JP2006084332A - Radiological image conversion panel, manufacturing method of radiological image conversion panel, and photographing method of radiological image conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiological image conversion panel having excellent contrast of an image quality, its manufacturing method, and a photographing method of the radiological image conversion panel. <P>SOLUTION: In this radiological image conversion panel having a stimulable phosphor which is a columnar crystal, a stimulable phosphor layer (phosphor layer) and a protection layer are laminated in this order on a support, and the stimulable phosphor layer is formed by a vapor-phase sedimentation method. The panel has characteristics wherein the support is a support having a laminated constitution of two or more layers, and the X-ray absorption efficiency per unit film thickness of a support layer on the stimulable phosphor layer side is higher than that of a support layer on the opposite side to the stimulable phosphor layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a radiation image conversion panel, a method for manufacturing a radiation image conversion panel, and an imaging method for a radiation image conversion panel.

  In recent years, a method of imaging a radiation image by a radiation image conversion panel using a photostimulable phosphor has been used.

  This uses a radiation image conversion panel in which a photostimulable phosphor layer is formed on a support as disclosed in, for example, US Pat. No. 3,859,527 and JP-A-55-12144. . A radiation image (accumulated image) is formed by applying radiation transmitted through the subject to the stimulable phosphor layer of the radiation image conversion panel and storing radiation energy corresponding to the radiation transmittance of each part of the subject in the stimulable phosphor layer. By forming and scanning this stimulable phosphor layer with stimulating excitation light (laser light is used), the radiation energy accumulated in each part is emitted and converted into light, and the intensity of this light is read. Get an image. This image may be reproduced on various displays such as a CRT, or may be reproduced as a hard copy.

  The stimulable phosphor layer of the radiation image conversion panel used in this radiation image conversion method is required to have high radiation absorption rate and light conversion rate, good image graininess, and high sharpness. .

  Usually, to increase the radiation sensitivity, it is necessary to increase the thickness of the photostimulable phosphor layer. However, if the thickness is too large, light emission is caused by scattering of photostimulated luminescence between photostimulable phosphor particles. There is a phenomenon that does not come out to the outside, there is a limit.

  The sharpness is improved as the stimulable phosphor layer is made thinner. However, if the thickness is too thin, the sensitivity is greatly reduced.

  As for the granularity, the granularity of the image is determined by the local fluctuation of the radiation quantum number (quantum motor) or the structural disorder (structural motor) of the stimulable phosphor layer of the radiation image conversion panel. When the layer thickness of the phosphor layer is reduced, the radiation quantum number absorbed in the photostimulable phosphor layer decreases and mottle increases, or structural disturbance becomes obvious and the structure mottle increases, resulting in an increase in image quality. Cause a drop. Therefore, in order to improve the graininess of the image, the stimulable phosphor layer needs to be thick.

  As described above, the image quality and sensitivity of the radiation image conversion method using the radiation image conversion panel are determined from various factors. In order to improve the sensitivity and image quality by adjusting a plurality of factors related to sensitivity and image quality, various studies have been conducted so far.

  As means for improving the sharpness of these internal radiation images, for example, attempts have been made to improve the sensitivity and sharpness by controlling the shape of the stimulable phosphor formed.

  As one of these attempts, for example, a fine pseudo-columnar block formed by depositing a photostimulable phosphor on a support having a fine concavo-convex pattern, as performed in, for example, JP-A No. 61-142497 There is a method using a photostimulable phosphor layer made of

  Further, as described in JP-A-61-142500, a crack between columnar blocks obtained by depositing a stimulable 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 surface of the photostimulable phosphor layer formed on the surface of a support as described in JP-A-62-39737. A method using a radiation image conversion panel in which a pseudo-columnar shape is formed by cracking from the side, and further, as described in JP-A-62-110200, a photostimulable phosphor layer having a cavity by vapor deposition on the upper surface of a support There has also been proposed a method in which a cavity is grown by heat treatment and a crack is formed after the formation.

  In JP-A-2-58000, 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 has been proposed.

  In attempts to control the shape of these photostimulable phosphor layers, all of the photostimulable phosphor layers are made columnar to suppress the lateral diffusion of photostimulated excitation light (or photostimulated luminescence). Since it can reach the support surface while repeating reflection at the crack (columnar crystal) interface, it has a feature that the sharpness of an image by stimulated emission can be remarkably increased.

  A radiation image conversion panel having a photostimulable phosphor layer formed by these vapor phase growth (deposition) methods, capable of withstanding repeated use over a long period or many times without degrading the image quality of the obtained radiation image For this purpose, the photostimulable phosphor layer of the conversion panel needs to be sufficiently protected from external physical or chemical stimulation. In particular, it is necessary to pay sufficient attention to the deterioration due to moisture, and in order to solve the above problems, a protective layer covering the stimulable phosphor layer surface of the support of the conversion panel is provided, and the periphery of the conversion panel is sealed. Methods have been taken to protect the photostimulable phosphor layer.

  This protective layer is formed, for example, by directly applying a protective layer coating solution on the photostimulable phosphor layer as disclosed in JP-A-59-42500, or separately formed in advance. The protective layer is formed by a method of adhering to the photostimulable phosphor layer.

  In order to seal the periphery of the conversion panel, for example, only the periphery of the conversion panel is immersed in a solution in an organic polymer, or an organic polymer solution is applied to the periphery to form a polymer film and sealed. A method, a method in which a peripheral portion is sealed with a sealing material, and the sealing material is fixed from the outside by a fixing member (Japanese Patent Laid-Open No. 61-237099), and sealing is performed in a state where the peripheral portion is covered with an extended portion of a protective layer The method (Japanese Patent Laid-Open No. 61-237100) is used.

  Furthermore, in order to reduce the internal humidity as much as possible, a notch is provided in the spacer when sealing the photostimulable phosphor layer inside by adhering the spacer around the protective film and the support. For example, a method of sealing the interior moisture after drying it by heating or vacuum, for example, is disclosed in Japanese Patent Application Laid-Open No. 2-85799. A further improvement method is described in JP-A-1-316697. In addition, Japanese Patent Application Laid-Open Nos. 6-308298 and 7-120598 also describe that sealing is performed after drying. When sealing the photostimulable phosphor in a low-humidity atmosphere, the sealing material or spacer and the support, protective film, even after the inside has been made sufficiently low-humidity, due to differences in internal and external atmospheric pressure and temperature In order to prevent this, the method of providing a notch in a part of the sealing material or spacer is effective. However, in the case of a phosphor whose characteristics are easily affected by the presence or intrusion of moisture, for example, when vacuum drying or the like is performed, the vicinity of the notch and the back part away from the notch are dried. Inhomogeneity occurs, stable characteristics cannot be obtained, the sensitivity of the phosphor is lowered after sealing, and the image quality may be affected.

  In addition, providing a notch in the spacer or sealing with a sealing agent is complicated by operations such as vacuum drying and gas replacement. If it is easy to absorb, the phosphor will absorb moisture from the surrounding atmosphere unless each operation is performed quickly.

Therefore, the photostimulable phosphor obtained by the vapor phase growth method and the method for producing a radiation image conversion panel in which the photostimulable phosphor is sealed from the outside air by a simpler operation and the deterioration due to moisture is suppressed. A method for producing a radiation image conversion panel that can be sealed to obtain a radiation image conversion panel having high sensitivity and stable characteristics is disclosed. (For example, see Patent Document 1)
However, although it is possible to obtain a radiation image conversion panel having high workability efficiency and no deterioration due to moisture and having high sensitivity and stable characteristics, it is still insufficient in terms of image quality contrast.
Japanese Patent Laid-Open No. 2003-232897

  Accordingly, an object of the present invention is to provide a radiographic image conversion panel excellent in image quality contrast, a method for manufacturing the same, and a radiographic image conversion panel imaging method.

  The above object of the present invention is achieved by the following configurations.

(Claim 1)
A photostimulable phosphor layer (phosphor layer) and a protective layer are laminated in this order on a support, and the photostimulable phosphor layer is formed by a vapor deposition method and is a columnar crystal. In a radiation image conversion panel having a stimulable phosphor, the support is a support having a laminated structure of two or more layers, and a support layer and a stimulable phosphor layer on the opposite side of the stimulable phosphor layer A radiation image conversion panel characterized in that the X-ray absorption efficiency per unit film thickness of the support layer on the side is higher on the phosphor layer side.

(Claim 2)
The radiation image conversion panel according to claim 1, wherein a film thickness of the support opposite to the phosphor layer of the support is thicker than that of the support on the phosphor layer side.

(Claim 3)
The support on the opposite side of the phosphor layer of the support is a carbon fiber or carbon-containing support having a film thickness of 0.5 to 10 mm, and the support on the phosphor layer side is aluminum. The radiation image conversion panel according to claim 1 or 2.

(Claim 4)
The radiation image conversion panel according to claim 1, wherein the photostimulable phosphor is a CsBr columnar crystal.

(Claim 5)
The radiation image conversion panel according to any one of claims 1 to 4 is provided on the support on the phosphor layer side by a vapor-depositing phosphor layer on the support on the phosphor layer side, and then on the back surface of the support on the phosphor layer side. Furthermore, the manufacturing method of the radiographic image conversion panel characterized by sticking and manufacturing the back surface support body.

(Claim 6)
5. A radiographic image characterized by irradiating a support on the opposite side of the phosphor layer of the radiographic image conversion panel according to any one of claims 1 to 4 with X-rays and reading information on a subject by the phosphor layer. How to shoot the conversion panel.

  The radiation image conversion panel, the manufacturing method thereof, and the radiographic image conversion panel photographing method according to the present invention have an excellent image quality contrast.

  The present invention will be described in more detail.

The invention of claim 1 of the present invention
A photostimulable phosphor layer (phosphor layer) and a protective layer are laminated in this order on a support, and the photostimulable phosphor layer is formed by a vapor deposition method and is a columnar crystal. In a radiation image conversion panel having a stimulable phosphor, the support is a support having a laminated structure of two or more layers, and a support layer and a stimulable phosphor layer on the opposite side of the stimulable phosphor layer It is an invention of a radiation image conversion panel characterized in that the X-ray absorption efficiency per unit film thickness of the support layer on the side is higher on the phosphor layer side, and the object of the present invention can be achieved by these configurations It is.

  Further, the thickness of the support on the opposite side of the phosphor layer of the support is characterized by being thicker than the thickness of the support on the phosphor layer side, which is preferable in that the effect of the present invention is further exhibited.

  The support on the opposite side of the phosphor layer of the support is a support having a film thickness of 0.5 to 10 mm containing carbon fiber or carbon, and the support on the phosphor layer side is aluminum. However, it is preferable from the viewpoint of further achieving the effects of the present invention, and as will be described later, it is particularly preferable that the stimulable phosphor is a CsBr columnar crystal from the viewpoint of achieving the effects of the present invention.

The invention of claim 5
The radiation image conversion panel according to any one of claims 1 to 4 is provided on the support on the phosphor layer side by a vapor-depositing phosphor layer on the support on the phosphor layer side, and then on the back surface of the support on the phosphor layer side. Furthermore, it is a manufacturing method of the radiographic image conversion panel characterized by sticking and manufacturing the back surface support, and the radiographic image conversion panel of the present invention can be obtained by the manufacturing method.

The invention of claim 6
5. A radiographic image characterized by irradiating a support on the opposite side of the phosphor layer of the radiographic image conversion panel according to any one of claims 1 to 4 with X-rays and reading information on a subject by the phosphor layer. It is an invention of an imaging method for conversion, and by these configurations, it is an imaging method that can achieve the object of the present application.

  The support of the present invention can be prepared using a support described later. For example, a support is prepared in advance with a different support, and a desired photostimulation is performed on the support by vapor deposition. In addition, after a desired stimulable phosphor layer is formed on a single support by vapor deposition, a different support is bonded to the back surface of the support. And can be used as a support. In the present invention, the latter is preferred.

Next, examples of the stimulable phosphor used in the radiation image conversion panel of the present invention include a phosphor represented by BaSO ₄ : Ax described in JP-A-48-80487, and JP-A-48. A phosphor represented by MgSO ₄ : Ax described in JP-80488, a phosphor represented by SrSO ₄ : Ax described in JP-A 48-80489, and described in JP-A 51-29889 A phosphor obtained by adding at least one of Mn, Dy, and Tb to Na ₂ SO ₄ , CaSO _4, BaSO _{4, and the} like, BeO, LiF, MgSO _4, and CaF ₂ described in JP-A-52-30487 Phosphors such as Li ₂ B ₄ O ₇ : Cu, Ag described in JP-A-53-39277, Li ₂ O. (Be described in JP-A-54-47883 _{2 O 2) x: Cu,} A Phosphors etc., are described in U.S. Pat. No. 3,859,527 SrS: Ce, Sm, SrS : Eu, Sm, La 2 O 2 S: Eu, Sm and (Zn, Cd) S: at Mnx And phosphors represented. Further, a ZnS: Cu, Pb phosphor described in JP-A-55-12142, a barium aluminate phosphor whose general formula is BaO.xAl ₂ O ₃ : Eu, and a general formula of M (II ) O.xSiO ₂ : An alkaline earth metal silicate phosphor represented by A can be used.

Further, an alkaline earth fluorohalide phosphor represented by the general formula (Ba1-x-yMgxCay) Fx: Eu ₂ ⁺ described in JP-A-55-12143, JP-A-55-12144 A phosphor represented by the general formula LnOX: xA, and a fluorescence represented by (Ba1-xM (II) x) Fx: yA represented by JP-A-55-12145. A phosphor represented by the general formula BaFX: xCe, yA described in JP-A No. 55-84389, and a general formula described in JP-A No. 55-160078 as M (II) FX. Rare earth element activated divalent metal fluorohalide phosphor represented by xA: yLn, phosphor represented by general formula ZnS: A, CdS: A, (Zn, Cd) S: A, X, JP-A 59- Any of the following listed in 38278 Formula _{xM 3 (PO 4) 2 ·} NX 2: yAxM 3 (PO 4) 2: phosphor represented by yA, either of the following general formula nReX that are described in JP-A-59-155487 _3- phosphors represented by mAX ' ₂ : xEunReX ₃ · mAX' ₂ : xEu, ySm, etc., and bismuth represented by the general formula M (I) X: xBi described in JP-A-61-2228400 Examples include activated alkali halide phosphors.

  However, alkali halide photostimulable phosphors represented by the following general formula (1) as described in JP-A Nos. 61-72087 and 2-58000 are particularly preferable.

General formula (1)
M1X · aM2X′2 · bM3X ″ 3: In the formula cA, M1 is at least one alkali metal selected from Li, Na, K, Rb and Cs, and M2 is Be, Mg, Ca, Sr, Ba, Zn. , Cd, Cu, and Ni, and M3 is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, And at least one trivalent metal atom selected from Tm, Yb, Lu, Al, Ga and In, and X, X ′ and X ″ are at least one halogen atom selected from F, Cl, Br and I. Yes, A is selected from Eu, Tb, In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg At least one metal atom Ri, also, a, b and c each represents a number between 0 ≦ a <0.5,0 ≦ b <0.5,0 <e ≦ 0.2.

  These alkali halide photostimulable phosphors are formed on a support by vapor deposition, so that they have a certain inclination with respect to the normal direction of the support (of course, there is no inclination and the support surface has It forms an elongated columnar crystal (although it may be perpendicular to it). By forming such columnar crystals, it is possible to suppress the diffusion of stimulated excitation light (or stimulated emission) in the lateral direction. Therefore, it is necessary to use these phosphors that the sharpness of the image by stimulated emission is good. It is a feature when there was.

  In the present invention, among alkali halide photostimulable phosphors, CsBr phosphors are preferable because they have high luminance and high image quality, but they are not susceptible to moisture, so the combined effect with the production method of the present invention is remarkable.

  Of these, the CsBr phosphors represented by the following general formula (2) are particularly preferable in the present invention.

General formula (2)
CsX: A
In the formula, X represents Br or I, and A represents Eu, In, Ga, or Ce.

  Among them, the CsBr phosphor is particularly preferable because it has a particularly high luminance and high image quality, has a remarkable combination effect with the sealing method (manufacturing method) of the present invention, and exhibits the effects of the present invention.

  The columnar crystals obtained by using these photostimulable phosphors that are preferable in the present invention, that is, the crystals growing in columnar form with a certain gap are described in JP-A-2-58000. Can be obtained by different methods.

  That is, a stimulable phosphor layer composed of independent elongated columnar crystals can be obtained by supplying vapor of the stimulable phosphor or the raw material on the support and performing vapor phase growth (deposition) such as vapor deposition. .

  For example, by making the vapor flow of the photostimulable phosphor at the time of vapor deposition enter in the range of 0 to 5 degrees with respect to the direction perpendicular to the substrate, it is possible to obtain crystals that are substantially perpendicular to the substrate surface.

  In these cases, it is appropriate that the distance between the shortest part of the support and the crucible is set to approximately 10 cm to 60 cm in accordance with the average range of the stimulable phosphor.

  The stimulable phosphor as an evaporation source is uniformly dissolved or formed by pressing or hot pressing and charged in a crucible. At this time, it is preferable to perform a degassing treatment. The method for evaporating the photostimulable phosphor from the evaporation source is performed by scanning the electron beam emitted from the electron gun, but it can also be evaporated by other methods.

  The evaporation source is not necessarily a stimulable phosphor, and may be a mixture of a stimulable phosphor material.

  Moreover, what activator mixed the activator with respect to a base substance (basic substance) may be vapor-deposited, and after depositing only a base material, you may dope an activator afterwards. For example, after vapor-depositing only CsBr that is a base material, for example, In that is an activator may be doped. That is, since the crystals are independent, even if the film is thick, it can be sufficiently doped, and crystal growth hardly occurs, so the MTF does not decrease.

  Doping can be performed by thermal diffusion and ion implantation of a doping agent (activator) in the base layer of the formed phosphor.

  In order to improve the modulation transfer function (MTF) in the photostimulable phosphor layer composed of these columnar crystals, the size of the columnar crystals (the columnar crystals when the columnar crystals are observed from a plane parallel to the support) is used. The average value of the diameter of the cross-sectional area in terms of a circle, calculated from a micrograph containing at least 100 columnar crystals in the field of view, is preferably about 0.5 to 50 μm, more preferably 0.5 to 20 μm. It is.

  That is, when the columnar crystal is thinner than 0.5 μm, the excitation excitation light is scattered by the columnar crystal, so that the MTF is lowered. When the columnar crystal is 50 μm or more, the directivity of the excitation excitation light is also reduced. , MTF decreases.

  As a method for vapor phase growth (deposition) of the photostimulable phosphor, there are an evaporation method, a sputtering method, and a CVD method.

In the vapor deposition method, after the support is placed in the vapor deposition apparatus, the inside of the apparatus is evacuated to a vacuum of about 1.333 × 10 ⁻⁴ Pa, and then at least one of the photostimulable phosphor is subjected to resistance heating, electron The photostimulable phosphor is obliquely deposited to a desired thickness on the surface of the support by heating and evaporating using a beam method or the like. 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. In the vapor deposition step, vapor deposition can be performed using a plurality of resistance heaters or electron beams. In the vapor deposition method, the stimulable phosphor material is deposited using a plurality of resistance heaters or electron beams, and the desired stimulable phosphor layer is synthesized on the support at the same time. It is also possible to form. Further, in the vapor deposition method, the deposition object may be cooled or heated as necessary during vapor deposition. Moreover, you may heat-process a photostimulable phosphor layer after completion | finish of vapor deposition.

In the sputtering method, after the support is installed in the sputtering apparatus, the inside of the apparatus is once evacuated to a vacuum degree of about 1.333 × 10 ⁻⁴ Pa, and then Ar, Ne are used as sputtering gases. An inert gas such as is introduced into the apparatus to obtain a gas pressure of about 1.333 × 10 ⁻¹ Pa. Next, the stimulable phosphor is obliquely deposited to a desired thickness on the surface of the support by sputtering obliquely using the stimulable phosphor as a target. In this sputtering process, it is possible to form the stimulable phosphor layer by dividing into multiple times as in the vapor deposition method. It is also possible to form In the sputtering method, a plurality of photostimulable phosphor materials can be used as targets, and these can be sputtered simultaneously or sequentially to form the desired photostimulable phosphor layer on the support. If necessary, reactive sputtering may be performed by introducing a gas such as O ₂ or H ₂ . Furthermore, in the sputtering method, the deposition object may be cooled or heated as necessary during sputtering. Alternatively, the photostimulable phosphor layer may be heat-treated after the end of sputtering.

  In the CVD method, the target stimulable phosphor or organometallic compound containing the stimulable phosphor raw material is decomposed with energy such as heat and high-frequency power, so that no stimulant containing a binder is contained on the support. In any case, the stimulable phosphor layer can be vapor-phase grown into independent elongated columnar crystals with a specific inclination with respect to the normal direction of the support.

  The thickness of the stimulable phosphor layer formed by these methods varies depending on the radiation sensitivity of the intended radiation image conversion panel, the type of stimulable phosphor, etc., but is selected from the range of 50 μm to 1000 μm. Preferably, it is selected from 80 μm to 800 μm.

  These columnar crystals are grown by the method described in JP-A-2-58000 as described above, that is, vapor of stimulable phosphor or the raw material is supplied onto a support and vapor phase growth (deposition) such as vapor deposition is performed. Can be obtained by the method.

  FIG. 1 is a schematic view showing an example of a state in which a photostimulable phosphor layer is formed on a support 11 by vapor deposition. 13 schematically represents the photostimulable phosphor columnar crystal formed. When the incident angle of the photostimulable phosphor vapor flow V with respect to the normal direction (P) of the support surface is θ2, the angle of the columnar crystal formed with respect to the normal direction (P) of the support surface is represented by θ1. A columnar crystal is formed at a constant angle θ1 depending on the incident angle θ2. In the present invention, as described above, for example, the vapor flow of the photostimulable phosphor during vapor deposition is changed with respect to the direction perpendicular to the substrate. By making incidence in the range of 0 to 5 degrees (that is, θ2 is 0 to 5 degrees), it is possible to obtain a crystal having a substantially vertical column shape (θ1 is approximately 0 degrees) with respect to the substrate surface.

  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.

  In addition, the gap between the columnar crystals may be filled with a filler or the like, which reinforces the photostimulable phosphor layer. Further, a substance having a high light absorption rate, a substance having a high light reflectance, or the like may be filled. As a result, the above-mentioned reinforcing effect can be provided, and the light diffusion in the lateral direction of the stimulated excitation light incident on the stimulable phosphor layer can be almost completely prevented.

  The substance having high light reflectance means a material having high reflectance with respect to stimulating excitation light (500 to 900 nm, particularly 600 to 800 nm), such as white pigment and green to red, such as aluminum, magnesium, silver, indium and other metals. Area colorants can be used.

White pigments can also reflect stimulated emission. As white pigments, TiO ₂ (anatase type, rutile type), MgO, PbCO ₃ .Pb (OH) ₂ , BaSO ₄ , Al ₂ O ₃ , M (II) FX (where M (II) is Ba, Sr and At least one of Ca, and X is at least one of Cl and Br.), CaCO ₃ , ZnO, Sb ₂ O ₃ , SiO ₂ , ZrO ₂ , lithopone (BaSO ₄ .ZnS), silicic acid Examples include magnesium, basic lead silicate, basic lead phosphate, and aluminum silicate. Since these white pigments have a strong hiding power and a high refractive index, they can easily scatter scattered light by reflecting or refracting light, and can significantly improve the sensitivity of the resulting radiation image conversion panel.

  Moreover, as a substance having a high light absorption rate, for example, carbon, chromium oxide, nickel oxide, iron oxide and the like and a blue color material are used. Of these, carbon also absorbs stimulated luminescence.

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. 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. Examples of inorganic color materials include ultramarine, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—Co—NiO pigments.

  As the support used in the radiation image conversion panel of the present invention, those having low moisture permeability are preferable, and various glasses, polymer materials, metals, etc. are used. For example, quartz, borosilicate glass, chemically tempered glass, and the like. Sheet glass such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film and other metal film, aluminum sheet, iron sheet, copper sheet and other metal sheet or the metal oxide A metal sheet having a coating layer of is preferable. The surface of these supports may be a smooth surface, or may be a matte surface for the purpose of improving the adhesion to the stimulable phosphor.

  Moreover, in this invention, in order to improve the adhesiveness of a support body and a photostimulable fluorescent substance, you may provide an adhesive layer in advance on the surface of a support body as needed.

  The thickness of these adhesive layers varies depending on the material of the support used, but is generally 80 μm to 2000 μm, and more preferably 80 μm to 1000 μm from the viewpoint of handling.

  Moreover, as a protective layer of this invention, what can be formed in a sheet form with good translucency can be used. Examples thereof include plate glass such as quartz, borosilicate glass and chemically tempered glass, and organic polymers such as PET, OPP and polyvinyl chloride.

  The protective layer of the present invention may be a single layer, may be a multilayer, or may be composed of two or more types of layers having different materials. For example, a film in which two or more polymer films are combined can be used. Examples of a method for producing such a composite polymer film include dry lamination, extrusion lamination, and coextrusion coating lamination. The combination of two or more protective layers is not limited to organic polymers, and includes plate glasses or plate glasses and organic polymers. For example, as a method of combining the plate glass and the polymer layer, there is a method in which a protective layer coating solution is directly applied on the plate glass, or a method in which a separately formed polymer protective layer is adhered on the plate glass. . Two or more protective layers may be in close contact with each other or may be separated from each other.

  The thickness of the protective layer of the present invention is practically 10 μm to 3 mm. In order to obtain good moisture resistance and impact resistance, the thickness of the protective layer is preferably 100 μm or more, and particularly when a protective layer of 500 μm or more is provided, a conversion panel excellent in durability and durability can be obtained. Even more preferred.

  Moreover, when plate glass is used as the protective layer, it is particularly preferable because it is extremely excellent in moisture resistance.

  The protective layer desirably exhibits high transmittance in a wide wavelength range in order to efficiently transmit stimulated excitation light and stimulated emission, and the transmittance is 60% or more, preferably 80% or more. For example, quartz glass, borosilicate glass, and the like can be given. Borosilicate glass exhibits a transmittance of 80% or more in the wavelength range of 330 nm to 2.6 μm, and quartz glass exhibits a high transmittance even at a shorter wavelength.

In addition, it is preferable to provide an antireflection layer such as MgF _{2 on} the surface of the protective layer because it effectively transmits the stimulating excitation light and the stimulable light emission and reduces the sharpness reduction. The refractive index of the protective layer is not particularly specified, but many practically used materials are between 1.4 and 2.0.

  In order to improve the sharpness, the glass may be colored by containing a colorant such as lead phosphate to absorb the stimulated excitation light.

  For that purpose, a film colored with a coloring material (pigment or coloring matter) that absorbs stimulating excitation light is laminated on the glass, or a layer containing a coloring matter or pigment is applied on either side of the glass, There is also a method in which the glass itself contains a dispersed pigment or colorant as a coloring material.

  As a method for producing a colored film, there is a method of forming a layer containing a coloring material (pigment or dye) on the surface of a plastic film or a plastic film kneaded with a coloring material, and bonding the colored plastic film. Colored glass can be obtained by a method of uniformly bonding to the glass surface using an agent or the like.

  Alternatively, a pigment or dye dispersed or dissolved in a binder (water glass, organic polymer such as polyvinyl butyral, etc.) having good adhesiveness with glass may be directly applied to the glass.

The coloring material that can absorb the excitation light used in these protective layers may be either an organic or inorganic coloring material. Examples of the organic coloring material include Zavon Fast Blue 3G (manufactured by Hoechst), Estrol Brill Blue N- 3RL (manufactured by 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. 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. Or a pigment is also mentioned. In particular, metal phthalocyanine pigments are preferred. Examples of inorganic color materials include ultramarine, cobalt blue, cerulean blue, chromium oxide, and TiO ₂ —ZnO—Co—NiO pigments.

  The spacer is not particularly limited as long as it can hold the photostimulable phosphor layer in a state of being blocked from the external atmosphere, and glass, ceramics, metal, plastic, or the like can be used.

The spacer preferably has a moisture permeability of 30 g / m ² · 24 hr or less. When this moisture permeability is too large, the photostimulable phosphor is deteriorated by moisture entering from the outside.

  The thickness of the spacer is preferably equal to or greater than the thickness of the stimulable phosphor layer, and the width is mainly related to the moisture resistance (moisture permeability) of the contact portion between the spacer and the support and the protective layer. 1 to 30 mm is preferable. If the width of the spacer is too small, it is not preferable from the viewpoint of the stability, strength and moisture resistance of the spacer. On the other hand, if the size is too large, the radiation image conversion panel becomes unnecessarily large, which is not preferable.

In addition, it is preferable that the moisture permeability of the adhesion part of a spacer, a support body, and a protective layer is 30 g / m < ² > * 24hr or less.

  The spacer is necessary from the point that the support and the protective layer are in close contact with each other to provide moisture resistance to the conversion panel and to keep the layer thickness of the low refractive index layer constant. Here, a sealing agent is used to adhere and seal the spacer to the support and the protective layer.

  In the present invention, the sealing agent means that the spacer is directly bonded to the support and the protective layer, and the support and the protective layer are directly bonded, and an adhesive may be used, and the adhesive has moisture resistance. Those are preferred.

  Specifically, epoxy resin, phenol resin, cyanoacrylate resin, vinyl acetate resin, vinyl chloride resin, urethane resin, acrylic resin, ethylene vinyl acetate resin, olefin resin, chloroprene rubber, Examples include organic polymer adhesives such as nitrile rubber, inorganic adhesives mainly composed of silicone adhesives, alumina, silica, and the like. Among these, epoxy resins and silicone resins used for sealing semiconductors and electronic components are excellent in moisture resistance, and epoxy adhesives are particularly preferable because of low moisture permeability.

  In addition, for the purpose of improving the adhesion of the contact portion between the spacer and the support or between the spacer and the protective layer, an undercoat layer is provided on the adhesion surface between the spacer, the support and the protective layer, or a roughening treatment is performed. It is also preferable to apply.

  Further, it is possible to adhere and seal the support and the protective layer using only the above-mentioned sealing agent without a spacer.

  In the present invention, a low refractive index layer may be provided. The low refractive index layer is made of a material having a refractive index lower than that of the protective layer, and the presence of this layer can reduce the reduction in sharpness even if the protective layer is thickened.

  Further, when a layer having a refractive index of substantially 1, such as a gas layer such as air, nitrogen, argon, or a vacuum layer, is used as the low refractive index layer preferably used in the present invention, the effect of preventing a reduction in sharpness can be obtained. High and particularly preferred.

  The thickness of the low refractive index layer preferably used in the present invention is practical from 0.05 μm to 3 mm. The low refractive index layer of the present invention may be in close contact with the photostimulable layer or may be separated. In order to adhere the low refractive index layer and the stimulating layer, one method is to use an adhesive. In that case, the refractive index of the adhesive is the refractive index of the stimulating layer or the refractive index of the low refractive index layer. It is preferable to be close to the rate.

  FIG. 2 is a schematic diagram showing an example of a radiation image conversion method using the radiation image conversion panel of the present invention.

  That is, in FIG. 2, 21 is a radiation generating device, 22 is a subject, 23 is a radiation image conversion panel according to the present invention, 24 is a stimulating excitation light source (such as a laser), and 25 is a stimulating light emitted by the converting panel. A photoelectric conversion device that detects fluorescence, 26 is a device that reproduces the signal detected in 25 as an image, 27 is a device that displays the reproduced image, and 28 is a device that separates stimulated excitation light and stimulated fluorescence. This is a filter that transmits only exhaust fluorescent light. It should be noted that anything after 25 can be used as long as the optical information from 23 can be reproduced as an image in some form, and is not limited to the above.

  As shown in FIG. 2, the radiation (R) from the radiation generator 21 enters the radiation image conversion panel 23 through the subject 22 (RI). The incident radiation is absorbed by the stimulating layer of the panel 23, the energy is accumulated, and an accumulated image of a radiation transmission image is formed.

  Next, this accumulated image is excited by stimulated excitation light from the stimulated excitation light source 24 and emitted as stimulated emission.

  Since the intensity of stimulated emission emitted is proportional to the amount of accumulated radiation energy, this optical signal is photoelectrically converted by a photoelectric conversion device 25 such as a photomultiplier tube, and reproduced as an image by an image generation device 26 to display an image. By displaying on the apparatus 27, a radiation transmission image of the subject can be observed.

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

Example 1 << Preparation of Radiation Image Conversion Panel Samples 1-7 >>
A stimulable phosphor layer having a stimulable phosphor (CsBr: Eu) as shown in FIG. 1 was formed on the surface of a carbon (Toray Industries, Inc.) support 11 having a thickness of 4 mm and an area of 410 mm × 410 mm. .

  In FIG. 1, an aluminum slit was used as the slit, provided that θ2 = 0 °, the distance d between the support and the slit was 60 cm, and vapor deposition was performed while the support was transported in a direction parallel to the support. By observation with an electron microscope, it was confirmed that a stimulable phosphor layer having a thickness of 300 μm composed of columnar crystals 13 having θ1 = 0 ° and a crystal diameter of 3 μm was provided.

  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.

After that, the inside of the vapor deposition unit is evacuated, and after maintaining the degree of vacuum in the vessel at 6.55 × 10 ⁻⁴ Pa, vapor deposition is started while maintaining the temperature of the support (also called the substrate temperature) at about 300 ° C. did. Deposition was terminated when the thickness of the photostimulable phosphor layer reached 300 μm.

The support on which the photostimulable phosphor layer thus obtained was formed was immediately transferred to a working chamber (absolute humidity 2.66 × 10 ³ Pa), and the back surface of the support had a thickness of 1 mm different from that of the support. An aluminum (made by Nippon Metals Co., Ltd.) support is adhered and bonded using adhesives (epoxy adhesives ALARDITE AW136H and HARDENER HY994 made by Ciba Geigy Co., Ltd.), thereby producing stimuli on the support. Sample 1 having a phosphor layer was obtained. Coating Sample 1 with a protective layer is sealed with a protective resin film and a phosphor layer or a support under reduced pressure using a sealing resin film (polyethylene terephthalate transparent film thickness 30 μm) coated with an adhesive resin. The resin film for use was sufficiently adhered. Thus, the radiation image conversion panel sample 1 (sample No. 1) in the sealed state was obtained.

  Preparation of the radiation image conversion panel sample 1 was performed in the same manner as the preparation of the radiation image conversion panel sample 1 except that the support on the phosphor layer side and the support on the opposite side of the phosphor layer were used as shown in Table 1. Radiation image conversion panel samples 2 to 7 (sample Nos. 2 to 7) were prepared. The following evaluation was performed.

(Evaluation of image quality contrast)
X-ray irradiation was set to 80 kV, a 1 cm thick acrylic plate was photographed, and output with a laser imager so that the acrylic part had a density of 1, and the difference in density from the peripheral part was measured. (The greater the density difference, the higher the contrast)
The results are shown below.

  As is apparent from the results of the table, it can be seen that the radiation image conversion panel of the present invention, its manufacturing method and imaging method are superior to the comparison.

It is the schematic which shows an example of a mode that a photostimulable phosphor layer is formed by vapor deposition on a support body. It is the schematic which shows an example of the radiographic image conversion method using the radiographic image conversion panel of this invention.

Explanation of symbols

11 Support 22 Subject 23 Radiation Image Conversion Panel

Claims (6)

A photostimulable phosphor layer (phosphor layer) and a protective layer are laminated in this order on a support, and the photostimulable phosphor layer is formed by a vapor deposition method and is a columnar crystal. In a radiation image conversion panel having a stimulable phosphor, the support is a support having a laminated structure of two or more layers, and a support layer and a stimulable phosphor layer on the opposite side of the stimulable phosphor layer A radiation image conversion panel characterized in that the X-ray absorption efficiency per unit film thickness of the support layer on the side is higher on the phosphor layer side. The radiation image conversion panel according to claim 1, wherein a film thickness of the support opposite to the phosphor layer of the support is thicker than that of the support on the phosphor layer side. The support on the opposite side of the phosphor layer of the support is a carbon fiber or carbon-containing support having a film thickness of 0.5 to 10 mm, and the support on the phosphor layer side is aluminum. The radiation image conversion panel according to claim 1 or 2. The radiation image conversion panel according to claim 1, wherein the photostimulable phosphor is a CsBr columnar crystal. The radiation image conversion panel according to any one of claims 1 to 4 is provided on the support on the phosphor layer side by a vapor-depositing phosphor layer on the support on the phosphor layer side, and then on the back surface of the support on the phosphor layer side. Furthermore, the manufacturing method of the radiographic image conversion panel characterized by sticking and manufacturing the back surface support body. 5. A radiographic image characterized by irradiating a support on the opposite side of the phosphor layer of the radiographic image conversion panel according to any one of claims 1 to 4 with X-rays and reading information on a subject by the phosphor layer. How to shoot the conversion panel.

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