JP2006119124A - Radiation image conversion panel and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel free from characteristic deterioration of an obtained radiation image by suppressing corrosion on a substrate by reaction of a stimulable phosphor and the metal substrate through moisture over a long period, and also to provide a production method therefor. <P>SOLUTION: This radiation image conversion panel has: the substrate formed of a metal or an alloy; an oxide layer formed on the substrate by a vapor phase deposition method such as a sputtering method, an ion plating method or an ion beam assist evaporation method; and a phosphor layer formed on the oxide layer by a vapor phase deposition method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation image conversion panel for recording and reproducing a radiation image with a photostimulable phosphor layer and a method for manufacturing the same, and in particular, suppresses corrosion of a substrate due to moisture absorption of the photostimulable phosphor layer, thereby reducing characteristic deterioration. The present invention relates to a radiation image conversion panel and a manufacturing method thereof.

  When irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), a part of this radiation energy is accumulated and then irradiated with excitation light such as visible light. In addition, phosphors that exhibit stimulated light emission according to the stored energy are known. This phosphor is called a stimulable phosphor (accumulating phosphor) and is used for various applications such as medical applications.

As an example, a radiation image information recording / reproducing system using a radiation image conversion panel having the photostimulable phosphor film (stimulable phosphor layer) is known. For example, an FCR manufactured by Fuji Photo Film Co., Ltd. Fuji Computed Radiography).
In this radiation image information recording / reproducing system, radiation image information of a subject is recorded on a radiation image conversion panel (stimulable phosphor layer) by irradiating X-rays or the like through a subject such as a human body. After recording, the radiation image conversion panel is scanned two-dimensionally with excitation light such as laser light to generate stimulated emission, and this stimulated emission light is photoelectrically read to obtain an image signal. Based on this image signal The reproduced image is output as a radiation image of a subject to a display device such as a CRT or a recording material such as a photographic photosensitive material.

The radiation image conversion panel is usually prepared by coating a stimulable phosphor powder in a solvent containing a binder and the like, and applying the paint to a panel-like support made of glass or resin. It is produced by drying.
In contrast, a phosphor panel in which a photostimulable phosphor layer (hereinafter also referred to as a phosphor layer) is formed on a support by a vacuum film formation method (vapor phase film formation method) such as vacuum deposition or sputtering. Are known. The phosphor layer formed by the vacuum film formation method is formed in a vacuum, so there are few impurities, and since there are almost no components such as binders other than the stimulable phosphor, there is little variation in performance, and the luminous efficiency Has excellent properties of being very good. Furthermore, since the phosphor layer is formed of a phosphor columnar structure, a good image quality with high sharpness can be obtained.

However, the radiation image conversion panel has a problem that the photostimulable phosphor layer has high hygroscopicity.
The photostimulable phosphor layer, in particular, the alkali halide photostimulable phosphor layer having good characteristics, has high hygroscopicity and easily absorbs moisture even in a normal (normal temperature / normal humidity) environment. . As a result, the photostimulable luminescence characteristics, that is, the sensitivity is lowered, or the crystallinity of the photostimulable phosphor is lowered (for example, if the alkali halide photostimulable phosphor having a columnar structure is collapsed) As a result, the sharpness of the reproduced image is reduced. For this reason, in the radiation image conversion panel, the photostimulable phosphor layer is sealed with a moisture-proof member.

  In the radiation image conversion panel, a substrate made of a metal or an alloy can be used as a support. In this case, even if the stimulable phosphor layer is sealed with a moisture-proof member, moisture absorption of the stimulable phosphor layer cannot be completely prevented. The substrate is corroded by the reaction through moisture. For this reason, a layer is formed between the substrate and the photostimulable phosphor layer so that the photostimulable phosphor layer and the substrate are not in direct contact (see Patent Document 1 and Patent Document 2). .

Patent Document 1 discloses a radiation image conversion panel in which a moisture-impermeable layer is formed on the front and back surfaces of a substrate, and a photostimulable phosphor layer is formed on the moisture-impermeable layer on the front surface side of the substrate. .
In the radiation image conversion panel of Patent Document 1, a metal oxide layer, an anodized layer, and a layer made of polyimide are exemplified as the moisture impermeable layer.

  Patent Document 2 discloses an X-ray image conversion sheet using a stimulable phosphor. In the X-ray image conversion sheet in Patent Document 2, a white oxide film is formed between a stimulable phosphor layer and a support made of aluminum in order to obtain image characteristics such as resolution. As this oxide, alumina is exemplified.

International Publication No. 02/0886540 Pamphlet Japanese Patent Laid-Open No. 4-118599

  However, in the radiation image conversion panel disclosed in Patent Document 1, as the moisture-impermeable layer, a metal oxide layer, an anodized layer, and a layer made of polyimide are exemplified, except for the anodized layer, There is no illustration of a specific manufacturing method. As disclosed in Patent Document 1, simply forming a layer made of a metal oxide layer, an anodized layer, and polyimide as a water-impermeable layer has a uniform thickness sufficient as a water-impermeable layer. It is difficult to obtain a film. For this reason, unevenness in moisture impermeability occurs, waviness occurs on the surface of the stimulable phosphor layer formed on the moisture impervious layer, and affects the film thickness uniformity of the phosphor layer. There is a problem that image characteristics such as cannot be obtained.

  Furthermore, in Patent Document 1 and Patent Document 2, when an anodized film is provided, the anodized film is porous, so that the surface roughness increases. For this reason, there is a problem that the columnar property of the photostimulable phosphor layer formed on the anodic oxide film is deteriorated and hillocks (point defects) are generated, and the finally obtained image characteristics are deteriorated.

  An object of the present invention is to solve the above-mentioned problems of the prior art, and can be obtained by suppressing the corrosion of the substrate due to the reaction between the stimulable phosphor and the metal substrate through moisture over a long period of time. It is an object of the present invention to provide a radiation image conversion panel and a method for manufacturing the same, in which there is no characteristic deterioration of the radiation image.

  To achieve the above object, according to a first aspect of the present invention, there is provided a substrate made of a metal or an alloy, an oxide layer formed on the substrate by a vapor deposition method, and an oxide layer formed on the oxide layer. The present invention provides a radiation image conversion panel having a phosphor layer formed by a vapor deposition method.

  In the present invention, the oxide layer formed by the vapor deposition method is preferably formed by a sputtering method, an ion plating method or an ion beam assisted deposition method.

In the present invention, the oxide layer is, for _example, made of SiO 2, _Al 2 _{O 3} or TiO _2.

  Furthermore, in the present invention, the thickness of the oxide layer is preferably 0.5 μm or more.

Moreover, in this invention, it is preferable that arithmetic mean roughness Ra of the surface of the said board | substrate is 0.005-0.1 micrometer.
Furthermore, in the present invention, the maximum height Rz of the surface of the substrate is preferably 0.005 to 1 μm.

In the present invention, the substrate is preferably made of aluminum.
Furthermore, in the present invention, the phosphor layer is preferably made of CsBr: Eu.

  According to a second aspect of the present invention, there is provided a step of forming an oxide layer by a vapor deposition method on a substrate composed of a metal or an alloy, and a phosphor layer by a vapor deposition method on the oxide layer. The manufacturing method of the radiation image conversion panel characterized by having a process to form.

According to the radiation image conversion panel of the first aspect of the present invention, the oxide layer is formed by vapor phase deposition on a substrate made of a metal or an alloy. It is highly uniform, smooth and dense, and has no defects such as pinholes. For this reason, even if exposed to severe conditions such as high temperature and high humidity, the corrosion of the substrate due to the moisture-mediated reaction between the stimulable phosphor and the substrate made of metal or alloy is suppressed for a long time. can do. Thereby, the characteristic deterioration of a radiation image can be suppressed over a long period of time.
In addition, since the oxide layer in the present invention is smooth, dense, and highly uniform, the abnormal growth (hillock) of the photostimulable phosphor layer formed on the oxide layer is suppressed. In addition, point defects such as missing pixels do not occur in the finally obtained radiation image.

Furthermore, according to the manufacturing method of the radiation image conversion panel of the second aspect of the present invention, the film thickness uniformity can be obtained by forming the oxide layer on the substrate made of metal or alloy by the vapor deposition method. An oxide layer that is high, smooth, dense, and free from defects such as pinholes can be obtained. For this reason, even if exposed to severe conditions such as high temperature and high humidity, the corrosion of the substrate due to the moisture-mediated reaction between the stimulable phosphor and the substrate made of metal or alloy is suppressed for a long time. can do. Thereby, the characteristic deterioration of a radiation image can be suppressed over a long period of time.
In addition, the oxide layer in the present invention is smooth and dense with high film thickness uniformity, and does not form point defects such as pinholes, and thus is formed on the oxide layer. Abnormal growth (hillock) of the photostimulable phosphor layer is suppressed, and point defects such as missing pixels do not occur in the finally obtained radiation image.

Hereinafter, a radiation image conversion panel and a manufacturing method thereof according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIG. 1 is a schematic cross-sectional view showing a radiation image conversion panel according to an embodiment of the present invention.

  As shown in FIG. 1, a radiation image conversion panel (hereinafter also referred to as a phosphor panel) 10 includes a substrate 12, an oxide layer 14 formed on a surface 12 a of the substrate 12, and an oxide layer 14 on the oxide layer 14. The photostimulable phosphor layer (hereinafter referred to as phosphor layer) 16 formed and a moisture-proof protective layer 18 formed on the phosphor layer 16 are provided.

  In the phosphor panel 10, the substrate 12 is made of metal or alloy, and is, for example, a thin plate member or sheet member. In this invention, if the board | substrate 12 is a metal or an alloy, it will not specifically limit, For example, aluminum, aluminum alloy, iron, stainless steel, copper, chromium, nickel etc. are mentioned. In the present embodiment, the substrate 12 is preferably composed of aluminum or an aluminum alloy.

Further, the substrate 12 has an arithmetic average roughness Ra (JIS B 0601-1994) of the surface 12a of 0.005 to 0.1 μm, and a maximum height Rz (JIS B 0601-2001) of the surface 12a. It is preferable to satisfy at least one of 0.005 to 1 μm.
The substrate 12 has a surface roughness that satisfies at least one of an arithmetic average roughness (Ra) of 0.005 to 0.1 μm and a maximum height (Rz) of 0.005 to 1 μm. The oxide layer 14 formed on the surface 12a by vapor deposition is further excellent in film thickness uniformity and free from defects such as pinholes. The phosphor layer 16 formed on the oxide layer 14 Abnormal growth (hillock) can be further suppressed. Furthermore, the phosphor layer 16 can also have excellent columnarity. Thereby, the image quality of the radiation image obtained with the phosphor panel 10 becomes higher.

The oxide layer 14 suppresses corrosion of the substrate 12 due to moisture absorbed by the phosphor layer 16, and is formed by a vapor deposition method. The oxide layer 14 is not particularly limited as long as it is formed by a vapor deposition method. For example, it can be made of SiO ₂ , Al ₂ O ₃ or TiO ₂ .

  If the vapor phase deposition method for forming the oxide layer 14 is capable of forming a film having high film thickness uniformity, smooth and dense without pinholes, and moisture-impermeable, Without being limited thereto, various physical vapor deposition (PVD) methods or chemical vapor deposition (CVD) methods can be used. In this embodiment, it is preferable to form by a sputtering method, an ion plating method, or an ion beam assisted vapor deposition method among vapor deposition methods. This is because the sputtering method, ion plating method, and ion beam assisted deposition method have high film thickness uniformity, smoothness and fineness, especially among vapor deposition methods, because the energy of particles (molecules) to be formed is high. This is because a film impermeable to moisture can be obtained.

  In the ion beam assisted vapor deposition method of the present embodiment, for example, an evaporation source and an ion gun are installed inside a film formation (evaporation) chamber provided with a plasma chamber, and a substrate is installed opposite the evaporation source. A device is used. This ion beam assisted deposition method (hereinafter also simply referred to as ion beam assist) is a method in which plasma generated in a plasma chamber is irradiated onto the substrate surface as gas ions by an ion gun, while particles flying from the evaporation source are simultaneously emitted to the substrate. It is a kind of special vacuum deposition method in which a film is formed by vapor deposition on the surface of the film.

In addition, the thickness A of the oxide layer 14 is preferably 0.5 μm or more. When the thickness of the oxide layer 14 is 0.5 μm or more, the effect of suppressing the corrosion of the substrate 12 due to the reaction between the phosphor layer 16 and the substrate 12 through the moisture is exhibited over a long period of time. Because.
Note that the upper limit of the thickness of the oxide layer 14 is 10 μm. This is because if the thickness of the oxide layer 14 exceeds 10 μm, light scattering by the oxide layer 14 may increase. The upper limit value of the thickness of the oxide layer 14 varies depending on the material of the oxide layer 14 and the required image quality, and is not limited to 10 μm in the present embodiment.

  As described above, the phosphor layer 16 accumulates part of the radiation energy when irradiated with radiation (X-rays, α-rays, β-rays, γ-rays, electron beams, ultraviolet rays, etc.), and then visible light. When irradiated with excitation light such as, it shows stimulated emission corresponding to the stored energy.

In the present invention, various photostimulable phosphors for forming the phosphor layer 16 can be used, but the following photostimulable phosphors are preferably exemplified as an example.
For example, the photostimulable phosphors described in US Pat. No. 3,859,527, “SrS: Ce, Sm”, “SrS: Eu, Sm”, “ThO ₂ : Er”, and “La ₂ O ₂ S: Eu, Sm”.

“ZnS: Cu, Pb”, “BaO · xAl ₂ O ₃ : Eu (provided that 0.8 ≦ x ≦ 10)” and the general formula “M ^II ” disclosed in JP-A-55-12142 Stimulable phosphor represented by “O.xSiO ₂ : A”.
(In the above formula, M ^II is at least one selected from the group consisting of Mg, Ca, Sr, Zn, Cd and Ba, and A is Ce, Tb, Eu, Tm, Pb, Tl, Bi and Mn. And at least one selected from the group consisting of 0.5 ≦ x ≦ 2.5.)

A stimulable phosphor represented by the general formula “LnOX: xA” disclosed in JP-A No. 55-12144.
(In the above formula, Ln is at least one selected from the group consisting of La, Y, Gd and Lu, X is at least one of Cl and Br, and A is at least one of Ce and Tb. Also, 0 ≦ x ≦ 0.1.)

A stimulable phosphor represented by the general formula “(Ba _1-x , M ²⁺ _x ) FX: yA” disclosed in JP-A No. 55-12145.
(In the above formula, M ²⁺ is at least one selected from the group consisting of Mg, Ca, Sr, Zn and Cd, and X is at least one selected from the group consisting of Cl, Br and I. , A is at least one selected from the group consisting of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb and Er, and 0 ≦ x ≦ 0.6, 0 ≦ y ≦ 0.2.)

A stimulable phosphor represented by the general formula “xM ₃ (PO ₄ ) ₂ .NX ₂ : yA” or “M ₃ (PO ₄ ) ₂ .yA” disclosed in JP-A-59-38278.
(In the above formula, M and N are each at least one selected from the group consisting of Mg, Ca, Sr, Ba, Zn and Cd, and X is selected from the group consisting of F, Cl, Br and I) A is at least one selected from the group consisting of Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Sb, Tl, Mn, and Sn. 0 ≦ x ≦ 6 and 0 ≦ y ≦ 1.)

A stimulable phosphor represented by the general formula “nReX ₃ · mAX ′ ₂ : xEu” or “nReX ₃ · mAX ′ ₂ : xEu, ySm”.
(In the above formula, Re is at least one selected from the group consisting of La, Gd, Y and Lu, A is at least one selected from the group consisting of Ba, Sr and Ca, and X and X 'Is at least one selected from the group consisting of F, Cl and Br. Also, 1 × 10 ⁻⁴ <x <3 × 10 ⁻¹ and 1 × 10 ⁻⁴ <y <1 × 10 ⁻¹ , and further 1 × 10 ⁻³ <n / m <7 × 10 ⁻¹ .)

An alkali halide photostimulable phosphor represented by the general formula “M ^I X · aM ^II X ′ ₂ · bM ^III X ″ ₃ : cA” disclosed in JP-A-61-72087.
(In the above formula, M ^I is at least one selected from the group consisting of Li, Na, K, Rb and Cs, and M ^II is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and M ^III is at least one divalent metal selected from the group consisting of Ni, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, At least one trivalent metal selected from the group consisting of Tm, Yb, Lu, Al, Ga and In, and X, X ′ and X ″ are selected from the group consisting of F, Cl, Br and I A is from Eu, Tb, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, Bi and Mg. At least one selected from the group consisting of . Also, a 0 ≦ a <0.5, a 0 ≦ b <0.5, it is 0 <c ≦ 0.2.)

A stimulable phosphor represented by the general formula “(Ba _1-X , M ^II _X ) F ₂ .aBaX ₂ : yEu, zA” disclosed in JP-A-56-116777.
(In the above formula, M ^II is at least one selected from the group consisting of Be, Mg, Ca, Sr, Zn and Cd, and X is at least one selected from the group consisting of Cl, Br and I. A is at least one of Zr and Sc, 0.5 ≦ a ≦ 1.25, 0 ≦ x ≦ 1, and 1 × 10 ⁻⁶ ≦ y ≦ 2 × 10 ⁻¹ . Yes, 0 <z ≦ 1 × 10 ⁻²

A stimulable phosphor represented by the general formula “M ^III OX: xCe”, disclosed in JP-A-58-69281.
(In the above formula, M ^III is at least one trivalent metal selected from the group consisting of Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb and Bi; Is at least one of Cl and Br, and 0 ≦ x ≦ 0.1.)

A stimulable phosphor represented by the general formula “Ba _1-x MaLaFX: yEu ²⁺ ” disclosed in JP _-A- 58-206678.
(In the above formula, M is at least one selected from the group consisting of Li, Na, K, Rb and Cs, and L is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Gd, It is at least one trivalent metal selected from the group consisting of Tb, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, In and Tl, and X is composed of Cl, Br and I And at least one selected from the group, 1 × 10 ⁻² ≦ x ≦ 0.5, 0 ≦ y ≦ 0.1, and a is x / 2.)

The stimuli represented by the general formula “M ^II FX · aM ^I X ′ · bM ′ ^II X ″ ₂ · cM ^III X ₃ · xA: yEu ²⁺ ” disclosed in JP-A-59-75200 Phosphor. (In the above formula, M ^II is at least one selected from the group consisting of Ba, Sr and Ca, and M ^I is at least one selected from the group consisting of Li, Na, K, Rb and Cs. , M ′ ^II is at least one divalent metal of Be and Mg, and M ^III is at least one trivalent metal selected from the group consisting of Al, Ga, In, and Tl, and A Is a metal oxide, and X, X ′ and X ″ are at least one selected from the group consisting of F, Cl, Br and I. Also, 0 ≦ a ≦ 2, 0 ≦ b ≦ 1 × 10 ⁻² , 0 ≦ c ≦ 1 × 10 ⁻² , a + b + c ≧ 10 ⁻⁶ , 0 <x ≦ 0.5, and 0 <y ≦ 0.2.)

In particular, the alkali halide photostimulable phosphor disclosed in Japanese Patent Application Laid-Open No. 59-38278 is preferable in that it has excellent photostimulated luminescence properties and the effects of the present invention can be satisfactorily obtained. In particular, alkali halide photostimulable phosphors in which M ^I contains at least Cs, X contains at least Br, and A is Eu or Bi are preferable. A photostimulable phosphor represented by “CsBr: Eu” is preferable.

The phosphor layer 16 is made of such a stimulable phosphor, and is formed by various vapor deposition methods such as vacuum deposition, sputtering, and CVD. Further, in the present invention, the phosphor layer 16 is manufactured from a film forming apparatus different from the oxide layer 14, for example.
Among them, the phosphor layer 16 formed by vacuum deposition is preferable in terms of productivity and the like, and in particular, the material of the phosphor component and the material of the activator (activator) component are separately heated and evaporated. The phosphor layer 16 formed by multi-source vacuum deposition is preferable. For example, in the case of the phosphor layer 16 of the “CsBr: Eu”, cesium bromide (CsBr) is used as the material of the phosphor component, and europium bromide (EuBr _x (x is typically 2) to 3)) are preferably used, each being heated and evaporated separately, and preferably formed by multi-source vacuum deposition.
There is no particular limitation on the heating method in vacuum deposition, and for example, it may be formed by electron beam heating using an electron gun or the like, or resistance heating. Further, when formed by multi-source vacuum deposition, all materials may be heated and evaporated by the same heating means (for example, electron beam heating), or the phosphor component material may be heated by electron beam heating. The material of the activator component that is a trace amount may be formed by resistance heating and heating and evaporation.

The phosphor layer 16 is not particularly limited in film formation conditions, and is obtained by appropriately forming the obtained phosphor layer according to the film formation method or the composition of the phosphor layer 16 to be formed. 16 may be sufficient. For example, in the case of vacuum deposition, a phosphor layer obtained by forming a film at a film formation rate of 0.05 μm / min to 300 μm / min at a vacuum degree of 1 × 10 ⁻⁵ Pa to 1 × 10 ⁻² Pa. 16 is preferred. In addition, when formed by multi-source vacuum evaporation, the evaporation rate of both materials is controlled so that the amount ratio of the base component and the activator component falls within the target range.

  Further, according to the examination by the present applicant, when the above-mentioned various storage phosphors, particularly alkali halide storage phosphors, particularly CsBr: Eu, are formed by vacuum deposition, the inside of the system is once temporarily used. After evacuating to a high degree of vacuum, argon gas or nitrogen gas or the like is introduced into the system to obtain a medium vacuum degree of about 0.01 Pa to 3 Pa, and this is obtained by performing vacuum vapor deposition by resistance heating under vacuum. The phosphor layer 16 is preferred. Although the alkali halide phosphor layer such as CsBr: Eu has a columnar crystal structure, the phosphor layer 16 obtained by forming a film under such a medium vacuum has a particularly good columnar crystal structure. In view of the sharpness of the photostimulated luminescence characteristic image, it is preferable.

The formed phosphor layer 16 may be heated at 300 ° C. or lower, preferably 200 ° C. or lower during film formation by heating the substrate 12 or the like.
Further, the thickness C of the phosphor layer 16 is not particularly limited, but is preferably 50 μm or more, particularly 200 μm or more.

The phosphor layer 16 thus formed is subjected to a heat treatment (annealing) in order to exhibit the photostimulable light emission characteristics well and improve the photostimulated light emission characteristics.
The annealing conditions of the phosphor layer 16 are not particularly limited, but as an example, under an inert atmosphere such as a nitrogen gas atmosphere, 50 ° C. to 600 ° C., particularly 100 ° C. to 300 ° C., 10 minutes to 10 hours, In particular, it is preferably performed for 30 minutes to 3 hours.
The heat treatment of the phosphor layer 16 may be performed by a known method such as a method using a firing furnace, and if it is a vacuum vapor deposition apparatus having a heating means for the substrate 12, the heat treatment is performed using this. May be.

  For example, the moisture-proof protective layer 18 is provided to cover and seal the phosphor layer 16 in order to seal the phosphor layer 16 formed by vacuum deposition and prevent moisture absorption. For sealing by the moisture-proof protective layer 18, for example, a thermal lamination method is used.

In the present invention, the moisture-proof protective layer 18 is not particularly limited as long as it has sufficient moisture-proof properties, and various types can be used.
As an example, a moisture-proof protective layer 18 formed by forming three layers of a SiO ₂ film, a hybrid layer of SiO ₂ and PVA (polyvinyl alcohol), and a SiO ₂ film on a PET (polyethylene terephthalate) film is exemplified. In addition to this, a glass plate (film), a resin film such as polyethylene terephthalate or polycarbonate, a film in which an inorganic substance such as SiO ₂ , Al ₂ O ₃ , or SiC is deposited on the resin film are also preferably exemplified. Incidentally, on the PET film, the SiO ₂ film / SiO ₂ and the moisture-proof protective layer 18 formed of three layers of hybrid layer / SiO ₂ film of PVA, for example, SiO ₂ film, by a sputtering method, SiO ₂ And PVA hybrid films may be formed by using a sol-gel method so that the ratio of PVA to SiO ₂ is 1: 1. The moisture-proof protective layer 18 preferably has a moisture permeability of 0.2 to 0.6 (g / (m ² · day)) in an environment where the relative humidity is 90% at a temperature of 40 ° C.

  In this embodiment, an oxide layer 14 is provided between the substrate 12 and the phosphor layer 16, which is excellent in film thickness uniformity formed by a vapor deposition method, has a smooth surface, and has a dense film quality. Yes. The oxide layer 14 has a dense film quality and does not have microporous or the like like an anodized film, and moisture absorbed by the phosphor layer 16 can suppress the penetration of the oxide layer 14 into the substrate 12. . For this reason, the corrosion of the board | substrate 12 by the chemical reaction through the water | moisture content of fluorescent substance and a board | substrate can be suppressed over a long period of time. As a result, the characteristic deterioration of the radiation image of the phosphor panel 10 can be suppressed over a long period of time.

Further, since the oxide layer 14 has a smooth and dense structure with high film thickness uniformity and no point defects such as pinholes, the phosphor layer 16 formed thereon has a structure with high columnarity. The film quality is excellent with no point defects.
Thus, in the phosphor panel 10 of the present embodiment, the phosphor layer 16 with excellent film quality with few defects can be formed. For this reason, when the image is recorded and reproduced, the obtained image is free from point defects such as missing pixels, and a good radiation image can be obtained over a long period of time.

In addition, in the phosphor panel 10 of the present embodiment, by providing the moisture-proof protective layer 18 on the phosphor layer 16, very excellent moisture resistance is expressed, and severe conditions such as high temperature and high humidity are exhibited. However, it is possible to suppress moisture absorption of the phosphor layer 16 over a long period of time and maintain good image recording characteristics.
Thereby, the photostimulable phosphor forming the phosphor layer 16, particularly the alkali halide photostimulable phosphor, has a hygroscopic property, and easily absorbs moisture under a normal environment. Decrease in sensitivity or sharpness of a reproduced image may occur. Such inconvenience can also be prevented.

Next, a method for manufacturing the phosphor panel 10 of the present embodiment will be described.
First, a substrate 12 (see FIG. 1) made of metal or alloy is prepared. The substrate 12 is made of, for example, aluminum and has a thickness B of 1 mm.
Next, the oxide layer 14 (see FIG. 1) is formed on the surface 12a (see FIG. 1) of the substrate 12 by a vapor phase growth method such as a sputtering method or an ion plating method. The oxide layer 14 is made of, for example, SiO ₂ , Al ₂ O ₃ , or TiO ₂ and has a thickness A of 0.5 μm or more. Note that the adjustment of the thickness A of the oxide layer 14 is performed, for example, by adjusting the deposition rate.

Next, the phosphor layer 16 (see FIG. 1) having the above composition is formed by vacuum deposition.
Next, heat treatment (annealing) is performed in order to cause the phosphor layer 16 to exhibit photostimulable light emission characteristics and improve the photostimulated light emission characteristics.

Next, an adhesive is applied onto the phosphor layer 16 using, for example, a dispenser.
Next, for example, a moisture-proof protective film (not shown) wound in a roll shape is pulled out, and a moisture-proof protective film is pasted on the phosphor layer 16 by a thermal lamination method, and the moisture-proof protective layer 18 (see FIG. 1). Form.
In this way, the phosphor panel 10 can be manufactured.
The moisture-proof protective layer 18 can also be formed using a protective film to which an adhesive has been applied in advance.

  In the method for manufacturing the phosphor panel 10 of the present invention, a reflective film or a barrier film may be formed before the oxide layer 14 is formed as described above. A substrate on which these films are formed may be used as the substrate.

  Further, the adhesive strength when the moisture-proof protective layer 18 and the substrate 12 are bonded with a sealing adhesive layer (not shown) is improved, and a good adhesive strength can be obtained with only one thermal lamination. Prior to sealing the phosphor layer 16 with the moisture-proof protective layer 18, it is preferable to heat the phosphor layer 16 to a temperature in the range of 30 ° C. to 150 ° C. below the softening temperature of the adhesive. For example, the substrate 12 can be heated to a temperature in this range.

  The radiation image conversion panel and the manufacturing method thereof according to the present invention have been described above. However, the present invention is not limited to the above-described embodiment, and various improvements or modifications may be made without departing from the gist of the present invention. Of course it is good.

Hereinafter, the present invention will be described in more detail with reference to specific examples of the present invention. Needless to say, the present invention is not limited to the following examples.
In this example, the radiation image conversion panels of Examples 1 to 20 shown in Table 1 below, the radiation image conversion panels of Comparative Examples 1 and 2, and the reference radiation image conversion panel were prepared, and each of these radiation image conversions was made. The panel was subjected to image evaluation under the following conditions.

  In this example, the radiation image conversion panels of Examples 1 to 20 were configured such that the moisture-proof protective layer 18 of the phosphor panel 10 shown in FIG. 1 was not provided. Moreover, the structure of the radiation image conversion panel of the comparative examples 1 and 2 was set as the structure by which the oxide layer 14 and the moisture-proof protective layer 18 of the fluorescent substance panel 10 shown in FIG.

In the radiation image conversion panels of Examples 1 to 20 and Comparative Examples 1 and 2, the following three types of aluminum substrates (rolled molded products, manufactured by Sumitomo Light Metal Industry Co., Ltd.) with different surface grades were used as substrates. Was used. An aluminum substrate having a purity of 95% by mass is used, and the size of the substrate is 200 mm × 200 mm.
As the type of the substrate, first, a substrate having a thickness of 1 mm and a relatively coarse variety (MF: arithmetic average roughness Ra is 0.196 μm) was used. Second, a product (SL electropolishing: arithmetic average) having a thickness of 1 mm and a relatively smooth original substrate (SL: arithmetic average roughness Ra is 0.074 μm) subjected to electropolishing to smooth the surface. A material having a roughness Ra of 0.048 μm was used. Thirdly, a product (rolling lapping polishing: arithmetic average roughness Ra of 0.083 μm) obtained by lapping polishing an aluminum substrate having a thickness of 10 mm was used. Only the third substrate has a thickness of 10 mm.

Next, the manufacturing method of the fluorescent substance panel of Examples 1-20 shown in following Table 1 is demonstrated.
First, various substrates were degreased with a weak alkaline cleaning solution containing a surfactant, washed with deionized water, and dried.
Next, as shown in Table 1 below, an oxide layer made of SiO ₂ or Al ₂ O ₃ is formed on the surface of each substrate by sputtering, ion plating, or ion beam assist with a thickness A ( (See FIG. 1). Note that the thickness A of the oxide layer was determined to be a predetermined thickness by adjusting the film formation time because the film formation rate was determined in advance.

In this embodiment, a high frequency (RF) sputtering method was used for sputtering. As the sputtering target, an oxide having substantially the same composition as SiO ₂ and Al ₂ O ₃ shown in Table 1 below was used. This sputter target has a high oxygen composition ratio in order to cope with oxygen vacancies caused by sputtering, and is elongated in one direction. Further, Ar gas was used as the introduction gas, and the pressure (vacuum degree) in the chamber was set to 0.5 Pa.
In this embodiment, the film formation rate by sputtering is set to 2 nm / second, and when the oxide layer is formed, the substrate is moved so as to intersect with the length direction of the sputter target so that the thickness is uniform. An oxide layer was formed.

In ion plating, a film deposition (evaporation) chamber provided with a plasma chamber was used. The film forming chamber is provided with an EB evaporation hearth below the inside thereof. A substrate holder is rotatably installed at a position facing the EB evaporation hearth.
In this film forming chamber, an oxide (film forming material) having substantially the same composition as SiO ₂ and Al ₂ O ₃ shown in Table 1 below was evaporated by an electron gun (EB) method. In addition, Ar gas was used as the introduction gas, and the pressure (degree of vacuum) in the plasma chamber was set to 0.1 Pa. Furthermore, the pressure (degree of vacuum) in the film formation chamber was set to 0.01 Pa or less.
In forming the oxide layer, Ar plasma was generated in the plasma chamber, and Ar plasma was irradiated in the vicinity of the oxide evaporation flow in the deposition chamber. Thereby, the energy of the evaporated particles of the oxide can be increased, and the denseness and adhesion of the formed oxide layer can be improved. The film formation rate by ion plating was set to 2 nm / second, and the oxide layer having a uniform thickness was formed while the substrate was rotated by the substrate holder when forming the oxide layer.

Furthermore, in ion beam assist, a film formation (evaporation) chamber provided with a plasma chamber was used. The film formation chamber is provided with an EB evaporation hearth and an ion gun below the inside thereof. A substrate holder is rotatably installed at a position facing the EB evaporation hearth. In addition, the ion gun irradiates the plasma generated in the plasma chamber as gas ions to the substrate attached to the substrate holder.
According to the ion beam assisted vapor deposition method, an oxide (film forming substance) having substantially the same composition as SiO ₂ shown in Table 1 below was evaporated in the film forming chamber by an electron gun (EB) method. In addition, Ar gas was used as the introduction gas, and the pressure (degree of vacuum) in the plasma chamber was set to 0.1 Pa. Furthermore, the pressure (degree of vacuum) in the film formation chamber was set to 0.01 Pa or less.
When forming the oxide layer, Ar plasma was generated in the plasma chamber, and Ar ⁺ ions were irradiated to the substrate in the deposition chamber by an ion gun.
In ion beam assist, the denseness and adhesion of an oxide layer to be formed are enhanced by the kinetic energy of Ar ⁺ ions. The film formation rate by ion beam assist was 0.8 nm / second, and the oxide layer having a uniform thickness was formed while the substrate was rotated by the substrate holder when forming the oxide layer.

Next, a method for forming the phosphor layer will be described.
First, a vacuum deposition apparatus that is a phosphor layer forming apparatus will be described. In this example, the phosphor layer forming apparatus was different from the oxide layer forming apparatus. In this embodiment, as shown in FIG. 2, a vacuum deposition apparatus that performs vacuum deposition while linearly transporting the substrate P in the transport direction was used.
In the vacuum vapor deposition apparatus, a heating evaporation unit 100 is disposed below a vacuum chamber (not shown). Further, the vacuum evaporation apparatus of this embodiment uses cesium bromide (CsBr) and europium bromide (EuBr ₂ ) as film forming materials, and performs binary vacuum evaporation in which these are individually heated and evaporated. Therefore, the heating evaporation unit 100 includes a europium evaporation unit (hereinafter referred to as Eu evaporation unit) 102b and a cesium evaporation unit (hereinafter referred to as Cs evaporation unit) 102a.

  In the heating evaporation unit 100 (Cs evaporation unit 102a and Eu evaporation unit 102b), six Cs evaporation units 102a and six Eu evaporation units 102b are arranged in a direction orthogonal to the transport direction of the substrate P, respectively. Further, shutters (not shown) corresponding to the Cs evaporation unit 102a and the Eu evaporation unit 102b are arranged above the heating evaporation unit 100, respectively.

The Eu evaporation section 102b has a function of resistance heating and evaporating europium bromide (activator material) contained in an evaporation position (crucible container) by resistance heating (not shown).
Further, the Cs evaporation unit 102a has a function of evaporating cesium bromide (matrix crystal material) accommodated in the evaporation position (crucible container) by resistance heating with a resistance heating device (not shown).
A substrate holder (not shown) for holding the substrate P is provided in the vacuum chamber. The substrate holder is attached to a transport mechanism capable of linearly transporting the substrate P in the transport direction (a direction orthogonal to the crucible arrangement direction). Thereby, the board | substrate P can be reciprocated several times linearly. Further, an evacuation device is connected to the vacuum chamber. The phosphor layer was formed using the vacuum vapor deposition apparatus having such a configuration.

Next, a method for forming the phosphor layer will be described.
In this example, a cesium bromide (CsBr) powder having a purity of 4N or more and a molten product of europium bromide (EuBr ₂ ) having a purity of 3N or more were prepared as an evaporation source. The EuBr ₂ melt was prepared by placing powder in a platinum crucible in a tube furnace having a sufficient halogen atmosphere to prevent oxidation, heating to 800 ° C. to melt and cooling, and then removing from the furnace. As a result of analyzing trace elements in each raw material by ICP-MS method (inductively coupled high-frequency plasma spectroscopy-mass spectrometry), alkali metals (Li, Na, K, Rb) other than Cs in CsBr are each 10 ppm by mass. The other elements such as alkaline earth metals (Mg, Ca, Sr, Ba) were 2 mass ppm or less. Moreover, rare earth elements other than Eu in EuBr ₂ were each 20 ppm by mass or less, and other elements were 10 ppm by mass or less. Since these raw materials have high hygroscopicity, they are stored in a desiccator that maintains a dry atmosphere with a dew point of −20 ° C. or less, and are taken out immediately before use.

In forming the phosphor layer, first, a substrate having an oxide layer formed on the surface was placed on a substrate holder in a vacuum deposition apparatus. The distance between the substrate P and the heating evaporation unit 100 was 15 cm.
After filling the crucible container for resistance heating in the apparatus with the CsBr evaporation source and the EuBr ₂ evaporation source, the main exhaust valve was opened to exhaust the interior of the apparatus to a vacuum degree of 1 × 10 ⁻³ Pa.
At this time, a combination of a rotary pump, a mechanical booster, and a diffusion pump was used as the vacuum exhaust device. Furthermore, a cryopump for exhausting moisture was used to remove moisture. Thereafter, the exhaust is switched from the main exhaust valve to the bypass, Ar gas is introduced into the apparatus, the degree of vacuum is 0.5 Pa, Ar plasma is generated by a plasma generator (ion gun), and the surface of the oxide layer is cleaned. Was done.

Thereafter, the exhaust was switched to the main exhaust valve and exhausted to a vacuum of 1 × 10 ⁻³ Pa, and then the exhaust was switched to bypass again, and Ar gas was introduced to obtain a vacuum of 1 Pa.

Each evaporation source (CsBr and EuBr ₂ ) was heated and melted with a resistance heating device in a state in which the shutter provided between the substrate P and the heating evaporation unit 100 (Cs evaporation unit 102a and Eu evaporation unit 102b) was closed. After that, first, only the shutter on the Cs evaporation unit 102a side was opened, and the CsBr phosphor matrix was deposited on the surface of the substrate P.
Next, 3 minutes after opening the shutter, the shutter on the Eu evaporation unit 102b side was also opened, and a CsBr: Eu stimulable phosphor was deposited on the CsBr phosphor matrix.
At this time, in order to make the thickness of the phosphor layer to be formed uniform, the substrate P was periodically linearly conveyed at a conveyance speed of 200 mm / second.

The deposition rate was 8 μm / min. In addition, the resistance current of each resistance heating device of the heating evaporation unit 100 was adjusted so that the molar concentration ratio of Eu / Cs in the stimulable phosphor layer was 0.001 / 1.
After vapor deposition, the inside of the apparatus was brought to atmospheric pressure, and the substrate was taken out from the apparatus. Next, the substrate was placed in a heat treatment furnace, the inside of the heat treatment furnace was placed in a nitrogen gas atmosphere, and heat treatment was performed at a temperature of 200 ° C. for 2 hours.

As a result, a phosphor layer having a densely forested structure in which the columnar crystals of the phosphor extend in a substantially vertical direction is formed on the oxide layer of the substrate. The thickness C of the phosphor layer was 600 μm, and the area where the phosphor layer was formed was 200 mm × 200 mm.
Thus, the radiation image conversion panel of Examples 1-20 which consists of a board | substrate, an oxide layer, and a fluorescent substance layer by co-evaporation was produced. In Comparative Examples 1 and 2, the phosphor layer is formed directly on the substrate surface without forming the oxide layer.

As a reference for evaluation, a radiation image conversion panel 20 (hereinafter referred to as a reference panel) including a glass substrate 22 as shown in FIG. 3 and a phosphor layer 24 formed on the surface 22a of the glass substrate 22 is used. Was made. The phosphor layer 24 in the reference panel 20 was formed in the same manner as in Examples 1 to 20, and the thickness s was 600 μm. In the reference panel 20 as well, a moisture-proof protective layer is not formed.
For the glass substrate, “Eagle 2000 (trade name)” manufactured by Corning Inc. was used. This glass substrate has a thickness of 0.63 mm and a size of 200 mm × 200 mm.

Further, the surface roughness of the substrate was measured as shown below. First, the surface shape of each type of substrate was observed with an ultra-deep shape measuring microscope (VK-8550) manufactured by Keyence Corporation, and data on the surface shape of each type of substrate was obtained. The measurement conditions for the surface roughness were a height measurement pitch (measurement resolution) of 0.01 μm and a measurement area of 100 μm square.
Next, the arithmetic average roughness Ra was determined using image measurement / analysis software (VK-H1A7) based on the surface shape data of each type of substrate. The arithmetic average roughness Ra is calculated according to JIS B 0601-1994.

In this example, each prepared radiation image conversion panel was evaluated by the “phosphor layer / substrate humidity degradation” evaluation method shown in Table 1 below. This “phosphor layer / substrate humidity degradation” will be described.
First, before exposing to a constant temperature and humidity environment, a tungsten tube is used on the surface of each of the produced radiation image conversion panels, and an X-ray with a tube voltage of 80 kVp is applied at a dose of 10 mR (2.58 × 10 ⁻⁶ C / kg). After that, the radiation image conversion panel is irradiated with a semiconductor laser beam having a wavelength of 660 nm with an excitation energy of 5 J / m ² , and the stimulated emission light emitted from the surface of the radiation image conversion panel is received by a light receiver (spectral sensitivity S). -5 photoelectron multiplier). The received light is converted into an electrical signal. Based on this, the electrical signal is converted into a digital signal, an image is obtained by an image reproducing device configured as an image, and the read image is output as a visible image on a film by a laser printer. did.

  Next, each prepared radiation image conversion panel was left in a constant temperature and humidity chamber having a temperature of 32 ° C. and a relative humidity of 80% for 24 hours. Thereafter, the image was taken out from the constant temperature and humidity chamber, an image after humidity deterioration was obtained under the same conditions and method as the method for obtaining the above-mentioned image, and the read image was output as a visible image on a film by a laser printer.

Each phosphor panel was evaluated for a change between an image before the test and an image after the test. About evaluation, it compared with the change of the reference | standard panel, and evaluated the image quality of each radiation image conversion panel in five steps of AE visually. These results are shown in Table 1 below.
In addition, the change of the reference panel showed a slight change in graininess due to the humidity deterioration of the phosphor layer.

The evaluation standard is “A” when the change in graininess after the test is equivalent to that of the reference panel before the test, and the case where the change in graininess after the test is slightly inferior to the reference panel when viewed carefully. “B”, “C” when the change in graininess after the test is clearly inferior to the reference panel, and a long period of 1 mm or more, although the change in graininess after the test is greatly inferior to the reference panel The case where no artifact was observed was “D”, and the case where an artifact with a clear change in graininess after the test was observed and the medical image was not possible was defined as “E”.
In this example, as a criterion for evaluation, a glass substrate that does not cause corrosion of the substrate is used, and all the same phosphor layers are formed, so that the influence of substrate corrosion can be examined. .

As shown in Table 1 above, all of Examples 1 to 20 provided sufficient image quality as medical images.
In Examples 1 to 3, since the thickness of the oxide layer was less than 0.5 μm and was out of the preferred range, the evaluation was low among the examples. In Examples 4 to 20, since the thickness of the oxide layer was 0.5 μm or more and was in a preferable range, the evaluation was relatively high.

Moreover, in Examples 4-20, if the surface roughness of the board | substrate was the same, the one where the thickness of the oxide layer was thick was favorable. Moreover, in Examples 4-20, if the material of the oxide layer was the same, the one where thickness was thick had the tendency for evaluation to be good.
Furthermore, Examples 10, 11, and 14 to 20 in which the surface roughness of the substrate is in a preferable range (arithmetic average roughness Ra is 0.005 to 0.1 μm) are examples in which the surface roughness of the substrate exceeds the preferable range. There was a tendency that evaluation was better than 8, 9, 12, and 13.

  On the other hand, in Comparative Example 1 and Comparative Example 2 in which no oxide layer was formed, the phosphor layer / substrate humidity change evaluation was “E”, and sufficient image quality as a medical image was not obtained.

It is a typical sectional view showing a radiation image conversion panel concerning an embodiment of the present invention. It is a typical top view which shows schematic structure of the vacuum evaporation system used for preparation of the radiation image conversion panel of the Example of this invention. It is typical sectional drawing which shows the radiation image conversion panel (reference | standard panel) used as the reference | standard of the Example of this invention.

Explanation of symbols

10, 20 Radiation image conversion panel (phosphor panel)
12 substrate 12a, 22a surface 14 oxide layer 16, 24 stimulable phosphor layer (phosphor layer)
18 Moisture-proof protective layer 22 Glass substrate

Claims (9)

A substrate made of metal or alloy;
An oxide layer formed on the substrate by vapor deposition;
A radiation image conversion panel comprising: a phosphor layer formed on the oxide layer by a vapor deposition method.   The radiation image conversion panel according to claim 1, wherein the oxide layer formed by the vapor deposition method is formed by a sputtering method, an ion plating method, or an ion beam assisted vapor deposition method. The radiation image conversion panel according to claim 1, wherein the oxide layer is made of SiO ₂ , Al ₂ O _3, or TiO ₂ .   The radiation image conversion panel according to claim 1, wherein the oxide layer has a thickness of 0.5 μm or more.   The arithmetic average roughness Ra of the surface of the said board | substrate is 0.005-0.1 micrometer, The radiographic image conversion panel of any one of Claims 1-4.   The radiation image conversion panel according to claim 1, wherein a maximum height Rz of the surface of the substrate is 0.005 to 1 μm.   The radiation image conversion panel according to claim 1, wherein the substrate is made of aluminum.   The radiation image conversion panel according to claim 1, wherein the phosphor layer is made of CsBr: Eu. Forming an oxide layer by vapor deposition on a substrate made of metal or alloy;
And a step of forming a phosphor layer on the oxide layer by a vapor deposition method.

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