JP7287515B2 - radiation detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to a radiation detector in which the moisture resistance of a scintillator is improved when a photoelectric conversion panel with a flexible resin substrate is used.

In recent years, digital radiation image detectors represented by computed radiography (CR) and flat panel detectors (FPD) can directly obtain digital radiation images, and cathode tubes Since images can be directly displayed on an image display device such as a liquid crystal panel or a liquid crystal panel, they are widely used for image diagnosis in hospitals, clinics, and the like. Recently, a flat panel that uses a scintillator layer containing cesium iodide (CsI) and is combined with a thin film transistor (TFT) has attracted attention as a highly sensitive X-ray image visualization system.

In FPDs, the light-receiving element and the switching element are often provided on a glass substrate, and the glass substrate has played the role of moisture-proof protection from the light-receiving element side of the scintillator to be coupled. In addition, from the viewpoint of moisture-proof protection, controlling the thermal expansion of members due to environmental temperature fluctuations, and preventing warping and peeling, a substrate made of glass is often used on the side of the scintillator facing the photoelectric conversion panel. rice field.

In recent years, for the purpose of flexibility and weight reduction, adoption of a photoelectric conversion panel in which a switching element and a light receiving element are provided on a resin substrate using a resin substrate instead of a glass substrate has been considered. Technologies for changing the base material from glass to resin, composite materials, etc. (for example, JP-A-2015-230175, JP-A-2013-126730) have also been proposed, and photoelectric conversion panels are used in radiation detectors that acquire medical images. There is an increasing demand to change the substrate to a resin substrate.

JP 2015-230175 A Japanese Patent Application Laid-Open No. 2013-126730

In the case of a resin substrate, the moisture that was blocked by the conventional glass substrate penetrates through the resin substrate, which may cause humidity deterioration of the scintillator and corrosion of the wiring. In addition, there is a problem that the resin substrate lowers the robustness and the detector itself deteriorates or breaks due to scratches on the surface.

In addition, with flexibility and weight reduction, there is a possibility that the impact and load during use may be deviated. In the radiographic image detection apparatus, unevenness and defects in each of the photoelectric conversion element array and the radiographic image conversion panel are corrected before photographing to make signals uniform. However, in the market environment, there is unevenness due to the accumulation of static electricity inside, and due to misalignment due to thermal fluctuations and impacts, the position information for correction is misaligned, and the original unevenness and defects are emphasized. It can also create defects and interfere with diagnosis.

Under such circumstances, the inventors of the present invention conducted intensive studies to improve the moisture resistance of the scintillator when using a flexible photoelectric conversion panel. The inventors have found that all of the above problems can be solved, and have completed the present invention. The configuration of the present invention is as follows.

[1] A scintillator panel having a scintillator layer composed of columnar crystals on a first polyimide film;
a photoelectric conversion panel having a light-receiving element and a switching element on a second polyimide film different from the first polyimide film, wherein the light-receiving element faces the scintillator layer;
an adhesive layer that bonds the scintillator panel and the photoelectric conversion panel;
a metal foil that seals at least the scintillator layer;
an adhesive layer that adheres the metal foil to a housing that is a rigid plate;
A radiation detector with
[2] The radiation detector according to [1], wherein the adhesive layer is a pressure-sensitive adhesive layer.
[3] The radiation detector according to [1] or [2], wherein the metal foil is aluminum .
[4] The radiation detector according to any one of [1] to [3], wherein the photoelectric conversion panel is flexible.
[5] The radiation detector according to any one of [1] to [4], wherein the pressure-sensitive adhesive layer has a thickness of 1 to 100 μm.

According to the present invention, when a photoelectric conversion panel made of a flexible material such as a resin substrate or a composite material is combined with a scintillator layer, the scintillator layer is coated with a predetermined moisture-proof material to reduce the humidity of the scintillator. Deterioration can be suppressed. Further, by adopting the configuration of the present invention, a radiation detector can be obtained that solves all of the problems associated with using a resin substrate, such as warpage, peeling, and unevenness due to accumulation of static electricity inside.

1 is a schematic cross-sectional view showing a radiation detector according to the present invention; FIG. 1 is a schematic cross-sectional view showing a first aspect of a radiation detector according to the present invention; FIG. FIG. 4 is a schematic cross-sectional view showing a second aspect of the radiation detector according to the present invention; FIG. 5 is a schematic cross-sectional view showing a third aspect of the radiation detector according to the present invention; FIG. 4 is a schematic cross-sectional view showing an embodiment using a rigid plate of the radiation detector according to the present invention; The schematic of a photoelectric conversion panel is shown. Fig. 7 shows an enlarged view of Fig. 6; FIG. 8 shows a pixel cross-sectional view (YY cross-sectional view) in FIG. FIG. 3 shows a cross-sectional view of a pixel of a flexible TFT. FIG. 10 shows another example of a pixel cross-sectional view of a flexible TFT. 1 shows a fabrication process of a flexible TFT.

The radiation detector of the present invention comprises a scintillator panel having a scintillator layer and a flexible photoelectric conversion panel.
Such constituent members of the present invention are shown below.

The scintillator panel scintillator layer contains a phosphor. The phosphor layer has a function of converting the energy of X-rays, which are radiation incident from the outside, into visible light.

In the present invention, the phosphor means a phosphor that emits light when atoms are excited when irradiated with ionizing radiation such as α-rays, γ-rays and X-rays. In other words, 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 capable of efficiently converting radiation energy such as X-rays incident from the outside into light. Moreover, the conversion of radiation into light does not necessarily have to be instantaneous, and a method of temporarily storing the latent image in the phosphor layer and reading it later may be used.

For example, as the phosphor 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 Phosphor Dome, Ohmsha, 1987), and the website of Lawrence Berkeley National Laboratory in the United States. Substances described in "Scintillation Properties (http://scintillator.lbl.gov/)" can be considered, but even substances not pointed out here are "converting radiation such as X-rays into different wavelengths such as visible light If it is a "substance capable of

Specific phosphor compositions include the following examples.
First, the basic compositional formula (I):
M ^I X・a M ^II X′ ₂・b M ^III X″ ₃ : zA
A metal halide-based phosphor represented by is exemplified.

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

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

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 lanthanides.

X, X' and X'' each represent a halogen element, but may be different elements or the same element.
A consists 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 represents a numerical value within the range of 0≦a<0.5, 0≦b<0.5 and 0<z<1.0.

Further, the basic compositional formula (II):
M ^II FX: zLn
Rare earth-activated metal fluorohalide-based phosphors represented by are also included.

In the above formula, M ^II represents at least one alkaline earth metal element, Ln represents at least one element belonging to lanthanides, and X represents at least one halogen element. Moreover, z is 0<z<=0.2.

Also, the basic composition (III):
_{Ln2O2S :} zA
Rare earth oxysulfide-based phosphors represented by are also included.

In the above formula, Ln is at least one element belonging to lanthanoids, A is Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg , Cu, Ag (silver), Tl and Bi (bismuth), respectively. Moreover, z is 0<z<1.

In particular, Gd ₂ O ₂ S using gadolinium (Gd) as Ln uses terbium (Tb), dysprosium (Dy), etc. as the element species of A, so that high light emission is obtained in the wavelength region where the light receiving element is most likely to receive light. It is known to exhibit properties and is particularly preferred.

Also, the basic composition (IV):
M ^II S: zA
A metal sulfide-based phosphor represented by is also included.

In the above formula, M ^II is an element that can become a divalent cation, i.e., at least one element selected from the group consisting of alkaline earth metals, Zn (zinc), Sr (strontium), Ga (gallium), etc. A is 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 consisting of Moreover, z is 0<z<1.

Also, the basic composition (V):
M _a (AG) _b : zA
A metal oxoacid salt phosphor represented by is also included.

In the above formula, M is a metal element that can become a cation, and (AG) is at least selected from the group consisting of phosphates, borates, silicates, sulfates, tungstates and aluminates. A is Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg, Cu, Ag (silver), Each represents at least one element selected from the group consisting of Tl and Bi (bismuth).
Moreover, a and b represent all possible values depending on the valence of the metal and oxoacid group. z is 0<z<1.

Also, the basic compositional formula (VI):
M _a O _b : zA
A metal oxide phosphor represented by is mentioned.

In the above formula, M is a metal element capable of becoming a cation and represents at least one element selected from any one of the above examples of M ^I to M ^II .
Moreover, a and b represent all possible values depending on the valence of the metal and oxoacid group. z is 0<z<1.

In addition, the basic compositional formula (VII):
LnOX: zA
A metal acid halide-based phosphor represented by is mentioned.

In the above formula, Ln is at least one element belonging to lanthanoids, A is Y, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Na, Mg , Cu, Ag (silver), Tl and Bi (bismuth), respectively. Moreover, z is 0<z<1.

In the present invention, the scintillator layer usually consists of a phosphor base compound and an activator. The scintillator layer may be composed of phosphor columnar crystals formed by a vapor phase deposition method, or may be a layer in which particles are deposited by applying a phosphor particle dispersion.

As the vapor phase deposition method, a heating vapor deposition method, a sputtering method, a CVD method, an ion plating method, or the like can be used, but a heating vapor deposition method is particularly desirable.
When the particle dispersion is used, it may contain a polymer binder (hereinafter also referred to as a "binder"). Specific examples of the polymer binder include polyurethane, vinyl chloride copolymer, chloride Vinyl-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, polyester, cellulose derivatives (nitrocellulose, etc.), styrene- Butadiene copolymers, various synthetic rubber resins, phenol resins, epoxy resins, urea resins, melamine resins, phenoxy resins, silicon resins, acrylic resins, ureaformamide resins, and the like can be used. Among them, it is preferable to use polyurethane, polyester, vinyl chloride copolymer, polyvinyl butyral, and nitrocellulose.

The structure of the scintillator panel is not particularly limited as long as it includes the scintillator layer, but a scintillator support substrate may be provided. The support substrate is used as a base for the phosphor forming the scintillator layer, and has a role of holding the structure of the scintillator layer. Note that the support may not always be necessary.

Examples of materials for the support substrate include films, sheets, plates, etc. of various glasses, polymers, metals, etc., which are capable of transmitting radiation such as X-rays. Specific examples of raw materials for the support include plate glass such as quartz, borosilicate glass, and chemically strengthened glass; amorphous carbon plate; plate ceramics such as sapphire, silicon nitride, and silicon carbide; silicon, germanium, gallium arsenide, and gallium. Semiconductors made of phosphorus, gallium nitrogen, etc. molded into plates; polymer films (plastic films) such as cellulose acetate films, polyester resin films, polyethylene terephthalate films, polyamide films, polyimide films, triacetate films, and polycarbonate films; and carbon fibers Polymer sheets (plastic sheets) such as reinforced resin sheets; metal sheets such as aluminum sheets, iron sheets, copper sheets, lead sheets, etc., or metal sheets having a coating layer of oxides of the metals; bio-nanofiber films, and the like. The support may be composed of one layer of the above raw material, or may be composed of two or more layers of the same or different kinds of the above raw material.
The scintillator layer may be formed on the support substrate, or may be provided on the surface of the light receiving element constituting the photoelectric conversion panel.

Photoelectric Conversion Panel The photoelectric conversion panel used in the present invention has a role of converting light into an electric signal and outputting it to the outside, and a flexible one is used. Here, although the structure of the photoelectric conversion panel used in the present invention is not particularly limited, it usually has a support substrate, a light receiving element and a switching element, and has a form in which the elements are stacked on the support substrate. there is These elements have the function of absorbing light generated in the scintillator layer and converting it into electric charges. Here, these elements may have any specific structure as long as they have such functions. For example, the light-receiving element can be composed of a transparent electrode, a charge-generating layer that is excited by incident light to generate charges, and a counter electrode. Conventionally known materials can be used for the transparent electrode, the charge generation layer and the counter electrode, and it is preferable that they are mainly composed of a glass plate or a resin film. Further, the light receiving element used in the present invention may be composed of a suitable photosensor, for example, a plurality of photodiodes arranged two-dimensionally, or a CCD (Charge Sensor). Coupled Devices), CMOS (Complementary metal-oxide-semiconductor) sensors, or other two-dimensional photosensors.

The switching element has a function of accumulating electric charges obtained by the light receiving element and outputting a signal based on the accumulated electric charges. Here, the switching element may have any specific structure. can be configured using a transistor which is an image signal output element for outputting as a signal. Here, a TFT (thin film transistor) is given as an example of a preferable transistor.

An outline of a photoelectric conversion panel is shown in FIG. As shown in FIG. 6, a plurality of scanning lines 5 and a plurality of signal lines 6 are arranged so as to cross each other on a surface (hereinafter referred to as a surface) 4a of the TFT substrate 4 facing the scintillator substrate. is set. A photodiode 7 as a light receiving element for detecting radiation is provided in each small area r defined by the plurality of scanning lines 5 and the plurality of signal lines 6 .

Of the area on the surface 4a of the TFT substrate 4, the area where a plurality of photodiodes 7 are arranged two-dimensionally (in a matrix) on the TFT substrate 4 (that is, the area surrounded by the dashed-dotted line in FIG. 6). area) constitutes the pixel area Ra, and the area on the TFT substrate 4 other than the pixel area Ra around the pixel area Ra (that is, the area outside the dashed line in FIG. 6) constitutes the peripheral area Rb.

Although the photodiode 7 is used as the light receiving element, it is also possible to use, for example, a phototransistor. Each photodiode 7 is connected to a source electrode 8s of a TFT 8, which is a switching element, as shown in FIG. 6 and its enlarged view in FIG. A drain electrode 8 d of the TFT 8 is connected to the signal line 6 .

When radiation is incident on the photodiode 7 and light such as visible light converted from the radiation by the scintillator substrate is irradiated, the photodiode 7 generates electron-hole pairs therein. The photodiode 7 is thus adapted to convert the irradiated visible light into electric charge.

The TFT 8 turns on when an on-voltage is applied to the gate electrode 8g, and discharges charges accumulated in the photodiode 7 to the signal line 6 via the source electrode 8s and the drain electrode 8d. Further, the TFT 8 is turned off when an off voltage is applied to the gate electrode 8g through the scanning line 5, stops the discharge of the charge from the photodiode 7 to the signal line 6, and stores the charge in the photodiode 7. It is designed to be accumulated.

That is, in the TFT off state, charges corresponding to visible light converted from X-rays are generated and stored in the PD, and then the TFTs are turned on to output the stored charges to an external circuit via the signal line 6. This realizes conversion into X-ray image information and electric information.

FIG. 8 shows a cross-sectional view of the pixel in FIG. 7 (YY cross-sectional view). Here, the TFT substrate is made of glass, and the above-mentioned TFTs and PDs, as well as appropriate insulators, are laminated thereon.
FIG. 9 shows a cross-sectional view of a pixel of a flexible TFT. A flexible film or plastic substrate is used for the support substrate in FIG.

FIG. 10 shows another embodiment of a pixel sectional view of a flexible TFT. After a moisture-proof layer is formed on a flexible film or plastic substrate, the above-described TFT and PD and an insulator are laminated as appropriate.

FIG. 11 shows the manufacturing process of the flexible TFT. With glass substrate TFTs, TFTs and PDs are directly fabricated on the glass substrate, whereas flexible TFTs
・TFTs and PDs are produced after applying a film material to the surface of the glass substrate. ・After the TFTs and PDs are produced, the film is peeled off from the glass. ・If necessary, a support substrate such as a plastic substrate is attached.

As another aspect,
・Apply a film material on the surface of the glass substrate ・Create TFTs and PDs after forming a moisture-proof layer on the film ・Peel off the film from the glass after manufacturing the TFTs and PDs ・Attach a supporting substrate such as a plastic substrate as necessary It is also possible to implement it with a flow such as

As described above, elements having various configurations can be used as elements constituting the photoelectric conversion panel that can be used in the present invention. For example, an element in which a plurality of photodiodes and a plurality of TFT elements are formed on a support substrate can be used.

Moreover, the support substrate functions as a support for the photoelectric conversion panel, and various types of glass, polymer materials, metals, and the like can be used. These may be used singly or in combination. Examples of such supporting substrate include materials similar to those of the substrate constituting the scintillator panel. In order for the photoelectric conversion panel to have flexibility, the support substrate is preferably a flexible film or sheet having a thickness of 50 to 500 μm, or an organic-inorganic composite material such as a thin glass coated with a resin. .

Here, "having flexibility" means having a flexible property, and as a guideline, the elastic modulus (E120) at 120° C. is 0.1 to 300 GPa. In addition, the "elastic modulus" is the strain indicated by the standard line of the sample conforming to JIS-C2318 using a tensile tester, and the slope of the stress with respect to the amount of strain in the area where the corresponding stress shows a linear relationship. is the value obtained by This value is called Young's modulus, and this Young's modulus is defined as the elastic modulus.
The support substrate preferably has an elastic modulus (E120) at 120° C. of 0.1 to 300 GPa, more preferably 1 to 100 GPa.

Among the raw materials described above, flexible polymer films and polymer sheets having a thickness of 50 to 500 μm are particularly preferred as raw materials for the flexible support substrate. Specific examples of flexible polymer films include polyethylene naphthalate film (E120=7 GPa), polyethylene terephthalate film (E120=4 GPa), polycarbonate film (E120=2 GPa), and polyimide film (E120=7 GPa). , polyetherimide film (E120=3GPa), aramid film (E120=12GPa), polysulfone film (E120=2GPa), polyethersulfone film (E120=2GPa), bio-nanofiber film, and the like. Note that the elastic modulus values may vary even for the same type of polymer film, so the values in parentheses are not necessarily the values in parentheses, but the values in parentheses are examples as a guideline.

For the purpose of adjusting the reflectance, the support substrate may be imparted with light absorbability or light reflectivity, for example, by coloring. That is, the support may also function as a reflective layer. Examples of such a support substrate include white PET and black PET in which a white pigment or carbon black is kneaded into the support.

Radiation Detector The radiation detector of the present invention comprises the scintillator panel and a photoelectric conversion panel. In the photoelectric conversion panel, the light receiving element and the switching element face the scintillator layer.

In the radiation detector according to the present invention, the scintillator layer is sealed with a moisture-proof material. FIG. 1 shows the basic configuration of such a radiation detector of the present invention. Although the scintillator support substrate is illustrated in FIG. 1, the scintillator support substrate is not necessarily essential in the present invention.

The moisture-proof material plays a role of preventing the scintillator panel from moisture and suppressing deterioration of the scintillator layer. For example, when the phosphor of the scintillator layer is deliquescent, the deterioration may include deterioration of the scintillator layer due to deliquescence of the phosphor. For this reason, the moisture-proof material can be used to protect the entire scintillator panel, or the photoelectric conversion panel and the scintillator panel. can be anything.

From the viewpoint of preventing deterioration of the scintillator layer, the moisture-proof material preferably has a moisture permeability of 1.0 g/m ² ·day or less, more preferably 0.1 g/m ² ·day or less, further preferably 0.01 g/m 2 ·day or less. It is preferably made of a material that is g/m ² ·day or less.

Here, the moisture permeability of the moisture-proof material can be measured according to the method specified by JIS Z 0208 as follows. A film made of a moisture-proof material is provided in a specified container, and while maintaining the temperature in the container at 40 ° C, the film is used as a boundary surface, and the space on one side is 90% RH (relative humidity), and the other side keep the space dry using a desiccant. In this state, the mass (g) of water vapor passing through the film made of this moisture-proof material in 24 hours (converting the protective film to 1 mm ² ·day) is defined as moisture permeability.

The moisture-proof material is composed of a material with low moisture permeability, such as paraxylylene, polyester such as polyethylene terephthalate, polymethacrylate, nitrocellulose, cellulose acetate, polypropylene, and polyethylene naphthalate.

From the viewpoint of improving the moisture resistance of moisture-proof materials, laminated films or laminated films in which multiple vapor-deposited films on which protective films and metal oxides are vapor-deposited are laminated, metal foils such as Al and Cu and resin films, It may be an organic-inorganic composite film in which a thin glass and a resin film are laminated. For example, such a laminated film or laminated film may include a polyethylene terephthalate film or polyethylene terephthalate film on which a metal oxide, a metal, or the like is vapor-deposited, or a plurality of vapor-deposited films are laminated. . Metal oxides include silicon dioxide ( _SiO2 ), aluminum oxide ( _Al2O3 ), ITO, and the like _.

In the case of forming a moisture-resistant film with polyparaxylylene, the substrate or panel on which the desired scintillator layer is formed is placed in the vapor deposition chamber of a CVD apparatus, and the entire surface is exposed to the vapor in which diparaxylylene is sublimated. is coated with a polyparaxylylene film.

The moisture-proof material may be made of a heat-sealable material containing a heat-sealable resin. The heat-sealable resin is not particularly limited as long as it is a resin that can be fused with a generally used impulse sealer. Examples include ethylene-vinyl acetate copolymer (EVA), polypropylene (PP), and polyethylene (PE). mentioned. Hot-melt resins can also be used, and those containing polyolefin-based, polyester-based, or polyamide-based resins as the main component are preferred, but are not limited to these. The hot-melt resin can also serve as an adhesive between the scintillator panel and the photoelectric conversion panel.

The hot-melt resin referred to in the present invention is an adhesive resin that does not contain water or solvent and is solid at room temperature and is composed of a non-volatile thermoplastic material. It melts when the resin temperature rises and solidifies when the resin temperature drops. In addition, it has adhesiveness when heated and melted, but becomes solid at room temperature and does not have adhesiveness. Polyolefin-based resins are more preferable from the viewpoint of light transmittance.

Furthermore, metals such as lead and stainless steel, and inorganic materials such as silicon nitride, silicon oxynitride, and silicon oxynitride carbide can also be used as moisture-proof materials. For example, in the case of metal, a method such as vapor deposition or plating can be adopted, and a sheet-like material can be used. In the case of inorganic materials, known methods such as CVD can be employed.

The thickness of the protective layer formed from a moisture-proof material is not particularly limited as long as it has a moisture-proof function, but it is preferably 10 to 100 μm.
The radiation detector of the present invention has the following aspects depending on its configuration.

(First aspect)
A first embodiment of a radiation detector according to the present invention is shown in FIGS. 2(a)-(g).
In the first mode, as shown in FIG. 2(a), the moisture-proof layer made of the moisture-proof material covers the moisture-proof layer (A) on the surface of the scintillator panel and the scintillator panel on the opposite surface of the radiation detector. (B).

One aspect is that the moisture-proof layer (A) and the moisture-proof layer (B) are integrated so as to cover the outer periphery of the scintillator panel, as shown in FIG. 2(b). By vapor-depositing paraxylylene or the like on the surface of the scintillator panel, it is possible to form such an integrated moisture-proof layer.

In one embodiment, the moisture-proof layer (A) and the moisture-proof layer (B) are joined at the side edges of the scintillator panel as shown in FIG. 2(c). In this case, the moisture-proof layer includes, as a barrier film, EVA, PP, LDPE, LLDPE, and LDPE and LLDPE produced using a metallocene catalyst for the innermost layer for edge bonding, or a mixture of these films and HDPE films. thermoplastic resins, commercially available thermoplastic resin sheets mainly composed of polyolefin, polyamide, polyester, polyurethane or acrylic resins, Cr ₂ O ₃ and _Six O _y ( x=1, y=1.5 to 2.0), Ta ₂ O ₃ , ZrN, SiC, TiC, PSG, Si ₃ N ₄ , single crystal Si, amorphous Si, W, aluminum, Al ₂ O ₃ and the like. Ethylene tetrafluoroethyl copolymer (ETFE), high density polyethylene (HDPE), oriented polypropylene (OPP), polystyrene (PS), polymethyl methacrylate (PMMA), biaxial as base material Film materials such as oriented nylon 6, polyethylene terephthalate (PET), polycarbonate (PC), polyimide, and polyetherstyrene (PES) that are used for general packaging films can be used. The periphery of the scintillator panel is bonded with the hot-melt resin described above, or the barrier films are thermo-compressed to each other. The joint may be configured such that one of the moisture-proof layers is used as a bottom material or a lid material, and the other is used as a box material to cover the whole.

Furthermore, the sides of the scintillator panel may be covered with a moisture-proof layer as well as the surface and the opposing surface. The coating of the side surface is exemplified by the moisture-proof protective film described above, and may be made of the same material as that used to coat the surface, or may be made of a different suitable resin. Polyester resin, silicone resin, urethane resin, epoxy resin, acrylic resin, fluororesin, etc., can be used as different resins for covering the side surfaces. Here, when forming the side coating, it is possible to improve the strength and adhesion to the hard coat film by using a mixture of these resins and a polyisocyanate curing agent. These resins may be used singly or in combination of two or more.

Furthermore, as shown in FIG. 2(d), it is also an aspect that the moisture-proof layer (A) and the moisture-proof layer (B) are composed of a sealant layer on the side edges of the scintillator panel. Side surfaces of the moisture-proof layer (A) and the moisture-proof layer (B) may be sealed with a resin (sealant). In this case, a barrier film is used for the moisture barrier and a sealant is used for peripheral sealing. As the sealant, thermosetting or ultraviolet-curing resins such as acrylic, epoxy, and silicon can be used. As the rubber sealant, block copolymers such as styrene-isoprene-styrene, synthetic rubber adhesives such as polybutadiene and polybutylene, and natural rubber can be used. As an example of a commercially available rubber sealant, one-liquid type RTV rubber KE420 (manufactured by Shin-Etsu Chemical Co., Ltd.) is preferably used. As the silicone sealant, a peroxide cross-linking type or an addition condensation type may be used alone or in combination. Further, it can be used by mixing with an acrylic or rubber-based pressure-sensitive adhesive, or a sealant in which a silicon component is pendant to the polymer main chain or side chain of an acrylic sealant may be used. When an acrylic resin is used as the sealant, it is preferable to use a resin obtained by reacting a radically polymerizable monomer containing an acrylic acid ester having an alkyl side chain of 1 to 14 carbon atoms as a monomer component. Further, as a monomer component, it is preferable to add an acrylic acid ester or other vinyl-based monomer having a polar group such as a hydroxyl group, a carboxyl group, or an amino group in the side chain. Furthermore, as a sealant, optical grease or the like having adhesiveness can be used. Any known adhesive can be used as long as it has high transparency and adhesiveness. As an example of commercially available optical grease, silicone oil KF96H (1 million CS: manufactured by Shin-Etsu Chemical Co., Ltd.) is preferably used.

Furthermore, it is preferable that the scintillator panel is attached to the light receiving element and the switching element via an adhesive layer. For example, as shown in FIG. may be attached to the switching element. Combining a thin-layer photoelectric conversion panel with a resin substrate and a scintillator panel makes it easier to warp and separate than when using a glass substrate or the like, but providing an adhesive layer solves these problems.

As the material forming the adhesive layer, it is preferable to use, for example, a hot-melt sheet, a pressure-sensitive adhesive sheet, or the like. Here, the hot-melt sheet refers to a sheet formed from an adhesive resin (hot-melt resin) that does not contain water or solvent, is solid at room temperature, and is made of a non-volatile thermoplastic material. The hot-melt sheet is inserted between adherends, melted at a temperature above the melting point, and solidified again at a temperature below the melting point, thereby joining the adherends together.

Since the scintillator layer does not deliquesce even when it is brought into contact with a scintillator layer having deliquescence such as a scintillator layer made of CsI(Tl), it is suitable for bonding a scintillator panel and a photoelectric conversion panel. In addition, the hot-melt sheet does not contain residual volatile matter and the like, and even after bonding the scintillator panel and the photoelectric conversion panel and then drying, the adhesive layer shrinks little and has excellent dimensional stability.

When the hot-melt sheet is used to bond the scintillator panel and the photoelectric conversion panel together, the hot-melt sheet must melt at an appropriate temperature and not melt in the market environment. Specifically, the melting point of the hot melt resin forming the adhesive layer is usually 50 to 150.degree. C., preferably 60 to 120.degree. C., more preferably 60 to 90.degree.

As the hot-melt resin, for example, a resin containing polyolefin-based, polyamide-based, polyester-based, polyurethane-based or acrylic-based resin as a main component can be used. Among these, from the viewpoint of light transmittance, moisture resistance and adhesiveness, those containing polyolefin resin as a main component are preferred. Examples of polyolefin resins include ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-acrylic acid ester copolymer (EMA), ethylene-methacrylic acid copolymer ( EMAA), ethylene-methacrylic acid ester copolymer (EMMA), ionomer resin and the like can be used. By adjusting the monomer ratio of the copolymer, the melting point of the resin can be arbitrarily adjusted. For example, in an EVA-based hot-melt resin, the melting point can be adjusted to 110°C to 60°C by adjusting the weight ratio of vinyl acetate to 1% to 40%. In addition, these resins may be used as a so-called polymer blend in which two or more kinds are combined.

The adhesive layer may be a layer made of a hot-melt sheet containing one or two or more hot-melt resins having different melting points, or a laminate of two or more hot-melt sheets. layers may be made of hot-melt resins having different melting points.

The hot-melt sheet may be formed by applying a molten hot-melt resin using a die coater or the like, or a commercially available hot-melt sheet may be used.
A pressure-sensitive adhesive sheet may be used for the adhesive layer. As a pressure-sensitive adhesive sheet that can be used for the adhesive layer of the present invention, for example, there is a so-called double-sided tape coated with a pressure-sensitive adhesive. Pressure-sensitive adhesives include, for example, those containing acrylic, urethane, rubber, or silicone resins as main components. Among them, from the viewpoint of light transmittance and adhesiveness, those containing acrylic or silicone resin as a main component are preferable. Commercially available double-sided tapes include, for example, No.5601, No.5603, No.5605 manufactured by Nitto Denko Corporation, No.7027, No.7029 manufactured by Teraoka Seisakusho Co., Ltd., and a tape manufactured by Sekisui Chemical Co., Ltd. #5402, #5402A, #5405, #5405A, etc.

The refractive index of the adhesive layer can be adjusted to a desired value by adding particles or the like, if necessary. In general, the adhesive layer often has a smaller refractive index than the scintillator, and it is desirable to add fine particles having a high refractive index to the adhesive layer to adjust the refractive index. Examples include alumina, yttrium oxide, zirconium oxide, titanium dioxide, barium sulfate, silica, zinc oxide, calcium carbonate, glass and resin. These may be used individually by 1 type, and may be used in mixture of 2 or more types. Among the above particles, titanium dioxide having a particularly high refractive index is preferred. Titanium dioxide may have any of rutile, brookite, and anatase crystal structures. The rutile type is particularly preferable from the viewpoint of efficiency and the like. The area-average particle size of the particles is preferably 1 to 50 nm, more preferably 1 to 20 nm, so as not to significantly impair the transparency of the adhesive layer. The particles are preferably contained in an amount of 3 to 30% by volume, and are contained in an amount of 5 to 20% by volume, when all the materials constituting the adhesive layer are 100% by volume. is more preferred. By containing the particles in such a range, the refractive index can be improved without significantly impairing the transparency of the adhesive layer.

The thickness of the adhesive layer is usually 1 to 100 μm, preferably 1 to 30 μm, more preferably 3 to 20 μm. Adhesion between the scintillator panel and the photoelectric conversion panel can be ensured by setting the lower limit of the film thickness within the above range. Further, by setting the upper limit of the film thickness within the above range, the light emitted from the scintillator layer is suppressed from being diffused inside the adhesive layer, and a highly sharp image can be obtained.

Furthermore, as shown in FIG. 2( f ), the moisture-proof layer (A) is one mode of bonding to the scintillator panel via an adhesive layer. Examples of the adhesive layer used at this time include those described above. When combined from a thin layer or resin substrate, there are unevenness due to peeling, warping, or static electricity buildup inside in the market environment, but these problems can be solved by fixing the moisture-proof layer (A).

Furthermore, as shown in FIG. 2(g), at least one or both of the moisture-proof layer (A) and the moisture-proof layer (B) may have a conductive function. Providing a conductive function makes it possible to release static electricity inside in a market environment, eliminating unevenness due to static electricity.

Providing a conductive function can be achieved by including an antistatic agent in the moisture-proof material, and a conductive layer can be provided on the surface of the moisture-proof material. Antistatic agents include, for example, carbon particles (carbon black, graphite, carbon fiber, carbon nanotubes), oxide semiconductor particles (zinc oxide, tin oxide, indium oxide), surfactants (tetraalkylammonium salts, tri Alkyl benzyl ammonium salt, alkyl sulfonate, alkyl phosphate, glycerin fatty acid ester, polyoxyethylene alkyl ether), hydrophilic polymer (sulfonate, quaternary ammonium salt, polyethylene glycol methacrylate copolymer, polyether ester amide , polyetheramide imide, polyethylene oxide-epichlorohydrin copolymer), conductive polymers (polyacetylene, polypyrrole, polythiophene, polyaniline, poly(3,4-dialkylpyrrole), poly(3,4-ethylenedioxythiophene), poly(aniline sulfonic acid)) and the like.

It is also possible to form only with materials having an antistatic function as described below. For example, surfactants (tetraalkylammonium salts, trialkylbenzylammonium salts, alkylsulfonates, alkylphosphates, glycerin fatty acid esters, polyoxyethylene alkyl ethers), hydrophilic polymers (sulfonates, quaternary ammonium salts , polyethylene glycol methacrylate copolymer, polyether ester amide, polyether amide imide, polyethylene oxide-epichlorohydrin copolymer), conductive polymer (polyacetylene, polypyrrole, polythiophene, polyaniline, poly(3,4-dialkylpyrrole), poly(3,4-ethylenedioxythiophene), poly(aniline sulfonic acid)) and the like.

It can also be made of a conductive sheet mixed with fine metal particles, a conductive polymer such as a conductive adhesive, or a conductive oxide such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide). Furthermore, a conductive oxide layer or a conductive metal layer may be formed.

(Second aspect)
A second embodiment of the radiation detector according to the present invention is shown in FIGS. 3(a)-(e).
As shown in FIG. 3(a), in the second embodiment, the moisture-proof material comprises a moisture-proof layer (A) on the surface of the scintillator panel and a moisture-proof layer (B) between the supports and the elements of the light receiving element and the switching element. Consists of

As shown in FIG. 3(b), the photoelectric conversion panel also has one mode in which a switching element and a light receiving element are provided on a moisture-proof layer (B) formed on a support substrate. For this reason, the moisture-proof layer (B) is preferably made of an inorganic material with high insulating properties.
Incidentally, the moisture-proof layer (A) can employ the same structure as in the first aspect.

In one embodiment, the moisture-proof layer (A) and the moisture-proof layer (B) are joined at the side edges of the scintillator panel as shown in FIG. 3(c). In this case, the moisture-proof layer (A) can employ the film described in the first aspect as a barrier film. The peripheral portion of the film is joined with the hot-melt resin provided in the innermost layer. The joint may be configured such that one of the moisture-proof layers is used as a bottom material or a lid material, and the other is used as a box material to cover the whole.

Furthermore, in the same manner as in the first embodiment, along with the moisture-proof layer (A) on the surface of the scintillator panel and the moisture-proof layer (B) between the support and the elements of the light receiving element and the switching element, the side surfaces of the scintillator layer and the elements are covered by the moisture-proof layer. It may be covered. The coating of the side surface is exemplified by the moisture-proof protective film described above, and may be made of the same material as that used to coat the surface in the same manner as in the first embodiment, or may be made of a different suitable resin. . Polyester resin, silicone resin, urethane resin, epoxy resin, acrylic resin, fluororesin, etc., can be used as different resins for covering the side surfaces. Here, when forming the side coating, it is possible to improve the strength and adhesion to the hard coat film by using a mixture of these resins and a polyisocyanate curing agent. These resins may be used singly or in combination of two or more.

Furthermore, as shown in FIG. 3(d), it is also an aspect to consist of a moisture-proof layer (A), a moisture-proof layer (B), and a sealant layer at the side edges of the scintillator panel. As the sealant, the same one as exemplified in the first aspect can be employed.

Furthermore, as shown in FIG. 3(e), the light receiving element and the switching element may be attached to the scintillator panel via an adhesive layer. Combining a thin-layer photoelectric conversion panel with a resin substrate and a cinch panel makes it easier to warp and separate than when using a glass substrate or the like, but providing an adhesive layer solves these problems.

Materials constituting the adhesive layer are as described above.
Further, as in the first mode, the moisture-proof layer (A) is bonded to the scintillator panel via an adhesive layer. Furthermore, at least one or both of the moisture-proof layer (A) and the moisture-proof layer (B) may have a conductive function. Providing a conductive function makes it possible to release static electricity inside in a market environment, eliminating unevenness due to static electricity.

(Third aspect)
A third embodiment of the radiation detector according to the present invention is shown in FIGS. 4(a)-(d).
As shown in FIG. 4(a), in the third aspect, a moisture-proof layer (A) on the surface of the scintillator panel,
It is composed of the scintillator of the photoelectric conversion panel and the moisture-proof layer (B) on the opposite surface.
Incidentally, the moisture-proof layer (A) can employ the same structure as in the first and second aspects.

In one embodiment, the moisture-proof layer (A) and the moisture-proof layer (B) are joined at the side edges of the scintillator panel as shown in FIG. 4(b). In this case, the moisture-proof layer (A) can employ the film described in the first aspect as a barrier film. The peripheral portion of the film is joined with the hot-melt resin provided in the innermost layer. The joint may be configured such that one of the moisture-proof layers is used as a bottom material or a lid material, and the other is used as a box material to cover the whole.

Furthermore, as in the first and second aspects, the sides of the scintillator panel and the photoelectric conversion panel together with the moisture-proof layer (A) on the surface of the scintillator panel and the moisture-proof layer (B) on the surface opposite to the scintillator of the photoelectric conversion panel It may be covered with a moisture-proof layer. The coating of the side surface is exemplified by the moisture-proof protective film described above, and may be made of the same material as that used to coat the surface as in the first and second embodiments, or may be made of a different suitable resin. can be Polyester resin, silicone resin, urethane resin, epoxy resin, acrylic resin, fluororesin, etc., can be used as different resins for covering the side surfaces. Here, when forming the side coating, it is possible to improve the strength and adhesion to the hard coat film by using a mixture of these resins and a polyisocyanate curing agent. These resins may be used singly or in combination of two or more.

Furthermore, as shown in FIG. 4(c), it is also an aspect to consist of a moisture-proof layer (A), a moisture-proof layer (B), and a sealant layer on the side edges of the scintillator panel. As the sealant, the same ones as exemplified in the first and second aspects can be employed.

Furthermore, as shown in FIG. 4(d), the scintillator panel may be attached to the light receiving element and switching element on the photoelectric conversion panel via an adhesive layer. Combining a thin-layer photoelectric conversion panel with a resin substrate and a cinch panel makes it easier to warp and separate than when using a glass substrate or the like, but providing an adhesive layer solves these problems.

Materials constituting the adhesive layer are as described above.
Furthermore, at least one or both of the moisture-proof layer (A) and the moisture-proof layer (B) may have a conductive function. Providing a conductive function makes it possible to release static electricity inside in a market environment, eliminating unevenness due to static electricity.

(Aspect of rigid plate)
In one aspect of the present invention, a rigid plate is further provided on the surface of the photoelectric conversion panel opposite to the scintillator side.
A flexible radiation detector constructed from a thin-layer resin substrate may be displaced due to impact during use. Therefore, by fixing with a rigid plate, it is possible to increase the adhesion of the members and obtain a radiation detector free from misalignment and increase in defects.

The rigid plate is not particularly limited in thickness and material as long as it has an elastic modulus of 10 GPa or more. Metals such as lead, glass, carbon, composite materials such as CFRP, and resin materials such as PET can be used without particular restrictions. Also, the moisture-proof material can also function as a rigid plate.

Bonding of the rigid plate to the object is preferably done via an adhesive layer. Although there are no particular restrictions on the materials to be joined, it is preferable to use a hot-melt sheet. A known hot-melt sheet can be used. The types of hot-melt sheets include, for example, polyolefin-based, polyamide-based, polyester-based, polyurethane-based, EVA-based, etc., depending on the main component. However, it is not limited to these.

As long as the rigid plate is used as a constituent member of the radiation detector, it may be used on the outer surface, the inner surface, or the inside.
An embodiment using a rigid plate is shown in FIGS. 5(a) to 5(f).
For example, as shown in FIG. 5(a), one mode is to have a rigid plate on the surface opposite to the scintillator side of the photoelectric conversion panel.

Further, as shown in FIG. 5(b), a rigid plate is provided on the surface of the photoelectric conversion panel opposite to the scintillator side, and a moisture-proof layer (B) is formed on the rigid plate between the photoelectric conversion panel support substrate and the photoelectric conversion panel support substrate. may have been Furthermore, as shown in FIG. 5(c), the rigid plate may have the function of the moisture-proof layer (B). When the function of the moisture-proof layer is provided, a metal plate made of a metal having an atomic number of 40 or higher such as lead, which does not easily transmit radiation, can be used as the rigid plate, and these also function as the moisture-proof layer.

As shown in FIG. 5(d), a rigid plate may be provided on the surface of the scintillator panel. The surface of the scintillator may be on the radiation incident side or on the radiation emitting side of the photoelectric conversion panel, but is preferably formed on the external surface.

As shown in FIG. 5(e), in one embodiment, the moisture-proof layer (A) is formed on the surface of a rigid plate on the surface of the scintillator panel.
Further, as shown in FIG. 5(f), the rigid plate may have the function of the moisture-proof layer (A).
The rigid plate may be the top plate of the housing that houses the radiation detector.

In addition, the radiation detector of the present invention may be irradiated with X-rays from either side, and when the X-rays are irradiated from the scintillator panel side, the scintillator uses the X-rays more efficiently and emits stronger light, When X-rays are irradiated from the photoelectric conversion panel side, the scintillator close to the light receiving element emits strong light, so the resolution of the radiographic image obtained by imaging is high.

According to the present invention, it is possible to provide a radiation detector that can be made thin and lightweight, and that does not cause warping, peeling, or unevenness due to accumulation of static electricity inside. Such a radiation detector according to the present invention can be applied to various types of X-ray imaging systems.

4 TFT substrate 5 Scanning line 6 Signal line 7 Photodiode 8 TFT

Claims (5)

a scintillator panel having a scintillator layer composed of columnar crystals on the first polyimide film;
a photoelectric conversion panel having a light-receiving element and a switching element on a second polyimide film different from the first polyimide film, wherein the light-receiving element faces the scintillator layer;
an adhesive layer that bonds the scintillator panel and the photoelectric conversion panel;
a metal foil that seals at least the scintillator layer;
an adhesive layer that adheres the metal foil to a housing that is a rigid plate;
A radiation detector with 2. The radiation detector according to claim 1, wherein said adhesive layer is a pressure-sensitive adhesive layer. 3. The radiation detector according to claim 1, wherein said metal foil is aluminum. 4. The radiation detector according to claim 1, wherein said photoelectric conversion panel is flexible. 3. The radiation detector according to claim 2 , wherein the pressure-sensitive adhesive layer has a thickness of 1 to 100 μm.

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