JP2006153475A - Radiological image conversion panel and manufacturing method of radiological image conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiological image conversion panel having excellent uniformity in manufacture and showing high brightness and high sharpness, and a manufacturing method of the radiological image conversion panel. <P>SOLUTION: In this radiological image conversion panel having a stimulable phosphor layer on a support, at least one stimulable phosphor layer is formed by a vapor phase method (vapor-phase sedimentation method) so as to have the film thickness of 50 μm-20 mm, and a protection film is formed on the phosphor layer by a deposition process, and the refractive index of the protection film on the phosphor layer is 1.2-2.0. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventionally, so-called radiography using a silver salt has been used to obtain a radiographic image, but a method for imaging a radiographic image without using a silver salt has been developed. That is, the radiation transmitted through the subject is absorbed by the phosphor, and then the phosphor is excited with a certain energy to emit the radiation energy accumulated in the phosphor as fluorescence, and this fluorescence is detected. A method for imaging is disclosed.

  As a specific method, a radiation image conversion method using a panel having a photostimulable phosphor layer on a support and using one or both of visible light and infrared light as excitation energy is known (for example, patents). Reference 1).

As a radiation image conversion method using a stimulable phosphor with higher brightness and sensitivity, for example, BaFX: Eu ²⁺ system (X: Cl, Br, I) described in JP-A-59-75200 and the like. Radiation image conversion method using phosphor, radiation image conversion method using alkali halide phosphor as described in JP-A-61-72087, etc., as described in JP-A-61-73786, 61-73787, etc. In addition, alkali halide phosphors containing Tl ⁺ and Ce ³⁺ , Sm ³⁺ , Eu ³⁺ , Y ³⁺ , Ag ⁺ , Mg ²⁺ , Pb ²⁺ , and In ³⁺ metals as co-activators were developed. Has been.

  In recent years, there has been a demand for a radiation image conversion panel with higher sharpness in analysis of diagnostic images. As means for improving the sharpness, for example, attempts have been made to improve the sensitivity and sharpness by controlling the shape of the photostimulable phosphor to be formed.

  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 photostimulable phosphor on a support having a fine pattern was further developed by applying a shock treatment. A method of using a radiation image conversion panel having a photostimulable phosphor layer, and further a 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.

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 a vapor deposition method has been proposed. (For example, see Patent Document 2)
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-ray conversion that has not been obtained by using Eu as an activator. It became possible to derive efficiency.

  However, in order to form the CsBr: Eu phosphor layer, it is required to form a film by a vapor deposition method. In the formation of a deposited film, a highly accurate film thickness distribution is realized by arranging a highly accurate substrate-evaporation source in order to control the film thickness distribution and devising a physical position.

  In particular, in CsBr: Eu, diffusion of Eu due to heat is remarkable, and since the vapor pressure under vacuum is also high, there is a problem that the presence of Eu in the base material is ubiquitous. It is important to the uniformity of the.

  In particular, it has a large area, and in order to increase the film thickness and improve the performance, the uniformity of adhesion between the base material and the phosphor layer is important. When a resin is present on the surface of the substrate, there are a large number of residual solvents and volatile components due to the resin production process, so that volatile components are generated during phosphor film formation, changing the degree of vacuum and causing film fluctuations.

  In the present invention, a radiation image conversion panel having excellent adhesion can be formed by making full use of the dry process in order to suppress the film fluctuation and forming a substrate surface, a phosphor layer, and a protective layer.

An object of the present invention is to improve the uniformity of manufacturing to meet the improvement in brightness and sharpness required from the market as a radiation image conversion panel.
US Pat. No. 3,859,527 JP-A-2-58000

  The objective of this invention is providing the manufacturing method of the radiographic image conversion panel which is excellent in the uniformity in manufacture, and shows high brightness and high sharpness, and the said radiographic image conversion panel.

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

(Claim 1)
In a radiation image conversion panel having a photostimulable phosphor layer on a support, at least one photostimulable phosphor layer has a thickness of 50 μm to 20 mm by a vapor phase method (also referred to as a vapor deposition method). Radiation image conversion, wherein a protective film is formed on the phosphor layer by a vapor deposition process, and the refractive index of the protective film on the phosphor layer is 1.2 to 2.0. panel.

(Claim 2)
The radiation image conversion panel according to claim 1, wherein the photostimulable phosphor is a compound represented by the following general formula (1).

General formula (1)
M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
Wherein, M ¹ is at least one alkali metal atom selected Li, Na, K, from Rb and Cs, of at least 1 M ² is selected Li other than M ^1, Na, K, from Rb and Cs M ³ is at least one trivalent selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu A metal atom, X, X ′ and X ″ are at least one halogen atom selected from F, Cl, Br and I, and A is Eu, Tb, In, Cs, Ce, Tm, Dy, Pr , Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, and at least one rare earth element selected from the group consisting of a, b, and e, where 0 ≦ a <0.5, 0 ≦ b <0.5, 0 <e ≦ 0.2 It is.]
(Claim 3)
The radiation according to claim 1 or 2, wherein a protective film having a refractive index of 1.5 to 1.7 is formed, and the thickness of the protective film is 1 to 20 µm. Image conversion panel.

(Claim 4)
A method for producing a radiation image conversion panel, wherein after the protective film is formed, the surface of the protective film is subjected to leveling adjustment by a plate heat treatment.

  The radiation image conversion panel and the method for manufacturing the radiation image conversion panel according to the present invention are excellent in manufacturing uniformity, exhibit high brightness and high sharpness, and have excellent effects.

  Hereinafter, the present invention will be described in more detail.

  In a radiation image conversion panel having a photostimulable phosphor layer on a support, at least one photostimulable phosphor layer has a thickness of 50 μm to 20 mm by a vapor phase method (also referred to as a vapor deposition method). The stimulable phosphor layer protective film is formed by a vapor deposition process, and the refractive index of the phosphor layer protective film is 1.2 to 2.0. The image conversion panel was able to achieve the object of the present invention with these configurations.

  That is, a protective film is formed on the photostimulable phosphor layer by a vapor deposition process, and the refractive index of the protective film on the phosphor layer is 1.2 to 2.0.

  As the protective film, a polyurea protective film is particularly preferable in the present invention.

  The reason is not clear, but when a polyurea protective film is used, since the columnar crystals provide a light guide effect, optical continuity via the protective film between the crystals can be prevented, and the total reflection conditions The light guide effect can be obtained, which is preferable in that the effect of the present invention is further exhibited.

  Further, the refractive index can be changed from 1.2 to 2.0 by changing the ratio of isocyanate and polyamine in the polyurea protective film, from aromatic to aliphatic.

  In the present invention, a protective film is provided on the phosphor layer by a vapor deposition process.

  In the CsBr phosphor film formation, the phosphor film is formed by a vapor deposition process. The point is to form columnar crystals as crystals with excellent brightness sharpness.

  In order to increase the light light guide effect, the present inventors desirably form a columnar crystal having a good crystallinity as a columnar shape and having a tip diameter of several microns. When this columnar crystal is formed by vacuuming in the vapor deposition chamber, it is found that there is a problem that moisture is adsorbed on the surface when taken out in the air after film formation, and the performance deteriorates. When the diameter is reduced, the adsorption effect due to the capillary effect appears. In order to prevent this effect, it was found that the formation of an anti-adsorption protective film by continuous film formation is effective.

  By combining the composition ratio of polyisocyanate and polyamine and the aromatic aliphatic, it becomes possible to arbitrarily control the refractive index, and it is possible to maintain transparency while relaxing the stress.

  As the film stress relaxation method, a buffering effect can be further obtained through a heating method after completion of vapor deposition.

In the general formula (1) preferably used in the present invention, M ¹ represents at least one alkali metal atom selected from Li, Na, K, Rb and Cs, and an alkaline earth metal selected from Rb and Cs. An atom is preferred, and Cs is more preferably used.

M ³ represents a trivalent metal atom selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, and is preferably used among them. Is a trivalent metal atom selected from Y, Ce, Sm, Eu, Al, La, Gd, Lu, Ga and In.

  X, X ′ and X ″ are at least one halogen atom selected from F, Cl, Br and I from the viewpoint of improving the photostimulated emission brightness of the photostimulable phosphor, but are selected from F, Cl and Br. At least one halogen atom is preferable, and a halogen atom selected from Br and I is more preferable.

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

  The photostimulable phosphor represented by the general formula (1) is produced, for example, by the production method described below.

  First, as a phosphor raw material, acid (HI, HBr, HCl, HF) is added to a carbonate so as to have the following composition, mixed and stirred, and then filtered at a neutral point to obtain a furnace solution The following crystals are produced by evaporating the water.

In general formula (1) (a) NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr, CsI
_{(B) MgF 2, MgCl 2} , MgBr 2, MgI 2, CaF 2, CaCl 2, CaBr 2, CaI 2, SrF 2, SrCI 2, SrBr 2, SrI 2, BaF 2, BaCl 2, BaBr 2, BaBr 2 2H ₂ O, BaI ₂ , ZnF ₂ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , CdF ₂ , CdCl ₂ , CdBr ₂ , CdI ₂ , CuF ₂ , CuCl ₂ , CuBr ₂ , CuI, NiF ₂ , NiCl ₂ , NiBr ₂ , one or more of NiI ₂ , and (c) is Eu, Tb, In, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y An activator raw material having a metal atom selected from Tl, Na, Ag, Cu and Mg is used.

In the stimulable phosphor of the general formula (I) stoichiometrically, 0 ≦ a <0.5, preferably 0 ≦ a <0.01, 0 ≦ b <0.5, preferably 0 ≦ b ≦ 10 ⁻² , 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 dissolved in pure water.
At this time, the mixture may be sufficiently mixed using a mortar, ball mill, mixer mill or the like.

  Next, a predetermined acid is added so as to adjust the pH value of the obtained aqueous solution, and then water is evaporated.

  Next, the obtained raw material mixture is filled in a heat-resistant container such as a quartz crucible or an alumina crucible and fired in an electric furnace. The firing temperature is suitably 500 to 1000 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature, and the like, but 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. If the firing is performed, the emission luminance of the phosphor can be further increased. When the fired product is cooled to the room temperature from the firing temperature, the desired fluorescence can also be obtained by removing the fired product from the electric furnace and allowing it to cool in the air. The body can be obtained, but it may be cooled in the same weakly reducing atmosphere or neutral atmosphere as at the time of firing. In addition, by moving the fired product from the heating unit to the cooling unit in an electric furnace and quenching in a weak reducing atmosphere, neutral atmosphere or weak oxidizing atmosphere, the emission luminance due to the phosphor phosphors obtained can be increased. It can be further increased.

  In addition, the photostimulable phosphor layer according to the present invention is formed by a vapor deposition method (also called a vapor deposition method).

  As the vapor phase growth method of the photostimulable phosphor, vapor deposition, sputtering, ion plating, and others can be used.

In the vapor deposition method as the first method, the support is first installed in the vapor deposition apparatus, and then the inside of the apparatus is evacuated to a degree of vacuum of about 1.333 × 10 ⁻⁴ Pa. Next, at least one of the photostimulable phosphors is heated and evaporated by a resistance heating method, an electron beam method, or the like to grow the photostimulable phosphor on the surface of the support to a desired thickness.

  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 vapor deposition is completed, the radiation image conversion panel of the present invention is manufactured by providing a protective layer on the side opposite to the support side of the photostimulable phosphor layer as necessary. In addition, after forming a photostimulable phosphor layer on a protective layer, a procedure for providing a support may be taken.

Further, in the vapor deposition method, during the vapor deposition, the deposition target (support or protective layer) may be cooled or heated as necessary. Further, the stimulable phosphor layer may be heat-treated after the vapor deposition. In the vapor deposition method, reactive vapor deposition may be performed by introducing a gas such as O ₂ or H ₂ as necessary.

In the sputtering method as the second method, as in the vapor deposition method, the support is placed in the sputtering apparatus, and then the inside of the apparatus is evacuated to a vacuum of about 1.333 × 10 ⁻⁴ Pa, and then for sputtering. As the gas, an inert gas such as Ar or Ne is introduced into the sputtering apparatus to obtain a gas pressure of about 1.333 × 10 ⁻¹ Pa. Next, a stimulable phosphor layer is grown on the surface of 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.

  There is a CVD method as a third method. A 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 radiation that is preferable in terms of sensitivity and resolution. An image conversion panel is obtained.

  The dry thickness of the photostimulable phosphor layer varies depending on the intended use of the radiation image conversion panel and the type of the photostimulable phosphor. It is necessary, preferably 50 μm to 300 mm, more preferably 100 μm to 500 μm, and particularly preferably 400 to 500 μm.

  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 to 400 degreeC.

  The stimulable phosphor layer according to the radiation image conversion panel of the present invention is formed by vapor-phase growth of the stimulable phosphor represented by the general formula (1) or the general formula (2) on a support. However, it is preferable that the photostimulable phosphor forms columnar crystals during layer formation.

  In order to form a columnar stimulable phosphor layer by a method such as vapor deposition or sputtering, a stimulable phosphor material represented by the general formula (1) is used. The general formula (2) The CsBr phosphor is particularly preferably used among them.

  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, 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.

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 silicic acid sulfate, 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.

Support used for the radiation panel of the present invention As the support used for the radiation image conversion panel of the present invention, various types of glass, polymer materials, metals, etc. are used. For example, quartz, borosilicate glass, chemically tempered glass, etc. Plate glass, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, plastic film such as polycarbonate film, metal sheet such as aluminum sheet, iron sheet, copper sheet or the metal oxide A metal sheet having a coating layer is preferred.

  The surface of these supports may be a smooth surface, or may be a mat surface for the purpose of improving the adhesion to the stimulable phosphor layer.

  Moreover, in this invention, in order to improve the adhesiveness of a support body and a photostimulable phosphor layer, you may provide an adhesive layer in advance on the surface of a support body as needed. The thickness of these supports 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, the photostimulable phosphor layer according to the present invention may have a protective layer.

  It is the schematic which shows an example of a structure of an image conversion panel.

  In FIG. 1, 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 stimulating excitation light source for emitting a latent image as stimulated emission, 25 a photoelectric conversion device for detecting the stimulated emission emitted from the radiation image conversion panel 23, and 26 a photoelectric conversion signal detected by the photoelectric conversion device 25. Is a device for displaying the reproduced image, and 28 is a filter for cutting off the reflected light from the light source 24 and transmitting only the light emitted from the radiation image conversion panel 23. FIG. 3 shows an example of obtaining a radiation transmission image of a subject. However, when the subject 12 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. 1, 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 transmission image RI is absorbed by the photostimulable phosphor layer of the radiation image conversion panel 23, so that a number of electrons and / or holes proportional to the amount of radiation absorbed in the photostimulable phosphor layer are generated. Occurs and accumulates at the trap level of the photostimulable phosphor. 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 by the light source 24 that emits light in the visible or infrared region to expel electrons and / or holes accumulated at the trap level, and the accumulated energy is released as stimulated emission. . The intensity of the emitted stimulated emission is proportional to the number of accumulated electrons and / or holes, that is, the intensity of the radiation energy absorbed in the stimulable phosphor layer of the radiation image conversion panel 23. The optical signal is converted into an electrical signal by a photoelectric conversion device 25 such as a photomultiplier tube, and reproduced as an image by an image processing device 26, and this image is displayed by an image display device 27. It is more effective to use an image processing device 26 that can not only reproduce an electrical signal as an image signal but also 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 according to the present invention is 300 to 500 nm, while the photostimulable excitation wavelength range is 500 to 900 nm, which satisfies the above conditions at the same time. A semiconductor laser that has a high output power and is easy to be compacted is preferably used for reading an image of the radiation image conversion panel. 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 according to the present invention emit light having a main peak at 500 nm or less, and the excitation light can be easily separated and coincides well with the spectral sensitivity of the light receiver, so that light can be received efficiently. As a result, 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 a laser beam is used, the optical system becomes simple, and since the intensity of the stimulated excitation light can be increased, the photostimulated emission efficiency can be increased, and a more preferable result can be obtained.

Lasers include He—Ne laser, He—Cd laser, Ar ion laser, Kr ion laser, N ₂ laser, YAG laser and its second harmonic, ruby laser, semiconductor laser, 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. In addition, when using a method of separating light emission using a delay of light emission as shown in JP-A-59-22046 without using a filter 28, a pulsed laser is used rather than a continuous wave laser. It is preferable to use it.

  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 photostimulation excitation wavelength is 500 to 900 nm and the photostimulation emission wavelength is 300 to 500 nm, examples of the filter include C-39, C-40, and V-40 manufactured by Toshiba Corporation. Purple-blue glass filters such as V-42, V-44, Corning 7-54, 7-59, Spectrofilm BG-1, BG-3, BG-25, BG-37, BG-38, etc. Can be used. If an interference filter is used, a filter having an arbitrary characteristic can be selected and used to some extent. The photoelectric conversion device 25 may be any device capable of converting a change in light quantity into a change in electronic signal, such as a photoelectric tube, a photomultiplier tube, a photodiode, a phototransistor, a solar cell, or a photoconductive element.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to these.

Example << Preparation of Radiation Image Conversion Panel Samples 1-8 (Examples 1-8) >>
Under the conditions shown in Table 1, the vapor deposition apparatus shown in FIG. 2 (provided that θ1 = 5 degrees and θ2 = 5 degrees) is provided on the surface of a 1 mm thick crystallized glass (manufactured by Nippon Electric Glass Co., Ltd.) support. A stimulable phosphor layer having a stimulable phosphor (CsBr: Eu) was used.

  In the vapor deposition apparatus shown in FIG. 2, an aluminum slit is used, the distance d between the support and the slit is set to 60 cm, vapor deposition is performed while the support is transported in a direction parallel to the support, and photostimulable fluorescence is performed. The thickness of the body layer was adjusted to 300 μm.

  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.

Thereafter, the inside of the vapor deposition device was once evacuated, then N ₂ gas was introduced and the degree of vacuum was adjusted to 0.133 Pa, and then vapor deposition was performed while maintaining the temperature of the support (also referred to as the substrate temperature) at about 350 ° C.

  Deposition was terminated when the thickness of the photostimulable phosphor layer reached 300 μm, and then this phosphor layer was heat-treated at a temperature of 400 ° C.

  Thereafter, a transparent protective film was formed on the phosphor layer using the vapor deposition device so as to have a refractive index shown in Table 1.

  In Examples 1 to 3, MDA (methylenediamine) was used as the polyamine, and the polyisocyanate was selected and adjusted from aliphatic isocyanates having 7 to 14 carbon atoms so as to have a predetermined refractive index.

  In Examples 4 to 8, an aliphatic polyamine HMDA (hexamethylenediamine) was used, and the polyisocyanate was selected and adjusted from aliphatic isocyanates having 7 to 14 carbon atoms so as to have a predetermined refractive index. In Example 7, an isocyanate having a silicon skeleton was used for adjustment. Table 1 shows the plate heat treatment temperature after forming the transparent protective film.

《Evaluation of sharpness》
The sharpness of the radiation image conversion panel sample was evaluated by obtaining a modulation transfer function (MTF).

  The MTF applies a CTF chart to the radiation image conversion panel sample, irradiates the radiation image conversion panel sample with 80 kVp X-rays at a distance of 10 mR (distance to the subject: 1.5 m), and then a semiconductor laser having a diameter of 100 μmφ ( 680 nm: the power on the panel was 40 mW), and the CTF chart image was scanned and read. The values in the table are MTF values of 2.0 lp / mm.

<Evaluation of luminance and luminance distribution>
The brightness was evaluated using Regius 350 manufactured by Konica Minolta.

  As in the sharpness evaluation, X-rays were irradiated with a tungsten tube at 80 kVp and 10 mAs at a distance of 2 m between the bombardment source and the plate, and then a plate was set on the Regius 350 and read. Relative evaluation was performed based on the electrical signal from the obtained photomultiplier. The luminance of Sample 2 was set to 1.0, and the subsequent values were expressed as relative values.

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

  When each of the above evaluations is good, the activator is uniformly contained in the phosphor base crystal.

Schematic which shows an example of a structure of the radiation image conversion panel of this invention. Schematic which shows an example of the method of producing a stimulable fluorescent substance layer on a support body by vapor deposition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Support body 12 Stimulable fluorescent substance layer 13 Columnar crystal 14 The space | gap formed between columnar crystals 15 Support body holder 21 Radiation generator 22 Subject 23 Radiation image conversion panel 24 Photoexcitation light source 25 Radiated by this conversion panel Photoelectric conversion device for detecting photostimulated fluorescence 26 Image reproduction device 27 Image display device 28 Filter

Claims (4)

In a radiation image conversion panel having a photostimulable phosphor layer on a support, at least one photostimulable phosphor layer has a thickness of 50 μm to 20 mm by a vapor phase method (also referred to as a vapor deposition method). Radiation image conversion, wherein a protective film is formed on the phosphor layer by a vapor deposition process, and the refractive index of the protective film on the phosphor layer is 1.2 to 2.0. panel. The radiation image conversion panel according to claim 1, wherein the photostimulable phosphor is a compound represented by the following general formula (1).
General formula (1)
M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
Wherein, M ¹ is at least one alkali metal atom selected Li, Na, K, from Rb and Cs, of at least 1 M ² is selected Li other than M ^1, Na, K, from Rb and Cs M ³ is at least one trivalent selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu X, X 'and X "are at least one halogen atom selected from F, Cl, Br and I, and A is Eu, Tb, In, Cs, Ce, Tm, Dy, Pr , Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, and at least one rare earth element selected from the group consisting of a, b, and e, where 0 ≦ a <0.5, 0 ≦ b <0.5, 0 <e ≦ 0.2 It is.] The radiation according to claim 1 or 2, wherein a protective film having a refractive index of 1.5 to 1.7 is formed, and the thickness of the protective film is 1 to 20 µm. Image conversion panel. A method for producing a radiation image conversion panel, wherein after the protective film is formed, the surface of the protective film is subjected to leveling adjustment by a plate heat treatment.

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