JP5751296B2 - Radiation image conversion panel and manufacturing method thereof - Google Patents

Description

  The present invention relates to a radiation image conversion panel that emits fluorescence upon receiving radiation and a method for manufacturing the same, and more particularly to a radiation image conversion panel characterized in that a phosphor crystal has a columnar shape.

  Conventionally, a radiographic imaging apparatus such as an X-ray image has been widely used for diagnosis of a medical condition in a medical field. In particular, radiographic imaging devices using intensifying screens and X-ray films have been used in medical sites around the world as a result of high sensitivity and high image quality in a long history.

  In recent years, digital radiation image detection means represented by a flat panel radiation detector (FPD; also referred to as “radiation image conversion panel”) have appeared, and a radiation image is acquired as digital information. Thus, image processing can be performed freely, and image information can be sent immediately.

  The radiation image detection means has, for example, a so-called “scintillator panel” that converts radiation into fluorescence. The scintillator panel receives radiation that has passed through a subject, and instantaneously emits fluorescence from the phosphor layer with an intensity corresponding to the radiation dose, and has a configuration in which a phosphor layer is formed on a substrate. The situation is the same for a panel using a photostimulable phosphor because a protective film for improving moisture resistance is provided on the phosphor.

  FIG. 1 is a cross-sectional configuration diagram of a flat panel detector (FPD) having a conventional scintillator panel 6, and FIG. 2 is a cross-sectional configuration diagram of a conventional scintillator panel. The scintillator panel includes a radiation transmissive substrate 1, a reflection layer 2 formed on one surface of the substrate, an undercoat layer 3 covering the reflection layer 2, and an undercoat layer 3 on the reflection layer 2. A phosphor 4 of alkali halide type (for example, CsI: Tl doped with Tl as a light emission center) formed as a large number of needle crystals by vapor deposition, and a protective film 5 as a moisture-proof layer covering the phosphor 4 are provided. It is a thing.

  Inside the FPD, as shown in FIG. 1, the scintillator panel 6 is pressed with a buffer material 8 so as to be in close contact with the photoelectric conversion element array 7, and after placing a front plate 9 for electromagnetic shielding, it is made of ABS resin or the like. It is sealed with a housing 10.

  X-rays that have passed through the affected area of the patient are incident from the front plate 9 side of the FPD and converted into light by the phosphor 4. This light is read by the photoelectric conversion element array 7 and an image is obtained. However, since the light of the phosphor 4 emits isotropically, the same amount of light as the light going to the photoelectric conversion element array is emitted also to the front plate side. ing. In order not to waste this light emission, the reflection layer 2 functions to reflect light toward the photoelectric conversion element array.

The reason why the phosphor 4 is covered with the protective film 5 including the reflective layer 2 and the substrate 1 in FIGS. 1 and 2 is as follows. The scintillator panel 6 inside the FPD may be exposed to high temperature and high humidity (for example, 60 ° C., humidity 70%) for several days. At this time, since the phosphor 4 generally used contains a halogen element, for example, when water enters, I of CsI is ionized to react with water molecules (H ₂ O + I ⁻ → HI + OH ⁻ ), Hydroxide ions are generated, and the phosphor 4 is dissolved. Therefore, the protective film 5 prevents such dissolution.

As a prior art, a protective film is formed by using polyparaxylylene as a material of the protective film 5 and inserting parylene into at least the upper gap of the scintillator crystal gap (see, for example, Patent Document 1). Alternatively, an example is disclosed in which the protective film of the scintillator is a transparent resin film having a moisture permeability of less than 1.2 g / m ² days (see, for example, Patent Document 2).

  The protective film made of the above film has 10 times higher moisture resistance than polyparaxylylene, but the film has a problem that it has a low glass transition temperature (Tg) and is softened at a relatively low temperature.

  For example, when a polyethylene terephthalate (PET) film is used as a protective film, the glass transition temperature (Tg) is 67 ° C., so the radiation conversion panel must withstand high temperature and high humidity such as 70 ° C., RH 60%, 3 days. Below, the protective film (film) of the radiation image conversion panel is softened by the buffer material, and the tip of the scintillator is stuck in the protective film (film). Then, since the refractive index is 1 when the substance around the scintillator is air, the refractive index is 1.79 if the phosphor is, for example, CsI, so the angle at which the light in the phosphor spreads from the crystal tip can be kept small. However, since the refractive index of the film is 1.5 to 1.6 for PET, the refracted light spreads. Then, there is a problem in that light also wraps around the originally shadowed portion and the edge portion of the image becomes invisible, that is, sharpness deteriorates.

JP 2000-284053 A JP 2005-308582 A

  The present invention has been made in view of the above problems, and the problem to be solved is that the phosphor columnar crystals are unlikely to pierce the external protective film under high temperature and high humidity, and the light from the phosphor columnar crystals to the external protective film is not affected. An object of the present invention is to provide a radiation image conversion panel capable of ensuring high sharpness in an X-ray diagnostic image by suppressing diffusion and to provide a method for manufacturing the radiation image conversion panel.

  The above-mentioned problem according to the present invention is solved by the following means.

[1] In the radiation image conversion panel provided with the phosphor columnar crystal and the external protective film covering the phosphor crystal, the shape of the tip of the phosphor columnar crystal is (a) a convex curved surface with respect to the external protective film, Or (b) The radiation image conversion panel, wherein the phosphor columnar crystal has a tip angle of 90 degrees or more (obtuse angle).
[2] The shape of the tip is formed by controlling the deposition end temperature in the phosphor columnar crystal formation step by vapor deposition, or by exposing to a water vapor atmosphere after the phosphor columnar crystal is formed. [1] The radiation image conversion panel according to [1].
[3] The radiation image conversion panel according to [1] or [2], wherein the external protective film covering the phosphor columnar crystal is formed of a polymer compound.
[4] Only the tip of the phosphor columnar crystal is covered with a material having a lower refractive index than that of the columnar crystal, and a substance having a lower refractive index than the material is filled between the fluorescent columnar crystals. The radiation image conversion panel according to any one of [1] to [3].
[5] A radiation image conversion panel according to any one of [1] to [4], comprising a scintillator panel and a planar light receiving element.
[6] The radiation image conversion panel according to any one of [1] to [5], wherein the phosphor columnar crystal contains CsI as a main component.
[7] The method for producing a radiation image conversion panel according to any one of [1] to [6], wherein the phosphor columnar crystal is formed by controlling a vapor deposition end temperature in a phosphor columnar crystal forming step by a vapor deposition method. By exposing to a water vapor atmosphere after formation, the shape of the tip of the phosphor columnar crystal is (a) a convex curved surface, or (b) the tip angle of the phosphor columnar crystal is 90 degrees with respect to the external protective film. A method for producing a radiation image conversion panel, wherein the radiation image conversion panel is formed to have the above-mentioned angle (obtuse angle).
The invention also relates to:
1. In the radiation image conversion panel provided with the phosphor columnar crystal and the external protective film covering the phosphor crystal, the shape of the tip of the phosphor columnar crystal is (a) a convex curved surface with respect to the external protective film, (c) A radiation image conversion panel characterized by being flat or (b) an angle (obtuse angle) of 90 degrees or more.

  2. 2. The shape of the tip is formed by controlling a vapor deposition end temperature in a phosphor columnar crystal forming step by a vapor deposition method, or by exposing to a water vapor atmosphere after forming the phosphor columnar crystal. Radiation image conversion panel.

  3. 3. The radiation image conversion panel as described in 1 or 2 above, wherein the external protective film covering the phosphor columnar crystal is formed of a polymer compound.

  4). The tip of the phosphor columnar crystal is flat, and only the tip is covered with a material having a refractive index lower than that of the columnar crystal, and a substance having a refractive index lower than that of the material is filled between the fluorescent columnar crystals. The radiation image conversion panel according to any one of Items 1 to 3, wherein

  5. 5. The radiographic image conversion panel according to any one of 1 to 4, further comprising a scintillator panel and a planar light receiving element.

  6). The radiation image conversion panel according to any one of 1 to 5, wherein the phosphor columnar crystal contains CsI as a main component.

  7). The method for producing a radiation image conversion panel according to any one of the above 1 to 6, wherein in a phosphor columnar crystal forming step by a vapor deposition method, a water vapor atmosphere is obtained by controlling a vapor deposition end temperature or after forming the phosphor columnar crystal. The shape of the tip of the phosphor columnar crystal becomes (a) a convex curved surface, (c) a plane, or (b) an angle of 90 degrees or more (obtuse angle) with respect to the external protective film. A method of manufacturing a radiation image conversion panel, characterized by comprising:

  8). After forming the phosphor columnar crystal, a step of coating only the tip of the phosphor columnar crystal with a material having a lower refractive index, polishing the phosphor columnar crystal and a material having a lower refractive index, 8. The method for producing a radiation image conversion panel as described in 7 above, further comprising a step of flattening the tip of the phosphor columnar crystal.

  In the X-ray diagnostic image, the above-mentioned means of the present invention makes it difficult for the phosphor columnar crystals to stick to the external protective film under high temperature and high humidity, and the diffusion of light from the phosphor columnar crystals to the external protective film is suppressed. A radiation image conversion panel that can ensure high sharpness can be provided. Furthermore, the manufacturing method of the said radiographic image conversion panel can be provided.

  That is, in the radiation image conversion panel of the present invention, the tip angle of the phosphor columnar crystal is a curved surface convex to the external protective film side, a plane or an angle of 90 degrees or more (obtuse angle) with respect to the external protective film, Even when placed in a high-temperature and high-humidity environment, the tip of the phosphor columnar crystal can be prevented from sticking into the film. Then, since the difference between the refractive index of the phosphor crystal (nD25; CsI: 1.79) and the refractive index of the surrounding air (1.79-1.00 = 0.79) is maintained, the light is in the columnar crystal. , It becomes difficult to spread, so that an image with high sharpness can be obtained.

  In addition, when the film (refractive index: nD25 = 1.5) is stabbed, the difference between the refractive index of the phosphor crystal and the surrounding refractive index (1.79-1.50 = 0.29) is reduced, so that the light Spreads out of the columnar crystal, and an image with low sharpness is obtained.

Radial image conversion panel sectional configuration diagram having a conventional scintillator panel Cross-sectional structure diagram of a conventional scintillator panel The shape of the tip of the phosphor columnar crystal; (a) a convex curved surface, (b) an angle of 90 degrees or more (obtuse angle), (c) a plane Schematic configuration diagram of a vapor deposition apparatus 61 used for producing phosphor columnar crystals according to the present invention. Process sectional drawing of the manufacturing method of the scintillator panel which concerns on this invention embodiment Partially broken perspective view showing schematic configuration of radiation image conversion panel Expanded sectional view of the radiation image conversion panel Process sectional drawing of the manufacturing method of the scintillator panel which concerns on this invention embodiment Process sectional drawing of the manufacturing method of the scintillator panel which concerns on this invention embodiment

  The radiation image conversion panel of the present invention is a radiation image conversion panel comprising a phosphor columnar crystal and an external protective film covering the phosphor columnar crystal. a) a convex curved surface, (c) a plane, or (b) an angle of 90 degrees or more (obtuse angle). This feature is a technical feature common to the inventions according to claims 1 to 8.

  As an embodiment of the present invention, the shape of the tip is formed by controlling the deposition end temperature in the phosphor columnar crystal formation step by vapor deposition, or by exposing it to a water vapor atmosphere after the phosphor columnar crystal is formed. It is preferable that

  Moreover, it is preferable that the external protective film which coat | covers the said fluorescent substance columnar crystal is formed from the high molecular compound. Furthermore, the tip of the phosphor columnar crystal is flat, and only the tip is coated with a material having a refractive index lower than that of the columnar crystal, and a substance having a refractive index lower than that of the material is present between the fluorescent columnar crystals. It is preferable that it is the aspect filled.

  The radiation image conversion panel of the present invention is particularly preferably a radiation image conversion panel having an aspect including a scintillator panel and a planar light receiving element. In this case, it is preferable that the phosphor columnar crystal has an aspect mainly containing CsI.

  As a method for producing the radiation image conversion panel of the present invention, in the step of forming phosphor columnar crystals by vapor deposition, the phosphor columnar crystals are exposed to a water vapor atmosphere by controlling the vapor deposition end temperature or after forming the phosphor columnar crystals. The manufacturing method of the aspect which forms the shape of the front-end | tip part of a crystal | crystallization so that it may become (a) convex curved surface, (c) plane, or (b) 90 degree or more angle (obtuse angle) with respect to an external protective film. It is preferable. In addition, after forming the phosphor columnar crystal, a step of coating only the tip of the phosphor columnar crystal with a material having a lower refractive index, and polishing the phosphor columnar crystal and a material having a lower refractive index than that. It is preferable that the manufacturing method of the radiation image conversion panel includes a step of flattening the tip of the phosphor columnar crystal.

  Hereinafter, the present invention, its components, and the best mode and mode for carrying out the present invention will be described in detail.

(Phosphor)
In the radiation image conversion panel of the present invention, conventionally known non-stimulable general phosphors and stimulable phosphors can be used depending on the purpose. As used herein, the “non-stimulable general phosphor” refers to a substance that exhibits a phenomenon (referred to as “scintillation”) that absorbs radiation energy and emits fluorescence when radiation is incident. Say. Therefore, in the present invention, a non-stimulable general phosphor can be used as a “scintillator”. On the other hand, a “stimulable phosphor” can store absorbed radiation energy and, for example, can emit the stored radiation energy as fluorescence when excited by light or thermal energy. Refers to phosphor.

  The phosphor according to the present invention is a columnar crystal, and the shape of the tip of the phosphor columnar crystal is (a) a convex curved surface, (c) a plane, or (b) 90 degrees with respect to the external protective film. It is the above angle (obtuse angle).

  Here, the “convex curved surface” refers to a shape in which the protruding portion at the tip of the columnar crystal has a higher curvature than the peripheral portion, as shown in FIG.

  “Plane” means a shape in which the tip of the columnar crystal has a parallel surface to the protective film, as shown in FIG.

  “An angle of 90 degrees or more (obtuse angle)” refers to a shape in which the angle of the protrusion at the tip of the columnar crystal is an angle of 90 degrees or more (obtuse angle), as shown in FIG.

  As a method for forming such a shape, in the step of forming phosphor columnar crystals by vapor deposition, the tip of the phosphor columnar crystals can be formed by controlling the vapor deposition end temperature or by exposing to a water vapor atmosphere after forming the phosphor columnar crystals. It is preferable that the method is formed in such a manner that the shape of (a) is a convex curved surface, (c) a plane, or (b) an angle of 90 degrees or more (obtuse angle) with respect to the external protective film. In addition, after forming the phosphor columnar crystal, a step of coating only the tip of the phosphor columnar crystal with a material having a lower refractive index, and polishing the phosphor columnar crystal and a material having a lower refractive index than that. And a step of flattening the tip of the phosphor columnar crystal. A specific method will be described in detail in the [Example] section.

  Hereinafter, the scintillator and the photostimulable phosphor will be individually described as appropriate.

[Scintillator layer]
The radiation image conversion panel of the present invention is preferably a radiation image conversion panel having a scintillator panel and a planar light receiving element. In this case, the scintillator panel is a scintillator panel (also referred to as “scintillator plate”) having a scintillator layer on the substrate, and is also referred to as a reflective layer and a reflective layer protective film (“undercoat layer”) on the substrate. ) And a scintillator layer are preferably provided in this order.

  The scintillator layer according to the present invention is characterized by containing at least a phosphor columnar crystal and a filler as its constituent elements.

  As a material for forming the phosphor constituting the scintillator layer (also referred to as “phosphor layer”), various known phosphor materials can be used, but the change rate from X-ray to visible light is compared. Since the phosphor can be easily formed into a columnar crystal structure by vapor deposition, it is possible to suppress the scattering of the emitted light in the crystal by the light guide effect, and to increase the thickness of the scintillator layer. Cesium iodide (CsI) is preferred.

  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. Further, for example, CsI as disclosed in Japanese Patent Application Laid-Open No. 2001-59899 is deposited, and thallium (Tl), europium (Eu), indium (In), lithium (Li), potassium (K), rubidium (Rb) ), CsI containing an activating substance such as sodium (Na) is preferred. In the present invention, thallium (Tl) and europium (Eu) are particularly preferable. Furthermore, thallium (Tl) is preferred.

  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 wide 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 scintillator layer of the present invention, the content of the additive is desirably an optimum amount according to the target performance and the like, but is 0.001 to 50 mol% with respect to the content of cesium iodide. It is preferable that it is 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.

  In the present invention, after a scintillator layer is deposited on a substrate, for example, a polymer film by vapor deposition of the raw material of the scintillator, the temperature range of −50 ° C. to + 20 ° C. is based on the glass transition temperature of the polymer film. It requires heat treatment for 1 hour or more in an atmosphere. Thereby, the deformation | transformation of a film and generation | occurrence | production of peeling of a fluorescent substance do not generate | occur | produce, and a scintillator panel with high luminous efficiency is realizable.

  As can be seen from the above description, the scintillator layer according to the present invention is preferably a columnar phosphor layer containing cesium iodide, and is preferably formed by a vapor phase growth method. As the vapor phase growth method, a conventionally known vacuum deposition method, sputtering method, CVD method or the like can be used.

  In addition, it is preferable that the thickness of a scintillator layer (phosphor layer) is 100-800 micrometers, and it is more preferable that it is 120-700 micrometers from the point from which the characteristic of a brightness | luminance and sharpness is acquired with sufficient balance.

<Formation of scintillator layer>
A typical example of the manufacturing method of the scintillator layer of the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing a schematic configuration of a vapor deposition apparatus 61 used in the manufacturing method.

  The vapor deposition apparatus 61 has a box-shaped vacuum vessel 62, and a vacuum vapor deposition boat 63 is arranged inside the vacuum vessel 62. The boat 63 is a member to be filled as an evaporation source, and an electrode is connected to the boat 63. When a current flows through the electrode to the boat 63, the boat 63 generates heat due to Joule heat.

  At the time of manufacturing the scintillator panel for radiation, the boat 63 is filled with a mixture containing cesium iodide and an activator compound, and when the current flows through the boat 63, the mixture can be heated and evaporated. ing. 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 is disposed inside the vacuum vessel 62 and immediately above the boat 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 adsorbate on the surface of the substrate 1 is removed and removed, or an impurity layer is formed between the substrate 1 and the scintillator layer (phosphor layer) formed on the surface. Can be prevented, the adhesion between the substrate 1 and the scintillator layer formed on the surface thereof can be strengthened, or the film quality of the scintillator layer formed on the surface of the substrate 1 can be adjusted. Yes.

  The holder 64 is provided with a rotation 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 for the rotating shaft 65. When the motor is driven, the rotating shaft 65a rotates to displace the holder 64 in the boat. It can be rotated in a state of being opposed to 63.

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

  The substrate 1 provided with the reflective layer protective film and the reflective layer is attached to the holder 64, and the boat 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 boat 63 and the substrate 1 is set to 100 to 1500 mm, and the later-described vapor deposition process 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 rotating mechanism 65 are driven, and the substrate 1 attached to the holder 64 is rotated while being heated while facing the boat 63.

  In this state, current is passed from the electrode to the boat 63, and the mixture containing cesium iodide and thallium iodide is heated at about 700 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 scintillator layer having a desired thickness (evaporation process).

[Stimulable phosphor layer]
In the radiation image conversion panel of the present invention, when a stimulable phosphor is used, the radiation image conversion panel in a mode in which a reflective layer protective film, a reflective layer, a stimulable phosphor layer, and the like are sequentially arranged on a substrate. Preferably there is.

Examples of the photostimulable phosphor that can be used in the photostimulable phosphor layer according to the present invention include, for example, a phosphor represented by BaSO ₄ : Ax described in JP-A-48-80487, A phosphor represented by MgSO ₄ : Ax described in JP-A-48-80488, a phosphor represented by SrSO ₄ : Ax described in JP-A-48-80489, and JP-A-51-29889 A phosphor obtained by adding at least one of Mn, Dy and Tb to Na ₂ SO ₄ , CaSO _4, BaSO _{4 and the} like described in Japanese Patent Publication No. 52-30487, BeO described in Japanese Patent Laid-Open No. 52-30487, Phosphors such as LiF, MgS O ₄ and CaF ₂ , phosphors such as Li ₂ B ₄ O ₇ : Cu, Ag described in JP-A-53-39277, JP-A-54-47883 Li ₂ O as described _{(Be 2 O 2) x:} Cu, phosphors such as Ag, are described in U.S. Pat. No. 3,859,527 SrS: Ce, Sm, SrS : Eu, Sm, La 2 O 2 S: Eu , Sm, and (Zn, Cd) S: Mnx phosphors.

Further, a ZnS: Cu, Pb phosphor described in JP-A-55-12142, a barium aluminate phosphor whose general formula is BaO.xAl ₂ O ₃ : Eu, and a general formula of M (II) Examples thereof include alkaline earth metal silicate phosphors represented by O.xSiO ₂ : A.

Further, an alkaline earth fluorohalide phosphor represented by the general formula (Ba _1-xy Mg _x Ca _y ) F _x : Eu ₂ ⁺ described in Japanese Patent Laid-Open No. 55-12143, A phosphor in which the general formula described in JP-A-55-12144 is represented by LnOX: xA, and a general formula described in JP-A-55-12145 is (Ba _1-x M (II) _x ) F _x: phosphor represented by yA, the general formulas described in JP-a-55-84389 BaFX: xCe, phosphor represented by yA, described in JP-a-55-160078 Rare earth element activated divalent metal fluorohalide phosphors represented by the general formula M (II) FX.xA: yLn, general formula ZnS: A, CdS: A, (Zn, Cd) S: A, X A phosphor represented by JP-A-59-38278. A phosphor represented by any one of the following general formulas:
General formula xM ₃ (PO ₄ ) ₂ · NX ₂ : yA
xM ₃ (PO ₄ ) ₂ : yA
A phosphor represented by any one of the following general formulas described in JP-A-59-155487,
General formula nReX ₃ · mAX ′ ₂ : xEu
nReX ₃ · mAX ′ ₂ : xEu, ySm
The following general formula described in JP-A-61-72087,
M (I) X · aM ( II) X '2 · bM (III) X "3: cA
Are described in JP-A 61-228400.

General formula M (I) X: xBi
And a bismuth-activated alkali halide phosphor represented by the formula: In particular, the alkali halide phosphor is preferable because a columnar photostimulable phosphor layer can be easily formed by a method such as vapor deposition or sputtering.

  In the present invention, a stimulable phosphor represented by the following general formula (1) is also preferable.

General formula (1) M ¹ X · aM ² X ′ ₂ : eA, A ″
(Wherein M ¹ is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs, and M ² is Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu and Ni. At least one divalent metal atom selected from each atom of X, X ′ is at least one halogen selected from the group consisting of F, Cl, Br and I, and A and A ″ are Eu, Tb , In, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, and Y, and a and e are each 0 ≦ a <Represents numerical values in the range of 0.5 and 0 <e ≦ 0.2.)

In the photostimulable phosphor represented by the general formula (1), M ^I represents at least one alkali metal atom selected from each atom such as Na, K, Rb and Cs. At least one alkaline earth metal atom selected from each atom is preferred, and a Cs atom is more preferred.

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

M ³ is at least selected from each atom such as Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Ga and In. One kind of trivalent metal atom is represented, and among these, trivalent metal atoms selected from each atom such as Y, Ce, Sm, Eu, Al, La, Gd, Lu, Ga and In are preferred. is there.

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

  From the viewpoint of improving the photostimulable emission brightness of the photostimulable phosphor, X, X ′ and X ″ each represents an atom with at least one halogen selected from F, Cl, Br and I atoms. And at least one halogen atom selected from Br and I, and more preferably at least one halogen atom selected from Br and I atoms.

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

The photostimulable phosphor represented by the general formula (1) is produced by, for example, the production method described below. As a phosphor material,
(A) At least one compound selected from NaF, NaCl, NaBr, NaI, KF, KCl, KBr, KI, RbF, RbCl, RbBr, RbI, CsF, CsCl, CsBr and CsI is used.

_{(B) MgF 2, MgCl 2} , MgBr 2, MgI 2, CaF 2, CaCl 2, CaBr 2, CaI 2, SrF 2, SrCI 2, SrBr 2, SrI 2, BaF 2, BaCl 2, BaBr 2, BaBr 2 2H ₂ O, BaI ₂ , ZnF ₂ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , CdF ₂ , CdCl ₂ , CdBr ₂ , CdI ₂ , CuF ₂ , CuCl ₂ , CuBr ₂ , CuI, NiF ₂ , NiCl ₂ , NiBr _At least one or two or more compounds selected from ₂ and NiI ₂ compounds are used.

  (C) In the general formula (1), Eu, Tb, In, Cs, Ce, Tm, Dy, Pr, Ho, Nd, Yb, Er, Gd, Lu, Sm, Y, Tl, Na, Ag, Cu And a compound having a metal atom selected from each atom such as Mg.

In the compound represented by the general formula (I), a is 0 ≦ a <0.5, preferably 0 ≦ a <0.01, b is 0 ≦ b <0.5, preferably 0 ≦ b ≦ 10 ^{−. 2} and e are 0 <e ≦ 0.2, preferably 0 <e ≦ 0.1.

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

  Next, the obtained phosphor raw material mixture is filled in a heat-resistant container such as a quartz crucible or an alumina crucible and fired in an electric furnace.

  The firing temperature is suitably 200 to 1000 ° C. The firing time varies depending on the filling amount of the raw material mixture, the firing temperature, and the like, but generally 0.5 to 6 hours is appropriate.

  The firing atmosphere includes a nitrogen gas atmosphere containing a small amount of hydrogen gas, a weak reducing atmosphere such as a carbon dioxide atmosphere containing a small amount of carbon monoxide, a neutral atmosphere such as a nitrogen gas atmosphere and an argon gas atmosphere, or a small amount of oxygen gas. A weak oxidizing atmosphere is preferred.

  After firing once under the above firing conditions, the fired product is taken out from the electric furnace and pulverized, and then the fired product powder is again filled in a heat-resistant container and placed in the electric furnace, and again under the same firing conditions as described above. Firing is preferable because it can further increase the emission luminance of the phosphor.

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

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

  The present invention is also effective in a normal columnar crystal phosphor such as CsI: Tl, which does not have stimulated light emission, and the same effect can be obtained.

  In addition, the photostimulable phosphor layer is formed by a vapor deposition method.

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

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

Subsequently, it is preferable to introduce argon gas and nitrogen gas and set a desired degree of vacuum. Usually, 1.0 × 10 ⁻³ or more and 1.0 Pa or less are preferable. Next, at least one of the photostimulable phosphor is heated and evaporated by a resistance heating method, an electron beam method, or the like to grow the photostimulable phosphor on the surface of the support to a desired thickness. As a result, a photostimulable phosphor layer containing no binder is formed, but it is also possible to form the photostimulable phosphor layer in a plurality of times in the vapor deposition step.

  In the vapor deposition step, it is possible to co-evaporate using a plurality of resistance heaters or electron beams to synthesize the desired photostimulable phosphor on the support and simultaneously form the photostimulable phosphor layer. is there.

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

  Furthermore, in the vapor deposition method, the vapor deposition target (support, protective layer or intermediate layer) may be cooled or heated as necessary during vapor deposition.

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

In the sputtering method as the second method, like the vapor deposition method, after a support having a protective layer or an intermediate layer is placed in the sputtering apparatus, the inside of the apparatus is once evacuated to about 1.333 × 10 ⁻⁴ Pa. The degree of vacuum is set, and then an inert gas such as Ar or Ne is introduced into the sputtering apparatus as a sputtering gas so as to have a gas pressure of about 0.01 Pa. Next, a stimulable phosphor layer is grown on the support to a desired thickness by sputtering using the stimulable phosphor as a target.

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

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

  The growth rate of the stimulable phosphor layer in the vapor phase growth is preferably 0.05 μm / min to 300 μm / min. When the growth rate is less than 0.05 μm / min, the productivity of the radiation image conversion panel of the present invention is low, which is not preferable. If the growth rate exceeds 300 μm / min, it is difficult to control the growth rate.

  When the radiation image conversion panel is obtained by the above-described vacuum deposition method, sputtering method, etc., since there is no binder, the packing density of the stimulable phosphor can be increased, and preferable radiation image conversion in terms of sensitivity and resolution. A panel is obtained and preferred.

  The layer thickness of the photostimulable phosphor layer is preferably 50 μm to 1 mm from the viewpoint of obtaining the effects of the present invention, although it varies depending on the purpose of use of the radiation image conversion panel and the type of stimulable phosphor. More preferably, it is 100-600 micrometers, More preferably, it is 100-400 micrometers.

  In producing the photostimulable phosphor layer by the vapor phase growth method described above, the temperature of the support on which the photostimulable phosphor layer is formed is preferably set to 100 ° C. or higher, more preferably 150 ° C. or higher. Especially preferably, it is 150-400 degreeC.

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

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

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

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

  In the present invention, from the viewpoint of brightness, storage stability, etc., it is particularly preferable that the phosphor is a phosphor having CsBr as a base material.

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

  In these cases, it is preferable that the distance between the shortest part of the support and the crucible is usually set to 10 to 60 cm in accordance with the average range of the stimulable phosphor.

  The stimulable phosphor as an evaporation source is uniformly dissolved or formed by pressing or hot pressing and charged in a crucible. At this time, it is preferable to perform a degassing treatment. The method for evaporating the photostimulable phosphor from the evaporation source is performed by scanning the electron beam emitted from the electron gun, but it can also be evaporated by other methods.

  The evaporation source is not necessarily a single stimulable phosphor, and may be a mixture of stimulable phosphor materials.

  Moreover, you may dope an activator afterwards with respect to the base material of fluorescent substance. For example, after depositing only RbBr as a base material, Tl as an activator may be doped. That is, since the crystals are independent, even if the layer (film) is thick, it can be sufficiently doped, and crystal growth hardly occurs, so the MTF does not decrease.

  Doping can be performed by thermal diffusion and ion implantation of a doping agent (activator) in the base layer of the formed phosphor.

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

<filler>
In the present invention, it is preferable to contain a filler in the gap between the phosphor columnar crystals.

  The filler preferably has a refractive index (nD25) of 1.70 or less. Furthermore, it is preferable that it is 1.40 or less. Obviously, there is no filler less than 1.0 in air, but a smaller refractive index is preferred.

  In the present invention, the filler can be used regardless of whether it is organic or inorganic, or liquid or solid, but is preferably organic. However, when the filler is a liquid, the solubility of the phosphor (fluorescent compound) constituting the scintillator layer or the stimulable phosphor layer in the liquid is preferably 0.1 or less.

  As the liquid that can be used as the filler, various water-repellent liquids can be used as long as the above requirements are satisfied. Preferred examples include fluorine-based water-repellent liquids (for example, Novec HFE7100, 7600 (hydrofluoroether; manufactured by Sumitomo 3M)), and silicone-based water-repellent liquids (for example, TSF451-0.65 (dimethylsilicone oil-based; Momentive Performance Materials Japan GK).

As a method for containing the filler according to the present invention, (1) a scintillator layer or a bright spot at least under a normal pressure of 1.0 × 10 ⁵ Pa (1 atm) or less, preferably under conditions closer to vacuum. It is possible to fill the space between the columnar crystals with the liquid by immersing only the surface on which the phosphor layer is present in the liquid as the filler. Alternatively, (2) the filler may be formed between the columnar crystals of the phosphor and on the columnar crystal surface by a vapor phase growth method. As materials that can be used for this purpose, paraxylylene resins (for example, parylene C, parylene N; manufactured by Japan Parylene Co., Ltd.), SiO films, SiOC films, SiC films, and the like can be used. Note that as the vapor deposition method, a vacuum deposition method, a sputtering method, a CVD method, or the like can be used. Further, (3) an SOG film or the like may be applied by an application method.

(External protective film)
The photostimulable phosphor layer disposed on the scintillator panel or substrate according to the present invention has an external protective film made of a polymer compound covering the entire surface thereof.

  The external protective film is for moisture-proofing the scintillator layer or the photostimulable phosphor layer and suppressing deterioration of the scintillator layer or the like, and is made of a material having low moisture permeability.

  For example, a polyethylene terephthalate film (PET) can be used as the external protective film. Besides PET, a polyester film, a polymethacrylate film, a nitrocellulose film, a cellulose acetate film, a polypropylene film, a polyethylene naphthalate film, or the like can be used. In addition, polyparaxylylene (10 to 14 S / cm) can easily form a polyparaxylylene film on the entire surface of the scintillator panel by CVD (Chemical Vapor Deposition). Since it is possible, it is preferable in the present invention.

  The thickness of the external protective film is preferably 12 to 100 μm, more preferably 20 to 80 μm, taking into consideration the formability of the void, the protection of the scintillator (phosphor) layer, sharpness, moisture resistance, workability, and the like. .

(Reflective layer)
The reflective layer according to the present invention is for reflecting light emitted from a phosphor (scintillator) to enhance light extraction efficiency. The reflective layer is preferably formed of a material containing any element selected from the element group consisting of Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, and Au. In particular, it is preferable to use a metal thin film composed of the above elements, for example, an Ag film, an Al film or the like. Two or more such metal thin films may be formed.

  In addition, it is preferable from a viewpoint of the emitted light extraction efficiency that the thickness of a reflection layer is 0.01-0.3 micrometer.

  In the present invention, as described later, a substrate made of anodized aluminum or the like can be used as the substrate. In this case, the effect of increasing the light output without providing a special reflective layer can be obtained by setting the regular reflectance of visible light at an incident angle of 45 ° of the anodized film to 60% or more.

(Reflective layer protective film)
The reflective layer protective film (also referred to as “undercoat layer”) according to the present invention needs to be provided between the reflective layer and the scintillator layer from the viewpoint of protecting the reflective layer.

  The reflective layer protective film preferably contains a polymer binder (binder), a dispersant and the like.

  In addition, as for the thickness of a reflection layer protective film, 0.1-3 micrometers is preferable. In addition, if it is 3 micrometers or less, the light scattering in a reflection layer protective film will be small, and sharpness will be favorable. Further, when the thickness of the reflective layer protective film is 2 μm or less, the columnar crystallinity is not disturbed even if heat treatment is performed.

  Hereinafter, components of the reflective layer protective film will be described.

<Polymer binder>
The reflective layer protective film according to the present invention is preferably formed by applying and drying a polymer binder (hereinafter also referred to as “binder”) dissolved or dispersed in a solvent. Specific examples of the polymer binder include polyimide or polyimide-containing resin, polyurethane, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer. Polymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, polyester, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea resin, melamine resin , Phenoxy resin, silicon resin, acrylic resin, urea formamide resin, and the like. Of these, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, and nitrocellulose are preferably used.

  As the polymer binder according to the present invention, polyimide or a polyimide-containing resin, polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, nitrocellulose and the like are particularly preferable in terms of close contact with the scintillator layer. Moreover, it is preferable that the glass transition temperature (Tg) is a polymer having a temperature of 30 to 100 ° C. from the viewpoint of attaching a film between the deposited crystal and the substrate. From this viewpoint, a polyester resin is particularly preferable. However, if the heat treatment temperature is improved to improve image characteristics such as luminance, a polymer having a Tg of 30 to 100 ° C. may not be able to ensure sufficient heat resistance. In this case, polyimide or a polyimide-containing resin is used.

  Solvents that can be used to prepare the protective film for the reflective layer include N, N-dimethylacetamide, N-methyl-2-pyrrolidone, lower alcohols such as methanol, ethanol, n-propanol, and n-butanol, methylene chloride, and ethylene. Chlorine-containing hydrocarbons such as chloride, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, aromatic compounds such as toluene, benzene, cyclohexane, cyclohexanone and xylene, lower fatty acids and lower alcohols such as methyl acetate, ethyl acetate and butyl acetate And ethers such as dioxane, ethylene glycol monoethyl ester, ethylene glycol monomethyl ester, and mixtures thereof.

  The reflective layer protective film according to the present invention may contain a pigment or a dye in order to prevent scattering of light emitted by the scintillator and improve sharpness and the like.

(substrate)
As the substrate according to the present invention, various metals, carbon, α-carbon, a heat-resistant resin substrate, and the like can be used, but a heat-resistant resin substrate is particularly preferable in view of image characteristics and cost.

  Conventionally known resins can be used as the heat resistant resin, but so-called engineering plastics are preferably used. Here, “engineering plastics” are high-performance plastics used in industrial applications (industrial applications), and generally have high strength, heat-resistant temperature, excellent chemical resistance, etc. Have advantages.

  The engineering plastics according to the present invention is not particularly limited. For example, polysulfone resin, polyethersulfone resin, polyimide resin, polyetherimide resin, polyamide resin, polyacetal resin, polycarbonate resin, polyethylene terephthalate resin Polybutylene terephthalate resin, aromatic polyester resin, modified polyphenylene oxide resin, polyphenylene sulfide resin, polyether ketone resin and the like are preferably used. These engineering plastics may be used independently and 2 or more types may be used together.

  Furthermore, depending on the curing temperature, it is also preferable to use a super engineering plastic represented by polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), or the like.

  In this invention, it is preferable to form a board | substrate with resin containing polyimide like the polyimide resin or polyetherimide resin excellent in heat resistance, workability, mechanical strength, and cost.

  In the present invention, a substrate made of various metals such as aluminum can be used. For example, it is also preferable to use a substrate made of anodized aluminum or the like.

  In order to make a substrate made of anodized aluminum or the like, it was immersed as an anode in a solution containing sulfuric acid, phosphoric acid, oxalic acid, chromic acid or sulfamic acid, an organic acid such as benzenesulfonic acid, or a mixture thereof. Current is passed through the aluminum plate. An electrolyte concentration of 1-70% by weight can be used at temperatures in the range of 0-70 ° C, more preferably at temperatures in the range of 35-60 ° C.

The anode current density may vary from 1 to 50 A / dm, and the voltage in the range of 1 to 100 V may be varied to obtain an anodized film of 1 to 8 g / m ² Al ₂ O ₃ .H ₂ O. Also good. The anodized aluminum plate may subsequently be rinsed with deionized water at a temperature in the range of 10-80 ° C.

  After the anodizing step, a post-treatment such as sealing may be applied to the anode surface. Sealing the holes in the aluminum oxide layer formed by anodization is a well-known technique in the technical field of aluminum anodization. This technology is, for example, “Belgsch-Nederlands tijdschft vooropervlacktechtechnieken van materialien” (surface technology and material route), Volume 24, January 1980, name “Sealing-kwaliteite min selenium en selenium en selenium en selenium en ele ent ele s ener sen Sealing quality and sealing control).

  When the scintillator panel and the planar light receiving element surface are bonded, uniform image quality characteristics can be obtained within the light receiving surface of the radiation image conversion panel (flat panel detector) due to the influence of deformation of the substrate and warpage during vapor deposition. With respect to the fact that the substrate is a resin substrate having a thickness of 50 μm or more and 500 μm or less, the scintillator panel is deformed into a shape that matches the shape of the planar light receiving element surface, and the entire light receiving surface of the radiation image conversion panel is uniformly sharpened. Sex is obtained.

(Production method of scintillator panel)
In the present invention, a scintillator panel can be produced by various conventionally known methods. As described above, after a reflective layer and a reflective layer protective film (also referred to as “undercoat layer”) are provided on the substrate. It is preferable that the scintillator layer is provided and then an external protective film is provided.

  FIG. 5 shows process cross-sectional views of a method of manufacturing a scintillator panel according to an embodiment of the present invention. A radiation transmissive substrate 14, a phosphor layer 17 that emits light when the substrate 14 is irradiated with radiation, and formed between the substrate 14 and the phosphor layer 17, reflects light from the phosphor layer. A reflective layer 15 and a reflective layer protective film 16 for protecting the reflective layer 15 from corrosion, and these include external protective films 18A and 18B connected by an external protective film connecting portion 19 made of a film. A scintillator panel for radiation.

  Here, by setting the tip angle of the phosphor layer made of columnar crystals to a curved surface convex to the external protective film 18A side, a plane or an angle (obtuse angle) of 90 degrees or more with respect to the external protective film 18A side, Even when placed in a humidity environment, the tip of the phosphor columnar crystal is less likely to stick into a film which is an external protective film.

(Radiation image conversion panel)
In the radiation image conversion panel (also referred to as “radiation image detector”) of the present invention, a non-stimulable phosphor (scintillator) and a stimulable phosphor can be used as the phosphor. A radiation image conversion panel using a nonstimulable phosphor (scintillator), that is, a scintillator panel will be described in detail.

  The radiation image conversion panel using a nonstimulable phosphor (scintillator) is preferably a radiation image conversion panel having a scintillator panel and a planar light receiving element as a basic configuration. As a result, the planar light receiving element surface converts the light emitted from the scintillator panel into electric charges, whereby the image can be converted into digital data.

  In the indirect vapor deposition type (separation independent type) according to the present invention, the scintillator panel is placed on the surface of the planar light receiving element. At this time, it is preferable that the scintillator panel is not physically bonded to the plane light receiving element surface. In the direct vapor deposition type (integrated type), the phosphor is directly vapor deposited on the surface of the planar light receiving element to form a scintillator panel in which the planar light receiving element and the scintillator layer are integrated.

  Hereinafter, the radiation image conversion panel will be described in more detail with reference to FIGS. 6 and 7.

  FIG. 6 is a partially broken perspective view showing a schematic configuration of the radiation image conversion panel 100. FIG. 7 is an enlarged cross-sectional view of the radiation image conversion panel 100.

  As shown in FIG. 6, the radiation image conversion panel 100 includes an imaging panel 51, a control unit 52 that controls the operation of the radiation image conversion panel 100, a rewritable dedicated memory (for example, a flash memory), and the like. A memory unit 53 that is a storage unit that stores an image signal output from the power source unit 54, a power supply unit 54 that is a power supply unit that supplies power necessary to obtain the image signal by driving the imaging panel 51, and the like. It is provided inside the body 55.

  The housing 55 includes a communication connector 56 for performing communication from the radiation image conversion panel 100 to the outside as necessary, an operation unit 57 for switching the operation of the radiation image conversion panel 100, and preparation for radiographic image capturing. A display unit 58 that indicates completion or a predetermined amount of image signal has been written in the memory unit 53 is provided.

  Here, if the radiation image conversion panel 100 is provided with the power supply unit 54 and the memory unit 53 for storing the image signal of the radiation image, and the radiation image detector 100 is detachable via the connector 56, the radiation image conversion panel. It can be set as the portable structure which can carry 100.

  As shown in FIG. 7, the imaging panel 51 includes a radiation scintillator panel 10 and an output board 20 that absorbs electromagnetic waves from the scintillator panel 10 and outputs an image signal.

  The scintillator panel 10 is disposed on the radiation irradiation surface side, and is configured to emit electromagnetic waves according to the intensity of incident radiation.

  The output substrate 20 is provided on the surface opposite to the radiation irradiation surface of the scintillator panel 10, and includes a diaphragm 20a, a photoelectric conversion element 20b, an image signal output layer 20c, and a substrate 20d in order from the radiation scintillator panel 10 side. ing. The diaphragm 20a is used to separate the radiation scintillator panel 10 from other layers.

  The photoelectric conversion element 20 b includes a transparent electrode 21, a charge generation layer 22 that is excited by electromagnetic waves that have passed through the transparent electrode 21 to enter the light, and generates a charge, and a counter electrode 23 that is a counter electrode for the transparent electrode 21. The transparent electrode 21, the charge generation layer 22, and the counter electrode 23 are arranged in this order from the diaphragm 20a side.

The transparent electrode 21 is an electrode that transmits an electromagnetic wave that is photoelectrically converted, and is formed using a conductive transparent material such as indium tin oxide (ITO), SnO ₂ , or ZnO.

  The charge generation layer 22 is formed in a thin film on one surface side of the transparent electrode 21 and contains an organic compound that separates charges by light as a compound capable of photoelectric conversion. Each of them contains a conductive compound as an electron acceptor. In the charge generation layer 22, when an electromagnetic wave is incident, the electron donor is excited to emit electrons, and the emitted electrons move to the electron acceptor, and charge, that is, holes and electrons, are transferred into the charge generation layer 22. Career is going to occur.

  Here, examples of the conductive compound as the electron donor include a p-type conductive polymer compound. Examples of the p-type conductive polymer compound include polyphenylene vinylene, polythiophene, poly (thiophene vinylene), polyacetylene, polypyrrole, Those having a basic skeleton of polyfluorene, poly (p-phenylene) or polyaniline are preferred.

  Examples of the conductive compound as the electron acceptor include an n-type conductive polymer compound, and the n-type conductive polymer compound preferably has a polypyridine basic skeleton, particularly poly (p-pyridylvinylene). Those having the following basic skeleton are preferred.

  The film thickness of the charge generation layer 22 is preferably 10 nm or more (particularly 100 nm or more) from the viewpoint of securing the amount of light absorption, and is preferably 1 μm or less (particularly 300 nm or less) from the viewpoint that the electric resistance does not become too large.

  The counter electrode 23 is disposed on the side opposite to the surface on which the electromagnetic wave of the charge generation layer 22 is incident. For example, a common metal electrode such as gold, silver, aluminum, or chromium, However, in order to obtain good characteristics, it is preferable to use a metal, an alloy, an electrically conductive compound, and a mixture thereof having a low work function (4.5 eV or less) as an electrode material. .

  In addition, a buffer layer may be provided between each electrode (transparent electrode 21 and counter electrode 23) sandwiching the charge generation layer 22 so as to act as a buffer zone so that the charge generation layer 22 and these electrodes do not react. Good. The buffer layer is made of, for example, lithium fluoride and poly (3,4-ethylenedioxythiophene), poly (4-styrenesulfonate), 2,9-dimethyl-4,7-diphenyl [1,10] phenanthroline. Formed using.

  The image signal output layer 20c performs accumulation of charges obtained by the photoelectric conversion element 20b and output of a signal based on the accumulated charges. Charge for accumulating the charges generated by the photoelectric conversion element 20b for each pixel. The capacitor 24 is a storage element, and the transistor 25 is an image signal output element that outputs the stored charge as a signal.

  As the transistor 25, for example, a TFT (Thin Film Transistor) is used. This TFT may be an inorganic semiconductor type used in a liquid crystal display or the like or an organic semiconductor, and is preferably a TFT formed on a plastic film.

  As the TFT formed on the plastic film, an amorphous silicon type is known, but in addition, the FSA (Fluidic Self Assembly) technology developed by Alien Technology in the United States, that is, a microfabrication made of single crystal silicon. TFTs may be formed on a flexible plastic film by arranging CMOS (Nanoblocks) on an embossed plastic film. Furthermore, Science, 283, 822 (1999) and Appl. Phys. It may be a TFT using an organic semiconductor as described in documents such as Lett, 771488 (1998), Nature, 403, 521 (2000).

  Thus, as the transistor 25 used in the present invention, a TFT manufactured by the FSA technique and a TFT using an organic semiconductor are preferable, and a TFT using an organic semiconductor is particularly preferable. If this organic semiconductor is used to form a TFT, equipment such as a vacuum deposition apparatus is not required as in the case where a TFT is formed using silicon, and the TFT can be formed by utilizing printing technology or ink jet technology. Is cheaper. Further, since the processing temperature can be lowered, it can be formed on a plastic substrate that is weak against heat.

  The transistor 25 accumulates electric charges generated in the photoelectric conversion element 20 b and is electrically connected to a collection electrode (not shown) that serves as one electrode of the capacitor 24. The capacitor 24 accumulates charges generated by the photoelectric conversion element 20 b and reads the accumulated charges by driving the transistor 25. That is, by driving the transistor 25, a signal for each pixel of the radiation image can be output.

  The substrate 20d functions as a support for the imaging panel 51, and can be made of the same material as the substrate 1.

  Next, the operation of the radiation image conversion panel 100 will be described.

  First, the radiation incident on the radiation image conversion panel 100 enters the imaging panel 51 from the scintillator panel 10 side toward the substrate 20d side. Then, the radiation incident on the radiation scintillator panel 10 is absorbed by the scintillator layer 2 in the scintillator panel 10 and emits an electromagnetic wave corresponding to its intensity.

  Of the emitted electromagnetic wave, the electromagnetic wave incident on the output substrate 20 passes through the diaphragm 20 a and the transparent electrode 21 of the output substrate 20 and reaches the charge generation layer 22. Then, the electromagnetic wave is absorbed in the charge generation layer 22 and a hole-electron pair (charge separation state) is formed according to the intensity.

  Thereafter, the generated charges are transported to different electrodes (transparent electrode film and conductive layer) by an internal electric field generated by application of a bias voltage by the power supply unit 54, and a photocurrent flows.

  Thereafter, the holes carried to the counter electrode 23 side are accumulated in the capacitor 24 of the image signal output layer 20c. The accumulated holes output an image signal when the transistor 25 connected to the capacitor 24 is driven, and the output image signal is stored in the memory unit 53.

  According to the radiation image conversion panel 100 described above, since the scintillator panel 10 is provided, the photoelectric conversion efficiency can be increased, the SN ratio at the time of low-dose imaging in a radiation image is improved, and image unevenness and linear noise are improved. Can be prevented.

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

[Example 1]
FIG. 5 is a process cross-sectional view of the method of manufacturing a scintillator panel according to the embodiment of the present invention. This will be described with reference to FIG. First, a 125 μm-thick polyimide substrate was selected as the substrate 14. The polyimide substrate is a resin and has an advantage of high X-ray transmission.

  Next, as shown in FIG. 5B, an Al film 15 is sputtered on the polyimide substrate by 90 nm. This is because the light emitted from the phosphor is reflected to improve the light extraction efficiency from the opposite side of the substrate. As for the substrate, the polyimide substrate 14 and the Al film 15 may be a single metal substrate (for example, an Al substrate having a thickness of 0.5 mm). Next, a polyester film 16 of 1 μm, for example, is formed as a protective layer. The polyester film is formed under the following conditions by a coating method.

Byron 630 (manufactured by Toyobo Co., Ltd .: polymer polyester resin) 300 parts by weight Methyl ethyl ketone (MEK) 200 parts by weight Toluene 400 parts by weight The above formulation is mixed and dispersed in a bead mill for 15 hours to obtain a coating solution for undercoating. . This coating solution is applied to the surface of the Al film 15 of the substrate 11 with a bar coater so that the dry film thickness is 1.0 μm, and then dried at 100 ° C. for 8 hours to thereby form a polyester film 16 that is a protective transparent insulating film. Is made.

  Next, as shown in FIG.5 (c), CsI: Tl is formed into a film as a fluorescent material on a board | substrate by a vapor deposition method. First, the phosphor materials CsI and TlI are filled in the boat at a ratio of, for example, 1: 0.03 (mol%). Next, after evacuating the inside of the vacuum chamber, Ar gas is introduced to make the inside of the vacuum chamber have a vacuum degree of 0.5 Pa. Here, the substrate is heated and rotated at about 200 ° C., the boat is heated to about 710 ° C., and the substrate temperature is set to 200 ° C. to evaporate CsI and TlI. As a result, a CsI: Tl columnar crystal phosphor layer: CsI: Tl17 having a diameter of several μm and a thickness of 600 μm can be formed on the substrate. At this time, 150, the tip angle of CsI: Tl can be controlled by the substrate temperature at the end of CsI deposition. That is, it is 170 degrees at 110 ° C., 60 degrees at 140 ° C., 70 degrees at 200 ° C., and 120 degrees at 260 ° C. Therefore, in order to form the scintillator panel according to the present invention, the temperature at the end of vapor deposition of CsI: Tl may be set to 140 ° C., 110 ° C., or 200 ° C., or 260 ° C.

  CsI: Tl may be vapor-deposited at a temperature of 140 to 200 ° C. in order to ensure a columnar shape at the initial stage of vapor deposition of CsI: Tl or during vapor deposition.

  Finally, as shown in FIG. 5 (d), as the external protective films 18A and 18B, a laminated film of PET 20 μm / alumina deposited 0.2 μm / polypropylene 30 μm having a total thickness of 50 μm is used. The external protective film 18A and the external protective film 18B are bonded by thermocompression bonding at the ends. The bonded location is shown in the external protective film connecting portion 19.

  In the radiation image conversion panel of the present invention, the tip angle of the phosphor columnar crystal is a curved surface convex to the external protective film side, a plane or an angle of 90 degrees or more (obtuse angle) with respect to the external protective film, Even when placed in a high humidity environment, the tip of the phosphor crystal is less likely to pierce the film.

  Then, the difference between the refractive index of the phosphor crystal (CsI: 1.79) and the refractive index of the surrounding air (1.79-1 = 0.79) is maintained, so that light advances and spreads in the columnar crystal. It becomes difficult. Therefore, a sharp image can be maintained. When the film is inserted into the film (refractive index n = 1.5), the difference between the refractive index of the phosphor crystal and the surrounding refractive index is as small as 1.79-1.5 = 0.29. And an image with low sharpness can be obtained.

  In fact, the MTF value deteriorated from 0.72 to 0.61 at 50 ° C., humidity 70%, high temperature for 1 week and high humidity storage when the tip angle was 70 degrees. In the present invention, since the tip of CsI: Tl is not sharp, CsI: Tl is not easily stuck in the protective film, and the deterioration of MTF as described above is not observed.

[Example 2]
FIG. 8 is a process cross-sectional view of the method of manufacturing a scintillator panel according to the second embodiment of the present invention. Hereinafter, a description will be given with reference to FIG.

  First, a 125 μm-thick polyimide substrate was selected as the substrate 14. The polyimide substrate is a resin and has an advantage of high X-ray transmission.

  Next, as shown in FIG. 8B, an Al film 15 is sputtered on the polyimide substrate by 90 nm. This is because the light emitted from the phosphor is reflected to improve the light extraction efficiency from the opposite side of the substrate. As for the substrate, the polyimide substrate 14 and the Al film 15 may be a single metal substrate (for example, an Al substrate having a thickness of 0.5 mm). Next, a polyester film 16 of 1 μm, for example, is formed as a protective layer. The polyester film is formed under the following conditions by a coating method.

Byron 630 (Toyobo Co., Ltd .: polymer polyester resin) 300 parts by weight Methyl ethyl ketone (MEK) 200 parts by weight Toluene 400 parts by weight The above formulation is mixed and dispersed in a bead mill for 15 hours to obtain a coating solution for undercoating. It was. This coating solution is applied to the surface of the Al film 15 of the substrate 14 with a bar coater so that the dry film thickness is 1.0 μm, and then dried at 100 ° C. for 8 hours to thereby form a polyester film 16 that is a protective film transparent insulating film. Is made.

Next, as shown in FIG. 8C, CsI: Tl is deposited on the substrate as a phosphor material by a vapor deposition method. First, phosphor materials CsI and TlI are filled in a boat at a ratio of, for example, 1: 0.03 mol%. Next, after evacuating the inside of the vacuum chamber, Ar gas is introduced to make the inside of the vacuum chamber have a vacuum degree of 0.5 Pa. Here, the substrate is heated and rotated at about 200 ° C., whereby a CsI: Tl columnar crystal phosphor layer: CsI: Tl17 having a diameter of several μm and a thickness of 600 μm can be formed on the substrate. Here, since the tip angle of CsI: Tl is determined by the angle when the tip is deposited, as described in the first embodiment, the control can be controlled by the substrate temperature at the end of the CsI deposition. Since it is 200 ° C. this time, it is 70 degrees.

  In the present invention, since it is necessary to make this larger than 90 degrees, it is exposed to water vapor as shown in FIG. Specifically, since CsI has a property of being dissolved in water, this step rounds the tip of CsI to an angle larger than 90 degrees and satisfies the constituent requirements of the present invention. For example, the water vapor may be formed by heating deionized water to 120 ° C. with a heater.

  Finally, as shown in FIG. 8 (e), as the external protective films 18A and 18B, a laminated film of PET 20 μm / alumina deposited 0.2 μm / polypropylene 30 μm having a total thickness of 50 μm is used. The external protective film 18A and the external protective film 18B are bonded by thermocompression bonding at the ends. The bonded location is shown in the external protective film connecting portion 19.

  In the image conversion panel for radiation of the present invention, the tip angle of the phosphor crystal is a curved surface convex toward the external protective film side, a flat surface or an angle of 90 degrees or more (obtuse angle) with respect to the external protective film, so Even when placed in a humidity environment, the tip of the phosphor crystal is less likely to pierce the film.

  Then, the difference between the refractive index of the phosphor crystal (CsI: 1.79) and the refractive index of the surrounding air (1.79-1 = 0.79) is maintained, so that light advances and spreads in the columnar crystal. This makes it difficult to maintain a sharp image. When the film is inserted into the film (refractive index n = 1.5), the difference between the refractive index of the phosphor crystal and the surrounding refractive index (1.79−1.5 = 0.29) becomes small, so that the light is columnar crystal. An image with low sharpness is obtained.

[ Reference Example 3]
FIG. 9 is a process sectional view of a method of manufacturing a scintillator panel according to the second embodiment of the present invention. First, a description will be given with reference to FIG. First, a 125 μm-thick polyimide substrate was selected as the substrate 14. The polyimide substrate is a resin and has an advantage of high X-ray transmission.

  Next, as shown in FIG. 9B, an Al film 15 is sputter-deposited on the polyimide substrate 14 by 90 nm. This is because the light emitted from the phosphor is reflected to improve the light extraction efficiency from the opposite side of the substrate. As for the substrate, the polyimide substrate 14 and the Al film 15 may be a single metal substrate (for example, an Al substrate having a thickness of 0.5 mm). Next, a polyester film 16 of 1 μm, for example, is formed as a protective layer. The polyester film is formed under the following conditions by a coating method.

Byron 630 (Toyobo Co., Ltd .: polymer polyester resin) 300 parts by weight Methyl ethyl ketone (MEK) 200 parts by weight Toluene 400 parts by weight The above formulation is mixed and dispersed in a bead mill for 15 hours to obtain a coating solution for undercoating. It was. This coating solution is applied to the surface of the Al film 15 of the substrate 14 with a bar coater so that the dry film thickness is 1.0 μm, and then dried at 100 ° C. for 8 hours to thereby form a polyester film 16 that is a protective film transparent insulating film. Is made.

  Next, as shown in FIG. 9C, CsI: Tl is formed as a phosphor material on the substrate by vapor deposition. First, phosphor materials CsI and TlI are filled in a boat at a ratio of, for example, 1: 0.03 mol%. Next, after evacuating the inside of the vacuum chamber, Ar gas is introduced to make the inside of the vacuum chamber have a vacuum degree of 0.5 Pa. Here, the substrate is heated and rotated at about 200 ° C., whereby a CsI: Tl columnar crystal phosphor layer: CsI: Tl 17 having a diameter of several μm and a thickness of 600 μm can be formed on the substrate. Here, since the tip angle of CsI: Tl is determined by the angle when the tip is deposited, as described in the first embodiment, the control can be controlled by the substrate temperature at the end of the CsI deposition. Since it is 200 ° C. this time, it is 70 degrees.

Next, a SiO ₂ film 21 is deposited on CsI: Tl by CVD. At this time, by adjusting the CVD conditions, SiO ₂ does not enter between the columns of CsI: Tl, and air 22 is formed.

Next, as shown in FIG. 9D, the tip of CsI: Tl is polished by a chemical mechanical polishing method and flattened together with the SiO ₂ film. Since air has a refractive index = 1 and SiO ₂ has a refractive index = 1.46, it is lower than 1.79 of CsI, so that the fiber effect that light hardly leaks out of CsI can be maintained. Since air has a refractive index = 1 and is smaller than SiO ₂ , most of the columnar crystals prevent the diffusion of light out of the CsI: Tl columnar crystals by the same fiber effect as before. Further, the tip of CsI: Tl is fixed with SiO ₂ , and there is an advantage that the mechanical strength of CsI: Tl is enhanced. SiO ₂ also has the advantage of preventing moisture from entering between the CsI: Tl pillars and increasing moisture resistance.

  Finally, as shown in FIG. 9E, as the external protective films 18A and 18B, a laminated film of PET 20 μm / alumina deposited 0.2 μm / polypropylene 30 μm having a total thickness of 50 μm is used. The external protective film 18A and the external protective film 18B are bonded by thermocompression bonding at the ends. The bonded location is shown in the external protective film connecting portion 19.

  In the radiation image conversion panel of the present invention, the tip of the phosphor crystal is flattened so that the tip of the phosphor crystal is less likely to pierce the film even in a high temperature and high humidity environment.

Then, the difference between the refractive index of the phosphor crystal (CsI: 1.79) and the refractive index of the surrounding air (1.79-1 = 0.79) is maintained, so that light advances and spreads in the columnar crystal. This makes it difficult to maintain a sharp image. SiO ₂ has a refractive index of 1.46 and light spreads in that portion, but the film (refractive index n = 1.5) is not stuck any further, so that light is exposed to the outside of the columnar crystal under high temperature and high humidity stress. It can maintain high sharpness without spreading.

  By using the radiographic image conversion panel of the present invention, it is possible to realize a radiographic image conversion panel excellent in durability without deterioration of sharpness in a high temperature and high humidity environment.

DESCRIPTION OF SYMBOLS 1 Substrate 2 Reflective layer 3 Reflective layer protective film 4 Scintillator (phosphor) layer 5 External protective film 6 Scintillator panel 7 Photoelectric conversion element array 8 Buffer material 9 Front plate 10 Housing 14 Polyimide substrate 15 Al film 16 Polyester film 17 CsI: Tl
18A External protective film 18B External protective film 19 External protective film connecting portion 20 Water vapor 21 SiO ₂ film 22 Air 1x Substrate 2x Scintillator (phosphor) layer 3x Reflective layer 4x Protective film 10x Scintillator panel 61 Deposition device 62 Vacuum vessel 63 Boat (covered) Filling member)
64 Holder 65 Rotating mechanism 66 Vacuum pump 100 Radiation image conversion panel

Claims (5)

In a radiation image conversion panel comprising a phosphor columnar crystal and an external protective film made of a polymer compound covering the phosphor crystal , and a planar light receiving element ,
A radiation image conversion panel, wherein the tip of the phosphor columnar crystal is less likely to touch the external protective film by setting the tip angle of the phosphor columnar crystal to an angle of 90 degrees or more (obtuse angle).   The shape of the tip portion is formed by controlling a vapor deposition end temperature in a phosphor columnar crystal forming step by a vapor deposition method or by exposing to a water vapor atmosphere after forming the phosphor columnar crystal. The radiation image conversion panel described. Only the tip of the phosphor columnar crystal is covered with a material having a refractive index lower than that of the columnar crystal, and a substance having a refractive index lower than that of the material is filled between the fluorescent columnar crystals. The radiation image conversion panel according to claim 1. The radiation image conversion panel according to any one of claims 1 to 3 , wherein the phosphor columnar crystal contains CsI as a main component. A method according to claim 1-4 radiographic image conversion panel according to any one of, in the process of forming the phosphor columnar crystals by evaporation, water vapor or after the phosphor columnar crystals formed by controlling the deposition end temperature By forming the phosphor columnar crystal so that the tip angle of the phosphor columnar crystal is an angle of 90 degrees or more (obtuse angle) by exposure to an atmosphere, the tip of the phosphor columnar crystal is less likely to touch the external protective film. A method for manufacturing a radiation image conversion panel.

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