JP2005114680A - Radiographic image conversion panel, and manufacturing method of radiographic image conversion panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation image conversion panel having high luminance, high sharpness, and no cracks in a stimulable phosphor layer. <P>SOLUTION: This radiation image conversion panel has a constitution wherein the stimulable phosphor layer 12 is formed on a support 11 by a vapor-phase sedimentation method. Since the support 11 comprises a substrate 11a, and a heat-resistant resin layer 11b applied on at least one surface of the substrate 11a, the surface properties of the substrate 11a is improved, and the stimulable phosphor layer 12 is formed on the heat-resistant resin layer 11b side. Hereby, the thermal expansion coefficient of the heat-resistant resin layer 11b is similar to the thermal expansion coefficient of the stimulable phosphor layer 12, and generation of cracks can be prevented at the formation of the stimulable phosphor layer 12. The radiation image conversion panel, having high brightness and high sharpness, can be acquired by adjusting the reflectivity of stimulable emission of the support 11 to be high and the reflectivity of excitation light to be somewhat low. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  Conventionally, as a method for obtaining a radiation image without using a silver salt, a radiation image conversion panel having a photostimulable phosphor layer on a substrate 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 applying radiation transmitted through the subject to the stimulable phosphor layer. 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.

  In order to improve the brightness and sharpness of the radiation image conversion panel, for example, in Patent Document 1, the thickness and the sharpness of the phosphor layer are set in the range of 300 to 700 μm and the relative density is set to 85 to 97%. The degree is improved.

  Further, Patent Document 2 uses a stimulable phosphor represented by the following general formula, in particular, a stimulable phosphor having an e value in the range of 0.003 ≦ e ≦ 0.005. It has been shown that a high brightness radiation image conversion panel can be obtained.

M ¹ X ・ aM ² X ' ₂・ bM ³ X'' ₃ : eA
[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. M ³ is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, at least one divalent metal selected from the group consisting of Is at least one trivalent metal selected from the group consisting of Lu, Al, Ga and In, and X, X ′ and X ″ are at least one halogen selected from the group consisting of F, Cl, Br and I. , A is 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 It is at least one metal selected, and a, b, and e represent numerical values in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0.0001 <e ≦ 1.0, respectively. ]

  Recently, a radiation panel using a stimulable phosphor activated with Eu based on an alkali halide such as CsBr has been proposed. In particular, by using Eu as an activator, X-ray conversion efficiency that has been impossible in the past has been proposed. The improvement is expected to be possible, and it is expected to be used in many medical X-ray diagnostic imaging equipment.

In the radiation image conversion panel, the photostimulable phosphor layer is provided by depositing the photostimulable phosphor on a substrate. As a substrate used in the radiation image conversion panel, various polymer materials, glass, metal, and the like are known (see, for example, Patent Document 3).
JP 2002-214397 A (second page) JP 2003-028995 A JP 2001-83299 A (page 5)

  However, depending on the material of the substrate, there is a problem that the surface has irregularities and the moldability is poor when the stimulable phosphor is deposited. Further, when a heat-sensitive resin is used as the substrate, the substrate may be deformed by the heat of the vapor flow when the stimulable phosphor is deposited. Glass and metal have a large amount of absorption of radiation energy such as X-rays, and it has been difficult to achieve high brightness in a system in which the radiation image conversion panel receives radiation from the substrate side.

  An object of the present invention is to provide a radiation image conversion panel that exhibits high brightness and high sharpness and has no cracking of the stimulable phosphor layer.

  In order to solve the above problems, the invention described in claim 1 of the present invention is a radiation in which a photostimulable phosphor layer 12 is formed on a support 11 by a vapor deposition method as shown in FIG. In the image conversion panel, the support 11 includes a substrate 11a and a heat resistant resin layer 11b coated on at least one surface of the substrate 11a, and the photostimulable phosphor layer 12 is disposed on the heat resistant resin layer 11b side. Is formed.

  According to a second aspect of the present invention, in the radiation image conversion panel according to the first aspect, the substrate 11a is made of any one of a thermosetting resin, a carbon fiber reinforced resin, and a thermoplastic resin.

  According to the invention described in claim 1 or 2, since the support 11 includes the substrate 11a and the heat-resistant resin layer 11b coated on at least one surface of the substrate 11a, the surface property of the substrate 11a. Can be improved.

The invention according to claim 3 is the radiation image conversion panel according to claim 1 or 2, wherein the stimulable phosphor layer 12 is made of a stimulable phosphor represented by the following general formula (1). It is characterized by.
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. .

  According to the invention described in claim 3, since the photostimulable phosphor layer 12 is made of the photostimulable phosphor represented by the general formula (1), a higher-luminance radiation image can be obtained.

  According to a fourth aspect of the present invention, in the radiation image conversion panel according to the third aspect, the heat-resistant resin layer 11b is made of at least one of polyimide, polyamideimide, and fluororesin.

  According to the invention described in claim 4, since the heat resistant resin layer 11b is made of at least one of polyimide, polyamideimide, and fluororesin, the thermal expansion coefficient of the heat resistant resin layer 11b is the stimulable phosphor layer 12. Thus, cracks can be prevented from occurring when the photostimulable phosphor layer 12 is formed.

  The invention according to claim 5 is the radiation image conversion panel according to any one of claims 1 to 4, wherein the heat resistant resin layer 11b has a reflectance of light having a wavelength of 400 to 500 nm of 8% or more. In addition, the reflectance of light having a wavelength of 640 to 700 nm is 5 to 70%.

  According to the invention described in claim 5, the heat resistant resin layer 11b has a reflectance of light having a wavelength of 400 to 500 nm of 8% or more, and a reflectance of light having a wavelength of 640 to 700 nm is 5 to 70%. Therefore, the support 11 having a high reflectance of light having a wavelength of 400 to 500 nm (stimulated emission wavelength) and a slightly low reflectance of light having a wavelength of 640 to 700 nm (excitation wavelength) can be obtained.

  The invention according to claim 6 is a method for manufacturing a radiation image conversion panel in which a photostimulable phosphor layer 12 is formed on a support 11 by vapor deposition, and a heat resistant resin is formed on at least one surface of a substrate 11a. The support 11 is formed by spray coating, and then the photostimulable phosphor layer 12 is formed on the surface of the support 11 on which the heat-resistant resin is applied.

  According to invention of Claim 6, the unevenness | corrugation of the board | substrate 11a can be made flat by spray-applying a heat resistant resin to at least one surface of the board | substrate 11a, and can form the unevenness | corrugation of the board | substrate 11a. The photostimulable phosphor layer 12 can be smoothly formed on the surface of the body 11 coated with the heat resistant resin by a vapor deposition method.

  According to the present invention, a support having a smooth surface can be obtained by coating a heat-resistant resin layer on at least one surface of a substrate. Moreover, since the thermal expansion coefficient of the heat resistant resin layer is close to the thermal expansion coefficient of the photostimulable phosphor layer, it is possible to prevent the occurrence of cracks during the formation of the photostimulable phosphor layer. Therefore, since the photostimulable phosphor layer can be formed smoothly, a high-quality reproduced image can be obtained.

  In addition, due to the low reflectivity of the light having the excitation wavelength of the support, the excitation light irradiated from the stimulable phosphor layer side is less likely to be reflected by the support, and the stimulated fluorescence is reflected by the reflected excitation light. Since the body is not excited, an image with high sharpness can be reproduced. Further, since the reflectance of the light having the stimulated emission wavelength is high, the stimulated emission is emitted only from the photostimulable phosphor layer to the opposite side of the support, and an image with higher luminance can be reproduced.

  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 having a heat-resistant resin layer 11b coated on one surface of a substrate 11a, and a heat-resistant resin layer 11b of the support 11. It consists of a stimulable phosphor layer 12 formed on the side surface and a protective layer 20 that covers and protects the stimulable phosphor layer 12.

  Examples of the substrate 11a include plate glass such as quartz, borosilicate glass, chemically strengthened glass, and crystallized glass, cellulose acetate film, polyester film, polyethylene terephthalate film, polyamide film, polyimide film, epoxy film, polyamideimide film, and screw. Thermosetting plastic film such as maleimide film, fluororesin film, siloxane film, acrylic film, polyurethane film, etc., made of thermoplastic resin such as nylon 12, nylon 6, polycarbonate, polyphenylene sulfide, polyethersulfone, polyetherimide Sheet, a laminate of these, a carbon fiber reinforced resin plate, a metal sheet such as aluminum, iron, copper, and chromium, or a coating of hydrophilic fine particles Metal sheets having a layer can be cited. Among these, a thermosetting plastic sheet and a carbon fiber reinforced resin plate are preferable.

  In addition, when a reflective material such as aluminum, white polyethylene terephthalate, or a silver foil laminated on a resin plate is used for the substrate 11a, the radiation image conversion panel that emits X-rays from the substrate 11a side is efficiently excited. Although it is possible to collect light, it is preferable, but there is a concern that the sharpness may be lowered, and the design of the thickness of the stimulable phosphor layer 12 described later is important.

  Here, the reflective material refers to a material having a reflectance of light having a wavelength of 400 to 500 nm of 60% or more and a reflectance of light having a wavelength of 640 to 700 nm of 50% or more. It is preferable that the substrate 11a has a high reflectance of light having a stimulated emission wavelength (400 to 500 nm) and a low reflectance of light having a reading laser wavelength (640 to 700 nm). The sharpness can be improved by the low reflectance of the reading laser wavelength, and the emission luminance can be improved by the high reflectance of the stimulated emission wavelength.

  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.

  A heat resistant resin layer 11b is provided 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, which will be described later, and therefore, there is no fear that cracking of the stimulable phosphor layer 12 occurs.

  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.

  The heat resistant resin layer 11b preferably has a low reflectance of light having a reading laser wavelength (640 to 700 nm). If the reflectance of the reading laser wavelength light is too high, the sharpness may be lowered. When the reflectance of the reading laser wavelength is low, the sharpness can be improved. The reflectance of light at 640 to 700 nm is 5 to 70%, preferably 5 to 50%.

  Moreover, it is preferable that the heat resistant resin layer 11b has a high reflectance of light having a stimulated emission wavelength (400 to 500 nm). If the reflectance of the stimulated emission wavelength is high, the emission luminance can be improved. The reflectance of light at 400 to 500 nm is 8% or more, preferably 20% or more.

  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, in particular, at least selected from Be, Mg, Ca, Sr and Ba A kind of divalent metal is preferable.

At least one M ³ represents that Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, selected from the group consisting of 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.

  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 kind of metal.

a, b, and e each represent a numerical value in the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <e ≦ 0.2. Particularly, b preferably represents a numerical value in the range of 0 ≦ b ≦ 10 ^−2. .

  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, RbI, CsF, CsCl, CsBr and CsI Species or 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, NiCl ₂ , at least one or two or more compounds selected from the group consisting of 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 , SmF ₃ , SmI _{3 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 , InBr ₃ and InI ₃ and at least one selected from the group consisting of Species or two or more compounds.

  (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 of the above (a) to (d) are weighed so as to satisfy the ranges of a, b and e in the general formula (1) and mixed with 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 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 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 sharpness (MTF) in the stimulable phosphor layer 12 made of columnar crystals, the size of the columnar crystals is preferably about 1 μm to 50 μm, and more preferably 1 μm to 30 μm. That is, when the columnar crystal is thinner than 1 μm, the excitation excitation light is scattered by the columnar crystal, so that the MTF decreases. When the columnar crystal is 50 μm or more, the directivity of the excitation excitation light decreases, and the MTF Will decline.

  The size of the columnar crystals is an average value of the diameters in terms of circles of the cross-sectional areas of the respective columnar crystals when the columnar crystals are observed from a plane parallel to the support 11, and at least 100 or more columnar crystals are viewed. Calculate from the photomicrograph included.

  Further, the size of the gap between the columnar crystals 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 is influenced by the temperature of the substrate 11a, the degree of vacuum, the incident angle of the vapor flow, and the like, and it is possible to produce a columnar crystal having a desired thickness by controlling these.

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. The photostimulable phosphor layer 12 can also be obtained by vapor phase growth of the photostimulable phosphor into independent elongated columnar crystals by the CVD method.

  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 and 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 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 , ZrO 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, or by adhering a separately formed protective layer 20 to the photostimulable phosphor layer 12. Also good.

  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 , ZrO ₂ , SnO ₂ , SiC, and SiN. Of these, Al ₂ O ₃ and SiO _x are particularly light transmissive. 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 method, sputtering method, CVD method, 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.

  Hereinafter, the present invention will be described with reference to examples. The present invention is not limited to these examples.

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

  A 2 mm thick, 300 mm square carbon fiber reinforced resin plate (CFRP # 155C impregnated resin cured epoxy resin manufactured by Toho Tenax) is used as a substrate, and polyimide (Ube Industries' underfill material UMEKOTE) is applied to it with a bar coater. Then, after drying in two stages of 80 ° C. for 30 minutes and 180 ° C. for 30 minutes, a heat-resistant resin layer made of a 10 μm thick polyimide film was formed.

  The polyimide of Example 1 was replaced with a fluorine resin (TC-7105GN manufactured by Daikin) and spray-dried to form a 25-μ thick fluorine resin film on a carbon fiber reinforced resin plate. Spray coating was performed with a high pressure spray gun at a nozzle pressure of 0.3 MPa and a distance of 15 cm from the substrate.

  The polyimide of Example 1 was replaced with polyamide imide (Vilomax HR12N2 manufactured by Toyobo Co., Ltd.) and applied and dried with a bar coater to form a 10 μm thick polyamide imide film on a carbon fiber reinforced resin plate.

  The polyimide of Example 1 was replaced with a fluorine resin (TC-7898SLM manufactured by Daikin) and spray-dried to form a 25-μ thick fluorine resin film on a carbon fiber reinforced resin plate.

  This is the same except that the carbon fiber reinforced resin plate of Example 1 is replaced with a cured epoxy plate (a custom-made epoxy plate 3.5 mm thick manufactured by Toho Tenax Co., Ltd.).

  The carbon fiber reinforced resin plate of Example 1 was replaced with a polycarbonate plate (4 mm thickness, manufactured by Toho Tenax Co., Ltd.), and polyimide was replaced with a fluorine resin (TC-7105GN, manufactured by Daikin). Was formed into a polycarbonate plate.

This is the same except that the carbon fiber reinforced resin plate of Example 1 is replaced with an aluminum plate (A1050-H24MF 0.5 mm thickness manufactured by Sumitomo Light Metal Co., Ltd.).
[Comparative Example 1]

The polyimide of Example 1 was applied and dried with a bar coater instead of the acrylic resin (Sunever SUN-4001 manufactured by Nissan Chemical Industries, Ltd.), and a 20 μ thick acrylic resin film was formed on a carbon fiber reinforced resin plate.
[Comparative Example 2]

The acrylic of Comparative Example 1 was applied with a bar coater instead of the polysiloxane resin (polysiloxane graft polymer SG-204 manufactured by Nippon Shokubai Co., Ltd.) and dried to form a 10 μm thick polysiloxane resin film on the carbon fiber reinforced resin plate.
[Comparative Example 3]

The carbon fiber reinforced resin plate of Comparative Example 1 was replaced with Tempax glass (Pyrex (registered trademark) glass) 0.7 mm.
[Comparative Example 4]

  The carbon fiber reinforced resin plate of Comparative Example 1 was replaced with a cured epoxy plate (prototype EA-2), and no heat resistant resin film 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).

  The photostimulable phosphor plate is wrapped with a moisture-proof protective film, and the substrate and the protective film are heated and fused with an impulse sealer or the like in a region outside the phosphor periphery on the phosphor surface side while reducing the pressure. A radiation image conversion panel was created.

  <Reflectance measurement> Using Hitachi spectrophotometer 557, reflectance (%) was measured on the basis of the board | substrate which vapor-deposited aluminum on the polyimide. The values are shown in Table 1 below.

  <Crack evaluation> A heat-resistant resin layer is applied to a substrate, and a stimulable phosphor layer is provided on the substrate by a vapor deposition method. The stimulable phosphor layer is immediately taken out from the vapor deposition apparatus and left at room temperature for 3 hours. It was evaluated whether the layer was cracked. In Table 1 below, ○ indicates that there is no visual crack, Δ indicates that there is a partial crack, and × indicates that the photostimulable phosphor layer is peeled from the substrate.

  <Luminance Evaluation> The radiation image conversion panel was irradiated with X-rays having a tube voltage of 80 kVp from a point 2 m away from the radiation image conversion panel at 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 brightness of Example 1 is 1.08.

  <Evaluation of Sharpness> After a CTF chart was attached to the sample on the substrate side of the radiation image conversion panel, 80 kVp X-rays were irradiated by 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.

Table 1 below shows the reflectance (%, relative value), crack evaluation, luminance evaluation, and sharpness evaluation of light having a wavelength of 400 to 500 nm or 640 to 700 nm in each example and comparative example.

  In the radiation image conversion panel of Example 1, the reflectance at a wavelength of 400 to 500 nm was 15%, and the reflectance at a wavelength of 640 to 700 nm was 10%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.08, and the sharpness was 37%.

  In the radiation image conversion panel of Example 2, the reflectance at a wavelength of 400 to 500 nm was 17%, and the reflectance at a wavelength of 640 to 700 nm was 12%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.11 and the sharpness was 36%.

  In the radiation image conversion panel of Example 3, the reflectance at a wavelength of 400 to 500 nm was 14%, and the reflectance at a wavelength of 640 to 700 nm was 14%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.07, and the sharpness was 35%.

  In the radiation image conversion panel of Example 4, the reflectance at a wavelength of 400 to 500 nm was 25%, and the reflectance at a wavelength of 640 to 700 nm was 15%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.21, and the sharpness was 35%.

  In the radiation image conversion panel of Example 5, the reflectance at a wavelength of 400 to 500 nm was 18%, and the reflectance at a wavelength of 640 to 700 nm was 15%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.1, and the sharpness was 36%.

  In the radiation image conversion panel of Example 6, the reflectance at a wavelength of 400 to 500 nm was 19%, and the reflectance at a wavelength of 640 to 700 nm was 17%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.08, and the sharpness was 34%.

  In the radiation image conversion panel of Example 7, the reflectance at a wavelength of 400 to 500 nm was 28%, and the reflectance at a wavelength of 640 to 700 nm was 58%. The photostimulable phosphor layer was not visually cracked, the luminance was 1.26, and the sharpness was 30%.

  In the radiation image conversion panel of Comparative Example 1, the reflectance at a wavelength of 400 to 500 nm was 17%, and the reflectance at a wavelength of 640 to 700 nm was 14%. The photostimulable phosphor layer was peeled off from the substrate completely. The brightness and sharpness could not be evaluated.

  In the radiation image conversion panel of Comparative Example 2, the reflectance at a wavelength of 400 to 500 nm was 15%, and the reflectance at a wavelength of 640 to 700 nm was 17%. The photostimulable phosphor layer was peeled off from the substrate completely. The brightness and sharpness could not be evaluated.

  In the radiation image conversion panel of Comparative Example 3, the reflectance at a wavelength of 400 to 500 nm was 12%, and the reflectance at a wavelength of 640 to 700 nm was 18%. The photostimulable phosphor layer was peeled off from the substrate completely. The brightness and sharpness could not be evaluated.

  In the radiation image conversion panel of Comparative Example 4, the reflectance at a wavelength of 400 to 500 nm was 27%, and the reflectance at a wavelength of 640 to 700 nm was 35%. The photostimulable phosphor layer was partially cracked visually, the luminance was 0.99, and the sharpness was 25%.

  In Examples 1-7, there existed a tendency for the brightness | luminance to become high, so that the reflectance of wavelength 400-500 nm was high. Further, the sharpness tended to be higher as the reflectance at a wavelength of 640 to 700 nm was lower.

  In Comparative Example 4 in which no resin layer was provided, the luminance was low although the reflectance at a wavelength of 400 to 500 nm was relatively high. Moreover, the sharpness was also low compared with Examples 1-7. The reason may be that the surface property of the substrate is poor when the stimulable phosphor layer is provided, and the stimulable phosphor layer is partially cracked.

  From the above results, by providing a heat-resistant resin layer on the substrate, the reflectance at a wavelength of 400 to 500 nm is high, and the reflectance at a wavelength of 640 to 700 nm is low, so that the photostimulable phosphor layer does not crack, It can be seen that a radiation image conversion panel having excellent brightness and sharpness can be obtained.

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 (6)

  In a radiation image conversion panel in which a photostimulable phosphor layer is formed on a support by a vapor deposition method, the support comprises a substrate and a heat resistant resin layer coated on at least one surface of the substrate. The radiation image conversion panel, wherein the photostimulable phosphor layer is formed on the heat-resistant resin layer side.   The radiation image conversion panel according to claim 1, wherein the substrate is made of any one of a thermosetting resin, a carbon fiber reinforced resin, and a thermoplastic resin. The radiation image conversion panel according to claim 1, wherein the photostimulable phosphor layer is composed of a stimulable 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 radiation image conversion panel according to claim 3, wherein the heat-resistant resin layer is made of at least one of polyimide, polyamideimide, and fluororesin.   The heat-resistant resin layer has a reflectance of light having a wavelength of 400 to 500 nm of 8% or more, and a reflectance of light having a wavelength of 640 to 700 nm is 5 to 70%. The radiation image conversion panel as described in any one of Claims. A method for producing a radiation image conversion panel in which a photostimulable phosphor layer is formed on a support by a vapor deposition method, wherein a support is formed by spray-coating a heat resistant resin on at least one surface of a substrate, A method for producing a radiation image conversion panel, comprising forming a stimulable phosphor layer on a surface of a support on which a heat resistant resin is applied.

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