JP2007024817A - Radiological image conversion panel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a radiological image conversion panel capable of forming a uniform stimulable phosphor layer by suppressing small a temperature difference due to the position in a substrate, concerning a manufacturing method of the radiological image conversion panel having the stimulable phosphor layer on the substrate, and the radiological image conversion panel, wherein uniformity of a brightness distribution and the number of image defects are improved significantly. <P>SOLUTION: The substrate 1 is made to adhere to a metal block 103 via a pressure-sensitive sheet 102 and an insulating material 130, and is installed on a substrate support inside a deposition device, and then the stimulable phosphor layer is formed on the substrate surface by a vapor-phase growth. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radiation image conversion panel using a photostimulable phosphor and a manufacturing method thereof.

  Radiation images such as X-ray images are often used in fields such as disease diagnosis. The X-ray image is obtained by irradiating the phosphor layer (phosphor screen) with X-rays that have passed through the subject, thereby generating visible light, and then using this visible light as when taking a normal photograph. Thus, a so-called radiographic method in which a silver halide photographic light-sensitive material (hereinafter also simply referred to as a light-sensitive material) is irradiated and then developed to obtain a visible silver image is widely used.

  However, in recent years, a new method for directly extracting an image from a phosphor layer has been disclosed in place of an image forming method using a light-sensitive material having a silver halide salt. In this method, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited by light or thermal energy, for example, so that the radiation energy accumulated by the phosphor is emitted as fluorescence. There is a method of detecting and imaging this fluorescence. Specifically, for example, a radiation image conversion method using a photostimulable phosphor as described in US Pat. No. 3,859,527 and Japanese Patent Application Laid-Open No. 55-12144 is known. This method uses a radiation image conversion panel using a stimulable phosphor containing a stimulable phosphor, and the radiation transmitted through the subject is applied to the stimulable phosphor layer of the radiation image conversion panel. , By storing radiation energy corresponding to the radiation transmission density of each part of the subject and then exciting the stimulable phosphor in time series with electromagnetic waves (excitation light) such as visible light and infrared light. Radiation energy accumulated in the body is emitted as stimulated emission, and a signal based on the intensity of this light is photoelectrically converted to obtain an electrical signal, which is used as a recording material such as a photosensitive material, CRT, etc. The image is reproduced as a visible image on the display device.

  According to the above radiographic image reproduction method, it is possible to obtain a radiographic image with a large amount of information with a much smaller exposure dose as compared with a radiographic method using a combination of a conventional radiographic film and an intensifying screen. It has the advantage of being able to.

  Radiation image conversion panels using these photostimulable phosphors, after accumulating radiation image information, release accumulated energy by scanning excitation light, so that radiation images can be accumulated again after scanning, and repeated Can be used. In other words, the conventional radiographic method consumes a radiographic film for each photographing, whereas this radiographic image conversion method repeatedly uses a radiographic image conversion panel, so that also from the viewpoint of resource protection and economic efficiency. It is advantageous.

  Furthermore, in recent years, a radiographic image conversion panel with higher sharpness has been required for analysis of diagnostic images. As means for improving the sharpness, for example, an attempt has been made to improve the sensitivity and sharpness by controlling the shape of the photostimulable phosphor itself. 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 JP-A No. 61-142497. There is a method using a stimulable phosphor layer.

  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 is subjected to shock treatment for further development. Method using a radiation image conversion panel having a photostimulable phosphor layer formed, and further, radiation image conversion in which a photostimulable phosphor layer formed on the surface of a support is cracked from the surface side to form a pseudo columnar shape A method using a panel (see Patent Document 1), a method of forming a stimulable phosphor layer having a cavity by vapor deposition on the upper surface of a support, and then growing a cavity by heat treatment to provide a crack are proposed. (See Patent Document 2). Furthermore, a radiation image conversion panel having a photostimulable 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 phase epitaxy has been proposed ( (See Patent Document 3).

  Recently, a radiation image conversion panel using a stimulable phosphor activated with Eu based on an alkali halide such as CsBr has been proposed, and in particular, high X-rays that have not been obtained by using Eu as an activator. It became possible to derive the conversion efficiency.

  Further, it is known that a high-luminance radiation image conversion panel can be obtained by selecting excitation light or stimulated light emission by selecting a high reflectance material such as aluminum as the substrate.

  However, since the substrate used for producing the radiation image conversion panel generally has a large substrate surface area (for example, 300 mm × 300 mm or more) and is thinner than the substrate surface area, it is supported in the vapor deposition apparatus. When the photostimulable phosphor is deposited, the central portion of the substrate is bent downward due to gravity, and it is difficult to form a uniform photostimulable phosphor layer on the substrate.

That is, when vapor-depositing on the substrate in the vapor deposition apparatus, the temperature of the substrate is raised to a predetermined temperature by heat transmitted by the heat conduction etc. from the substrate support part supporting this substrate, but vapor deposition is performed. Since the substrate is supported at the peripheral edge of the substrate by the substrate support portion, the center portion of the substrate is bent downward, and heat is not directly transferred from the substrate support portion to the center portion of the substrate by heat conduction. Therefore, the heat transmitted to the central part of the substrate is transmitted from the substrate support part through the peripheral part of the substrate, and the heat is lost by radiation or the like until it is transmitted to the central part of the substrate, and the temperature of the central part of the substrate is the peripheral part. It wo n’t be as expensive. Therefore, a temperature distribution is generated in the substrate, and a difference in vapor deposition conditions occurs depending on the position in the substrate. This makes it difficult to form a uniform stimulable phosphor layer on the substrate as described above.
JP 62-39737 A JP-A-62-110200 JP-A-2-58000

  The present invention has been made in view of the above circumstances, and an object of the present invention is a method of manufacturing a radiation image conversion panel having a stimulable phosphor layer on a substrate, and a temperature difference depending on a position in the substrate. The present invention provides a radiation image conversion panel manufacturing method capable of forming a uniform photostimulable phosphor layer by suppressing the size of the image, and a radiation image conversion panel in which the uniformity of luminance distribution and the number of image defects are greatly improved. There is.

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

(Claim 1)
In a method for producing a radiation image conversion panel having a photostimulable phosphor layer on a substrate, the substrate is brought into close contact with a metal block, placed on a substrate support in a vapor deposition apparatus, and then illuminated on the substrate surface by vapor phase growth. A method for producing a radiation image conversion panel, comprising forming a stimulable phosphor layer.

(Claim 2)
The method for producing a radiation image conversion panel according to claim 1, further comprising an adhesive material between the substrate and the metal block.

(Claim 3)
3. The method according to claim 1, wherein after the adhesive material is installed on the metal block, the substrate is placed on the adhesive material, and the substrate is brought into close contact with the metal block without contacting an image region on the substrate. The manufacturing method of the radiation image conversion panel of description.

(Claim 4)
After the adhesive material is placed on the metal block, the substrate is placed on the adhesive material, and the region of the contact portion between the substrate and the adhesive is reduced in pressure so that the substrate is brought into close contact with the metal block. The manufacturing method of the radiographic image conversion panel of any one of Claims 1-3.

(Claim 5)
It is a radiographic image conversion panel manufactured by the manufacturing method of any one of Claims 1-4, Comprising: The photostimulable phosphor layer which the said radiographic image conversion panel has is represented by following General formula (1). A radiation image conversion panel comprising a stimulable phosphor based on an alkali halide.
General formula (1) M ¹ X · aM ² X ′ ₂ : eA, A ″
(Wherein M ¹ is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and M ² is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. At least one divalent metal atom selected from each atom of X, X ′ is at least one halogen selected from the group consisting of F, Cl, Br and I, and A and A ″ are Eu, Tb , In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, and Y, and a and e are each 0 ≦ a <Represents numerical values in the range of 0.5 and 0 <e ≦ 0.2.)

  According to the above configuration of the present invention, in a method for manufacturing a radiation image conversion panel having a photostimulable phosphor layer on a substrate, a uniform photostimulable phosphor layer can be obtained by suppressing a temperature difference depending on a position in the substrate. Can be provided, and a radiation image conversion panel in which the uniformity of the luminance distribution and the number of image defects are greatly improved can be provided.

  In the method for producing a radiation image conversion panel of the present invention, in a radiation image conversion panel having a photostimulable phosphor layer on a substrate, the substrate is brought into close contact with a metal block and placed on a substrate support in a vapor deposition apparatus. A stimulable phosphor layer is formed on the surface of the substrate by a phase growth method. In addition, after the adhesive material is installed on the metal block, the substrate is placed on the adhesive material, and the substrate is brought into close contact with the metal block without contacting the image area on the substrate. Hereinafter, the present invention and components will be described in detail.

(Method for manufacturing radiation image conversion panel)
[Substrate support section]
In the present invention, since the substrate support part (substrate holder) is a metal block and the substrate and the metal block are in close contact with each other, deformation of the substrate is suppressed during vapor deposition, and heat conduction from the substrate support part to the substrate is within the substrate surface. Can be made uniform. Furthermore, in order to control the thermal conductivity from the substrate support portion to the substrate, a member having a heat insulation effect may be sandwiched between the adhesive material and the substrate.

  The metal block according to the present invention is not particularly limited as long as it has a high thermal conductivity and has a thickness that does not cause partial deformation due to gravity. Aluminum is preferable from the viewpoint of compatibility between cost and strength.

[Adhesive]
The pressure-sensitive adhesive material according to the present invention is effective in uniformly bringing the substrate surface into close contact with the metal block when the substrate is in close contact with the metal block. As the adhesive material, an adhesive sheet is preferable from the viewpoint of workability and environmental performance.

  After attaching the adhesive sheet to the metal block, as a means of attaching the substrate on it, touching and pressing the substrate directly by hand will cause irregularities in the substrate surface or cause foreign matter to adhere to the substrate surface, and as a result An image defect may occur in an image conversion panel obtained by vapor deposition. Therefore, as a means for suppressing adhesion of foreign matter, a means for placing a substrate on the adhesive sheet, placing a sheet-like material on the surface of the substrate, and pressing from above is preferable. Furthermore, it is more preferable to use means for bringing the substrate into close contact with the metal block without contacting the image area on the substrate. When this method is used, it is possible to suppress unevenness of the substrate surface that occurs during pasting. In addition, there is a method of pressing the outside of the image area on the substrate, that is, the peripheral portion of the substrate, as means for suppressing unevenness of the substrate surface that occurs during pasting. As a means for bringing the substrate into close contact with the metal block without being brought into contact with the image region on the substrate, it is more preferable to depressurize the region of the contact portion between the substrate and the adhesive material.

  The vacuum pasting method will be described with reference to the drawings. After the pressure-sensitive adhesive sheet and the substrate are placed on the metal block (hereinafter referred to as “a laminate of the metal block and the substrate”), the laminate (FIG. 4) is placed on the suction and attachment jig 104. FIG. 5 and FIG. 6 show a cross-sectional view when a laminate is placed on the suction sticking jig and a view seen from directly above, respectively. At this time, the substrate contact portion 105 is dimensionally adjusted so as to contact the non-image area 111 of the substrate. Next, when a suction device such as a vacuum pump is connected to the suction port 106 and sucked, the region closed by the suction sticking jig and the substrate becomes the decompression region 107. Then, atmospheric pressure is uniformly applied to the substrate surface, and the substrate can be brought into close contact with the adhesive sheet without touching the image area 112 (FIG. 7) of the substrate. At this time, in order to control the thermal conductivity from the substrate support part to the substrate, a member 130 having a heat insulating effect may be sandwiched between the adhesive sheet and the substrate.

〔substrate〕
As the substrate used in the radiation image conversion panel according to the present invention, various glasses, polymer materials, metals, and the like are used. For example, plate glass such as quartz, borosilicate glass, chemically tempered glass, cellulose acetate, and the like. 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.

[Stimulable phosphor layer]
The photostimulable phosphor layer according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of a columnar crystal shape formed on a substrate of the present invention. 1A and 1B, reference numeral 2 denotes a columnar crystal of a photostimulable phosphor formed on a substrate 1 by a vapor deposition method, and a perpendicular line passing through the center of the crystal growth direction at the tip of the crystal. The angle (θ) formed by 3 and the tangent 4 of the crystal tip cross section is preferably 20 ° to 80 °, more preferably 40 ° to 80 °. FIG. 1 a) is an example having a cusp at substantially the center of the columnar crystal, and FIG. 1 b) is an example in which the tip of the columnar crystal has a certain inclination, and the columnar crystal has a side surface. It is an example which has a cusp part.

  Moreover, in this invention, it is preferable that the average crystal diameter of a columnar crystal is 0.5-50 micrometers, More preferably, it is 1-50 micrometers. By setting the average crystal diameter of the columnar crystal as defined above, the haze ratio of the photostimulable phosphor layer b can be reduced, and as a result, excellent sharpness can be realized. The average crystal diameter of the columnar crystals is an average value of the diameters in terms of circles of the cross-sectional areas of the columnar crystals when the columnar crystals are observed from a plane parallel to the support, and at least 100 or more columnar crystals are being viewed. Calculated from the electron micrographs included.

The columnar crystal diameter is influenced by the support temperature, the degree of vacuum, the vapor flow incident angle, and the like, and by controlling these, a columnar crystal having a desired thickness can be formed. For example, the support temperature tends to become thinner as the temperature decreases, but if it is too low, it becomes difficult to maintain the columnar state. The temperature of the support is preferably 100 to 300 ° C, more preferably 150 to 270 ° C. The incident angle of the vapor flow is preferably 0 to 5 °. Further, the degree of vacuum is preferably 1.3 × 10 ⁻¹ Pa or less.

[Vapor phase growth method]
Examples of the stimulable phosphor that can be used in the stimulable phosphor layer formed by the vapor phase growth method (also referred to as “vapor phase deposition method”) according to the present invention include, for example, JP-A-48-80487. Phosphors represented by BaSO ₄ : A _x described in JP-A-48-80488, phosphors represented by MgSO ₄ : A _x described in JP-A-48-80488, and JP-A-48-80489. SrSO ₄ : A phosphor represented by A _x , fluorescence obtained by adding at least one of Mn, Dy, and Tb to Na ₂ SO ₄ , CaSO _4, BaSO _4, etc. described in JP-A No. 51-29889 , Phosphors such as BeO, LiF, MgSO ₄ and CaF ₂ described in JP-A No. 52-30487, Li ₂ B ₄ O ₇ : Cu, Ag described in JP-A No. 53-39277 Phosphors described in JP-A-54-47883 Is to have _{Li 2 O · (Be 2 O} 2) x: Cu, phosphors such as Ag, are described in U.S. Pat. No. 3,859,527 SrS: Ce, Sm, SrS : Eu, Sm, La Examples include phosphors represented by ₂ O ₂ S: Eu, Sm and (Zn, Cd) S: Mnx.

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 XSiO2: An alkaline earth metal silicate phosphor represented by A is included.

Further, an alkaline earth fluorinated halide phosphor represented by the general formula (Ba _1-xy Mg _x Ca _y ) F _x : Eu ₂ ⁺ described in Japanese Patent Laid-Open No. 55-12143, A phosphor in which the general formula described in Japanese Patent No. 55-12144 is represented by LnOX: xA, and a general formula described in Japanese Patent Laid-Open No. 55-12145 is (Ba _1-x M (II) _x ) F _x : A phosphor represented by yA, a phosphor represented by the general formula described in JP-A-55-84389, BaFX: xCe, yA, a formula represented by JP-A-55-160078 Is a rare earth element-activated divalent metal fluorohalide phosphor represented by M (II) FX · xA: yLn, fluorescence represented by the general formula ZnS: A, CdS: A, (Zn, Cd) S: A, X And any one of the following general formulas described in JP-A-59-38278 A phosphor represented by
General formula xM ₃ (PO ₄ ) ₂ · NX ₂ : yA
xM ₃ (PO ₄ ) ₂ : yA
A phosphor represented by any one of the following general formulas described in JP-A-59-155487,
General formula nReX ₃ · mAX ′ ₂ : xEu
nReX ₃ · mAX ′ ₂ : xEu, ySm
The following general formula described in JP-A-61-72087,
M (I) X · aM ( II) X '2 · bM (III) X "3: cA
And an alkali halide phosphor represented by the general formula M (I) X: xBi described in JP-A-61-2228400
And a bismuth-activated alkali halide phosphor represented by the formula: In particular, the alkali halide phosphor is preferable because a columnar photostimulable phosphor layer can be easily formed by a method such as vapor deposition or sputtering.

Next, the photostimulable phosphor represented by the general formula (1) of the present invention will be described. In the photostimulable phosphor represented by the general formula (1) of the present invention, M ^I represents at least one alkali metal atom selected from each atom such as Na, K, Rb and Cs, among which Rb And at least one alkaline earth metal atom selected from each atom of Cs, and more preferably a Cs atom.

M ² represents at least one divalent metal atom selected from atoms such as Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu, and Ni, and among them, Be, Mg are preferably used. , A divalent metal atom selected from atoms such as Ca, Sr and Ba.

M ³ is at least 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. One kind of trivalent metal atom is represented, and among these, trivalent metal atoms selected from each atom such as Y, Ce, Sm, Eu, Al, La, Gd, Lu, Ga and In are preferred. is there.

  A is at least selected from each atom of Eu, Tb, In, Ga, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. One kind of metal atom.

  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.

In the general formula (1), the b value represents 0 ≦ b <0.5, and preferably 0 ≦ b ≦ 10 ⁻² .

The photostimulable phosphor represented by the general formula (1) of the present invention is produced, for example, by the production method described below. 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.
_{(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 _At least one or two or more compounds selected from ₂ and NiI ₂ compounds are used.
(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.

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} and e are 0 <e ≦ 0.2, preferably 0 <e ≦ 0.1.

  The phosphor materials (a) to (c) are weighed so as to have a mixed composition in the above numerical range, and sufficiently mixed using a mortar, ball mill, mixer mill or the like.

  Next, the obtained phosphor 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 suitably 300 to 1000 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature, and the like, but generally 0.5 to 6 hours is appropriate.

  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.

  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. Firing is preferable because it can further increase the emission luminance of the phosphor.

  In addition, when the fired product is cooled to the room temperature from the firing temperature, the desired phosphor can be obtained by taking the fired product from the electric furnace and allowing it to cool in the air. You may cool in an atmosphere or neutral atmosphere.

  In addition, by moving the fired product from the heating part to the cooling part in an electric furnace and quenching it in a weak reducing atmosphere, neutral atmosphere or weak oxidizing atmosphere, the emission brightness due to the phosphors obtained is increased. It can be further increased.

  In addition, the photostimulable phosphor layer of the present invention is formed by a vapor phase growth method.

  As a vapor phase growth method of the photostimulable phosphor, an evaporation method, a sputtering method, a CVD method, an ion plating method, and other methods can be used.

In the present invention, for example, the following methods can be mentioned. In the vapor deposition method of the first method, first, after the support is installed in the vapor deposition apparatus, the inside of the apparatus is evacuated to a vacuum degree of about 1.333 × 10 ⁻⁴ Pa.

  Next, at least one of the photostimulable phosphor 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. 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, 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.

  After the vapor deposition, it is preferable that 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.

  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.

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

In the sputtering method as the second method, like the vapor deposition method, after a support having a protective layer or an intermediate layer is placed in the sputtering apparatus, the inside of the apparatus is once evacuated to about 1.333 × 10 ⁻⁴ Pa. The degree of vacuum is set, and then an inert gas such as Ar or Ne is introduced into the sputtering apparatus as a sputtering gas to obtain a gas pressure of about 1.333 × 10 ⁻¹ Pa. Next, a stimulable phosphor layer is grown on the support to a desired thickness by sputtering using the stimulable phosphor as a target.

  Various applied treatments can be used in the sputtering step as in the vapor deposition method.

  The third method is a CVD method, and the fourth method is an ion plating method.

  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 low, which is not preferable. If the growth rate exceeds 300 μm / min, it is difficult to control the growth rate.

  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 preferable radiation image conversion in terms of sensitivity and resolution. A panel is obtained and preferred.

  The film thickness of the photostimulable phosphor layer is preferably 50 μm to 1 mm from the viewpoint of obtaining the effects of the present invention, although it varies depending on the purpose of use of the radiation image conversion panel and the type of stimulable phosphor. More preferably, it is 100-600 micrometers, More preferably, it is 300-600 micrometers.

  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.

  The stimulable phosphor layer of the radiation image conversion panel according to the present invention is preferably formed by vapor-phase growth of the stimulable phosphor represented by the general formula (1) on the support. More preferably, the stimulable phosphor forms columnar crystals during formation.

  In order to form a columnar photostimulable phosphor layer by a method such as vapor deposition or sputtering, the compound represented by the general formula (1) (stimulable phosphor) is used. Among them, a CsBr phosphor Is particularly preferably used.

  In the present invention, the columnar crystal preferably has a stimulable phosphor represented by the following general formula (2) as a main component.

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

  As a method of forming a phosphor layer on a support by a vapor deposition method, an elongate columnar shape independent by a vapor deposition (deposition) method such as vapor deposition by supplying a vapor of the stimulable phosphor or the raw material. A photostimulable phosphor layer made of crystals can be obtained.

  In these cases, it is preferable that the distance between the shortest part of the support and the crucible is usually set to 10 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 single stimulable phosphor, and may be a mixture of stimulable phosphor materials.

  Moreover, you may dope an activator afterwards with respect to the base material of fluorescent substance. For example, after depositing only RbBr as a base material, Tl as 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.

  Further, the size of the gap between the columnar crystals is preferably 30 μm or less, and more preferably 5 μm or less. That is, when the gap exceeds 30 μm, the scattering of the laser light in the phosphor layer increases and the sharpness decreases.

[Formation of photostimulable phosphor layer]
Next, formation of the photostimulable phosphor layer according to the present invention will be described with reference to FIG. FIG. 2 is a diagram showing a state where a photostimulable phosphor layer is formed by vapor deposition on a support, and the photostimulable phosphor vapor flow 16 is 0 to 5 as an incident angle with respect to the normal direction of the support surface. A columnar crystal is formed by incidence in the range of °.

  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 thinner 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, 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.

  A highly reflective material means a material having a high reflectivity to stimulated excitation light (500 to 900 nm, particularly 600 to 800 nm), such as white pigments and green to red regions such as aluminum, magnesium, silver, indium and other metals. The coloring material can be used.

  From the viewpoint of obtaining a radiation image conversion panel having high sensitivity, the reflectance of the photostimulable phosphor layer of the present invention is preferably 20% or more, more preferably 30% or more, and particularly preferably 40% or more. It is. The upper limit is 100%.

  A highly reflective material means a material having a high reflectivity to stimulated excitation light (500 to 900 nm, particularly 600 to 800 nm), such as white pigments and green to red regions such as aluminum, magnesium, silver, indium and other metals. The coloring material can be used.

  In the present invention, when a mirror surface treatment (for example, vapor deposition) that reflects light such as aluminum is performed on the substrate, the reflectance of the stimulable phosphor layer is measured.

  Here, the reflectance can be measured under the same measurement conditions using the following measuring apparatus.

Equipment: HITACHI 557, Spectrophotometer
(Measurement condition)
Measurement light wavelength: 680 nm
Scan speed: 120 nm / min
Number of repetitions: 10 times Response: automatic setting The white pigment 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 silicic acid sulfate, basic lead phosphate, and aluminum silicate. Since these white pigments have a strong hiding power and a high refractive index, it is possible to easily scatter scattered light by reflecting or refracting light, thereby significantly improving the sensitivity of the resulting radiation image conversion panel. it can.

  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.

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.

[Protective layer]
Moreover, the photostimulable phosphor layer according to the present invention may have a protective layer. The protective layer may be formed by directly applying a coating solution for the protective layer on the photostimulable phosphor layer, or a protective layer separately formed in advance may be adhered on the photostimulable phosphor layer. Or you may take the procedure of forming a photostimulable phosphor layer on the protective layer formed separately. 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-ethylene chloride Ordinary protective layer materials such as 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. The protective layer may be formed by laminating inorganic materials such as SiC, SiO ₂ , SiN, Al ₂ O ₃ by vapor deposition, sputtering, or the like. The thickness of these protective layers is generally preferably about 0.1 to 2000 μm.

  FIG. 3 is a schematic diagram showing an example of the configuration of the radiation image conversion panel and the radiation image reading apparatus according to the present invention.

  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 that detects 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. 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.

  The photoelectric conversion device 25 and the subsequent devices are not limited to the above as long as they can reproduce optical information from the radiation image conversion panel 23 as an image in some form.

  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, A transmission image RI (that is, an image of the intensity of radiation) enters the radiation image conversion panel 23. The incident transmitted 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. 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. That is, the photostimulable 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 to emit light. Let it be released as. 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 electric signal by a photoelectric conversion device 25 such as a photomultiplier tube, and reproduced as an image by an image reproduction device 26, and this image is displayed by an image display device 27. 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.

  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. 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 power and is easy to make compact is preferred for the image reading of the radiation image conversion panel, and the wavelength of the laser light is 680 nm, and is incorporated in the radiation image conversion panel of the present invention. The photostimulable phosphor exhibits extremely good sharpness when an excitation wavelength of 680 nm is used.

  That is, all of the photostimulable phosphors of the present invention emit light having a main peak at 500 nm or less, and the excitation excitation light can be easily separated and coincides well with the spectral sensitivity of the light receiver. The sensitivity of the image receiving system can be solidified.

  As the excitation light source 24, a light source including the 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 excitation light intensity can be increased, so that the photostimulative emission efficiency can be increased, and a more preferable result can be obtained.

  In the present invention, the laser diameter irradiated to the photostimulable phosphor layer is preferably 100 μm or less, more preferably 80 μm or less.

As the laser, the He-Ne laser, the He-Cd laser, Ar ion laser, Kr ion laser, N ₂ laser, YAG laser and its second harmonic, ruby laser, semiconductor lasers, various dye lasers, copper vapor laser, etc. There are metal vapor lasers. 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. 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 pulse oscillation laser is used rather than modulation using a continuous wave laser. Is preferred.

  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.

  Since the filter 28 transmits the stimulated luminescence emitted from the radiation image conversion panel 23 and cuts the stimulated excitation light, this is the stimulation 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.

  For example, in the case of a practically preferable combination in which the excitation wavelength is 500 to 900 nm and the emission wavelength is 300 to 500 nm, examples of the filter include C-39, C-40, and V- 40, V-42, V-44, Corning 7-54, 7-59, Spectrofilm BG-1, BG-3, BG-25, BG-37, BG-38, etc. A filter 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.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Production of radiation image conversion panel>
(Production of radiation image conversion panels 1 to 4)
A 43 cm × 43 cm (17 inch × 17 inch) size aluminum substrate No. 1 bonded to a metal block under the conditions shown in Table 1. 1 to 4 are each installed in a vacuum chamber of a vapor deposition apparatus one by one, and a stimulable phosphor (CsBr: Eu) is provided on each aluminum substrate by the following method using the vapor deposition apparatus shown in FIG. A photostimulable phosphor layer was formed.

First, the substrate was placed in a vacuum chamber, and then placed in a crucible that was press-molded and water-cooled using a phosphor material (CsBr: Eu) as an evaporation source. Thereafter, the inside of the vacuum chamber is once evacuated, then N ₂ gas is introduced, the degree of vacuum is adjusted to 0.133 Pa, and then the undercoat resin layer is applied while rotating the undercoat resin layer applied sample at a speed of 10 rpm. The temperature of the finished sample (also referred to as the substrate temperature) was maintained at about 140 ° C. Next, the resistance heating crucible was heated to deposit the stimulable phosphor, and the deposition was terminated when the thickness of the stimulable phosphor layer reached 300 μm. Next, the photostimulable phosphor layer was placed in a protective layer bag in dry air, and the photostimulable phosphor layer was sealed. Radiation image conversion panel samples 1 to 4 corresponding to 1 to 4 were obtained.

  Sample 1 was obtained by placing only an aluminum substrate on the substrate support before vapor deposition. Sample 2 was a laminate obtained by attaching an adhesive sheet on an aluminum block before vapor deposition, placing a substrate thereon, and directly pressing it by hand. Sample 3 was a laminate obtained by placing a substrate on an adhesive sheet in the same manner as Sample 2, then placing a pet film cut to 50 cm × 50 cm on the substrate, and pressing the substrate by hand from above. . In the case of Sample 4, after placing the substrate on the adhesive sheet, similarly to Samples 2 and 3, the laminate was placed in a suction bonding jig, and a vacuum pump was connected and the suction bonding jig and the substrate were closed. A laminate obtained by reducing the pressure for 1 minute in a state where the differential pressure between the region and the atmospheric pressure was 10 kPa and bringing the substrate into close contact with the adhesive sheet was used.

<Evaluation>
The following evaluation was performed using each radiographic image conversion panel produced as described above. The obtained results are shown in Table 1.

<Evaluation of image defects>
After vapor deposition, the substrate surface was visually observed and evaluated by the number of protrusions having a diameter of 0.5 mm or more.

<Evaluation of luminance and luminance distribution>
The luminance was evaluated using a Regius 350 manufactured by Konica Corporation. X-rays were irradiated with a tungsten tube at 80 kVp, 10 mAs at a distance of 2 m between the bombardment source and the plate, and then the plate was placed on the Regius 350 and read. Evaluation was performed based on the electrical signal from the obtained photomal.

  The electrical signal distribution from the photographed in-plane photomultiplier was relatively evaluated, the standard deviation was obtained, and the luminance distribution (SD) was obtained.

  The evaluation results are shown in Table 1.

  From the results of Table 1, the uniformity of the luminance distribution was greatly improved by having the metal block and the pressure-sensitive adhesive sheet. In addition, after placing the adhesive material on the metal block, the substrate is placed on the adhesive material, and the contact area between the substrate and the adhesive is decompressed without bringing the substrate into contact with the image area on the substrate, thereby causing image defects. Remarkably reduced.

Schematic showing an example of the columnar crystal shape formed on the support Schematic showing an example of how the photostimulable phosphor layer is formed on the support by vapor deposition Schematic which shows an example of a structure of a radiographic image conversion panel and a radiographic image reading apparatus. Laminates such as substrates, adhesive sheets and metal blocks Suction pasting jig (cross section) Suction pasting jig (view from above) Vapor deposition surface (view from above) Sectional drawing which shows schematic structure of an example of vapor deposition apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Columnar crystal 3 Line passing through center of crystal growth direction 4 Tangent line of crystal tip cross section 5 Crystal diameter of columnar crystal 15 Substrate support 16 Stimulable phosphor vapor flow 21 Radiation generator 22 Subject 23 Radiation image conversion panel 24 Photoexcitation light source 25 Photoelectric conversion device 26 Image reproduction device 27 Image display device 28 Filter 102 Adhesive sheet 103 Metal block 104 Suction sticking jig 105 Substrate contact portion 106 Suction port 107 Depressurized region (shaded portion)
DESCRIPTION OF SYMBOLS 111 Non-image area | region 112 Image area | region 120 Substrate support part 121 Substrate rotation mechanism 130 Heat insulating material 140 Stimulable phosphor raw material 150 Crucible 160 Vacuum chamber (for vapor deposition apparatus)

Claims (5)

In a method for producing a radiation image conversion panel having a photostimulable phosphor layer on a substrate, the substrate is brought into close contact with a metal block, placed on a substrate support in a vapor deposition apparatus, and then illuminated on the substrate surface by vapor phase growth. A method for producing a radiation image conversion panel, comprising forming a stimulable phosphor layer. The method for producing a radiation image conversion panel according to claim 1, further comprising an adhesive material between the substrate and the metal block. 3. The method according to claim 1, wherein after the adhesive material is installed on the metal block, the substrate is placed on the adhesive material, and the substrate is brought into close contact with the metal block without contacting an image region on the substrate. The manufacturing method of the radiation image conversion panel of description. After the adhesive material is placed on the metal block, the substrate is placed on the adhesive material, and the region of the contact portion between the substrate and the adhesive is reduced in pressure so that the substrate is brought into close contact with the metal block. The manufacturing method of the radiographic image conversion panel of any one of Claims 1-3. It is a radiographic image conversion panel manufactured by the manufacturing method of any one of Claims 1-4, Comprising: The photostimulable phosphor layer which the said radiographic image conversion panel has is represented by following General formula (1). A radiation image conversion panel comprising a stimulable phosphor based on an alkali halide.
General formula (1) M ¹ X · aM ² X ′ ₂ : eA, A ″
(Wherein M ¹ is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and M ² is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. At least one divalent metal atom selected from each atom of X, X ′ is at least one halogen selected from the group consisting of F, Cl, Br and I, and A and A ″ are Eu, Tb , In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, and Y, and a and e are each 0 ≦ a <Represents numerical values in the range of 0.5 and 0 <e ≦ 0.2.)

Images