JP2018036197A - Radiographic detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiographic detector which is prevented from cracking during heating and cooling when used and is superior in emission luminance while maintaining sharpness necessary for image quality.SOLUTION: The radiographic detector includes a photoelectric transducer array, a scintillator layer, a reflective layer located in the side opposite to the photoelectric transducer array, of the scintillator layer, an underlying layer disposed between the scintillator layer and the reflective layer, and an intermediate layer disposed between the photoelectric transducer array and the scintillator layer. When a portion within a distance of 50 μm and shorter from a front end of the scintillator layer toward the photoelectric transducer array is defined as a scintillator adjacent part A and a portion within a distance of 5 μm and shorter from a surface of the scintillator layer toward the side opposite to the photoelectric transducer array is defined as a scintillator adjacent part B, each of the scintillator adjacent part A and the scintillator adjacent part B contains one or more kinds of mineral matters, and a difference in thermal expansion coefficient between matters having the lowest thermal expansion coefficients respectively in the scintillator adjacent part A and the scintillator adjacent part B is 1.5×10[/K] or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a radiation image detector capable of preventing cracks generated in a scintillator layer during substrate heating / cooling during vapor deposition of the scintillator layer and suppressing image quality deterioration due to the crack.

  In recent years, digital radiographic image detectors such as computed radiography (CR) and flat panel detectors (FPD) have been capable of directly obtaining digital radiographic images, and cathode tubes. Since it is possible to directly display an image on an image display device such as a liquid crystal panel, it is widely used for image diagnosis in hospitals and clinics. Recently, a flat panel using a scintillator layer containing cesium iodide (CsI) and combined with a thin film transistor (TFT) has attracted attention as a highly sensitive X-ray image visualization system.

  Such a scintillator layer is provided with an undercoat layer (for example, a metal reflective layer) that reflects the light converted by the phosphor in the scintillator layer to the sensor panel side, thereby reducing the loss of emitted light and emitting light. Attempts have been made to obtain scintillators with excellent brightness.

Such an undercoat layer is usually composed of an inorganic material.
For example, Patent Document 1 discloses that a flattening layer made of an organic resin containing ceramic particles made of titanium oxide having a high refractive index is provided on a fluorescent layer provided on a photoelectric conversion element to scatter emitted light. Has been. In Patent Document 2, a phosphor base layer made of an organic film is provided on a base material, a phosphor layer (scintillator layer) is formed on the base layer, and a metal reflective layer is provided on the surface of the phosphor. It is disclosed. Patent Document 2 discloses that an underlayer corresponds to an undercoat layer and an organic film (silicon oxide film) made of a methoxysilane polymer is provided. In these patent documents 1 and 2, since the phosphor layer (scintillator layer) is directly formed on the base material by vapor deposition, it is also called a direct vapor deposition type.

  Patent Document 3 discloses a scintillator panel in which a scintillator layer (phosphor layer) is provided on a support substrate provided with a light-reflective metal thin film and its protective layer. Furthermore, in Patent Document 4, in a scintillator panel including a phosphor layer and a base material for supporting the phosphor layer, the phosphor layer is disposed on a surface opposite to a radiation incident surface of the base material. A scintillator panel having a reflection function for emitting the light converted in step 1 to the outside is disclosed.

  When the scintillator layer is formed as in Patent Documents 3 and 4, the structure is the order of the support, the reflective layer, and the scintillator layer. With such a layer structure, a detachable type in which the scintillator panel can be freely attached to and detached from the planar light receiving element is obtained.

  The present applicant uses a dielectric material such as silicon oxide or titanium oxide as a reflection layer of such a scintillator panel, and uses a polymer material such as polyparaxylylene as an undercoat layer between the reflection layer and the scintillator layer. Suggests what to use. Patent Document 5 proposes to define the difference in thermal expansion coefficient between the intermediate layer and the support in order to eliminate problems such as adhesion between the support and the protective film and film peeling due to heat, impact, and the like. In addition, Patent Document 6 proposes to define the overall thermal expansion coefficient of the radiation image conversion panel and the difference in thermal expansion coefficient at the contact surface in order to reduce image defects and image unevenness due to temperature fluctuations. doing.

Further, in Patent Document 7, a metal reflection film and a dielectric mirror film of SiO ₂ film and TiO ₂ film are laminated on one surface of a substrate, and these are covered with a reflection film protection film, and a scintillator layer is formed on the surface of the reflection film protection film. Further, the whole is covered with a moisture-resistant protective film. It is disclosed that the reflective film protective film and the moisture-resistant protective film used in Patent Document 7 can be either an organic film or an inorganic film, and may be the same material or different materials.

  In Patent Document 7, although a combination of a reflective film protective film and a moisture-resistant protective film of a wide range of materials is possible, it is merely provided in terms of protection, not focusing on the viewpoint of thermal expansion, Some with a large coefficient of thermal expansion are included. Usually, since the scintillator receives heat at the time of vapor deposition in the manufacturing process, there is a problem that the scintillator itself is stressed due to a difference in thermal expansion between heating and cooling, causing cracks and lowering the image quality. Patent document 7 is not recognized at all about a subject.

JP 2015-001397 JP 2006-052978 A JP 2008-064763 A JP2003-075592 JP 2012-083186 JP JP 2010-281624 JP 2012-211925 A

  The present invention provides a radiation detector that is excellent in light emission luminance while maintaining the sharpness necessary for image quality without generating cracks during the manufacturing method received by the scintillator and heating-cooling received during use. With the goal.

  Under such circumstances, as a result of intensive studies, the present inventors focused on the difference in thermal expansion coefficient. And it discovered that the said subject could be solved by comprising especially the adjacent part adjacent to a scintillator from an inorganic substance, and defining the thermal expansion coefficient difference between the adjacent parts, and came to complete this invention. The configuration of the present invention is as follows.

[1] a photoelectric conversion element array;
A scintillator layer that converts radiation into visible light;
A reflective layer located on the opposite side of the photoelectric conversion element array with the scintillator layer interposed therebetween,
An undercoat layer present between the scintillator layer and the reflective layer and in contact with the scintillator layer in the image forming region;
A radiation detector including an intermediate layer composed of at least one layer, present between the photoelectric conversion element array and the scintillator layer,
A location within a distance of 50 μm from the tip of the scintillator layer toward the photoelectric conversion element array is a scintillator adjacent portion A,
When a location within a distance of 5 μm from the surface on which the scintillator layer is deposited toward the side opposite to the photoelectric conversion element array is defined as a scintillator adjacent portion B,
Each of the scintillator adjacent part A and the scintillator adjacent part B contains at least one kind of inorganic substance,
In addition, among the substances contained in the scintillator adjacent part A and the scintillator adjacent part B, the difference in thermal expansion coefficient between the substances having the smallest thermal expansion coefficient is 1.5 × 10 ⁻⁵ [/ K] or less. Radiation detector.
[2] In the radiation detector,
The radiation detector according to [1], wherein the layer included in the scintillator adjacent part A is only an intermediate layer.
[3] In the radiation detector,
The radiation detector according to [1] or [2], wherein a thickness of the intermediate layer in contact with the scintillator is 1 μm or less.
[4] The radiation detector according to [1] or [3], wherein the scintillator adjacent portion A is a layer in contact with the scintillator in the intermediate layer.
[5] The radiation detector according to any one of [1] to [4], wherein a main component of the undercoat layer is an inorganic substance.
[6] The radiation according to any one of [1] to [5], wherein in the radiation detector, the thermal expansion coefficient of the undercoat layer is 1.5 × 10 ⁻⁵ [/ K] or less. Detector.
[7] The radiation detector according to any one of [1] to [6], wherein the main component of at least one of the intermediate layers is an inorganic substance.
[8] In any one of [1] to [7], in the radiation detector, a thermal expansion coefficient of at least one of the intermediate layers is 1.5 × 10 ⁻⁵ [/ K] or less. The radiation detector according to 1.
[9] The radiation detector according to any one of [1] to [8], wherein the undercoat layer is composed of a single layer.
[10] The radiation detector according to any one of [1] to [9], wherein the main component of the undercoat layer and the main component of the intermediate layer are the same.
[11] The radiation detector according to any one of [1] to [10], wherein the intermediate layer is formed of a single layer.
[12] The radiation detector according to any one of [1] to [11], wherein the scintillator layer is made of an inorganic substance crystal.
[13] The radiation detector according to [12], wherein a main component of the scintillator layer is cesium iodide.

  According to the present invention, the adjacent portion adjacent to the scintillator is made of an inorganic material, and the difference in thermal expansion coefficient between the adjacent portions is adjusted to a predetermined range, so that expansion is performed during heating-cooling during vapor deposition. -Generation of cracks due to shrinkage is suppressed, and a radiation detector with excellent emission luminance can be obtained while maintaining the sharpness necessary for image quality.

It is a schematic cross section which shows the radiation detector which concerns on this invention.

  The radiation detector of the present invention exists between a scintillator layer and a reflection layer, a photoelectric conversion element array, a scintillator layer, a reflection layer located on the opposite side of the photoelectric conversion element array with the scintillator layer interposed therebetween, and an image An undercoat layer in contact with the scintillator layer in the formation region; and an intermediate layer composed of at least one layer existing between the photoelectric conversion element array and the scintillator layer.

A basic configuration of such a radiation detector according to the present invention is shown in FIG.
As shown in FIG. 1, a scintillator adjacent portion A is a portion within a distance of 50 μm from the tip of the scintillator layer (surface on the photoelectric conversion element array side) directly and vertically toward the photoelectric conversion element array,
A spot within a distance of 5 μm from the surface on which the scintillator layer is deposited (the surface opposite to the photoelectric conversion element array) to the opposite side to the photoelectric conversion element array is defined as a scintillator adjacent portion B. .

In the present invention, each of the scintillator adjacent part A and the scintillator adjacent part B includes at least one kind of inorganic substance,
And among the substances contained in the scintillator adjacent part A and the scintillator adjacent part B, the difference in thermal expansion coefficient between the substances having the smallest thermal expansion coefficients is 1.5 × 10 ⁻⁵ [/ K] or less.

In this way, by limiting the difference in thermal expansion coefficient between adjacent portions AB containing an inorganic substance, cracks are not generated between heating and cooling, and while maintaining sharpness necessary for image quality, light emission luminance It is possible to provide a radiation detector excellent in the above.
Hereinafter, each component will be described in order.

Support In the radiation detector according to the present invention, a support is not always necessary. The support is used as a base of the phosphor forming the scintillator layer and has a role of maintaining the structure of the scintillator layer. Examples of the material for the support include various glasses, polymer materials, metals, and the like. In the final radiation detector, the support may be detached.

Specifically, plate glass such as quartz, borosilicate glass, chemically tempered glass; ceramics such as sapphire, silicon nitride, silicon carbide; semiconductors such as silicon, germanium, gallium arsenide, gallium phosphorus, gallium nitrogen; cellulose acetate film, Polymer films (plastic film) such as polyester film, polyethylene terephthalate film, polyamide film, polyimide film, triacetate film, polycarbonate film, carbon fiber reinforced resin sheet;
A metal sheet such as an aluminum sheet, an iron sheet, or a copper sheet or a metal sheet having a coating layer of an oxide of these metals; a bionanofiber film or the like can be used. These may be used alone or in a stacked manner.

Among the materials for the support, a flexible polymer film is preferable.
Such polymer films include polyethylene terephthalate, polyethylene naphthalate, cellulose acetate, polyamide, polyimide, polyetherimide, epoxy, polyamideimide, bismaleimide, fluororesin, acrylic, polyurethane, aramid, nylon, polycarbonate, polyphenylene sulfide. And a film made of polyethersulfone, polysulfone, polyetheretherketone, liquid crystal polymer, bionanofiber and the like.

  When vapor-depositing the phosphor on the resin film, a resin film containing polyimide is preferable from the viewpoint of heat resistance. As a commercially available product, for example, UPILEX-125S (manufactured by Ube Industries) may be used.

  The thickness of the polymer film is preferably 20 to 1000 μm, more preferably 50 to 750 μm. By making the thickness of the support 50 μm or more, the handling property after forming the scintillator layer is improved. Moreover, by making the thickness of the support 750 μm or less, functional layers such as an adhesion layer, a conductive layer, and an easy-adhesion layer can be easily processed by roll-to-roll, and productivity is improved. From the viewpoint of improvement, it is very useful.

The scintillator layer The scintillator layer has a role of converting X-ray energy, which is radiation incident from the outside, into visible light.
In the present invention, the term “phosphor” refers to a phosphor that emits light when atoms are excited when it is irradiated with ionizing radiation such as α-rays, γ-rays, and X-rays. That is, it refers to a phosphor that converts radiation into ultraviolet / visible light and emits it. The phosphor is not particularly limited as long as it is a material that can efficiently convert radiation energy such as X-rays incident from the outside into light. Further, the conversion of radiation into light is not necessarily performed instantaneously, and a method of temporarily storing a latent image in the scintillator layer and reading it out later may be used.

  As the scintillator according to the present invention, a substance capable of converting radiation such as X-rays into different wavelengths such as visible light can be appropriately used. Specifically, scintillators and phosphors described on pages 284 to 299 of “Phosphor Handbook” (Edited by Fluorescent Materials Association, Ohmsha, 1987), and the website of Lawrence Berkeley National Laboratory, USA Although the substances described in “Scintillation Properties (http://scintillator.lbl.gov/)” can be considered, even if the substance is not pointed out here, “radiation such as X-rays is converted into different wavelengths such as visible light” Any substance that can be used can be used as a scintillator.

  In the present invention, the scintillator layer is preferably made of an inorganic substance crystal. When a scintillator layer made of an inorganic substance crystal is employed, the crack suppression effect due to the difference in thermal expansion coefficient between adjacent portions A and B sandwiching the layer is enhanced.

Specific examples of the scintillator composition include the following examples. First,
Basic composition formula (I): M _I X · aM _II X ′ ₂ · bM _III X ″ ₃ : zA
And metal halide phosphors represented by the formula:

In the basic composition formula (I), M _I is an element that can be a monovalent cation, that is, lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), thallium. It represents at least one selected from the group consisting of (Tl) and silver (Ag).

M _II is an element that can be a divalent cation, that is, beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), nickel (Ni), copper (Cu), It represents at least one selected from the group consisting of zinc (Zn) and cadmium (Cd).

M _III represents at least one selected from the group consisting of scandium (Sc), yttrium (Y), aluminum (Al), gallium (Ga), indium (In), and elements belonging to lanthanoids.

X, X ′, and X ″ each represent a halogen element, but each may be a different element or the same element.
A is composed of Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg, Cu, Ag (silver), Tl and Bi (bismuth). Represents at least one element selected from the group;
a, b and z each independently represent a numerical value within the range of 0 ≦ a <0.5, 0 ≦ b <0.5, and 0 <z <1.0.

Also,
Also included are rare earth activated metal fluorohalide phosphors represented by the basic composition formula (II): M _II FX: zLn.

In the basic composition formula (II), M _II represents at least one alkaline earth metal element, Ln represents at least one element belonging to the lanthanoid, and X represents at least one halogen element. Z is 0 <z ≦ 0.2.

Also,
Basic composition formula (III): Ln ₂ O ₂ S: zA
And rare earth oxysulfide phosphors.

  In the basic composition formula (III), Ln is at least one element belonging to the lanthanoid, A is Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, At least one element selected from the group consisting of Lu, Na, Mg, Cu, Ag (silver), Tl and Bi (bismuth) is represented. Z is 0 <z <1.

In particular, Gd ₂ O ₂ S using gadolinium (Gd) as Ln emits high light in a wavelength region where the sensor panel is most likely to receive light by using terbium (Tb), dysprosium (Dy), etc. as the element species of A. This is preferred because it is known to exhibit properties.

Also,
Basic formula _{(IV): M II S:} zA
The metal sulfide type fluorescent substance represented by these is also mentioned.

In the basic composition formula (IV), M _II is selected from the group consisting of elements that can be divalent cations, ie, alkaline earth metals, Zn (zinc), Sr (strontium), Ga (gallium), and the like. At least one element, A is Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg, Cu, Ag (silver), Tl And at least one element selected from the group consisting of Bi (bismuth). Z is 0 <z <1.

Also,
Basic composition formula (V): M _IIa (AG) _b : zA
And metal oxoacid salt phosphors represented by the formula:

In the basic composition formula (V), _MII is a metal element that can be a cation, and (AG) is a group consisting of phosphate, borate, silicate, sulfate, tungstate, and aluminate. At least one oxo acid group selected from the group consisting of A, Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg, Cu, Each represents at least one element selected from the group consisting of Ag (silver), Tl, and Bi (bismuth).

A and b represent all possible values depending on the valence of the metal and oxo acid group. z is 0 <z <1.
Also,
Basic composition formula (VI): M _a O _b : zA
The metal oxide fluorescent substance represented by these is mentioned.

In the basic composition formula (VI), M represents at least one element selected from metal elements that can be cations.
A is composed of Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg, Cu, Ag (silver), Tl and Bi (bismuth). Each represents at least one element selected from the group.

A and b represent all possible values depending on the valence of the metal and oxo acid group. z is 0 <z <1.
In addition,
Basic composition formula (VII): LnOX: zA
And metal acid halide phosphors represented by the formula:

  In the basic composition formula (VII), Ln represents at least one element belonging to the lanthanoid, X represents at least one halogen element, A represents Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb. , Dy, Ho, Er, Tm, Yb, Lu, Na, Mg, Cu, Ag (silver), Tl, and Bi (bismuth), each represents at least one element. Z is 0 <z <1.

  The material constituting the scintillator is not particularly limited as long as it can efficiently convert X-ray energy incident from the outside into light. Therefore, as long as the above conditions are satisfied, various conventionally known phosphors can be used as the scintillator. Among them, cesium iodide (CsI), gadolinium sulfate (GOS), cadmium tungstate (CWO), gadolinium silicate, and the like. (GSO), bismuth germanate (BGO), lutetium silicate (LGO), lead tungstate (PWO) and the like can be suitably used. Note that the scintillator used in the present invention is not limited to an instantaneous light emitting phosphor such as CsI, and may be a stimulable phosphor such as cesium bromide (CsBr) depending on applications.

  In the present invention, among these materials, CsI has a relatively high efficiency in converting the energy of radiation such as X-rays into visible light, and the light reflection at a specific wavelength as described above by combination with an activator. It is preferable because a scintillator with a small decrease in rate can be configured.

In the present invention, it is preferable that CsI is used as a phosphor base material and an activator is included together with this. The concentration of the activator is shown in mol%.
As the activator, those containing thallium (Tl), europium (Eu), indium (In), lithium (Li), potassium (K), rubidium (Rb), sodium (Na) and the like are preferable. These activators are present in the scintillator in the elemental state. As the activator, for example, thallium iodide (TlI), thallium bromide (TlBr), thallium chloride (TlCl), thallium fluoride (TlF, TlF ₃ ) or the like is used.

  The activator contained in the scintillator preferably contains at least thallium. When thallium is included, the wavelength of fluorescence when irradiated with X-rays is not shifted, the accuracy of fluorescence detection by the photoelectric conversion element is high, and the decrease in light reflectance after radiation irradiation at 520 nm is reduced. Therefore, it is possible to obtain a scintillator that satisfies the predetermined light reflectance defined in the present invention.

  In the present invention, the scintillator layer may be composed of one layer or may be composed of two or more layers. The scintillator layer may be composed of only a base layer or a scintillator layer, and the base layer and the scintillator layer are laminated in this order on the support. Also good. When the scintillator layer includes two layers of an underlayer and a scintillator layer, these layers may be made of the same material or different materials as long as the phosphor base material compound is the same. There may be. That is, the scintillator layer may be a single layer consisting entirely of the phosphor base material, or may be a single layer containing the phosphor base material compound and the activator, and only the phosphor base compound. And a scintillator layer containing a phosphor base material compound and an activator, a base layer containing a phosphor base material compound and a first activator, and a phosphor base It may consist of a scintillator layer containing a material compound and a second activator.

  In the scintillator layer according to the present invention, it is desirable that the relative content of the activator is an optimal amount depending on the target performance and the like, but 0.001 mol% to 50 mol% with respect to the scintillator content, It is preferable that it is 0.1-10.0 mol%. When the concentration of the activator is 0.001 mol% or more with respect to the scintillator, the emission luminance is improved more than when the scintillator is used alone, and this is preferable in terms of obtaining the target emission luminance. Moreover, it is preferable that it is 50 mol% or less because scintillator properties and functions can be maintained.

  The relative content of the activator in the underlayer is preferably from 0.01 to 1 mol%, more preferably from 0.1 to 0.7 mol%. In particular, the relative content of the activator in the underlayer is preferably 0.01 mol% or more from the viewpoint of improving the light emission luminance and storage stability of the scintillator panel 10. Further, it is very preferable that the relative content of the activator in the underlayer is lower than the relative content in the scintillator layer, and the molar ratio of the relative content of the activator in the underlayer to the relative content of the activator in the scintillator layer ( (Relative content of activator in underlayer) / (relative content in scintillator layer)) is preferably 0.1 to 0.7.

  As a method of forming the scintillator layer, a method of forming a coating film by applying a liquid formed by mixing scintillator powder with an organic resin, or a regular arrangement structure by processing the liquid or the coating film. It is possible to use a method for forming a film having a crystal film, a method for forming a crystal film using a vapor deposition method, or the like. In particular, the phosphor can be easily formed into a columnar crystal structure, the scattering of the emitted light within the crystal can be suppressed by the light guide effect, and the scintillator layer can be thickened. It is preferable to use a method of forming a crystal film by a layer deposition method. As the vapor deposition method, a heat vapor deposition method, a sputtering method, a CVD method, an ion plating method, or the like can be used, and the heat vapor deposition method is particularly desirable.

  When the scintillator layer is formed by using the above vapor deposition method, various substances can be used as the scintillator material. In particular, cesium iodide having a characteristic that the rate of change from X-rays to visible light is relatively high. It is particularly preferable to use (CsI). When cesium iodide is used for the scintillator, thallium is more preferably used as the activator because it has a wide emission wavelength from 400 nm to 750 nm and can detect light emission with high sensitivity for a photodetector member such as a TFT. . That is, it is more preferable to use thallium activated cesium iodide (CsI: Tl).

  In addition, it is preferable that the thickness of a scintillator 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. The layer thickness of the underlayer is preferably 0.1 μm to 50 μm, more preferably 5 μm to 40 μm from the viewpoint of maintaining high brightness and sharpness.

The intermediate layer includes at least one layer existing between the photoelectric conversion element array and the scintillator layer. Therefore, the intermediate layer may be a single layer or a plurality of laminates of two or more layers. Furthermore, the intermediate layer may be a plurality of layers having different functions as long as it exists between the photoelectric conversion element array and the scintillator layer. For example, the following protective layers and optical coupling layers can be mentioned. The order of these layers is not particularly limited.

-Protective layer A protective layer protects the whole scintillator layer and has a role which suppresses deterioration of fluorescent substance. The protective layer is made of an organic material, may be any of inorganic materials, may be a combination of both, and may be composed of a laminate of two or more layers. In addition, the moisture-proof protective layer which has a role which suppresses degradation of a scintillator layer is also contained in a protective layer.

  For example, the moisture-resistant protective layer is made of polyparaxylylene, but polymonochloroparaxylylene, polydichloroparaxylylene, polytetrachloroparaxylylene, polyfluoroparaxylylene, polydimethylparaxylylene, polydiethylparaxylylene. It may be made of a xylylene-based material such as len. Further, it may be a protective layer made of polyethylene terephthalate (PET), polymethacrylate, nitrocellulose, cellulose acetate, polypropylene, polyethylene naphthalate, polyurea, polyimide or the like.

The protective layer is made of graphite, iron, copper, aluminum, magnesium, beryllium, titanium, silicon, a composite material of aluminum and carbon, a metal or carbon-based inorganic material such as a composite material of copper and carbon, LiF, MgF ₂ , SiO _2. A protective layer containing a non-metallic inorganic material such as Al ₂ O ₃ , TiO ₂ , MgO, ITO, glass (sodium silicate), or SiN may be used. In the case of a protective layer containing an inorganic material, the protective layer may be composed of an inorganic material alone or a protective layer containing an inorganic material and an organic material. As the protective layer, non-metallic inorganic materials and xylylene polymers such as polyparaxylylene are preferable.

The thickness of the protective layer needs to be thin so as not to diffuse the light converted by the scintillator layer, and is preferably 50 μm or less, but is not limited thereto.
The protective layer can be produced by attaching a film containing the above organic material or inorganic material or applying a paint. When a moisture-resistant film such as polyparaxylylene is formed, the support on which the scintillator layer is formed is formed. It is possible to obtain a radiation detector in which the entire surface of the scintillator layer and the support is coated with a polyparaxylylene film by placing it in a vapor deposition chamber of a CVD apparatus and exposing it in vapor sublimated with polyparaxylylene. it can.

Optical coupling layer The optical coupling layer has a function of closely bonding the scintillator layer and the photoelectric conversion element.

  The optical coupling layer is transparent so that visible light, etc. emitted by being converted by the scintillator layer by irradiation of radiation reaches the photoelectric conversion element via the optical coupling layer or the outermost layer of the photoelectric conversion element panel, It is preferable that the light transmittance is a high transmittance of 90% or more.

  Further, the thickness of the optical coupling layer needs to be thin so as not to diffuse the light emitted from the scintillator layer, and is preferably 50 μm or less, more preferably 30 μm or less.

The component constituting the optical coupling layer is not particularly limited as long as the object of the present invention is not impaired, but a thermosetting resin, a hot melt sheet, and a pressure-sensitive adhesive sheet are preferable.
As a thermosetting resin, resin which has acrylic type, an epoxy type, a silicone type etc. as a main component is mentioned, for example. Of these, resins mainly composed of acrylic and silicon are preferred from the viewpoint of low-temperature thermosetting. Examples of commercially available products include methyl silicone-based JCR6122 manufactured by Toray Dow Corning Co., Ltd.

  The optical coupling layer may be a hot melt sheet. The hot melt sheet in the present invention is a sheet formed of an adhesive resin (hereinafter referred to as hot melt resin) made of a non-volatile thermoplastic material that does not contain water or a solvent and is solid at room temperature. Inserting a hot melt sheet between the adherends, melting the hot melt sheet at a temperature equal to or higher than the melting point, and then solidifying the melt at a temperature equal to or lower than the melting point allows the adherends to be joined together via the hot melt sheet. I can do it. Since hot-melt resin does not contain polar solvent, solvent, and water, it does not deliquesce even when it comes into contact with phosphors having deliquescence (for example, phosphors having a columnar crystal structure made of an alkali halide). Suitable for joining of photoelectric conversion element and scintillator layer. Further, since the hot melt sheet does not contain residual volatiles, shrinkage due to drying is small, and the gap filling property and dimensional stability are also excellent.

  Specific examples of the hot melt sheet include those based on resins such as polyolefin, polyamide, polyester, polyurethane, acrylic, EVA, etc., depending on the main component. Of these, those based on polyolefin, EVA, and acrylic resins are preferred from the viewpoints of light transmittance and adhesiveness.

  The optical coupling layer may be a pressure sensitive adhesive sheet. Specific examples of the pressure-sensitive adhesive sheet include those based on acrylic, urethane, rubber, and silicon. Among these, from the viewpoint of light transmittance and adhesiveness, those mainly composed of acrylic or silicon are preferred.

In the case of a thermosetting resin, the optical coupling layer is applied on the scintillator layer or the photoelectric conversion element by a technique such as spin coating, screen printing, and dispenser.
In the case of a hot melt sheet, the optical coupling layer is formed by inserting the hot melt sheet between the scintillator layer and the photoelectric conversion element and heating under reduced pressure. The pressure-sensitive adhesive sheet is bonded with a lamination device or the like.

It is possible to use an inorganic substance for the optical coupling layer, and as described above, an inorganic substance having transparency such as MgF ₂ , SiO ₂ , Al ₂ O ₃ , glass (sodium silicate) may be used. . Such an optical coupling layer made of an inorganic substance and an optical coupling layer made of an organic substance may be laminated.

When both the protective layer and the optical coupling layer are formed, the stacking order is not particularly limited as long as the adjacent layer A containing an inorganic material can be formed.
The scintillator adjacent portion A is a portion within a distance of 50 μm from the tip of the scintillator layer (surface on the photoelectric conversion element array side) directly and vertically toward the photoelectric conversion element array. Therefore, the adjacent portion A usually includes an intermediate layer, but may also include a part of a photoelectric conversion element array described later.

  In the present invention, the scintillator adjacent part A contains at least one kind of inorganic substance. For this reason, it is a preferable aspect that the protective layer containing the above-described inorganic material is formed in the adjacent portion A.

  Therefore, the layer included in the scintillator adjacent portion A is preferably only the intermediate layer, and the photoelectric conversion element is not included in the adjacent portion A. When the adjacent portion A is configured only from the intermediate layer, it is easy to adjust the thermal expansion coefficient to a predetermined configuration.

The intermediate layer may be a single layer or may be composed of a laminate of two or more layers.
It is also a preferred aspect that the thickness of the intermediate layer directly contacting the scintillator is 1 μm or less. If the intermediate layer having this thickness is provided directly on the scintillator layer, the influence of expansion and contraction in heating / cooling is small regardless of the thermal expansion coefficient, so that the occurrence of cracks in the scintillator layer can be suppressed.

  Moreover, when an intermediate | middle layer is comprised from multiple layers, it is also a preferable aspect that the adjacent part A is a layer which is in contact with the scintillator. That is, when the intermediate layer is composed of a plurality of layers, the configuration of the intermediate layer other than the adjacent portion A is not particularly limited as long as the adjacent portion A contains an inorganic material and satisfies a predetermined thermal expansion coefficient.

  It is one of the preferred embodiments of the present invention that the main component of at least one of the intermediate layers is an inorganic substance. The main component may be constituted by itself or may contain other components of less than 50% by mass. If the adjacent portion A contains an inorganic substance, the intermediate layer other than the adjacent portion A may not contain an inorganic substance as a main component, and more preferably, the intermediate layer directly in contact with the adjacent portion A The main component of is an inorganic substance.

It is also a preferred embodiment that the thermal expansion coefficient of at least one of the intermediate layers is 1.5 × 10 ⁻⁵ [/ K] or less. Table 1 shows the thermal expansion coefficient of each material. Any organic material, inorganic material, metallic or non-metallic material may be used as long as it satisfies such a thermal expansion coefficient, but preferably silicon oxide (SiO ₂ ), glass (sodium silicate), aluminum oxide (Al ₂ O _3), titanium oxide (TiO _2: rutile, anatase) composed of an inorganic material, such as.

  It is also a preferred embodiment that the intermediate layer is formed from a single layer. Further, the intermediate layer may be provided with an adhesive layer and a moisture-resistant protective layer in addition to the protective layer and the optical coupling layer.

Reflective layer In the present invention, the reflective layer is not necessarily required, and the reflective layer may also serve as the undercoat layer. By providing the reflective layer, the light converted in the direction opposite to that of the sensor is reflected, whereby the light converted by the scintillator layer is efficiently guided to the sensor and the sensitivity is improved.

  The reflective layer is preferably made of a material having a high light reflectivity, and is usually composed of a metal reflective layer. Specific examples of metal materials that can form such a metal reflective layer include metal materials such as aluminum, silver, platinum, palladium, gold, copper, iron, nickel, chromium, cobalt, magnesium, titanium, rhodium, and stainless steel. It is preferable. Among these, silver or aluminum is particularly preferable from the viewpoint of reflectivity. Here, the metal material which comprises a metal reflective layer has the form of the metal single-piece | unit or its alloy in the typical aspect of this invention.

However, as long as the light scattering does not increase, it is not necessarily limited to those having a single metal form or an alloy thereof, and may be a corresponding metal oxide form. In this case, a so-called dielectric multilayer film that has a reflection function by stacking a plurality of thin films of metal oxides can be assumed. As a suitable example of the metal oxide used for such a dielectric multilayer film, aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), niobium oxide (Nb ₂ O ₅ ) And tantalum oxide (Ta ₂ O ₅ ).

  An organic material can also be used as the dielectric layer. The organic material layer preferably contains a polymer binder (binder), a dispersant and the like. The refractive index of the organic material layer is approximately in the range of 1.4 to 1.6 depending on the type of material. The thickness of the organic material layer is preferably 0.5 to 4 μm. When the thickness is 4 μm or less, light scattering in the organic material layer is reduced and sharpness is improved. Moreover, the effect as a reflection layer becomes large because the thickness of an organic material layer shall be 0.5 micrometer or more. Specific examples of the polymer binder used in the organic material layer include 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.

  As a method of providing the metal reflection layer on the support surface, a method using a known process such as vapor deposition or sputtering, or a metal such as aluminum can be formed into a thin film and pasted later. In addition, the metal foil can be pressure-bonded via an adhesive, but if the adhesive is present, light absorption may occur and the amount of light may be reduced. From such a viewpoint, sputtering is preferable. In addition, when taking the form in which the photodetector is present on the support side, it is also possible to provide a metal reflection layer on the opposite side of the support with the scintillator layer interposed therebetween, in which case a thin metal is affixed This is particularly preferable because it is not necessary for the film to be easily cracked by following the unevenness of the scintillator layer, such as a film formed by vapor deposition or sputtering. The organic material layer is preferably formed by applying and drying a polymer binder (hereinafter also referred to as “binder”) dissolved or dispersed in a solvent.

  Further, the reflective layer may be a reflective layer composed of a binder resin and at least one of light scattering particles or voids. As one aspect thereof, a coating-type reflective layer can be mentioned.

  The binder resin may be an easily adhesive polymer such as polyurethane, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, 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, silicone Examples thereof include resins, acrylic resins, urea formamide resins, and the like.

Among them, it is preferable to use polyurethane, polyester, silicone resin, acrylic resin or polyvinyl butyral. Moreover, these binders can also be used in mixture of 2 or more types.
As the light scattering particles, those made of a white pigment are preferable from the viewpoint of light refraction.

Examples of the white pigment include TiO ₂ (anatase type, rutile type), MgO, PbCO ₃ · Pb (OH) ₂ , BaSO ₄ , Al ₂ O ₃ , M (II) FX (where M (II) is Ba). , Sr and Ca, and X is a Cl atom or a Br atom.), CaCO ₃ , ZnO, Sb ₂ O ₃ , SiO ₂ , ZrO ₂ , lithopone (BaSO _4. ZnS), magnesium silicate, basic silicic acid sulfate, basic lead phosphate, aluminum silicate and the like can be used. These white pigments may be used alone or in combination.

Of these white pigments, TiO ₂ , Al ₂ O _{3 and the} like have a strong hiding power and a high refractive index. For this reason, by reflecting and refracting the diffused light, the scattered light can be returned to the scintillator layer before propagating in the lateral direction. As a result, it is possible not only to increase the obtained luminance but also to effectively return the diffused light, which was the cause of image blurring, to the scintillator layer, and to significantly improve the image quality.

As the crystal structure of titanium oxide, either a rutile type or an anatase type can be used, but a rutile type is preferable from the viewpoint that a difference in refractive index from the resin is large and high luminance can be achieved.
Specific examples of titanium oxide include CR-50, CR-50-2, CR-57, CR-80, CR-90, CR-93, CR-95, and CR-97 manufactured by the hydrochloric acid method. , CR-60-2, CR-63, CR-67, CR-58, CR-58-2, CR-85, R-820, R-830, R-930, R-550 manufactured by the sulfuric acid method , R-630, R-680, R-670, R-580, R-780, R-780-2, R-850, R-855, A-100, A-220, W-10 : Ishihara Sangyo Co., Ltd.).

  The primary particle size of the light scattering particles is preferably in the range of 0.1 to 0.5 μm, more preferably in the range of 0.2 to 0.3 μm. Further, the light scattering particles are particularly preferably those that have been surface-treated with an oxide such as Al, Si, Zr, and Zn in order to improve the affinity and dispersibility with the polymer and to suppress the deterioration of the polymer.

  Further, instead of the light scattering particles, the reflective layer may include voids. Since the light is similarly refracted even in the gap, the return of the diffuse reflected light to the scintillator layer can be increased in the same manner as the light scattering particles.

  As a means for forming a void in the interior, there are various methods such as a method using a foaming agent, a method of lowering pressure by injecting a gas, and a method using stretching. Since the voids are spherical or elliptical, and a large number of fine voids can be formed uniformly, a method of forming voids with a foaming agent is more desirable.

Undercoat layer In the present invention, the undercoat layer is formed between the support and the scintillator layer (when no reflective layer is provided) or between the reflective layer and the scintillator layer (when the reflective layer is provided on the scintillator side of the support). Is provided.

As long as the undercoat layer protects the reflective layer and has adhesion to the scintillator layer, any organic material or inorganic material can be used without limitation.
For example, metal materials such as aluminum, silver, platinum, palladium, gold, copper, iron, nickel, chromium, cobalt, rhodium, magnesium, titanium, stainless steel,
Aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), magnesium oxide (MgO), silicon oxide (SiO ₂ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), zinc oxide ( ZnO), antimony trioxide (Sb ₂ O ₃ ), zirconium oxide (ZrO ₂ ), metal oxides of elements such as silver, copper, chromium, cobalt, rhodium and stainless steel used in the above metal materials, lithium fluoride ( In addition to metal fluorides such as LiF) and magnesium fluoride (MgF ₂ ), PbCO ₃ · Pb (OH) ₂ , BaSO ₄ , Al ₂ O ₃ , M (II) FX (where M (II) is Ba , Sr and Ca, and X is a Cl atom or a Br atom.), CaCO ₃ , lithopone (BaSO ₄ .ZnS), magnesium silicate, basic silicic acid salt, base sex Lead, aluminum silicate, aluminum nitride, silicon nitride, silicon oxynitride, mica, inorganic materials such as talc,
In addition to polyparaxylylene, polyurethane, vinyl chloride copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride exemplified as the polymer binder (binder) in the reflective layer. -Acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, polyester, cellulose derivative (nitrocellulose, etc.), styrene-butadiene copolymer, various synthetic rubber resins, phenol resin, epoxy resin, urea Examples thereof include organic materials such as resin, melamine resin, phenoxy resin, silicon resin, acrylic resin, and urea formamide resin.

  The undercoat layer includes a method of forming a polyparaxylylene film by a CVD method (vapor phase chemical growth method) and a formation method using a polymer binder (binder). Can be adopted.

  Further, the thickness of the undercoat layer is preferably 20 to 400 nm. When the thickness is 400 nm or less, light scattering in the undercoat layer is reduced and sharpness is improved. In addition, by setting the thickness of the undercoat layer within a predetermined range, it is possible to prevent disturbance in the crystal growth of the phosphor.

  The scintillator adjacent portion B usually corresponds to an undercoat layer, but may also include a part of the reflective layer. Further, the undercoat layer may be a laminate of a plurality of layers, but the portion where the thickness of the laminate is within 5 μm is the adjacent portion B.

  In a preferred embodiment of the present invention, the main component of such an undercoat layer is an inorganic substance. The main component may be composed of a single component as described in the intermediate layer or may contain any other component in an amount of, for example, less than 50% by mass.

In the present invention, the thermal expansion coefficient of the undercoat layer is preferably 1.5 × 10 ⁻⁵ [/ K] or less. Having such a thermal expansion coefficient makes it easy to adjust the difference in thermal expansion coefficient with the adjacent layer A, and it is possible to suppress the occurrence of cracks.

The thermal expansion coefficient of each material is shown in Table 1 above, and the materials of the intermediate layer and the undercoat layer are appropriately selected so as to have a predetermined thermal expansion coefficient.
In the radiation detector according to the present invention, it is preferable that the undercoat layer is formed of a single layer. That is, if the undercoat layer has a two-layer structure, the object of the present invention may not be achieved because of the difference in thermal expansion coefficient between the layers.

  In the present invention, the main component of the undercoat layer and the main component of the intermediate layer may be the same or different. If the main components are the same, there will be no difference in thermal expansion coefficient between adjacent portions A and B, and the crack suppression effect will be higher. Even if they are different, the same effect can be obtained if they are configured so that the difference in thermal expansion coefficient is small.

In the present invention, the combination of the adjacent portions B and A is a combination of an undercoat layer and an intermediate layer, SiO ₂ —SiO ₂ , Al ₂ O ₃ —SiO ₂ , TiO ₂ —SiO ₂ , MgF ₂ —SiO ₂ , Examples include polyester-polyparaxylylene, acrylic (PMMA, etc.)-Polyparaxylylene, and the like.

Photoelectric conversion element array The photoelectric conversion element array absorbs visible light converted by the scintillator layer, converts it into a charge form, converts it into an electrical signal, and outputs it to the outside of the radiation image detector It can have a conventionally well-known thing.

Here, although the configuration of the photoelectric conversion element array used in the present invention is not particularly limited, it usually has a form in which a substrate, an image signal output layer, and a photoelectric conversion element are stacked in this order.
Among these, the photoelectric conversion element has a function of absorbing the generated visible light converted by the scintillator layer and converting it into a charge form. Here, the photoelectric conversion element may have any specific structure as long as it has such a function. For example, the photoelectric conversion element used in the present invention can be composed of a transparent electrode, a charge generation layer that is excited by incident light to generate charges, and a counter electrode. Any of these transparent electrodes, charge generation layers, and counter electrodes may be conventionally known ones. The photoelectric conversion element used in the present invention may be composed of an appropriate photosensor. For example, the photoelectric conversion element may be a two-dimensional arrangement of a plurality of photodiodes, or a CCD ( A two-dimensional photosensor such as a charge coupled device (CMOS) or a complementary metal-oxide-semiconductor (CMOS) sensor may be used.

  The image signal output layer has a function of accumulating the charge obtained by the photoelectric conversion element and outputting a signal based on the accumulated charge. Here, the image signal output layer may have any specific structure. For example, the image signal output layer is stored with a capacitor that is a charge storage element that stores the charge generated by the photoelectric conversion element for each pixel. And a transistor that is an image signal output element that outputs the charges as a signal. Here, a TFT (thin film transistor) is given as an example of a preferable transistor.

The substrate functions as a support for the radiation detector and can be the same as the support used in the radiation detector of the present invention described above.
In this manner, various photoelectric conversion elements that can be used in the present invention can be used. For example, a photoelectric conversion element formed by forming a plurality of photodiodes and a plurality of TFT elements on a glass substrate can be used as the photoelectric conversion element, as used in Examples of the present application described later.

  Further, the photoelectric conversion element is a memory unit for storing an image signal based on the intensity information and position information of the X-rays converted into an electric signal, and a power supply unit that supplies electric power necessary for driving the photoelectric conversion element panel Various components that can be included in a photoelectric conversion element panel constituting a known radiation detector, such as a communication output unit for extracting image information to the outside, can be further provided.

Manufacturing method of radiation detector The radiation detector according to the present invention, for example, if necessary, forms a reflective layer on a support according to a conventionally known method, and then forms an undercoat layer and a scintillator layer. And by stacking with a photoelectric conversion element with an intermediate layer interposed.

The scintillator layer is preferably formed by a vapor phase method, and specifically by a vapor deposition method.
The scintillator layer includes a step of depositing a phosphor material while rotating the support by setting the support on the support rotation mechanism using a vapor deposition apparatus having an evaporation source and a substrate rotation mechanism in a vacuum vessel. The manufacturing method of the aspect which forms a scintillator layer by the vapor phase deposition method containing is preferable.

  A scintillator layer and a photoelectric conversion element are stacked via an intermediate layer. For example, a radiation detector composed of predetermined adjacent portions A and B can be formed by sandwiching an intermediate layer forming sheet between a scintillator layer and a photoelectric conversion element and heating in a pressurized state.

Further, an adhesive layer may be provided as necessary. Examples of the material constituting the adhesive layer include the hot melt resins described above.
The support may be detached or left as it is. When it is used as it is, it is desirable that it is made of a transparent material.
The radiographic image detector of the present invention can be applied to various types of X-ray imaging systems.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this.
[Production example]
As a support, a polyimide film having a thickness of 125 μm (UPILEX-125S manufactured by Ube Industries, Ltd.) was used.

(Production of reflective layer)
The resin reflective layers of Examples 1 to 6 and Comparative Examples 1 to 5 were prepared by coating titanium oxide in polyertel resin to a thickness of 50 μm.
In Example 7, silver was used, and in Example 8, aluminum was sputtered to form a reflective layer (100 nm).
The reflective layers of Examples 9 and 10 were not formed.

(Preparation of undercoat layer)
The SiO ₂ undercoat layers of Examples 1, 9, and 10 and Comparative Examples 2 and 3 were formed by sputtering of silica. The thickness is 100 nm.
The subbing layer made of Al ₂ O ₃ of Example ₂ , TiO _{2 of} Examples 3 and 5 and MgF _{2 of} Examples 4 and 4 has a dispersion of 50 μm in which these particles are dispersed in a solvent. It was applied and dried so as to have a thickness. As the binder, a polyester resin containing 30% by mass with respect to the particles was used.

The polyester undercoat layers of Examples 5, 7 and 8 and Comparative Example 1 were prepared by dissolving Byron (registered trademark) “200 (brand)” (manufactured by Toyobo Co., Ltd .: high molecular polyester resin) in methyl ethyl ketone [MEK]. The undercoat layer was formed by coating so that the dry film thickness was 3 μm.
The polymethylmethacrylate (PMMA) undercoat layer of Example 6 was prepared by dissolving in methyl ethyl ketone [MEK] and applying the dry film thickness to 3 μm.

(Preparation of scintillator layer)
A phosphor material (CsI (Tl) (0.3 mol%)) was vapor-deposited on the surface of the support on which the undercoat layer was formed to form a scintillator layer having a thickness of 500 μm.

(Preparation of intermediate layer)
The SiO ₂ protective layers of Examples 1 to 4 and Comparative Example 1 were prepared to have a thickness of 100 nm by sputtering of silica.

The protective layers of Examples 5 to 8 and Comparative Examples 2, 4, and 5 were formed by vapor-depositing Parylene C (manufactured by Japan Parylene Godo Kaisha) having a melting point of 290 ° C. so as to be 10 μm. Parylene C has a basic structure in which a benzene ring is polymerized through —CH ₂ —, and one hydrogen of the benzene ring is substituted with chlorine.

The polymethyl methacrylate (PMMA) protective layers of Examples 9 and 10 and Comparative Example 3 were prepared by dissolving in methyl ethyl ketone [MEK] and applying a dry film thickness of 3 μm. In Examples 9 and 10, as the optical coupling layer adjacent to the scintillator, SiO ₂ and MgF ₂ were each formed to be 50 nm by sputtering, and then optically coupled to the sensor by OCA (3M).

[Examples 1 to 10 and Comparative Examples 1 to 5]
The layer configuration was laminated as shown in Table 2 and bonded to a photoelectric conversion element on the surface of PaxScan (Varian's flat panel display FPD: 2520).

  For the radiation detectors produced in each of the examples and comparative examples, the panel before being adhered or bonded to the photoelectric conversion element is cut, an arbitrary surface perpendicular to the incident / exiting surface of the X-ray is exposed, and the cross section is scanned. Observation with a scanning electron micrograph was performed to evaluate the presence or absence of cracks.

Moreover, the X-ray was irradiated to the radiation detector which equipped the scintillator panel using the X-ray irradiation apparatus which set the tube voltage to 80 Kvp, the obtained solid image was analyzed, and the following references | standards evaluated.
○: No image loss △: Slight streak or unevenness is generated ×: Large streaks are visible at a level that is visible, or there is a uniform black or white part in the field of view. .

Claims (13)

A photoelectric conversion element array;
A scintillator layer that converts radiation into visible light;
A reflective layer located on the opposite side of the photoelectric conversion element array with the scintillator layer interposed therebetween,
An undercoat layer present between the scintillator layer and the reflective layer and in contact with the scintillator layer in the image forming region;
A radiation detector including an intermediate layer composed of at least one layer, present between the photoelectric conversion element array and the scintillator layer,
A location within a distance of 50 μm from the tip of the scintillator layer toward the photoelectric conversion element array is a scintillator adjacent portion A,
When a spot within a distance of 5 μm from the surface where the scintillator layer is deposited toward the opposite side of the photoelectric conversion element array is defined as a scintillator adjacent part B,
Each of the scintillator adjacent part A and the scintillator adjacent part B contains at least one kind of inorganic substance,
In addition, among the substances contained in the scintillator adjacent part A and the scintillator adjacent part B, the difference in thermal expansion coefficient between the substances having the smallest thermal expansion coefficient is 1.5 × 10 ⁻⁵ [/ K] or less. Radiation detector. In the radiation detector,
The radiation detector according to claim 1, wherein a layer included in the scintillator adjacent portion A is only an intermediate layer. In the radiation detector,
The radiation detector according to claim 1 or 2, wherein a thickness of the intermediate layer in contact with the scintillator is 1 µm or less. In the radiation detector,
The radiation detector according to claim 1, wherein the scintillator adjacent portion A is a layer in contact with the scintillator in the intermediate layer.   5. The radiation detector according to claim 1, wherein a main component of the undercoat layer is an inorganic substance. 6. The radiation detector according to claim 1, wherein the undercoat layer has a thermal expansion coefficient of 1.5 × 10 ⁻⁵ [/ K] or less.   The radiation detector according to claim 1, wherein a main component of at least one of the intermediate layers is an inorganic substance. In the said radiation detector, the thermal expansion coefficient of at least 1 layer of the said intermediate | middle layer is 1.5 * 10 < ^-5 > [/ K] or less, The radiation detection in any one of Claim 1 thru | or 7 characterized by the above-mentioned. vessel.   The radiation detector according to any one of claims 1 to 8, wherein the undercoat layer is formed of a single layer.   The radiation detector according to claim 1, wherein a main component of the undercoat layer and a main component of the intermediate layer are the same.   11. The radiation detector according to claim 1, wherein the intermediate layer is composed of a single layer.   The radiation detector according to claim 1, wherein the scintillator layer is made of an inorganic substance crystal.   The radiation detector according to claim 12, wherein a main component of the scintillator layer is cesium iodide.

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