4 according to the present invention.

[Invention 1-5]
Among the production conditions of the present invention 1-3, the degree of vacuum from 40 to 400 μm was changed to 0.05 Pa to obtain a radiation image conversion panel 1-5 according to the present invention.

[Invention 1-6]
Among the production conditions of the present invention 1-2, the vapor deposition mass rate was changed to 1.0 mg / cm ² · min to obtain a radiation image conversion panel 1-6 according to the present invention.

[Invention 1-7]
Among the production conditions of the present invention 1-6, the degree of vacuum was changed to 1.0 Pa to obtain a radiation image conversion panel 1-7 according to the present invention.

[Invention 1-8]
Among the production conditions of the present invention 1-6, the degree of vacuum was changed to 5.0 Pa to obtain a radiation image conversion panel 1-8 according to the present invention.

[Invention 1-9]
Among the production conditions of the present invention 1-6, the degree of vacuum was changed to 10.0 Pa to obtain a radiation image conversion panel 1-9 according to the present invention.

[Comparative Example 1-3]
Among the production conditions of the present invention 1-6, the degree of vacuum was changed to 12.0 Pa to obtain a radiation image conversion panel 1-3 of a comparative example.

[Comparative Example 1-4]
Among the production conditions of Invention 1-1, the vapor deposition mass rate was changed to 2.1 mg / cm ² · min to obtain a radiation image conversion panel 1-4 of a comparative example.

[Evaluation]
The radiation image conversion panel obtained as described above was set in PaxScan 2520 (VPD manufactured by Varian) and evaluated as follows.

<Luminance>
X-rays with a tube voltage of 80 kVp were irradiated from the back surface (surface on which the phosphor layer was not formed) of the sample, and image data was detected with an FPD disposed on the phosphor, and the average signal value of the image was taken as the emission luminance. Then, the brightness of the radiation conversion panel of Comparative Example 1-1 was displayed as a relative value with the brightness set at 100. The higher this value, the higher the luminance and the better.

<Sharpness>
(Evaluation of sharpness)
X-rays with a tube voltage of 80 kVp were irradiated to the radiation incident surface side of the FPD through a lead MTF chart, and image data was detected and recorded on a hard disk. Thereafter, the recording on the hard disk was analyzed by a computer, and the modulation transfer function MTF (MTF value at a spatial frequency of 1 cycle / mm) of the X-ray image recorded on the hard disk was used as an index of sharpness. The relative value was displayed with the MTF of the radiation conversion panel of Comparative Example 1-1 set to 100. It shows that it is excellent in sharpness, so that this value is high. MTF is an abbreviation for Modulation Transfer Function.

(Evaluation of moisture resistance)
The obtained radiation conversion panel was left to stand in an environment of 70 ° C./90% for 3 days, and the brightness deterioration range after being left was displayed as a relative value with the value before being left as 100.

Table 1 summarizes the results obtained from the above evaluations.

As is clear from the results in Table 1, the radiographic image conversion panels of the present invention (Inventions 1-1 to 1-5) all have improved relative luminance values and relative MTF values. It has been seen. On the other hand, the conventional radiographic image conversion panels (Comparative Examples 1-1 to 1-2) having a low degree of vacuum and a vapor deposition mass rate had poor relative luminance values and relative MTF values. Similarly, regarding the moisture resistance, the radiation image conversion panels of the present invention (Inventions 1-1 to 1-5) were all excellent.

[Comparative Example 2-1]
(Production of radiation image conversion panel)
Among the preparation conditions of Comparative Example 1-1, the phosphor 1 was changed to the phosphor 3 (only CsBr) and the phosphor 2 was changed to the phosphor 4 (CsBr: 0.003Eu) to obtain a radiation image conversion panel.

[Comparative Example 2-2]
Among the production conditions of Comparative Example 2-1, the degree of vacuum was changed to 0.04 Pa and the vapor deposition mass rate was changed to 2.0 mg / cm ² · min to obtain a radiation image conversion panel 2-2 of Comparative Example. It was.

[Invention 2-1]
Among the production conditions of Comparative Example 2-1, the substrate temperature up to 40 μm was changed to 30 ° C., the deposition mass rate was changed to 1.8 mg / cm ² · min, and the radiation image conversion panel 2-1 according to the present invention was changed. Got.

[Invention 2-2]
Among the production conditions of the present invention 2-1, the degree of vacuum was changed to 0.10 Pa to obtain a radiation image conversion panel 2-2 according to the present invention.

[Invention 2-3]
Among the production conditions of the present invention 2-2, the vapor deposition mass rate up to 40 μm was changed to 0.01 mg / cm ² · min to obtain a radiation image conversion panel 2-3 according to the present invention.

[Invention 2-4]
Of the invention 2-3, the degree of vacuum was changed to 0.05 Pa to obtain a radiation image conversion panel 2-4 according to the invention.

[Invention 2-5]
Among the production conditions of the present invention 2-3, the degree of vacuum from 40 to 400 μm was changed to 0.05 Pa to obtain a radiation image conversion panel 2-5 according to the present invention.

[Invention 2-6]
Among the preparation conditions of the present invention 2-2, the vapor deposition mass rate was changed to 1.0 mg / cm ² · min to obtain a radiation image conversion panel 2-6 according to the present invention.

[Invention 2-7]
Among the production conditions of the present invention 2-6, the degree of vacuum was changed to 1.0 Pa to obtain a radiation image conversion panel 2-7 according to the present invention.

[Invention 2-8]
Among the production conditions of the present invention 2-6, the degree of vacuum was changed to 5.0 Pa to obtain a radiation image conversion panel 2-8 according to the present invention.

[Invention 2-9]
Among the production conditions of the present invention 2-6, the degree of vacuum was changed to 10.0 Pa to obtain a radiation image conversion panel 2-9 according to the present invention.

[Comparative Example 2-3]
Among the production conditions of the invention 2-6, the degree of vacuum was changed to 12.0 Pa, and a radiation image conversion panel 2-3 of a comparative example was obtained.

[Comparative Example 2-4]
Among the production conditions of the present invention 2-1, the deposition mass rate was changed to 2.1 mg / cm ² · min to obtain a radiation image conversion panel 2-4 of a comparative example.

<< Evaluation of radiation image conversion panel >>
It set to the radiographic image conversion panel produced as mentioned above, and the brightness | luminance and sharpness were evaluated in accordance with the following method.

(Measurement of brightness)
For evaluation of luminance, a 2 mm-thick lead disk is imprinted on each prepared radiation image conversion panel, X-ray with a tube voltage of 80 kVp is uniformly irradiated, and then a semiconductor laser beam (oscillation is provided from the surface side on which the phosphor layer is provided. Excitation is performed by scanning at a wavelength of 780 nm and a beam diameter of 100 μm. The stimulated emission emitted from each phosphor layer is received by a photoreceiver (photoelectron image multiplier of spectral sensitivity S-5), and the intensity is measured. This was defined as luminance, and the value of Comparative Example 2-1 was set as 100 and indicated as a relative value. The higher this value, the higher the luminance and the better.

(Measure sharpness)
After a CTF chart is attached to the radiation image conversion panel, X-ray with a tube voltage of 80 kVp-p is irradiated with 10 mR (distance from the tube to the panel: 1.5 m), and then a semiconductor laser beam (oscillation wavelength: 780 nm, beam diameter) : 100 μm) and excited to excite, read the CTF chart image as stimulated luminescence emitted from the stimulable phosphor layer, and photoelectrically convert it with a photodetector (photomultiplier) to obtain an image signal It was. Based on this signal value, the modulation transfer function (MTF) of the image was examined, and the value of Comparative Example 2-1 was set as 100 and indicated as a relative value. MTF is a value when the spatial frequency is 1 cycle / mm.

(Evaluation of moisture resistance)
The obtained radiation image conversion panel was left to stand in an environment of 70 ° C./90% for 3 days, and the brightness deterioration range after being left was displayed as a relative value with the value before being left as 100.

As is clear from the results in Table 2, all of the radiation image conversion panels of the present invention (Inventions 2-1 to 1-5) have improved relative luminance values and relative MTF values, and the effects of the present invention are improved. It has been seen. On the other hand, all of the conventional radiation image conversion panels (Comparative Examples 2-1 and 2-2) with a low degree of vacuum and a vapor deposition mass rate had poor relative luminance values and relative MTF values. Similarly, regarding the moisture resistance, the radiation image conversion panels of the present invention (Inventions 2-1 to 2-5) were all excellent.

Claims (8)

1. A radiation image conversion panel having a phosphor layer containing a phosphor columnar crystal composed mainly of a cesium halide phosphor formed by a vapor deposition method, wherein the phosphor layer has a degree of vacuum of 0. It is characterized in that it is formed under the condition that it is maintained within the range of 05 Pa to 10 Pa and the deposition mass rate is maintained within the range of 0.01 mg / cm ² · min to 2.0 mg / cm ² · min. Radiation image conversion panel.
2. The phosphor columnar crystal is (1) an additive containing at least one of cesium iodide (CsI) and cesium bromide (CsBr) and (2) at least one of thallium (Tl) and europium (Eu); The radiation image conversion panel according to claim 1, wherein the radiation image conversion panel is formed from a raw material.
3. A method for producing a radiation image conversion panel for producing the radiation image conversion panel according to claim 1 or claim 2, comprising a cesium halide phosphor or a raw material thereof in a vapor deposition apparatus. A process of forming a phosphor layer by vapor-depositing a substance generated by heating an evaporation source on a support, and after introducing an inert gas into the vapor deposition apparatus, the degree of vacuum is 0.05 to A method for producing a radiation image conversion panel, characterized in that vapor deposition is carried out while maintaining a pressure within a range of 10 Pa and a vapor deposition mass rate within a range of 0.01 to 2.0 mg / cm ² · min.
4. The radiographic image according to claim 3, wherein the phosphor layer is formed by performing vapor deposition while changing the degree of vacuum in the vapor deposition apparatus within the range in the course of forming the phosphor layer. A method for manufacturing a conversion panel.
5. The phosphor layer is formed by performing vapor deposition while changing the vapor deposition mass rate within the range in the course of forming the phosphor layer. The manufacturing method of the radiation image conversion panel of description.
6. 6. The phosphor layer according to claim 3, wherein the phosphor layer is formed by performing vapor deposition while changing the temperature of the support in the course of forming the phosphor layer. The manufacturing method of the radiographic image conversion panel of item.
7. The method for producing a radiation image conversion panel according to any one of claims 3 to 6, wherein the thickness of the support is in the range of 30 袖 m to 500 袖 m.
8. The method of manufacturing a radiation image conversion panel according to any one of claims 3 to 7, wherein a vapor deposition apparatus having an evaporation source and a support rotating mechanism in a vacuum vessel is used. Radiation image conversion characterized in that a phosphor layer is formed by a vapor phase deposition method including a step of evaporating a phosphor material while rotating the support and placing the support on the support rotating mechanism. Panel manufacturing method.

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