JP2008224422A - Scintillator panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scintillator panel that has high production appropriateness, high light emission extraction efficiency of a scintillator, high sharpness, and low degradation of the sharpness between flat light receiving element surfaces, and to provide a radiation FPD (Flat Panel Detector) using this. <P>SOLUTION: This scintillator panel includes a phosphor layer produced on a substrate by vapor deposition, and is sealed with a first protection film arranged on the phosphor layer side and a second protection film arranged on the substrate side. The end side of the surface on which the phosphor layer of the substrate is arranged does not have angle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scintillator panel.

  Radiographic images such as X-ray images are widely used for diagnosis of medical conditions in the medical field. In recent years, radiation imaging systems using radiation detectors have become widespread. In this system, image data based on two-dimensional radiation by a radiation detector is acquired as an electrical signal, and this signal is processed and displayed on a monitor.

  The scintillator panel plays a role of converting radiation incident from the substrate side into light. An FPD (Flat Panel Detector) developed as a radiographic image capturing apparatus in the 1990s is a radiation detector that combines a scintillator panel and an image sensor. At this time, cesium iodide (CsI) is often used as a material of the scintillator. Since CsI has a relatively high conversion rate from X-rays to visible light, and can easily form a columnar crystal structure by vapor deposition, scattering of emitted light can be suppressed by the light guide effect.

  However, since the luminous efficiency is low only with CsI, a mixture of CsI and sodium iodide (NaI) at an arbitrary molar ratio is deposited as sodium-activated cesium iodide (CsI: Na) on the substrate using vapor deposition. By performing annealing as a post process, the visible conversion efficiency is improved and used as an X-ray phosphor (for example, see Patent Document 1).

  Recently, an X-ray phosphor preparation method or the like in which an activator such as indium (In), thallium (Tl), lithium (Li), potassium (K), rubidium (Rb), or sodium (Na) is formed by sputtering. Proposed. However, the scintillator based on CsI has a deliquescent property, and has a drawback that the characteristics deteriorate with time. In order to prevent such deterioration with time, it has been proposed to form a moisture-proof protective layer on the surface of the CsI scintillator (see, for example, Patent Document 2).

  Conventionally, as a manufacturing method of a scintillator by a gas layer method, it is common to form a phosphor layer on a rigid substrate such as aluminum or amorphous carbon, and to cover the entire surface of the scintillator with a protective film (for example, Patent Document 3). However, when a phosphor layer is formed on these substrates that cannot be bent freely, when the scintillator panel and the planar light receiving element surface are bonded, the FPD is affected by deformation of the substrate and warpage during vapor deposition. There is a drawback that uniform image quality characteristics cannot be obtained within the light receiving surface. In addition, when the substrate is a metal, X absorption is large, which is a problem especially in terms of promoting low exposure. On the other hand, amorphous carbons that have begun to be used in recent years are useful in practical production because they have low X-ray absorption, but are not widely used for large-sized products and are very expensive. It was hard to say. Therefore, such a problem has become serious with the recent increase in size of FPD.

  To avoid this problem, the scintillator panel can be replaced with a method of forming a scintillator by vapor deposition directly on the surface of the light receiving element (on the image sensor) or a medical intensifying screen with low sharpness but flexibility. It is generally used. Further, an example in which a flexible protective layer such as polyparaxylylene is used as the protective layer is shown (for example, see Patent Document 4).

  However, although the scintillator material deposited directly on the planar light receiving element has high image characteristics, the cost characteristic of wasting the expensive light receiving element when a defective product is deposited and the image characteristics of the scintillator material can be improved by heat treatment. Since the light receiving element is vulnerable to heat, the processing temperature is limited. Alternatively, there is a problem that it is necessary to incorporate cooling of the light receiving element in the heat treatment process.

Therefore, in order to improve the situation with the problems as described above, it is excellent in production, prevents deterioration of the characteristics of the scintillator (phosphor) layer over time, and chemically or physically changes the scintillator (phosphor) layer. Therefore, it is strongly desired to develop a radiation FPD that protects against an impact, causes little deterioration in sharpness between the scintillator panel and the plane light receiving element surface, and provides uniform image quality characteristics.
Japanese Examined Patent Publication No. 54-35060 JP 2001-59899 A Japanese Patent No. 3669926 JP 2002-116258 A

  An object of the present invention is to provide a scintillator panel that is excellent in production suitability, has high light emission extraction efficiency and sharpness of the scintillator, and has little deterioration in sharpness between plane light receiving element surfaces, and a radiation FPD using the scintillator panel. .

  The above object of the present invention can be achieved by the following configuration.

  1. In a scintillator panel sealed with a phosphor layer produced by vapor deposition on a substrate, a first protective film disposed on the phosphor layer side, and a second protective film disposed on the substrate side, the substrate A scintillator panel characterized in that the end side of the surface on which the phosphor layer is disposed has no corners.

  2. 2. The scintillator panel according to 1 above, wherein the substrate is a polyimide (PI) or polyethylene naphthalate (PEN) film.

  3. The scintillator panel according to 1 or 2, wherein the first and second protective films each have a thickness of 10 to 100 µm.

4). 4. The scintillator panel according to any one of 1 to 3, wherein the first and second protective films each have a moisture permeability of 50 g / m ² · day or less.

  5. The scintillator panel according to any one of 1 to 4, wherein the phosphor layer is CsI (cesium iodide).

  According to the present invention, it is possible to provide a scintillator panel that is excellent in production suitability, has high scintillator emission extraction efficiency and high sharpness, and has little deterioration in sharpness between plane light receiving element surfaces, and a radiation FPD using the scintillator panel. .

  The present invention will be described in more detail.

(Phosphor layer)
In the present invention, the fact that the end side of the surface on which the phosphor layer is disposed has no corner will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of the scintillator panel 10. In FIG. 1A, the end side of the surface has a corner, and in FIG. 1B, the end side of the present invention does not have a corner. FIG.1 (c) is an enlarged view of the edge part side of the surface where a fluorescent substance layer is arrange | positioned. In FIG. 1, a reflective layer 3 is provided on a substrate 1, and a phosphor layer 2 is provided thereon. In some cases, an undercoat layer (not shown) is provided between the substrate 1 and the reflective layer 3, or between the reflective layer 3 and the phosphor layer 2, or both.

  In FIG.1 (c), the auxiliary line C1 shows the cut line of an edge part. The auxiliary line C2 is an extension line of the upper surface of the phosphor layer 2, and the auxiliary line C3 is an extension line of the vertical surface of the phosphor layer 2. α represents the distance between the auxiliary line C2 and the auxiliary line C3 to the auxiliary line C1. In the present invention, α is 1/10 to 1/1000 of the thickness of the phosphor layer 2, and preferably 1/100 to 1/1000.

  The scintillator panel of FIG. 1A is cut by a punching press cutter or the like, and the end portion of the phosphor layer is substantially perpendicular. On the other hand, the scintillator panel in FIG. 1B is cut with a paper cutter or the like, or the corners of the scintillator panel in FIG. 1A are scraped off with sand paper or the like. When the scintillator panel is cut with a paper cutter or the like, the corners of the phosphor layer 2 are slightly peeled off to have the shape of the present invention.

  Various known phosphor materials can be used as the material for forming the phosphor layer, but the rate of change from X-ray to visible light is relatively high, and the phosphor is easily formed into a columnar crystal structure by vapor deposition. Therefore, cesium iodide (CsI) is preferable because scattering of the emitted light in the crystal can be suppressed by the light guide effect and the thickness of the phosphor layer can be increased.

  However, since only CsI has low luminous efficiency, various activators are added. For example, as shown in Japanese Patent Publication No. 54-35060, a mixture of CsI and sodium iodide (NaI) at an arbitrary molar ratio can be mentioned. Also, for example, CsI as disclosed in Japanese Patent Application Laid-Open No. 2001-59899 is deposited, and indium (In), thallium (Tl), lithium (Li), potassium (K), rubidium (Rb), sodium (Na CsI containing an activating substance such as) is preferred. Particularly preferred phosphor activators include TlI, TlBr, and EuI.

  In the present invention, it is particularly preferable to use an additive containing one or more types of thallium compounds and cesium iodide as raw materials. That is, thallium-activated cesium iodide (CsI: Tl) is preferable because it has a broad emission wavelength from 400 nm to 750 nm.

  As the thallium compound as an additive containing one or more types of thallium compounds according to the present invention, various thallium compounds (compounds having oxidation numbers of + I and + III) can be used.

In the present invention, a preferable thallium compound is thallium bromide (TlBr), thallium chloride (TlCl), thallium fluoride (TlF, TlF ₃ ), or the like.

  The melting point of the thallium compound according to the present invention is preferably in the range of 400 to 700 ° C. If the temperature exceeds 700 ° C., the additives in the columnar crystals exist non-uniformly, resulting in a decrease in luminous efficiency. In the present invention, the melting point is a melting point at normal temperature and pressure.

  Moreover, it is preferable that the molecular weight of a thallium compound exists in the range of 206-300.

  In the phosphor layer of the present invention, the content of the additive is desirably an optimum amount according to the target performance, but is 0.001 mol% to 50 mol% with respect to the content of cesium iodide. It is preferable that it is 0.1-10.0 mol%.

  Here, when the additive is less than 0.001 mol% with respect to cesium iodide, the target light emission luminance cannot be obtained without much difference from the light emission luminance obtained by using cesium iodide alone. Moreover, when it exceeds 50 mol%, the property and function of cesium iodide cannot be maintained.

(Protective film)
The protective film according to the present invention focuses on protecting the phosphor layer. That is, cesium iodide (CsI) absorbs water vapor in the air and deliquesces when exposed to a high hygroscopic property, and therefore the main purpose is to prevent this. The protective film can be formed using various materials. For example, a polymer protective film is provided on the phosphor layer.

  The thickness of the polymer protective film is preferably 12 μm or more and 60 μm or less, more preferably 20 μm or more and 40 μm in consideration of the formation of voids, the phosphor layer protection, sharpness, moisture resistance, workability, and the like. The following is preferred. The haze ratio is preferably 3% or more and 40% or less, more preferably 3% or more and 10% or less in consideration of sharpness, radiation image unevenness, manufacturing stability, workability, and the like. A haze rate shows the value measured by Nippon Denshoku Industries Co., Ltd. NDH 5000W. The required haze ratio is appropriately selected from commercially available polymer films and can be easily obtained.

  The light transmittance of the protective film is preferably 70% or more at 550 nm in consideration of photoelectric conversion efficiency, scintillator emission wavelength, etc., but a film having a light transmittance of 99% or more is difficult to obtain industrially. Substantially 99% to 70% is preferable.

The moisture permeability of the protective film is preferably 50 g / m ² · day (40 ° C., 90% RH) (measured in accordance with JIS Z0208) or less, more preferably 10 g / m ² taking into account the protective properties and deliquescence of the phosphor layer. m ² · day (40 ° C, 90% RH) (measured according to JIS Z0208) or less is preferable, but a film with a water vapor transmission rate of 0.01 g / m ² · day (40 ° C, 90% RH) or less is industrial. Is practically 0.01 g / m ² · day (40 ° C, 90% RH) or more, 50 g / m ² · day (40 ° C., 90% RH) (measured according to JIS Z0208) ) Or less, more preferably 0.1 g / m ² · day (40 ° C./90% RH) or more and 10 g / m ² · day (40 ° C./90% RH) (measured according to JIS Z0208) or less. .

(substrate)
The substrate of the scintillator panel of the present invention is a dielectric having radiation transparency, light transparency, and a refractive index smaller than the refractive index of the phosphor layer. Therefore, polymer films such as cellulose acetate film, polyester film, polyethylene terephthalate film, polyethylene naphthalate film, polyamide film, polyimide film, triacetate film, and polycarbonate film can be used.

  In particular, a polymer film containing polyimide or polyethylene naphthalate is suitable when a columnar scintillator is formed by a vapor phase method using cesium iodide as a raw material. In particular, the substrate is preferably a flexible polymer film having a thickness of 50 to 500 μm.

Here, “a substrate having flexibility” means a substrate having an elastic modulus (E120) at 120 ° C. of 1000 to 6000 N / mm ² , and a polymer film containing polyimide or polyethylene naphthalate as such a substrate. Is preferred.

  Note that the “elastic modulus” means the slope of the stress with respect to the strain amount in a region where the strain indicated by the standard line of the sample conforming to JIS-C2318 and the corresponding stress have a linear relationship using a tensile tester. Is what we asked for. This is a value called Young's modulus, and in the present invention, this Young's modulus is defined as an elastic modulus.

Substrate used in the present invention, the elastic modulus at the 120 ° C. as described above (E120) is preferably a ^{1000N / mm 2 ~6000N / mm 2} . More preferably ^{1200N / mm 2 ~5000N / mm 2} .

Specifically, polyethylene naphthalate ^{(E120 = 4100N / mm 2)} , polyethylene terephthalate ^{(E120 = 1500N / mm 2)} , polybutylene naphthalate ^{(E120 = 1600N / mm 2)} , polycarbonate (E120 = 1700N / mm ²⁾ , Syndiotactic polystyrene (E120 = 2200 N / mm ² ), polyetherimide (E120 = 1900 N / mm ² ), polyarylate (E120 = 1700 N / mm ² ), polysulfone (E120 = 1800 N / mm ² ), polyethersulfone Examples thereof include a polymer film made of (E120 = 1700 N / mm ² ).

  These may be used singly or may be laminated or mixed. Among them, as a particularly preferable polymer film, a polymer film containing polyimide or polyethylene naphthalate is preferable as described above.

  In addition, when bonding the scintillator panel and the planar light receiving element surface, due to the influence of deformation of the substrate and warping during vapor deposition, it is not possible to obtain uniform image quality characteristics within the light receiving surface of the flat panel detector. By making the substrate into a polymer film having a thickness of 50 μm or more and 500 μm or less, the scintillator panel is deformed into a shape suitable for the shape of the planar light receiving element surface, and uniform sharpness is obtained over the entire light receiving surface of the flat panel detector. .

(Production method of scintillator panel)
A typical example of a method for manufacturing a scintillator panel of the present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional view when the scintillator panel is sealed with a protective film. FIG. 3 is a diagram showing a schematic configuration of the vapor deposition apparatus 61.

  In FIG. 2, the first protective film 4 on the phosphor layer 2 surface side and the second protective film 5 on the substrate 1 side are sealed, but the sealing position is preferably closer to the substrate 1. FIG. 2 (a) uses the scintillator panel of FIG. 1 (a). As a result, at the time of sealing, force concentrates on the end portion, and the protective film or the phosphor layer is broken. On the other hand, FIG. 2 (a) uses the scintillator panel of FIG. 1 (b). At the time of sealing, the force is not concentrated on the end portion, and the protective film and the phosphor layer are held.

<Vapor deposition equipment>
As shown in FIG. 3, the vapor deposition apparatus 61 has a box-shaped vacuum vessel 62, and a resistance heating crucible 63 for vacuum vapor deposition is disposed inside the vacuum vessel 62. The resistance heating crucible 63 is a filling member of a vapor deposition source, and an electrode is connected to the resistance heating crucible 63. When a current flows through the electrode to the resistance heating crucible 63, the resistance heating crucible 63 generates heat due to Joule heat. At the time of manufacturing the scintillator panel 10, the mixture containing the cesium iodide and the activator compound is filled in the resistance heating crucible 63, and an electric current flows through the resistance heating crucible 63, thereby heating and evaporating the mixture. It can be done.

  An alumina crucible around which a heater is wound may be applied as the member to be filled, or a refractory metal heater may be applied.

  A holder 64 for holding the substrate 1 is disposed inside the vacuum vessel 62 and immediately above the resistance heating crucible 63. The holder 64 is provided with a heater (not shown), and the substrate 1 mounted on the holder 64 can be heated by operating the heater. When the substrate 1 is heated, the adsorbed material on the surface of the substrate 1 is removed or removed, or an impurity layer is prevented from being formed between the substrate 1 and the phosphor layer formed on the surface. The adhesion between the substrate 1 and the phosphor layer formed on the surface thereof can be enhanced, and the film quality of the phosphor layer formed on the surface of the substrate 1 can be adjusted.

  The holder 64 is provided with a rotating mechanism 65 that rotates the holder 64. The rotating mechanism 65 is composed of a rotating shaft 65a connected to the holder 64 and a motor (not shown) as a driving source thereof. When the motor is driven, the rotating shaft 65a rotates to resist the holder 64. It can be rotated while facing the heating crucible 63.

  In the vapor deposition apparatus 61, in addition to the above configuration, a vacuum pump 66 is disposed in the vacuum container 62. The vacuum pump 66 exhausts the inside of the vacuum vessel 62 and introduces gas into the inside of the vacuum vessel 62. By operating the vacuum pump 66, the inside of the vacuum vessel 62 has a gas atmosphere at a constant pressure. Can be maintained below.

<< Formation of phosphor layer >>
The substrate 1 provided with the reflection layer as described above is attached to the holder 64, and the resistance heating crucible 63 is filled with a powdery mixture containing cesium iodide and thallium iodide (preparation step). In this case, it is preferable that the distance between the resistance heating crucible 63 and the substrate 1 is set to 100 to 1500 mm, and the vapor deposition process described below is performed within the set value range.

  When the preparation process is completed, the vacuum pump 66 is operated to evacuate the inside of the vacuum vessel 62, and the inside of the vacuum vessel 62 is brought to a vacuum atmosphere of 0.1 Pa or less (vacuum atmosphere forming step). Here, “under vacuum atmosphere” means under a pressure atmosphere of 100 Pa or less, and preferably under a pressure atmosphere of 0.1 Pa or less.

  Thereafter, an inert gas such as argon is introduced into the vacuum vessel 62, and the inside of the vacuum vessel 62 is maintained in a vacuum atmosphere of 0.1 Pa or less. Next, the heater of the holder 64 and the motor of the rotation mechanism 65 are driven, and the substrate 1 attached to the holder 64 is rotated while being heated while facing the resistance heating crucible 63.

  In this state, a current is passed from the electrode to the resistance heating crucible 63, and the mixture containing cesium iodide and thallium iodide is heated at about 700 ° C. to 800 ° C. for a predetermined time to evaporate the mixture. As a result, innumerable columnar crystals are sequentially grown on the surface of the substrate 1 to form a phosphor layer having a desired thickness (evaporation process). Thereby, the scintillator panel according to the present invention can be manufactured.

  As the scintillator panel of the present invention, a conductive metal reflective layer shown below can be provided on a substrate, a protective layer can be further provided thereon, and a phosphor layer can be provided thereon by vapor deposition.

<Formation of reflective layer>
A metal thin film (Al film, Ag film, etc.) as a reflective layer is formed on one surface of the substrate 1 by sputtering. Moreover, various types of films in which an Al film is sputter-deposited on a polymer film are distributed in the market, and these can be used as the substrate of the present invention.

《Protective layer》
The protective layer is preferably formed by applying and drying a resin dissolved in a solvent. It is preferable that the glass transition point is a polymer having a temperature of 30 to 100 ° C. in terms of attaching a film between the deposited crystal and the substrate. Specifically, a polyurethane resin, a vinyl chloride copolymer, a vinyl chloride-vinyl acetate copolymer, Vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, polyester resin, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various Synthetic rubber resins, phenol resins, epoxy resins, urea resins, melamine resins, phenoxy resins, silicon resins, acrylic resins, urea formamide resins and the like can be mentioned, and polyester resins are particularly preferable.

  The film thickness of the protective layer is preferably 0.1 μm or more from the viewpoint of adhesion, and preferably 3.0 μm or less from the viewpoint of ensuring the smoothness of the surface of the protective layer. More preferably, the thickness of the protective layer is in the range of 0.2 to 2.5 μm.

  Solvents used for preparing the protective layer include lower alcohols such as methanol, ethanol, n-propanol and n-butanol, hydrocarbons containing chlorine atoms such as methylene chloride and ethylene chloride, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, toluene , Aromatic compounds such as benzene, cyclohexane, cyclohexanone, xylene, esters of lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate, butyl acetate, ethers such as dioxane, ethylene glycol monoethyl ester, ethylene glycol monomethyl ester and the like Can be mentioned.

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

Example 1
(Production of scintillator panel)
(Preparation of substrate)
A polyimide film (90 mm × 90 mm) having a thickness of 0.125 mm was prepared as a substrate.

(Formation of reflective layer)
Regarding the polyimide (PI) film substrate, aluminum was sputtered on one surface to a thickness of 2000 mm (0.2 μm).

(Formation of protective layer)
Protective layer coating solution formulation Byron 630 (Toyobo Co., Ltd .: polymer polyester resin) 100 parts by weight Methyl ethyl ketone (MEK) 100 parts by weight Toluene 100 parts by weight The above formulation is mixed and dispersed in a bead mill for 15 hours for coating a protective layer. A coating solution was obtained. The coating solution was applied on the reflective layer of the substrate with a bar coater so that the dry film thickness was 1.0 μm, and then dried at 100 ° C. for 8 hours to prepare a protective layer.

(Formation of phosphor layer)
Using the vapor deposition apparatus shown in FIG. 3, a phosphor (CsI: 0.003 Tl) was deposited on the protective layer of the prepared substrate to form a phosphor layer, and a scintillator panel was produced.

  A phosphor material (CsI: 0.003 Tl) was filled in a resistance heating crucible, a substrate was placed on the support holder, and the distance between the resistance heating crucible and the substrate was adjusted to 400 mm. Subsequently, the inside of the vapor deposition apparatus was once evacuated, Ar gas was introduced and the degree of vacuum was adjusted to 0.5 Pa, and then the substrate temperature was maintained at 140 ° C. while rotating the substrate at a speed of 10 rpm. Next, the resistance heating crucible was heated to deposit a phosphor, and when the phosphor layer had a thickness of 600 μm, the deposition was terminated to obtain a scintillator panel.

(Cutting the scintillator panel)
About the obtained scintillator panel,
Shape (A): sample cut with a punch press cutter (FIG. 1 (a)),
Shape (B): 2 using a KW paper cutter manufactured by Oshima Kogyo Co., Ltd., and cutting the side face of the phosphor layer so that the edges of the face have no corners (FIG. 1 (b)). A seed was produced.

(Preparation of protective film)
As the protective film (first protective film) on the phosphor layer surface side, “Barrier Rocks” (coated) 1011HG-CW (# 12) Toray Film Processing Co., Ltd., which is a barrier film with a laminate layer, was used.

  The protective film (second protective film) on the substrate side of the scintillator panel was the same as the protective film on the phosphor layer surface side.

(Production of scintillator panel)
The two types of cut scintillator panels were sealed in the form shown in FIG. 2 using the prepared protective film to prepare a scintillator panel. 2A is a cross-sectional view of the scintillator panel in which the comparative shape (A) is sealed, and FIG. 2B is a cross-sectional view of the scintillator panel in which the shape (B) of the present invention is sealed.

  The sealing was performed so that the distance from the fused part to the peripheral part of the scintillator sheet was 1 mm under a reduced pressure of 1000 Pa. The impulse sealer used for the fusion was a 3 mm wide heater.

(Measurement of emission luminance)
The scintillator panel is set on a 10 cm × 10 cm CMOS flat panel (Radicon X-ray CMOS camera system Shad-o-Box 4KEV), and an X-ray with a tube voltage of 80 kVp is applied to the back surface of each sample (scintillator phosphor). Irradiation was performed from the surface where no layer was formed, and the measured count value was defined as emission luminance (sensitivity). However, it represents with the relative value which sets the light-emitting luminance of the scintillator panel of a comparative example to 1.0.

(Moisture resistance test)
20 ° C 5.5 hours → temperature rise 0.5 hours → 30 ° C 80% RH 5 hours → temperature drop 1 hour → 20 ° C humidification cycle forced deterioration test was conducted for 7 days, and the deterioration rate of the sharpness of this sample was measured. (The sharpness evaluation method is based on the following method).

Sharpness degradation rate = {1- (sharpness after test / initial sharpness)} × 100%
The sharpness deterioration rate was evaluated as follows.

◎ Less than 0-5% ○ Less than 5-20% △ Less than 20-30% x 30% or more.

(Sharpness evaluation)
Each sample is set on a 10 cm long × 10 cm wide CMOS flat panel (X-ray CMOS camera system Shad-o-Box 4KEV manufactured by Radicon), and MTF is measured and calculated for each sample from 12-bit output data.

  Specifically, X-rays with a tube voltage of 80 kVp are irradiated from the back of each sample (surface on which no phosphor layer is formed) through a lead MTF chart, and image data is detected by a CMOS flat panel and recorded on a hard disk. did. Thereafter, the recording on the hard disk was analyzed by a computer to calculate the modulation transfer function (MTF (Modulation Transfer Function)) of the X-ray image recorded on the hard disk. The calculation result (MTF value (%) at a spatial frequency of 1 cycle / mm) was obtained.

(Specific failure rate in moisture resistance test)
A specific failure occurrence rate when 1000 samples of the above moisture resistance test were performed was calculated as follows.

  The specific failure occurrence means an evaluation sample that is lowered by two ranks from the average value, with the above-mentioned ◎, ◯, Δ, and × being four ranks.

  The occurrence rate of specific failure occurrence samples is defined as a specific failure occurrence rate (Equation 1).

Specific failure rate = (number of specific failure occurrence samples / 1000 evaluation samples) × 100% (Equation 1)
From the above-mentioned specific failure rate, the following evaluation was made.

◎ 0%
○ Less than 5% Δ 5 to less than 20% × 20% or more.

(Evaluation of image unevenness and linear noise)
Each sample was set in a 10 cm × 10 cm CMOS flat panel (Radicon X-ray CMOS camera system Shad-o-Box 4KEV), and tube voltage of 80 kVp X-rays was applied to the back of each sample (scintillator phosphor). A solid image was taken by irradiating from a surface on which no layer was formed. This was reproduced as an image by an image reproducing device, enlarged twice as much as the output device and printed out, and the obtained printed image was visually observed to evaluate the appearance of image unevenness and linear noise. Each of image unevenness and linear noise was evaluated as shown below and shown in Table 1.

◎ No image unevenness or linear noise ○ Light image unevenness or linear noise is observed in less than 1 to 2 locations in the plane △ Light image unevenness or linear noise is observed in less than 2 to 4 locations in the plane × Table 1 summarizes the evaluation results over which image unevenness and linear noise are observed at four or more locations in the plane.

  As is apparent from the results shown in Table 1, in the examples according to the present invention, the sharpness deterioration rate and the specific failure occurrence rate in the moisture resistance test are low and the image unevenness is maintained in a state where the light emission luminance is maintained. It can also be seen that there is significantly less linear noise.

It is sectional drawing which shows schematic structure of a scintillator panel. It is sectional drawing of the sealed scintillator panel sealed with the protective layer. It is a figure which shows schematic structure of a vapor deposition apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Phosphor layer 3 Reflective layer 4 First protective film 5 Second protective film 10 Scintillator panel 61 Deposition device 62 Vacuum container 63 Resistance heating crucible 64 Holder 65 Rotating mechanism 66 Vacuum pump

Claims (5)

In a scintillator panel sealed with a phosphor layer produced by vapor deposition on a substrate, a first protective film disposed on the phosphor layer side, and a second protective film disposed on the substrate side, the substrate A scintillator panel characterized in that the end side of the surface on which the phosphor layer is disposed has no corners. The scintillator panel according to claim 1, wherein the substrate is a polyimide (PI) or polyethylene naphthalate (PEN) film. The scintillator panel according to claim 1 or 2, wherein each of the first and second protective films has a thickness of 10 to 100 µm. The scintillator panel according to any one of claims 1 to 3, wherein each of the first and second protective films has a moisture permeability of 50 g / m ² · day or less. The scintillator panel according to any one of claims 1 to 4, wherein the phosphor layer is CsI (cesium iodide).

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