JP3807347B2 - Radiation image conversion panel and method for manufacturing radiation image conversion panel - Google Patents

Description

【０１１４】
表１から明らかなように、本発明の試料が比較の試料に比して優れていることが分かる。
【０１１５】
【発明の効果】
実施例で実証した如く、本発明による放射線像変換パネル及び放射線像変換パネルの製造方法は、賦活剤の均一性に優れ、且つ、高輝度、高鮮鋭性にも優れた効果を有する。
【図面の簡単な説明】
【図１】支持体上に形成した柱状結晶を有する輝尽性蛍光体層の一例を示す断面図である。
【図２】支持体上に輝尽性蛍光体層を蒸着法により形成される様子を示す図である。
【図３】本発明の放射線像変換パネルの構成の一例を示す概略図である。
【図４】蒸着により支持体上に輝尽性蛍光体層を作製する方法の一例を示す概略図である。
【符号の説明】
１１ 支持体
１２ 輝尽性蛍光体層
１３ 柱状結晶
１４ 柱状結晶間に形成された間隙
１５ 支持体ホルダ
２１ 放射線発生装置
２２ 被写体
２３ 放射線像変換パネル
２４ 輝尽励起光源
２５ 光電変換装置
２６ 画像再生装置
２７ 画像表示装置
２８ フィルタ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a radiation image conversion panel and a method for manufacturing a radiation image conversion panel.
[0002]
[Prior art]
Conventionally, so-called radiography using a silver salt has been used to obtain a radiographic image, but a method for imaging a radiographic image without using a silver salt has been developed. That is, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited with a certain energy to emit the radiation energy accumulated in the phosphor as fluorescence, and this fluorescence is detected. A method for imaging is disclosed.
[0003]
As a specific method, a radiation image conversion method using a panel having a photostimulable phosphor layer on a support and using one or both of visible light and infrared light as excitation energy is known (US Patent No. 1). 3,859,527).
[0004]
As a radiation image conversion method using a stimulable phosphor with higher brightness and sensitivity, for example, BaFX: Eu described in JP-A-59-75200 and the like. ²⁺ Radiation image conversion method using system (X: Cl, Br, I) phosphor, Radiation image conversion method using alkali halide phosphor as described in JP-A-61-72087, etc., JP-A-61-73786 As described in JP-A-61-73787, Tl as a co-activator ⁺ And Ce ³⁺ , Sm ³⁺ , Eu ³⁺ , Y ³⁺ , Ag ⁺ , Mg ²⁺ , Pb ²⁺ , In ³⁺ Alkali halide phosphors containing these metals have been developed.
[0005]
In recent years, there has been a demand for a radiation image conversion panel with higher sharpness in analysis of diagnostic images. As means for improving the sharpness, for example, attempts have been made to improve the sensitivity and sharpness by controlling the shape of the photostimulable phosphor to be formed.
[0006]
As one of these attempts, for example, it is composed of a fine pseudo-columnar block formed by depositing a photostimulable phosphor on a support having a fine concavo-convex pattern described in, for example, JP-A No. 61-142497. There is a method using a stimulable phosphor layer.
[0007]
Further, as described in JP-A-61-142500, a crack between columnar blocks obtained by depositing a photostimulable phosphor on a support having a fine pattern was further developed by applying a shock treatment. A method of using a radiation image conversion panel having a photostimulable phosphor layer, and further a crack from the surface side of a photostimulable phosphor layer formed on a support described in JP-A-62-39737. And a stimulable phosphor layer having a cavity formed by vapor deposition on a support, as described in JP-A-62-110200. There has also been proposed a method in which a cavity is grown by heat treatment and a crack is formed after the formation.
[0008]
Further, JP-A-2-58000 discloses a radiation having a stimulable phosphor layer in which elongated columnar crystals having a certain inclination with respect to the normal direction of the support are formed on the support by vapor deposition. An image conversion panel is described.
[0009]
In any of the methods for controlling the shape of the photostimulable phosphor layer, the stimulable phosphor layer is formed into a columnar shape, thereby suppressing the lateral diffusion of the photostimulated excitation light or the photostimulated luminescence (crack ( The columnar crystal) can reach the support surface while repeating reflection at the interface), and is therefore characterized in that the sharpness of the image due to stimulated emission can be remarkably increased.
[0010]
Recently, a radiation image conversion panel using a stimulable phosphor in which Eu is activated with an alkali halide such as CsBr as a base has been proposed, and in particular, X-ray conversion efficiency that has been impossible in the past by using Eu as an activator. It became possible to improve.
[0011]
However, Eu has a remarkable diffusion due to heat, and since there is a high vapor pressure under vacuum, there is a problem of ubiquitous existence of Eu in the matrix, and the intended high X-ray conversion efficiency can be obtained. However, it has not been put to practical use in the market.
[0012]
In particular, in the activation of rare earth elements that are excellent in terms of X-ray conversion efficiency, it has been difficult to make the activator uniform due to vapor pressure characteristics in the formation of a deposited film under vacuum. In particular, in the manufacturing method, in the stimulable phosphor layer formed by vapor phase growth (deposition), the raw material is heated when the stimulable phosphor layer is produced, the substrate (support) is heated during vacuum deposition, and the film is formed. There is a problem that the presence state of the activator becomes non-uniform because a large amount of heat treatment is performed by a later annealing (substrate strain relaxation) treatment.
[0013]
For this reason, the brightness | luminance requested | required as a radiation image conversion panel, the improvement of sharpness, and the improvement about the uniformity of an activator were calculated | required.
[0014]
[Problems to be solved by the invention]
Therefore, the objective of this invention is providing the manufacturing method of the radiation image conversion panel which is excellent in the uniformity of an activator, and shows high brightness | luminance and high sharpness, and a radiation image conversion panel.
[0015]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following constitution.
[0016]
1. In a radiation image conversion panel having a photostimulable phosphor layer on a support, at least one photostimulable phosphor layer is formed to have a film thickness of 50 μm to 1 mm by vapor deposition, A radiation image conversion panel, wherein the pH value A of the fluorescent phosphor layer is in the range of 0 <A <7.
[0017]
2. At least one photostimulable phosphor layer contains a photostimulable phosphor based on an alkali halide represented by the general formula (1), and the photostimulable phosphor layer is formed by vapor phase growth. 2. The radiation image conversion panel according to 1 above, wherein the radiation image conversion panel is formed to have a film thickness of 50 μm to 1 mm.
[0018]
3. 3. The method for producing a radiation image conversion panel according to 1 or 2, wherein the radiation image conversion panel according to 1 or 2 is produced using a phosphor material having a pH value B of the phosphor material in a range of 0 <B <7. .
[0019]
Hereinafter, the present invention will be described in more detail.
The radiation image conversion panel of the present invention is formed so that at least one stimulable phosphor layer has a film thickness of 50 μm to 1 mm by a vapor phase growth method, and the pH value A of the stimulable phosphor layer is The radiation image conversion panel is manufactured using a phosphor material (hereinafter, also referred to as an evaporation source) having a pH value B of 0 <B <7. It is characterized by that.
[0020]
In other words, by setting the pH value B of the phosphor raw material into which the activator is introduced to 0 <B <7, Eu in the vapor deposition source crystal is stabilized to be bivalent, and the vapor deposition source radiant heat during the vapor deposition and after the vapor deposition is completed. It is possible to eliminate the influence of contact oxidation or the like in the deposited film formation process that undergoes the subsequent annealing treatment, and it is estimated that Eu can be stabilized to a divalent state by the gas atmosphere generated from the Br compound during evaporation. .
[0021]
Further, by setting the pH value A of the phosphor layer (hereinafter also referred to as a vapor deposition film) to 0 <A <7, it is possible to obtain a vapor deposition film from which double salts and carbonates of impurities existing in the vapor deposition source are removed. it can.
[0022]
When the above-mentioned double salt and carbonate as an impurity are contained in the deposited film, local heat generation occurs due to the atmosphere during the heat treatment after the deposition, and the film is peeled off or cracked due to the difference in thermal expansion. This phenomenon appears remarkably when reducing gas (hydrogen) is flowed in the treatment.
[0023]
The pH was measured by dissolving 5 g of a measurement sample (phosphor raw material) in 100 g of pure water having a pH of 7.00, stirring and dissolving with a magnetic stirrer, and allowing to stand for 5 minutes, and then measuring by a glass electrode method.
[0024]
The pH of the deposited film was 5 g of the deposited film, and the pH was measured in the same manner as the phosphor material.
[0025]
The measuring method was measured according to the pH measuring method of JIS-Z-8802. Moreover, the apparatus used for the measurement is Shimadzu Corporation handy pH meter WAT-1.
[0026]
In the present invention, it is preferable that 1 to 100 times the amount of rare earth Eu to be introduced into the deposited film is contained in the phosphor material.
[0027]
Using an activator-containing crystal as a vapor deposition source and including the activator in the vapor deposition source (phosphor raw material) is more preferable than a mixture of the activator and the crystal from the viewpoint of uniformity of Eu in the vapor deposition film and oxidation prevention. preferable.
[0028]
Moreover, as an activator containing method, it is preferable to synthesize | combine in aqueous solution with a wet method.
[0029]
Next, the stimulable phosphor represented by the general formula (1) preferably used in the present invention will be described.
[0030]
In the photostimulable phosphor represented by the general formula (1), M ^I Represents at least one alkali metal atom selected from each atom such as Li, Na, K, Rb and Cs, among which at least one alkaline earth metal atom selected from each atom of Rb and Cs is preferable. More preferred is a Cs atom.
[0031]
M ² Represents at least one divalent metal atom selected from atoms such as Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu, and Ni. Among them, Be, Mg, Ca are preferably used. , A divalent metal atom selected from each atom such as Sr and Ba.
[0032]
M ^Three Is at least one selected from each atom such as Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga and In Among these, trivalent metal atoms selected from each atom such as Y, Ce, Sm, Eu, Al, La, Gd, Lu, Ga, and In are preferably used.
[0033]
A is at least one selected from Eu, Tb, In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. It is a metal atom.
[0034]
From the viewpoint of improving the photostimulable emission brightness of the photostimulable phosphor, X, X ′ and X ″ each represents an atom with at least one halogen selected from F, Cl, Br and I atoms. And at least one halogen atom selected from Br and I, and more preferably at least one halogen atom selected from Br and I atoms.
[0035]
The photostimulable phosphor represented by the general formula (1) is produced, for example, by the production method described below.
[0036]
First, as a phosphor material, an acid (HI, HBr, HCl, HF) is added to a carbonate so as to have the following composition, mixed and stirred, and then filtered at a neutralization point. Is evaporated to produce the following crystals.
[0037]
As a phosphor material,
(A) At least one compound selected from NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr and CsI is used.
[0038]
(B) MgF ₂ MgCl ₂ , MgBr ₂ , MgI ₂ , CaF ₂ , CaCl ₂ , CaBr ₂ , CaI ₂ , SrF ₂ , SrCI ₂ , SrBr ₂ , SrI ₂ , BaF ₂ , BaCl ₂ , BaBr ₂ , BaBr ₂ ・ 2H ₂ O, BaI ₂ ZnF ₂ ZnCl ₂ ZnBr ₂ , ZnI ₂ , CdF ₂ , CdCl ₂ , CdBr ₂ , CdI ₂ , CuF ₂ CuCl ₂ , CuBr ₂ , CuI, NiF ₂ NiCl ₂ , NiBr ₂ And NiI ₂ At least one compound selected from these compounds is used.
[0039]
(C) In the general formula (1), Eu, Tb, In, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu And a compound having a metal atom selected from each atom such as Mg.
[0040]
In the compound represented by the general formula (I), a is 0 ≦ a <0.5, preferably 0 ≦ a <0.01, b is 0 ≦ b <0.5, preferably 0 ≦ b ≦ 10. ^-2 , E is 0 <e ≦ 0.2, preferably 0 <e ≦ 0.1.
[0041]
The phosphor materials (a) to (c) are weighed so as to have a mixed composition in the above numerical range, and dissolved in pure water.
[0042]
At this time, the mixture may be sufficiently mixed using a mortar, ball mill, mixer mill or the like. Next, a predetermined acid is added so that the pH value C of the obtained aqueous solution is adjusted to 0 <C <7, and then water is evaporated.
[0043]
Next, the obtained raw material mixture is filled in a heat-resistant container such as a quartz crucible or an alumina crucible and fired in an electric furnace. The firing temperature is preferably 500 to 1000 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature and the like, but is preferably 0.5 to 6 hours.
[0044]
The firing atmosphere includes a nitrogen gas atmosphere containing a small amount of hydrogen gas, a weak reducing atmosphere such as a carbon dioxide gas atmosphere containing a small amount of carbon monoxide, a neutral atmosphere such as a nitrogen gas atmosphere and an argon gas atmosphere, or a small amount of oxygen gas. A weak oxidizing atmosphere is preferred.
[0045]
After firing once under the above firing conditions, the fired product is taken out from the electric furnace and pulverized, and then the fired product powder is again filled in a heat-resistant container and placed in the electric furnace, and again under the same firing conditions as described above. If the calcination is performed, the emission luminance of the phosphor can be further increased. When the baked product is cooled to the room temperature from the calcination temperature, the desired fluorescence can also be obtained by removing the baked product from the electric furnace and allowing it to cool in air. The body can be obtained, but it may be cooled in the same weakly reducing atmosphere or neutral atmosphere as at the time of firing. In addition, by moving the fired product from the heating unit to the cooling unit in an electric furnace and quenching in a weak reducing atmosphere, neutral atmosphere or weak oxidizing atmosphere, the emission luminance due to the phosphor phosphors obtained can be increased. It can be further increased.
[0046]
Further, the photostimulable phosphor layer of the present invention is formed by a vapor phase growth method.
Vapor deposition methods, sputtering methods, CVD methods, ion plating methods, and others can be used as the vapor phase growth method of the photostimulable phosphor.
[0047]
In the present invention, for example, the following methods can be mentioned.
In the first vapor deposition method, first, a support is placed in a vapor deposition apparatus, and then the interior of the apparatus is evacuated to 1.333 × 10 6. ^-Four The degree of vacuum is about Pa.
[0048]
Next, at least one of the photostimulable phosphors is heated and evaporated by a resistance heating method, an electron beam method, or the like to grow the photostimulable phosphor on the surface of the support to a desired thickness.
[0049]
As a result, a photostimulable phosphor layer containing no binder is formed, but it is also possible to form the photostimulable phosphor layer in a plurality of times in the vapor deposition step.
[0050]
In the vapor deposition step, it is possible to co-evaporate using a plurality of resistance heaters or electron beams to synthesize the desired photostimulable phosphor on the support and simultaneously form the photostimulable phosphor layer. is there.
[0051]
After the vapor deposition is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the side opposite to the support side of the photostimulable phosphor layer as necessary. In addition, after forming a photostimulable phosphor layer on a protective layer, a procedure for providing a support may be taken.
[0052]
Furthermore, in the vapor deposition method, the vapor deposition target (support, protective layer or intermediate layer) may be cooled or heated as necessary during vapor deposition.
[0053]
Further, the stimulable phosphor layer may be heat-treated after the vapor deposition. In the vapor deposition method, O as necessary. ₂ , H ₂ Reactive vapor deposition may be performed in which gas such as gas is introduced for vapor deposition.
[0054]
In the sputtering method as the second method, like the vapor deposition method, a support having a protective layer or an intermediate layer is placed in the sputtering apparatus, and then the inside of the apparatus is evacuated to 1.333 × 10 6. ^-Four The degree of vacuum was set to about Pa, and then an inert gas such as Ar or Ne was introduced into the sputtering apparatus as a sputtering gas to obtain 1.333 × 10 6. ^-1 The gas pressure is about Pa. Next, a stimulable phosphor layer is grown on the support to a desired thickness by sputtering using the stimulable phosphor as a target.
[0055]
Various applied treatments can be used in the sputtering step as in the vapor deposition method.
[0056]
The third method is a CVD method, and the fourth method is an ion plating method.
[0057]
The growth rate of the stimulable phosphor layer in the vapor phase growth is preferably 0.05 μm / min to 300 μm / min. When the growth rate is less than 0.05 μm / min, the productivity of the radiation image conversion panel of the present invention is unfavorable. If the growth rate exceeds 300 μm / min, it is difficult to control the growth rate.
[0058]
When the radiation image conversion panel is obtained by the above-described vacuum deposition method, sputtering method, etc., since there is no binder, the packing density of the stimulable phosphor can be increased, and radiation that is preferable in terms of sensitivity and resolution. An image conversion panel is preferably obtained.
[0059]
The film thickness of the photostimulable phosphor layer varies depending on the intended use of the radiation image conversion panel and the type of stimulable phosphor, but is 50 μm to 1 mm, preferably 50 from the viewpoint of obtaining the effects of the present invention. It is -300 micrometers, More preferably, it is 100-300 micrometers, Most preferably, it is 150-300 micrometers.
[0060]
In producing the photostimulable phosphor layer by the vapor phase growth method described above, the temperature of the support on which the photostimulable phosphor layer is formed is preferably set to 100 ° C. or higher, more preferably 150 ° C. or higher. Especially preferably, it is 150-400 degreeC.
[0061]
Further, from the viewpoint of obtaining a radiation image conversion panel exhibiting high sharpness, the reflectance of the stimulable phosphor layer of the present invention is preferably 20% or more, more preferably 30% or more, and still more preferably. 40% or more. The upper limit is 100%.
[0062]
In addition, the gap between the columnar crystals may be filled with a filler or the like, and in addition to reinforcing the stimulable phosphor layer, it may be filled with a high light absorption substance, a high light reflectance substance, or the like. In addition to providing a reinforcing effect, this is effective in reducing the lateral light diffusion of the stimulated excitation light incident on the stimulable phosphor layer.
[0063]
Next, formation of the photostimulable phosphor layer of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view showing an example of a photostimulable phosphor layer having columnar crystals formed on a support using the vapor phase growth method described above. Reference numeral 11 denotes a support, 12 denotes a stimulable phosphor layer, and 13 denotes a columnar crystal constituting the stimulable phosphor layer. Reference numeral 14 denotes a gap formed between the columnar crystals.
[0064]
FIG. 2 is a diagram showing a state in which a photostimulable phosphor layer is formed on the support by vapor deposition. The incident angle of the photostimulable phosphor vapor flow 16 with respect to the normal direction (R) of the support surface is shown. θ ₂ (In the figure, it is incident at 60 °), the angle of the formed columnar crystal with respect to the normal direction (R) of the support surface is θ ₁ (In the figure, it is approximately 30 °, and empirically, it is approximately half), and columnar crystals are formed at this angle.
[0065]
Since the photostimulable phosphor layer formed on the support in this manner does not contain a binder, it has excellent directivity, high directivity of stimulated excitation light and stimulated emission, and high brightness. The layer thickness can be made thicker than that of a radiation image conversion panel having a dispersive stimulable phosphor layer in which a stimulable phosphor is dispersed in a binder. Furthermore, the sharpness of the image is improved by reducing the scattering of the stimulating light in the stimulable phosphor layer.
[0066]
In addition, the gap between the columnar crystals may be filled with a filler or the like, and in addition to reinforcing the stimulable phosphor layer, it may be filled with a high light absorption substance, a high light reflectance substance, or the like. Thus, in addition to providing the above-mentioned reinforcing effect, it is effective for reducing the light diffusion in the lateral direction of the stimulated excitation light incident on the stimulable phosphor layer.
[0067]
A highly reflective substance refers to a substance having a high reflectivity with respect to stimulated excitation light (500 to 900 nm, particularly 600 to 800 nm). For example, white pigments such as aluminum, magnesium, silver, indium, and other metals In addition, a color material in the green to red region can be used. White pigments can also reflect stimulated emission.
[0068]
As a white pigment, for example, TiO ₂ (Anatase type, rutile type), MgO, PbCO _Three ・ Pb (OH) ₂ , BaSO _Four , Al ₂ O _Three , M (II) FX (where M (II) is at least one atom selected from Ba, Sr and Ca atoms, and X is a Cl atom or a Br atom), CaCO _Three , ZnO, Sb ₂ O _Three , SiO ₂ , ZrO ₂ , Lithopone (BaSO _Four ZnS), magnesium silicate, basic silicate, basic lead phosphate, aluminum silicate and the like.
[0069]
Since these white pigments have a strong hiding power and a high refractive index, they can easily scatter photostimulated luminescence by reflecting or refracting light, thereby significantly improving the sensitivity of the resulting radiation image conversion panel. it can.
[0070]
In addition, as a material having a high light absorption rate, for example, carbon black, chromium oxide, nickel oxide, iron oxide, and the like and a blue color material are used. Among these, carbon black absorbs stimulated light emission.
[0071]
The color material may be either an organic or inorganic color material.
Examples of organic colorants include Zavon First Blue 3G (Hoechst), Estrol Brill Blue N-3RL (Sumitomo Chemical), D & C Blue No. 1 (made by National Aniline), Spirit Blue (made by Hodogaya Chemical), Oil Blue No. 1 603 (made by Orient), Kitten Blue A (made by Ciba Geigy), Eisen Katyron Blue GLH (made by Hodogaya Chemical), Lake Blue AFH (made by Kyowa Sangyo), Primocyanin 6GX (made by Inabata Sangyo), Brill Acid Green 6BH (Hodogaya) Chemical Blue), Cyan Blue BNRCS (Toyo Ink), Lionoyl Blue SL (Toyo Ink), etc. are used.
[0072]
In addition, the color index No. 24411, 23160, 74180, 74200, 22800, 23154, 23155, 24401, 14830, 15050, 15760, 15707, 17941, 74220, 13425, 13361, 13420, 11836, 74140, 74380, 74350, 74460, etc. There are also materials.
[0073]
As an inorganic color material, ultramarine blue, for example, cobalt blue, cerulean blue, chromium oxide, TiO ₂ Examples include inorganic pigments such as -ZnO-Co-NiO.
[0074]
As the support used in the radiation image conversion panel of the present invention, various types of glass such as polymer materials and metals are used. For example, plate glass such as quartz, borosilicate glass and chemically tempered glass, or cellulose acetate. A metal sheet such as a film, a polyester film, a polyethylene terephthalate film, a polyamide film, a polyimide film, a triacetate film, a polycarbonate film, a metal sheet such as an aluminum sheet, an iron sheet, or a copper sheet, or a metal sheet having a coating layer of the metal oxide. preferable.
[0075]
That is, the surface of the support may be a smooth surface, or the surface of the support may be a matte surface for the purpose of improving the adhesion to the stimulable phosphor layer.
[0076]
Moreover, in this invention, in order to improve the adhesiveness of a support body and a photostimulable phosphor layer, you may provide an adhesive layer in advance on the surface of a support body as needed.
[0077]
The thickness of the support varies depending on the material of the support used, but is generally 80 to 2000 μm, and more preferably 80 to 1000 μm from the viewpoint of handling.
[0078]
Moreover, the photostimulable phosphor layer of the present invention may have a protective layer.
The protective layer may be formed by directly applying a protective layer coating solution on the photostimulable phosphor layer, or a protective layer separately formed in advance may be adhered on the photostimulable phosphor layer. Alternatively, a means for forming a stimulable phosphor layer on a separately formed protective layer may be taken.
[0079]
Materials for the protective layer include cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polyvinylidene chloride, nylon, polytetrafluoroethylene, polytrifluoride-chloride. Usual protective layer materials such as ethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer are used. In addition, a transparent glass substrate can be used as a protective layer.
[0080]
In addition, this protective layer is made of SiC, SiO, etc. by vapor deposition or sputtering. ₂ , SiN, Al ₂ O _Three Alternatively, an inorganic substance such as the above may be laminated.
[0081]
The thickness of these protective layers is preferably 0.1 to 2000 μm.
FIG. 3 is a schematic diagram showing an example of the configuration of the radiation image conversion panel of the present invention.
[0082]
In FIG. 3, 21 is a radiation generator, 22 is a subject, 23 is a radiation image conversion panel having a visible or infrared photostimulable phosphor layer containing a stimulable phosphor, and 24 is a radiation of the radiation image conversion panel 23. A stimulated excitation light source for emitting a latent image as stimulated emission, 25 is a photoelectric conversion device for detecting the stimulated emission emitted from the radiation image conversion panel 23, and 26 is a photoelectric conversion signal detected by the photoelectric conversion device 25. 27 is an image display device that displays the reconstructed image, and 28 is a device that cuts off the reflected light from the stimulating excitation light source 24 and transmits only the light emitted from the radiation image conversion panel 23. It is a filter to make it.
[0083]
FIG. 3 shows an example of obtaining a radiation transmission image of a subject. However, when the subject 22 itself emits radiation, the radiation generator 21 is not particularly necessary.
[0084]
The photoelectric conversion device 25 and the subsequent devices are not limited to the above as long as the optical information from the radiation image conversion panel 23 can be reproduced as an image in some form.
[0085]
As shown in FIG. 3, when the subject 22 is placed between the radiation generator 21 and the radiation image conversion panel 23 and irradiated with the radiation R, the radiation R is transmitted according to the change in the radiation transmittance of each part of the subject 22. The transmission image RI (that is, an image of the intensity of radiation) enters the radiation image conversion panel 23.
[0086]
The incident transmission image RI is absorbed by the photostimulable phosphor layer of the radiation image conversion panel 23, so that a number of electrons and / or holes proportional to the amount of radiation absorbed in the photostimulable phosphor layer are generated. Occurs and accumulates at the trap level of the photostimulable phosphor.
[0087]
That is, a latent image in which the energy of the radiation transmission image is accumulated is formed. Next, this latent image is made visible by being excited with light energy.
[0088]
In addition, the stimulable phosphor layer is irradiated with light in the visible or infrared region and the photostimulable phosphor layer is irradiated to expel electrons and / or holes accumulated at the trap level, and the accumulated energy is stimulated. Release as luminescence.
[0089]
The intensity of the emitted stimulated emission is proportional to the number of accumulated electrons and / or holes, that is, the intensity of the radiation energy absorbed in the stimulable phosphor layer of the radiation image conversion panel 23. The optical signal is converted into an electrical signal by a photoelectric conversion device 25 such as a photomultiplier tube, and is reproduced as an image by an image reproduction device 26, and this image is displayed by an image display device 27.
[0090]
The image reproducing device 26 is more effective not only for reproducing an electrical signal as an image signal but also using what can perform so-called image processing, image calculation, image storage, storage, and the like.
[0091]
In addition, when excited by light energy, it is necessary to separate the reflected light of the stimulated excitation light from the stimulated emission emitted from the stimulable phosphor layer, and it is emitted from the stimulable phosphor layer. Photoelectric converters that receive light emission generally have high sensitivity to light energy with a short wavelength of 600 nm or less, so that the stimulated emission emitted from the stimulable phosphor layer has a spectral distribution in the short wavelength region as much as possible. What you have is desirable.
[0092]
The emission wavelength range of the photostimulable phosphor of the present invention is 300 to 500 nm, while the photostimulable excitation wavelength range is 500 to 900 nm, which satisfies the above-mentioned conditions at the same time. Recently, downsizing of diagnostic devices has progressed. A semiconductor laser that has a high output and is easy to be compacted is preferable for the excitation wavelength used for image reading of the radiation image conversion panel. The wavelength of the laser light is preferably 680 nm. The stimulable phosphor incorporated in the panel exhibits very good sharpness when using an excitation wavelength of 680 nm.
[0093]
That is, all of the photostimulable phosphors of the present invention emit light having a main peak at 500 nm or less, the photostimulated excitation light is easily separated, and coincides well with the spectral sensitivity of the light receiver, so that light can be received efficiently. The sensitivity of the image receiving system can be increased.
[0094]
As the stimulated excitation light source 24, a light source including the stimulated excitation wavelength of the stimulable phosphor used in the radiation image conversion panel 23 is used. In particular, when laser light is used, the optical system is simplified, and the intensity of the stimulated excitation light can be increased, so that the stimulated emission efficiency can be increased, and a more preferable result can be obtained.
[0095]
Examples of lasers include He—Ne laser, He—Cd laser, Ar ion laser, Kr ion laser, N ₂ There are lasers, YAG lasers and second harmonics thereof, ruby lasers, semiconductor lasers, various dye lasers, metal vapor lasers such as copper vapor lasers, and the like. Normally, a continuous wave laser such as a He—Ne laser or an Ar ion laser is desirable, but a pulsed laser can also be used if the scanning time and pulse of one pixel of the panel are synchronized.
[0096]
Further, when using a method of separating light emission using a delay of light emission as shown in Japanese Patent Laid-Open No. 59-22046 without using the filter 28, a pulsed laser is used rather than modulation using a continuous wave laser. It is preferable to use it.
[0097]
Among the various laser light sources described above, the semiconductor laser is particularly preferably used because it is small and inexpensive and does not require a modulator.
[0098]
Since the filter 28 transmits the stimulated emission emitted from the radiation image conversion panel 23 and cuts the stimulated excitation light, this is the excitation of the stimulable phosphor contained in the radiation image conversion panel 23. It is determined by the combination of the emission wavelength and the wavelength of the stimulated excitation light source 24.
[0099]
For example, in the case of a practically preferable combination in which the photostimulation excitation wavelength is 500 to 900 nm and the photostimulation emission wavelength is 300 to 500 nm, examples of the filter include C-39, C-40, V-40, manufactured by Toshiba Corporation. Purple-blue glass filters such as V-42, V-44, Corning 7-54, 7-59, Spectrofilm BG-1, BG-3, BG-25, BG-37, BG-38, etc. Can be used. If an interference filter is used, a filter having an arbitrary characteristic can be selected and used to some extent. The photoelectric conversion device 25 may be any device capable of converting a change in light quantity into a change in electronic signal, such as a photoelectric tube, a photomultiplier tube, a photodiode, a phototransistor, a solar cell, or a photoconductive element.
[0100]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to these.
[0101]
Example 1
<< Preparation of Radiation Image Conversion Panel Samples 1-8 (in Table 1, described as Samples 1-8) >>
Under the conditions shown in Table 1, the deposition apparatus shown in FIG. 4 (provided that θ1 = 5 degrees and θ2 = 5 degrees) is provided on the surface of a 1 mm thick crystallized glass (manufactured by Nippon Electric Glass Co., Ltd.) support. A stimulable phosphor layer having a stimulable phosphor (CsBr: Eu) was used.
[0102]
Using the vapor deposition apparatus shown in FIG. 4, using an aluminum slit, setting the distance d between the support and the slit to 60 cm, vapor deposition is carried out while transporting the support in a direction parallel to the support, and the photostimulability The thickness of the phosphor layer was adjusted to be 300 μm.
[0103]
In the vapor deposition, the support was placed in a vapor deposition device, and then, the phosphor raw material (CsBr: Eu) was pressed using a vapor deposition source and placed in a water-cooled crucible.
[0104]
Thereafter, the inside of the vapor deposition device is once exhausted, ₂ After introducing gas and adjusting the degree of vacuum to 0.133 Pa, vapor deposition was performed while maintaining the temperature of the support (also referred to as substrate temperature) at about 350 ° C. Deposition was terminated when the thickness of the photostimulable phosphor layer reached 300 μm, and then this phosphor layer was heat-treated at a temperature of 400 ° C. In a dry air atmosphere, the periphery of the protective layer having a support and borosilicate glass was sealed with an adhesive to obtain a radiation image conversion panel sample 1 (comparative example) having a structure in which the phosphor layer was sealed.
[0105]
In production of the radiation image conversion panel sample 1 (comparative example), radiation image conversion panel samples 2 to 8 were produced in the same manner except that the conditions described in Table 1 were used.
[0106]
The obtained radiation image conversion panel samples 1 to 8 were evaluated as follows.
[0107]
《Evaluation of sharpness》
The sharpness of each prepared radiation image conversion panel sample was evaluated by obtaining a modulation transfer function (MTF).
[0108]
In the MTF, after attaching a CTF chart to the radiation image conversion panel sample, the radiation image conversion panel sample is irradiated with 80 kVp X-rays at a distance of 10 mR (distance to the subject: 1.5 m), and then a semiconductor laser having a diameter of 100 μmφ (680 nm). : Scanning and reading of CTF chart image using panel power of 40 mW). The values in the table are shown as values obtained by adding MTF values of 2.0 lp / mm. The obtained results are shown in Table 1.
[0109]
<Evaluation of luminance and luminance distribution>
The luminance was evaluated using a Regius 350 manufactured by Konica Corporation.
[0110]
As in the sharpness evaluation, X-rays were irradiated with a tungsten tube at 80 kVp and 10 mAs at a distance of 2 m between the bombardment source and the plate, and a plate was set on the Regius 350 and read. Relative evaluation was performed based on the electrical signal from the obtained photomultiplier. The luminance of Sample 2 was set to 1.0, and the subsequent values were expressed as relative values.
[0111]
The electrical signal distribution from the photomultiplier in the photographed surface was relatively evaluated, the standard deviation was obtained, and the luminance distribution (SD) of each sample was obtained. The smaller the value, the better the uniformity of the activator.
[0112]
The pH of the phosphor material and the deposited film was measured by the method described in the above detailed description.
[0113]
[Table 1]

[0114]
As can be seen from Table 1, the sample of the present invention is superior to the comparative sample.
[0115]
【The invention's effect】
As demonstrated in the examples, the radiation image conversion panel and the method for producing the radiation image conversion panel according to the present invention have excellent uniformity of the activator, and also have excellent effects of high brightness and high sharpness.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a photostimulable phosphor layer having columnar crystals formed on a support.
FIG. 2 is a view showing a state in which a photostimulable phosphor layer is formed on a support by a vapor deposition method.
FIG. 3 is a schematic view showing an example of the configuration of the radiation image conversion panel of the present invention.
FIG. 4 is a schematic view showing an example of a method for producing a photostimulable phosphor layer on a support by vapor deposition.
[Explanation of symbols]
11 Support
12 photostimulable phosphor layer
13 Columnar crystals
14 Gaps formed between columnar crystals
15 Support holder
21 Radiation generator
22 Subject
23 Radiation image conversion panel
24 Excited light source
25 Photoelectric conversion device
26 Image playback device
27 Image display device
28 Filter

Claims (3)

In a radiation image conversion panel having a photostimulable phosphor layer on a support, at least one photostimulable phosphor layer has a thickness of 50 μm to 1 mm by vapor deposition (also referred to as vapor deposition). A radiation image conversion panel, wherein the stimulable phosphor layer has a pH value A in a range of 0 <A <7. At least one photostimulable phosphor layer contains a photostimulable phosphor based on an alkali halide represented by the following general formula (1), and the photostimulable phosphor layer is a vapor phase growth method. The radiation image conversion panel according to claim 1, wherein the radiation image conversion panel is formed to have a film thickness of 50 μm to 1 mm.
General formula (1)
M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
[Wherein, M ¹ is at least one alkali metal atom selected from Li, Na, K, Rb and Cs atoms, and M ² is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu. And at least one divalent metal atom selected from each atom of Ni, and M ³ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, At least one trivalent metal atom selected from each atom of Tm, Yb, Lu, Al, Ga and In, and X, X ′ and X ″ are at least selected from each atom of F, Cl, Br and I 1 type of halogen atom, A is Eu, Tb, In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu and Mg. At least one metal atom selected from each atom, and a, b, e each represent a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.] A radiation image conversion panel according to claim 1 or 2, wherein the radiation image conversion panel is manufactured using a phosphor material having a pH value B of the phosphor material in a range of 0 <B <7. Method.

Images