JP4281524B2 - Radiation image conversion panel - Google Patents

Description

  The present invention relates to a radiation image conversion panel using a photostimulable phosphor.

  Conventionally, as a method for obtaining a radiation image without using a silver salt, a radiation image conversion panel in which a photostimulable phosphor layer is provided on a support has been developed.

  The radiation image conversion panel can accumulate radiation energy corresponding to the radiation transmission density of each part of the subject by irradiating the stimulable phosphor layer with radiation transmitted through the subject. Thereafter, the stimulable phosphor is excited in time series with electromagnetic waves (excitation light) such as visible light and infrared rays, thereby releasing the radiation energy accumulated in the stimulable phosphor as stimulated luminescence. For example, an electric signal is obtained by photoelectrically converting the signal based on the intensity of the light, and this signal can be reproduced as a visible image on a recording material such as a silver halide photographic material or a display device such as a CRT. .

  The superiority or inferiority of the radiation image conversion method using the radiation image conversion panel greatly depends on the stimulable light emission luminance of the panel and the light emission uniformity of the panel, and in particular, these characteristics greatly depend on the characteristics of the stimulable phosphor used. It is known to be ruled.

  Recently, a radiation panel using a stimulable phosphor in which Eu is activated with an alkali halide such as CsBr as a base has been proposed, and in particular, X-ray conversion efficiency, which has been impossible in the past by using Eu as an activator, has been proposed. It can be improved and is often used for medical X-ray diagnostic imaging equipment.

  In medical X-ray diagnostic imaging equipment and the like, a radiation image conversion panel is arranged vertically or horizontally, supports an edge portion, irradiates X-rays from one surface, and irradiates excitation light to the other surface. In many cases, the method of reading the exhaust light is taken. In such an apparatus, the radiation image conversion panel may be distorted due to its own weight or the horizontality may be lowered.

In order to prevent distortion of the radiation image conversion panel and a decrease in horizontality, a stimulable phosphor layer is laminated on the first rigid layer having an elastic modulus of 1 × 10 ⁵ kgf / cm ² or more, and the stimulable phosphor layer is formed on the stimulable phosphor layer. There is also a radiation image conversion panel in which a filler layer is laminated, a second rigid layer is laminated on the filler layer, and rigidity is increased (for example, see Patent Document 1).
JP 2002-303696 A

  The reproduction image is usually read by detecting the photostimulated luminescence while scanning the photostimulable phosphor in the lateral direction with an excitation light laser. If vibration is applied to the apparatus at the time of reading this image, there is a problem that the radiation image conversion panel vibrates to generate horizontal line noise in the reproduced image.

  It is also conceivable to increase the rigidity of the radiation image conversion panel as a whole to make it more resistant to vibration. However, since a radiographic image conversion panel is arranged vertically in medical X-ray image diagnostic equipment, it is supported by the left and right edges and the lower edge of the radiographic image conversion panel, and the radiographic image conversion panel can be inserted from above. There are many things. In such a reader, even if the rigidity in both the vertical and horizontal directions of the radiation image conversion panel is increased, vibration of the radiation image conversion panel cannot be efficiently prevented.

  An object of the present invention is to suppress horizontal line noise generated in a reproduced image when a radiation image conversion panel that is vertically arranged and supported by left and right edges and a lower edge is used.

In order to solve the above problems, the invention according to claim 1 of the present invention is such that a photostimulable phosphor layer is provided on a support, and the photostimulable phosphor layer is scanned with excitation light. In the radiation image conversion panel that is vertically arranged in the reading device that reads an image and is supported by the left and right edges and the lower edge of the support,
The lateral stiffness value corresponding to the horizontal direction of the support arranged vertically is larger than the longitudinal stiffness value corresponding to the vertical direction of the support, and the lateral stiffness value is 3 to 200 kgf · mm ² , The longitudinal rigidity value is 1-150 kgf · mm ² ,
And the unidirectional prepreg, which is a heat-resistant carbon fiber reinforced resin plate in which carbon fiber in a form aligned in one direction is impregnated in a resin, is used for the support,
The support is configured such that the unidirectional prepregs are alternately stacked in the horizontal direction and the vertical direction and integrated by pressure bonding, and the ratio of the unidirectional prepregs stacked in the horizontal direction is overlapped in the vertical direction. More than directional prepregs .

According to the first aspect of the present invention, the lateral stiffness value of the support 11 is made larger than the longitudinal stiffness value, the lateral stiffness value is 3 to 200 kgf · mm ² , and the longitudinal stiffness value. 1 to 150 kgf · mm ² , the excitation image is irradiated to the stimulable phosphor layer, and even when the reader is subjected to vibration when detecting the stimulated emission, the obtained image is affected by the vibration. It is hard to receive and can suppress horizontal noise.

Further, according to the invention described in claim 1, by using a heat-resistant carbon fiber reinforced resin plate for the support, the support can withstand heat when the stimulable phosphor layer is provided, and the rigidity value is It can be set to any value.

The invention according to claim 2 is the radiation image conversion panel according to claim 1 , wherein the support is provided with a heat-resistant resin layer.

According to the invention described in claim 2, by providing the heat-resistant resin layer on the support, the surface property of the support is improved and the support is protected from heat when the stimulable phosphor layer is provided. be able to.

According to a third aspect of the present invention, in the radiation image conversion panel according to the first or second aspect, the stimulable phosphor layer is made of a stimulable phosphor represented by the following general formula (1). Features.
CsX: eA (1)
[Wherein X represents Cl, Br or I, A represents Eu, Sm, In, Tl, Ga or Ce, and e represents a numerical value in the range of 1 × 10 ⁻⁷ <e <1 × 10 ^−2. To express. ]

According to the invention described in claim 3, by forming the photostimulable phosphor layer from the photostimulable phosphor represented by the general formula (1), it is possible to obtain a radiation image conversion panel having higher luminance. .

According to the first aspect of the present invention, the lateral stiffness value of the support supported on the left and right sides of the reading device is made larger than the longitudinal stiffness value, and the lateral stiffness value is 3 to 200 kgf.・ By setting mm ² and the longitudinal rigidity value to 1 to 150 kgf · mm ² , even if the stimulating phosphor layer is irradiated with excitation light and the stimulating light emission is detected, the reading device is subjected to vibration. The obtained image is not easily influenced by vibration, and horizontal noise can be suppressed.

In addition, according to the invention described in claim 1 , by using a heat-resistant carbon fiber reinforced resin plate for the support, it is possible to obtain a support that can withstand the heat when the stimulable phosphor layer is provided, and the rigidity value. Can be set to an arbitrary value.

According to the invention described in claim 2 , by providing the heat-resistant resin layer on the support, the surface property of the support is improved and the support is protected from heat when the stimulable phosphor layer is provided. be able to.

According to the invention described in claim 3 , by forming the photostimulable phosphor layer from the photostimulable phosphor represented by the general formula (1), it is possible to obtain a radiation image conversion panel having higher luminance. .

  Hereinafter, embodiments of the present invention will be described in detail. As shown in FIG. 1, the radiation image conversion panel according to the embodiment of the present invention includes a support 11 on which at least one surface of a substrate 11a is coated with a heat-resistant resin layer 11b, and the heat resistance of the support 11. It consists of a photostimulable phosphor layer 12 formed on the surface of the resin layer 11b and a protective layer 20 that covers and protects the photostimulable phosphor layer 12.

In the radiation image conversion panel of the present invention, it is preferable to use a substrate 11a having a lateral stiffness value larger than a longitudinal stiffness value. The substrate 11a preferably has a lateral stiffness value of 3 to 200 kgf · mm ² and a longitudinal stiffness value of 1 to 150 kgf · mm ² .

  As the substrate 11a, for example, a carbon fiber reinforced resin plate (prepreg) in which a carbon fiber is impregnated with a resin can be used. Examples of the prepreg include a unidirectional prepreg in which carbon fibers are aligned in one direction, and a woven prepreg in a form in which carbon fibers are woven into a plain weave or a twill weave. Since the woven prepreg has irregularities on the surface, it is preferable to apply a unidirectional prepreg to flatten the surface of the substrate 11a. In order to form the substrate 11a using the unidirectional prepreg, the unidirectional prepreg may be alternately stacked in the vertical direction and the horizontal direction and bonded together.

  In order to make the lateral stiffness value of the substrate 11a larger than the longitudinal stiffness value, for example, when unidirectional prepregs are overlapped and integrated, the ratio of the lateral prepregs is made larger than that of the longitudinal prepregs. There are methods.

  As the substrate 11a, as long as the above-mentioned rigidity value is satisfied, for example, plate glass such as quartz, borosilicate glass, chemically tempered glass, crystallized glass, cellulose acetate film, polyester film, polyethylene Thermosetting plastic films such as terephthalate film, polyamide film, polyimide film, epoxy film, polyamideimide film, bismaleimide film, fluororesin film, siloxane film, acrylic film, polyurethane film, nylon 12, nylon 6, polycarbonate, polyphenylene Sheets made of thermoplastic resins such as sulfide, polyethersulfone, polyetherimide, etc., and those bonded together, metals such as aluminum, iron, copper, and chromium It can be used over preparative or metal sheets having a coating layer of hydrophilic fine particles.

  The thickness of the substrate 11a varies depending on the material used, but is generally 80 μm to 5000 μm, and more preferably 250 μm to 4000 μm from the viewpoint of handling.

  It is preferable to provide a heat resistant resin layer 11b on at least the surface of the substrate 11a on which the photostimulable phosphor layer 12 is formed. By providing the heat resistant resin layer 11b, the surface of the substrate 11a can be smoothed, and the photostimulable phosphor layer 12 can be formed smoothly. The heat resistant resin layer 11b may be provided on both sides of the substrate. By providing the heat resistant resin layer 11b on both surfaces, it is possible to prevent the support 11 from being distorted due to the difference in thermal expansion coefficient between the substrate 11a and the heat resistant resin layer 11b when heated.

  The heat resistant resin preferably has a Tg of 180 ° C. or higher, and at least one of polyimide, polyamideimide, fluororesin, acrylic resin, siloxane and the like can be used. Among these, the thermal expansion coefficients of polyimide, polyamideimide, and fluororesin are close to the thermal expansion coefficient of the stimulable phosphor layer 12 to be described later, and therefore, there is no fear that the photostimulable phosphor layer 12 will crack.

  As a method of providing the heat-resistant resin layer 11b on the substrate 11a, there are a method of attaching a resin sheet and a method of providing by applying a resin on the substrate 11a, but the latter is preferable. This is because by providing the heat-resistant resin layer 11b by coating, the unevenness of the surface of the substrate 11a can be covered and the surface on which the photostimulable phosphor layer 12 is formed can be made flat.

  Examples of the method for applying the heat resistant resin include a method using a spin coater and a bar coater, a method using spray coating, and the like, and spray coating is preferable. Spray coating may be performed by fixing the substrate 11a and moving the spray gun at a constant speed, or by moving the substrate 11a at a constant speed and using one or a plurality of fixed spray nozzles, but the size of the substrate 11a is 350 mm square. When it becomes the above big thing, the method of moving the board | substrate 11a at a fixed speed and performing with several fixed spray nozzles is preferable.

  The dry film thickness of the heat-resistant resin layer 11b is preferably 10 to 150 μm, particularly preferably 20 to 100 μm. If it is too thin, the unevenness of the substrate 11a is noticeable on the surface, and if it is too thick, it is overcoated, resulting in poor film thickness distribution.

  When the heat-resistant resin layer 11b is provided on the substrate 11a as described above, the photostimulable phosphor layer 12 is provided on the surface of the heat-resistant resin layer 11b opposite to the substrate 11a.

  As the stimulable phosphor preferably used in the present invention, those represented by the following general formula can be used.

M ¹ X · aM ² X ′ ₂ · bM ³ X ″ ₃ : eA
Here, M ¹ is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and in particular, is at least one alkali metal selected from the group consisting of K, Rb and Cs. preferable.

M ² is at least one divalent metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni, and in particular, at least selected from Be, Mg, Ca, Sr and Ba A kind of divalent metal is preferable.

M ³ is at least one selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga, and In. In particular, at least one trivalent metal selected from the group consisting of Y, La, Ce, Sm, Eu, Gd, Lu, Al, Ga, and In is preferable.

  X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I, and particularly X is preferably at least one halogen selected from the group consisting of Br and I. .

  A is selected from the group consisting of Eu, Tb, In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. At least one metal selected from the group consisting of Eu, Cs, Sm, Tl and Na.

a, b, and e are numerical values in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <e ≦ 0.2, respectively. In particular, b is in the range of 0 ≦ b ≦ 10 ⁻² . It is preferable to show a numerical value.

  In particular, the photostimulable phosphor layer 12 preferably has a photostimulable phosphor represented by the following general formula (1).

  CsX: eA (1)

Here, X represents Cl, Br or I, A represents Eu, Sm, In, Tl, Ga or Ce, and e represents a numerical value in the range of 1 × 10 ⁻⁷ <e <1 × 10 ^−2. .

  The photostimulable phosphor is manufactured by the following manufacturing method using, for example, the following phosphor materials (a) to (d).

  (A) At least one selected from the group consisting of LiF, LiCl, LiBr, LiI, NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbICsF, CsCl, CSBr, and CsI Two or more compounds.

_{(B) BeF 2, BeCl 2} , BeBr 2, BeI 2, MgF 2, MgCl 2, MgBr 2, MgI 2, CaF 2, CaCl 2, CaBr 2, CaI 2, SrF 2, SrCl 2, SrBr 2, SrI 2 , BaF ₂ , BaCl ₂ , BaBr ₂ , 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 ₂ , NiF ₂ , at least one compound selected from the group consisting of NiCl ₂ , NiBr ₂ and NiI ₂ .

_{(C) ScF 3, ScCl 3} , ScBr 3, ScI 3, YF 3, YCl 3, YBr 3, YI 3, LaF 3, LaCl 3, LaBr 3, LaI 3, CeF 3, CeCl 3, CeBr 3, CeI 3 _{, PrF 3, PrCl 3, PrBr} 3, PrI 3, NdF 3, NdCl 3, NdBr 3, NdI 3, PmF 3, PmCl 3, PmBr 3, PmI 3, SmF 3, SmCl 3, SmBr 3, SmI 3, EuF _{3, EuCl 3, EuBr 3,} EuI 3, GdF 3, GdCl 3, GdBr 3, GdI 3, TbF 3, TbCl 3, TbBr 3, TbI 3, DyF 3, DyCl 3, DyBr 3, DyI 3, HoF 3, HoCl ₃ , HoBr ₃ , HoI ₃ , ErF ₃ , ErCl ₃ , ErBr ₃ , ErI ₃ , TmF ₃ , TmCl ₃ , TmBr ₃ , TmI ₃ , YbF ₃ , YbCl ₃ , YbBr ₃ , YbI ₃ , LuF ₃ , LuCl ₃ , LuBr ₃ , LuI ₃ , AlF ₃ , AlCl ₃ , AlBr ₃ , AlI ₃ , GaF ₃ , GaCl ₃ , GaBr ₃ , GaI ₃ , InF ₃ , InCl ₃ At least one compound selected from the group consisting of InBr ₃ and InI ₃ .

  (D) From the group consisting of Eu, Tb, In, Ga, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu, and Mg. At least one or two or more metals selected.

  The phosphor materials (a) to (d) are weighed and mixed with pure water. At this time, the mixture can be sufficiently mixed by using a mortar, a ball mill, a mixer mill or the like.

  Next, a predetermined acid is added so that the pH value C of the obtained mixed solution is adjusted to 0 <C <7, 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 preferably 500 to 1000 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature and the like, but is preferably 0.5 to 6 hours.

  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 of 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 refired under the same firing conditions. If this is done, the luminous brightness of the photostimulable phosphor can be further increased, and when the fired product is cooled to the room temperature from the firing temperature, the desired brightness can also be obtained by removing the fired product from the electric furnace and allowing it to cool in the air. Although a photostimulable phosphor can be obtained, it may be cooled in the same weakly reducing atmosphere, neutral atmosphere or weakly oxidizing atmosphere as at the time of firing.

  In addition, by moving the fired product from the heating part to the cooling part in an electric furnace and quenching in a weakly reducing atmosphere, neutral atmosphere or weakly oxidizing atmosphere, the resulting stimulable phosphor is excited. The light emission luminance can be further increased.

  The photostimulable phosphor layer 12 is formed by vapor deposition on the one surface of the substrate 11a using the photostimulable phosphor as an evaporation source. As the vapor deposition method, an evaporation method, a sputtering method, a CVD method, or the like can be used.

In the vapor deposition method, first, after the substrate 11a is installed in a vapor deposition apparatus, the inside of the apparatus is evacuated to a vacuum degree of about 1.333 × 10 ⁻⁴ Pa. Next, the stimulable phosphor is set as an evaporation source in an evaporation apparatus in the vapor deposition apparatus, and is heated and evaporated by a resistance heating method, an electron beam method, or the like, so that the stimulable phosphor is formed on the surface of the substrate 11a with a desired thickness. Let it grow.

  As a result, the photostimulable phosphor layer 12 containing no binder is formed. In the above vapor deposition step, the photostimulable phosphor layer 12 can be formed in a plurality of times.

  In the vapor deposition step, a plurality of photostimulable phosphor materials are co-deposited using a plurality of resistance heaters or electron beams as an evaporation source, and the target photostimulable phosphor is synthesized on the substrate 11a. It is also possible to form the photostimulable phosphor layer 12.

  In preparation of the photostimulable phosphor layer 12 by the vapor deposition method, the temperature of the support 11 on which the photostimulable phosphor layer 12 is formed is preferably set to 50 ° C. to 400 ° C. 100 ° C. to 250 ° C. is preferable, and when a resin is used for the substrate 11a, it is preferably 50 ° C. to 150 ° C., more preferably 50 ° C. to 100 ° C. in consideration of the heat resistance of the resin.

FIG. 2 is a diagram showing a state in which the photostimulable phosphor layer 12 is formed on the support 11 by vapor deposition. The incident angle of the vapor flow 16 of the stimulable phosphor with respect to the normal direction (R) of the surface of the support 11 fixed to the support holder 15 on the heat resistant resin layer 11b side is θ ₂ (for example, 60 ° in the figure). Assuming that the angle of the formed columnar crystal 13 with respect to the normal direction (R) of the surface of the substrate 11a is θ ₁ (for example, 30 ° in the figure), empirically θ ₁ is about half of θ ₂ and this angle Thus, the columnar crystal 13 is formed.

  The growth angle of the columnar crystal 13 of the photostimulable phosphor is preferably 0 ° to 70 °, and preferably 0 ° to 55 °.

  In these cases, it is preferable that the distance between the shortest part of the support 11 and the evaporation source is approximately 10 cm to 80 cm in accordance with the average range of the stimulable phosphor.

  In order to improve the sharpness (MTF) in the photostimulable phosphor layer 12 composed of the columnar crystals 13, the size of the columnar crystals 13 is preferably about 1 μm to 50 μm, and more preferably 1 μm to 30 μm. That is, when the columnar crystal 13 is thinner than 1 μm, the MTF decreases because the stimulated excitation light is scattered by the columnar crystal 13, and the directivity of the stimulated excitation light also decreases when the columnar crystal 13 is 50 μm or more. However, the MTF decreases.

  The size of the columnar crystal 13 is an average value of the diameter in terms of a circle of the cross-sectional area of each columnar crystal 13 when the columnar crystal 13 is observed from a plane parallel to the support 11, and has at least 100 columnar crystals. Calculated from a micrograph containing crystal 13 in the field of view.

  Further, the size of the gap between the columnar crystals 13 is preferably 30 μm or less, and more preferably 5 μm or less. When the gap exceeds 30 μm, the filling rate of the phosphor in the phosphor layer is lowered, and the luminance is lowered.

  The thickness of the columnar crystal 13 is affected by the temperature of the substrate 11a, the degree of vacuum, the incident angle of vapor flow, and the like. By controlling these, the columnar crystal 13 having a desired thickness can be produced.

In the sputtering method, like the vapor deposition method, after the support 11 is installed in the sputtering apparatus, the inside of the apparatus is once evacuated to a vacuum degree of about 1.333 × 10 ⁻⁴ Pa, and then Ar, An inert gas such as Ne is introduced into the sputtering apparatus to obtain a gas pressure of about 1.333 × 10 ⁻¹ Pa. Next, the stimulable phosphor layer 12 is grown obliquely to a desired thickness on the support 11 by sputtering obliquely using the stimulable phosphor as a target.

In the sputtering process, it is possible to form the photostimulable phosphor layer 12 in a plurality of times as in the vapor deposition method, and a plurality of photostimulable phosphor materials are used as targets, and these are simultaneously or sequentially sputtered. Thus, it is possible to form the desired photostimulable phosphor layer 12 on the support 11. If necessary, reactive sputtering may be performed by introducing a gas such as O ₂ or H ₂ . Furthermore, the deposition object may be cooled or heated as necessary during sputtering. Moreover, you may heat-process the photostimulable phosphor layer 12 after completion | finish of sputtering.

  The CVD method does not contain a binder on the support 11 by decomposing an organometallic compound containing the desired stimulable phosphor or stimulable phosphor raw material with energy such as heat and high-frequency power. The photostimulable phosphor layer 12 is obtained. Also by the CVD method, the stimulable phosphor layer 12 can be obtained by vapor-phase-growing the stimulable phosphor into independent elongated columnar crystals 13.

  The thickness of the photostimulable phosphor layer 12 formed by these methods varies depending on the brightness of the intended radiation image conversion panel with respect to radiation, the type of stimulable phosphor, etc., but is preferably in the range of 10 μm to 1000 μm. Preferably, it is the range of 20 micrometers-800 micrometers.

  The growth rate of the photostimulable phosphor layer 12 in the vapor deposition method 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 is poor, which is not preferable. Further, when the growth rate exceeds 300 μm / min, it is difficult to control the growth rate, which is not preferable.

  Since the photostimulable phosphor layer 12 formed on the support 11 in this way does not contain a binder, it has excellent directivity and high directivity of stimulated excitation light and stimulated emission. The layer thickness can be made larger than that of the radiation image conversion panel having the dispersive stimulable phosphor layer 12 in which the stimulable phosphor is dispersed in the binder. Further, the sharpness of the image is improved by reducing the scattering of the stimulating light in the stimulable phosphor layer 12.

  In addition, the gap between the columnar crystals 13 may be filled with a filler or the like, which will reinforce the stimulable phosphor layer 12. Further, a substance having a high light absorption rate, a substance having a high light reflectance, or the like may be filled. As a result, the reinforcing effect can be provided, and the light diffusion in the lateral direction of the stimulated excitation light incident on the stimulable phosphor layer 12 can be almost completely prevented.

  A substance having a high light reflectance means a material having a high reflectance with respect to stimulating light emission (400 to 600 nm, particularly 400 to 500 nm), and a white pigment and a color material (blue color material) in a purple to blue region are used. Can do.

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 , ZnO ₂ , lithopone (BaSO 4 .ZnS), magnesium silicate , Basic lead silicic acid sulfate, basic lead phosphate, aluminum silicate, aluminum, magnesium, silver, indium and the like. Since these white pigments have a strong hiding power and a high refractive index, they can easily scatter stimulated luminescence by reflecting or refracting light, and can significantly improve the brightness of the obtained radiation image conversion panel.

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

  For example, carbon, chromium oxide, nickel oxide, iron oxide or the like is used as the substance having a high light absorption rate.

  After forming the photostimulable phosphor layer 12 as described above, a protective layer 20 is provided on the side of the photostimulable phosphor layer 12 opposite to the substrate 11a as necessary. The protective layer 20 may be formed by directly applying a coating solution for protection to the surface of the photostimulable phosphor layer 12. Alternatively, a protective layer 20 formed in advance may be formed on the periphery of the photostimulable phosphor layer 12. You may adhere | attach to the support body 11 by a part.

  As a material for the protective layer 20, a moisture-proof resin film can be suitably used. As moisture-proof resin film, cellulose acetate, nitrocellulose, polymethyl methacrylate, polyvinyl butyral, polyvinyl formal, polycarbonate, polyester, polyethylene terephthalate, polyethylene, polyvinylidene chloride, nylon, polytetrafluoroethylene, polytrifluoride-chloride Ethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer, and the like can be used. The resin film is easy to process, and even if the thickness is reduced to 100 μm or less, there is no problem in strength during the manufacturing process, and since it is a thin layer, it is preferable in terms of initial image quality.

Moreover, these moisture-proof resin films may have laminated | stacked the layer of the inorganic substance with low moisture permeability and oxygen permeability. Examples of such inorganic substances include SiO _x (SiO, SiO ₂ ), Al ₂ O ₃ , ZnO ₂ , SnO ₂ , SiC, SiN, etc. Among them, particularly Al ₂ O ₃ and SiO _x are light transmittances. The moisture permeability and oxygen permeability are low, that is, a dense film with few cracks and micropores can be formed, which is particularly preferable. SiO _x and Al ₂ O ₃ may be laminated alone, but if both are laminated together, moisture permeability and oxygen permeability can be lowered, so both SiO _x and Al ₂ O ₃ should be laminated. Is more preferable.

  Lamination of the inorganic substance to the resin film can be performed by methods such as PVD, sputtering, CVD, PE-CVD (Plasma enhanced CVD). Lamination may be performed after the phosphor layer is coated with the resin film, or may be performed before the phosphor layer is coated. The laminated thickness is preferably about 0.01 μm to 1 μm. Or you may use the commercially available moisture-proof resin film in which the vapor deposition layer was formed previously. Examples of such a moisture-proof resin film include Toppan Printing Co., Ltd. GL-AE.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

  Supports were produced by changing the combination of the substrate and the heat-resistant resin layer.

2mm thick, 300mm square size carbon fiber reinforced resin board (CFRP # 155C impregnated resin cured epoxy resin manufactured by Toho Tenax Co., Ltd., longitudinal stiffness value 1 kgf · mm ² , lateral stiffness value 3 kgf · mm ² ) This was coated with polyimide (Ube Industries' underfill material UMEKOTE) with a bar coater, dried in two stages of 80 ° C. for 30 minutes and 180 ° C. for 30 minutes, and then composed of a 10 μm thick polyimide film. A heat resistant resin layer was formed.

  These supports were placed in a vacuum chamber of a vapor deposition apparatus, and a crucible (vapor deposition source) containing a stimulable phosphor composed of CsBr: 0.001 Eu was placed. Except for Comparative Example 4, the surface of the substrate on which the heat-resistant resin layer was formed was directed to the vapor deposition source. In Comparative Example 4, one side of the substrate was directed to the vapor deposition source. An aluminum slit was disposed between the substrate and the evaporation source. The distance between the substrate and the evaporation source was 60 cm. Next, argon gas was introduced into the vacuum chamber, and the degree of vacuum was 0.27 Pa.

  The vapor of the stimulable phosphor was made to enter through an aluminum slit at an incident angle of 0 ° with respect to the normal direction of the substrate, and was deposited while transporting the substrate in a direction parallel to the substrate. . Except for the comparative example 4, it vapor-deposited on the surface in which the heat resistant resin layer of the board | substrate is formed. In Comparative Example 4, vapor deposition was performed on one surface of the substrate. As described above, a photostimulable phosphor layer having a columnar crystal structure with a thickness of 300 μm was obtained.

  A laminated protective film A including an alumina-deposited polyethylene terephthalate resin layer represented by the following configuration was prepared and used as a moisture-proof protective film.

  Laminated protective film A: VMPET12 /// VMPET12 /// PET

  In the laminated protective film A, VMPET represents polyethylene terephthalate deposited on alumina (commercial product: manufactured by Toyo Metallizing Co., Ltd.), and PET represents polyethylene terephthalate. Further, the above “///” indicates that the thickness of the two-component reactive urethane adhesive layer in the dry lamination adhesive layer is 3.0 μm, and the numbers displayed after each resin film are the numbers of each film. Represents film thickness (μm).

  Enclose the photostimulable phosphor plate with a moisture-proof protective film, and heat and fuse the substrate and protective film with an impulse sealer etc. in a region outside the phosphor periphery on the phosphor surface side while reducing the pressure. A radiation image conversion panel was created.

Except that the carbon fiber reinforced resin plate of Example 1 was changed to CFRP # 167B manufactured by Toho Tenax (impregnated resin cured epoxy resin, longitudinal rigidity value 9 kgf · mm ² , lateral rigidity value 10 kgf · mm ² ) A radiation image conversion panel was prepared in the same manner as in Example 1.

Except that the carbon fiber reinforced resin plate of Example 1 was changed to CFRP # 167C manufactured by Toho Tenax (impregnated resin cured epoxy resin, longitudinal rigidity value 15 kgf · mm ² , lateral rigidity value 80 kgf · mm ² ) A radiation image conversion panel was prepared in the same manner as in Example 1.

Except that the carbon fiber reinforced resin plate of Example 1 was changed to CFRP # 167D (impregnated resin cured epoxy resin, longitudinal stiffness value 3 kgf · mm ² , lateral stiffness value 60 kgf · mm ² ) manufactured by Toho Tenax A radiation image conversion panel was prepared in the same manner as in Example 1.

Implemented except that the carbon fiber reinforced resin plate of Example 1 was changed to CFRP # 167E (impregnated resin cured epoxy resin, longitudinal stiffness value 150 kgf · mm ² , lateral stiffness value 200 kgf · mm ² ) manufactured by Toho Tenax A radiation image conversion panel was prepared in the same manner as in Example 1.

<Comparative Example 1>
The carbon fiber reinforced resin plate of Example 1 was changed to CFRP # 167E manufactured by Toho Tenax (impregnated resin-cured epoxy resin, longitudinal stiffness value 0.5 kgf · mm ² , lateral stiffness value 2 kgf · mm ² ). Produced a radiation image conversion panel in the same manner as in Example 1.

<Comparative example 2>
Implemented except that the carbon fiber reinforced resin plate of Example 1 was changed to CFRP # 167F (impregnated resin cured epoxy resin, longitudinal stiffness value 250 kgf · mm ² , lateral stiffness value 250 kgf · mm ² ) manufactured by Toho Tenax A radiation image conversion panel was prepared in the same manner as in Example 1.

<Luminance evaluation>
The X-ray with a tube voltage of 80 kVp was irradiated to the radiation image conversion panel from a point 2 m away from the radiation image conversion panel by 10 mAs. Thereafter, a radiation image conversion panel was installed in Konica Regius 350 to read out the photostimulated luminescence. Evaluation was performed based on the electrical signal from the obtained photomultiplier tube. The values in Table 1 below are average values of the entire photostimulable phosphor surface, and are relative values when the luminance of Example 1 is 1.00.

<Evaluation of sharpness>
A CTF chart was attached to the sample on the substrate side of the radiation image conversion panel, and then 80 kVp X-rays were irradiated at 10 mAs from a point 1.5 m away from the subject. Thereafter, the photostimulable phosphor layer is scanned with a semiconductor laser having a diameter of 100 μm and a wavelength of 680 nm (power of 40 mW on the radiation image conversion panel), and stimulated emission emitted from the excited photostimulable phosphor layer is emitted. Light was received by a photomultiplier tube (R1305, manufactured by Hamamatsu Photonics), converted into an electrical signal, A / D converted, and recorded on a magnetic tape. The recorded magnetic tape was analyzed with a computer to determine the modulation transfer function of the X-ray image recorded on the magnetic tape. The values in the table indicate MTF values (modulation transfer function,%) at a spatial frequency of 2.0 Lp / mm. The higher the MTF value, the better the sharpness.

<Vibration characteristic evaluation>
A strap was attached to the hard tennis ball, and it was suspended from the upper part of the reader so that the front tennis ball on the substrate side of the radiation image conversion panel was in contact with the hard tennis ball. Next, a spacer having a thickness of 5 cm was sandwiched between the front plate and the hard tennis ball to fix the hard tennis ball.

  The radiation image conversion panel was irradiated with 200 mAs of X-rays having a tube voltage of 80 kVp from a radiation source 2 m away. One minute later, laser reading was started. At that time, the spacer was gently pulled out, and a vibration was given by hitting a hard tennis ball against the front plate.

The signal value step difference from the surroundings of the horizontal noise generated at that time was analyzed and evaluated as follows. Since the horizontal line noise has a higher signal value than the surrounding noise, it is better that the step difference is small.
○ ・ ・ ・ Excellent when step difference is 0-2 ○ △ ・ ・ ・ Good when step difference is 3-5 × Poor when step difference is 12 or more

The above evaluation results are shown in Table 1 below.

  In Examples 1 to 5, horizontal line noise generated by vibration was small, and both luminance and sharpness were good. In Comparative Examples 1 and 2, the vibration characteristics were poor.

  From the above results, by making the lateral stiffness value of the substrate higher than the longitudinal stiffness value, the generation of horizontal line noise can be suppressed, and a radiation image conversion panel with excellent vibration characteristics can be obtained. I understand.

It is sectional drawing which shows the example of a form of the radiographic image conversion panel of this invention. It is sectional drawing which shows the formation method of the photostimulable phosphor layer of the radiographic image conversion panel of this invention.

Explanation of symbols

11 Support 11a Substrate 11b Heat Resistant Resin Layer 12 Stimulable Phosphor Layer

Claims (3)

A photostimulable phosphor layer is provided on the support, and the photostimulable phosphor layer is vertically arranged on a reading device that scans the photostimulable phosphor layer with excitation light and reads an image, and the right and left edges and the lower side of the support. In the radiation image conversion panel supported at the edge,
The lateral stiffness value corresponding to the horizontal direction of the support arranged vertically is larger than the longitudinal stiffness value corresponding to the vertical direction of the support, and the lateral stiffness value is 3 to 200 kgf · mm ² , The longitudinal rigidity value is 1-150 kgf · mm ² ,
And the unidirectional prepreg, which is a heat-resistant carbon fiber reinforced resin plate in which carbon fiber in a form aligned in one direction is impregnated in a resin, is used for the support,
The support is configured such that the unidirectional prepregs are alternately stacked in the horizontal direction and the vertical direction and integrated by pressure bonding, and the ratio of the unidirectional prepregs stacked in the horizontal direction is overlapped in the vertical direction. Radiation image conversion panel characterized by having more than directional prepregs .   The radiation image conversion panel according to claim 1, wherein the support is provided with a heat resistant resin layer. 3. The radiation image conversion panel according to claim 1, wherein the photostimulable phosphor layer is composed of a photostimulable phosphor represented by the following general formula (1).
CsX: eA (1)
[Wherein X represents Cl, Br or I, A represents Eu, Sm, In, Tl, Ga or Ce, and e represents a numerical value in the range of 1 × 10 ⁻⁷ <e <1 × 10 ^−2. To express. ]

Images