JP2007248283A - Scintillator, fluorescent screen, and x-ray detector using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly sensitive scintillator and an X-ray detector using it which are especially useful for the X-ray detector for, for example, industrial nondestructive inspection or medical radiography. <P>SOLUTION: This layered scintillator constituted of an organic polymer material and phosphor powder, attached to a photoelectric conversion element has characteristics wherein the phosphor powder has the average particle size over 25 μm and below 50 μm, and a filling factor of the phosphor powder is over 30% and below 65%, and the layer thickness is over 400 μm and below 1,000 μm. A fluorescent screen and the X-ray detector using it are also provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a scintillator and an X-ray detector using the scintillator, and more particularly to a scintillator suitable for an industrial nondestructive inspection apparatus or a medical X-ray diagnostic apparatus and an X-ray detector using the scintillator. Is.

  Conventionally, a device that irradiates an object with radiation and detects the intensity distribution of the radiation that has passed through the object to obtain a radiation image of the object has been widely used in industrial nondestructive inspection and medical diagnosis. ing. As a general method for such photographing, an intensifying screen / film method has been conventionally used. In this method, a phosphor sheet (intensifying screen) that emits visible light when irradiated with X-rays is brought into intimate contact with both sides of the photosensitive film, and X-rays transmitted through the object are emitted by the phosphor. It consists of visualizing the light captured by the film and developing the latent image formed on the film by chemical processing.

On the other hand, due to recent advances in digital technology, there is a need for a method of obtaining a high-quality radiographic image by converting a radiographic image into an electrical signal, processing the electrical signal, and then reproducing it as a visible image on a CRT or the like. Yes. As a method of converting such a radiation image into an electrical signal, a radiation transmission image is temporarily accumulated as a latent image in a phosphor, and then the latent image is photoelectrically irradiated by irradiating excitation light such as laser light later. A radiation image recording / reproducing system (CR: Computed Radiography) that reads out and outputs a visible image has been proposed.
Further, an image intensifier TV (II-TV) system has been realized in which a large vacuum tube provided with a photoelectric film, an accelerating electrode and a fluorescent film and a CCD camera of about 1 inch are directly digitized.

  Further, along with recent progress in semiconductor process technology, an apparatus for taking a radiographic image using a semiconductor sensor has been developed. This type of system has an extremely wide dynamic range compared to a radiographic system using a conventional photosensitive film, and can obtain a radiographic image that is not easily affected by fluctuations in the exposure dose of radiation. have. Furthermore, there is an advantage that an output image can be obtained immediately without requiring chemical processing.

  As one of the methods, in addition to the direct conversion method that directly converts an X-ray image using an amorphous silicon thin film transistor (a-Si TFT) into an electrical signal, the X-ray image is once converted into an optical signal, and the converted optical signal is converted into an optical signal. So-called indirect conversion type X-ray detectors have been proposed for converting a signal into an electric signal.

Conventionally, an indirect conversion type X-ray detector uses a radiation fluorescent plate used to convert an X-ray image into an optical signal. For example, in Japanese Patent Application Laid-Open No. 2004-317300 (Patent Document 1), a radiation phosphor plate is provided with a phosphor layer made of a phosphor such as Gd ₂ O ₂ S: Tb on a support. The sensitivity of the combination is equal to or less than that of the conventional intensifying screen / film system, CR, and II-TV.

An X-ray line sensor is used in food inspection for industrial purposes. The X-ray line sensor has photoelectric conversion elements arranged in a row, and a fluorescent screen is attached. It is installed along with an X-ray tube on a conveyor where food is transported, and continuously displays images of the flowing food. It is a device that inspects. The X-ray usage is intense due to its use, and repair and maintenance of the X-ray tube and replacement of the X-ray tube frequently occur. Accordingly, there remains a strong demand for increasing the sensitivity of the fluorescent plate and reducing the burden on the X-ray tube.
JP 2004-317300 A

As described above, the sensitivity of the conventional radiation fluorescent plate due to the combination with the photoelectric conversion element is insufficient.
Accordingly, an object of the present invention is to study a stable material that does not adversely affect the human body, and to provide a scintillator that can further improve sensitivity and an X-ray detector using the scintillator.

  A scintillator according to the present invention is a layered scintillator that is attached to a photoelectric conversion element and is composed of an organic polymer material and a phosphor powder, and the phosphor powder has an average particle size of 25 μm or more and 50 μm or less. The powder filling rate is 30% or more and 65% or less, and the layer thickness is 400 μm or more and 1000 μm or less.

  Such a scintillator according to the present invention includes, as a preferred embodiment, one in which the phosphor is a rare earth oxychalcogenide phosphor.

  The fluorescent plate according to the present invention comprises at least one layer of the scintillator and a support.

  Such a fluorescent plate according to the present invention includes, as a preferred embodiment, one in which the support is a reflective material having a reflectance of 80% or more.

  An X-ray detector according to the present invention comprises the above scintillator and a plurality of photoelectric conversion films and pixel electrodes arranged on the scintillator.

  Such an X-ray detector according to the present invention includes, as a preferred embodiment, one in which a reflection layer having a reflectance of 80% or more is provided on a surface other than the scintillator surface of the above scintillator.

  Such an X-ray detector according to the present invention includes, as a preferred embodiment, one in which the X-ray detector is an X-ray line sensor.

  A scintillator according to the present invention is a layered scintillator that is attached to a photoelectric conversion element and is composed of an organic polymer material and a phosphor powder, and the phosphor powder has an average particle size of 25 μm or more and 50 μm or less. Since the powder filling rate is 30% or more and 65% or less and the layer thickness is 400 μm or more and 1000 μm or less, the sensitivity is excellent. Therefore, according to the scintillator and the X-ray detector using the scintillator according to the present invention, it becomes possible to inspect the inspection object with higher accuracy.

  According to the scintillator and the X-ray detector using the scintillator according to the present invention having such excellent sensitivity, the intensity of X-ray irradiation can be lowered as compared with the prior art. The lifetime of the irradiation device can be extended, and the energy consumption can be reduced.

Such a scintillator according to the present invention and an X-ray detector using the scintillator are particularly preferable as an X-ray detector for industrial non-destructive inspection and medical X-ray imaging, for example, utilizing its excellent characteristics. It is.
In the present invention, phosphor particles having a relatively large particle diameter of an average particle diameter of 25 μm or more and 50 μm or less are used with a relatively low filling ratio of 30% or more and 65% or less. It is unexpected that a higher sensitivity was obtained than before. That is, when the amount of the phosphor present in the scintillator layer is the same, when using a phosphor particle having a large particle size, the entire phosphor particle is compared with using a phosphor particle having a small particle size. In spite of the fact that the surface area of the particles is reduced and the surface area of the particles subjected to X-ray irradiation and the area for converting X-rays into visible light or the emission area are considered to be reduced, the present invention, on the contrary, provides high sensitivity. It is. In addition, although it is generally considered that the sensitivity is improved as the filling rate of the fluorescent powder capable of converting X-rays into visible light is higher, according to the present invention, the filling rate is relatively low such as 30% or more and 65% or less. Higher sensitivity can be obtained.

Hereinafter, modes for carrying out the present invention will be described.
FIG. 1 is a conceptual diagram of a system using an X-ray inspection apparatus.
In FIG. 1, X-rays emitted from the X-ray generation device 3 are irradiated to a subject 4, and X-rays transmitted through the subject 4 are detected by the X-ray image photographing device 1. The X-ray imaging apparatus 1 includes an X-ray detector 2 including a scintillator layer that converts at least one layer of X-rays into visible light and a plurality of photoelectric conversion elements arranged on the scintillator layer. ing. The plurality of photoelectric conversion elements are preferably arranged in a line shape or a two-dimensional lattice shape, and an image signal obtained from the output of each photoelectric conversion element is subjected to image processing in the image processing means 5, and the monitor 6 Is displayed as an X-ray image of the subject 4.

  The scintillator, fluorescent plate, and X-ray inspection apparatus according to the present invention can be applied to the X-ray detector 2 shown in FIG.

  FIG. 2 shows a schematic sectional view of a scintillator, a fluorescent screen and an X-ray inspection apparatus according to the present invention. The scintillator 7 according to the present invention shown in FIG. 2 is a layered scintillator composed of an organic polymer material 7a and a phosphor powder 7b, and the phosphor powder 7b has an average particle size of 25 μm or more and 50 μm or less, The filling rate of the fluorescent powder 7b is 30% or more and 65% or less, and the layer thickness is 400 μm or more and 1000 μm or less. A photoelectric conversion element 8 is disposed on one surface of the scintillator 7. A circuit board (not shown) for processing an electrical signal is connected to the photoelectric conversion element 8 via a wiring 10.

  In FIG. 2, X-rays that have passed through the subject and reached the scintillator 7 from the left side of the scintillator 7 are converted into visible light by the scintillator 7, and the converted visible light is converted into an electrical signal by the photoelectric conversion element 8. Converted. By arranging a plurality of photoelectric conversion elements 8 and using electric signals output from these photoelectric conversion elements, it is possible to detect an X-ray irradiation pattern to the scintillator 7, that is, an X-ray transmission pattern of a subject. it can.

  The scintillator 7 can be provided with a support 9 made of plastic or nonwoven fabric. The fluorescent plate according to the present invention comprises a scintillator 7 and a support 9.

  The material of the support 9 and the formation position thereof are arbitrary, and can be appropriately determined in consideration of the purpose and function of the scintillator, the fluorescent plate, or the X-ray inspection apparatus according to the present invention. A specific example of the support 9 that is particularly preferable in the present invention includes a reflector having a reflectance of 80% or more, particularly 90% or more. The reflectance in the present invention is the total reflectance.

  As shown in FIG. 2, visible light in the detection region of the photoelectric conversion element 8 is provided by providing a reflector at a position where the visible light converted from the X-rays by the scintillator 7 is reflected in the direction of the photoelectric conversion element 8. As a result, the X-ray detection sensitivity of the X-ray detector 2 is improved and the resolution of the X-ray irradiation pattern, that is, the X-ray transmission pattern of the subject is improved.

  In some cases, the support can be formed on the X-ray irradiation surface side of the scintillator 7. For example, when the reflecting material 11 is formed on the X-ray irradiation surface side of the scintillator 7, the reflecting material 11 transmits X-rays, while visible light converted from X-rays by the scintillator 7 is directed toward the photoelectric conversion element 8. Since the light is reflected, the amount of visible light in the detection region of the photoelectric conversion element 8 can be further increased.

  The reflecting material is a surface other than the scintillator surface of the scintillator 7 (that is, a surface not involved in the conversion of X-rays into visible light), for example, the side surfaces 12 and 13 of the X-ray detector 2 or the plurality of photoelectric conversion elements 8. The boundary portion 14 can be provided as necessary.

  In the X-ray detector according to the present invention, a plurality of the above-described materials can be simultaneously formed as needed, and other materials other than those described above can be formed. Preferable specific examples of other materials formed as necessary include, for example, a light control layer formed between the scintillator 7 and the photoelectric conversion element 8, such as a filter layer (not shown), and a scintillator. 7 is a protective layer 15 formed on the surface of 7.

<Scintillator>
The scintillator according to the present invention is a layered scintillator composed of an organic polymer material and a phosphor powder attached to the photoelectric conversion element as described above, and the phosphor powder has an average particle size of 25 μm or more and 50 μm or less. The filling rate of the fluorescent powder is 30% or more and 65% or less, and the layer thickness is 400 μm or more and 1000 μm or less.

For the above phosphor used in the phosphor powder present invention is not particularly limited, for _{example, CaWO 4, YTaO 4, YTaO} 4: Nb, LaOBr: Tm, BaSO 4: Pb, ZnS: Ag, BaSO 4: Eu, YTaO ₄ : Tm, BaFCl: Eu, BaF (Br, I): Eu, Gd ₂ O ₂ S: Tb, Y ₂ O ₂ S: Tb, La ₂ O ₂ S: Tb, (Y, Gd) ₂ O ₂ S: Tb, _{also, (Y, Gd) 2 O} 2 S: can be used Tb, known phosphor such as Tm, either alone or in combination.

In the scintillator of the present invention, it is particularly preferable to use a rare earth oxychalcogenide-based phosphor represented by the following formula.
M ₂ O ₂ X: Y
[Wherein M is at least one element selected from the group consisting of yttrium, lanthanum, gadolinium, and lutetium, and X is at least one element selected from the group consisting of sulfur, selenium, and tellurium, and Y is It is at least one element selected from the group consisting of terbium and europium. ]
The Y component is preferably 0.01 mol% or more and 3.5 mol% or less.
In the present invention, a more preferable phosphor is a phosphor that emits light in accordance with the light receiving sensitivity distribution of the photoelectric conversion element. As shown in FIG. 3, a-Si often used in a photoelectric conversion element has a broad light receiving sensitivity distribution with a light receiving peak near 600 nm, and is also a single unit often used in a photoelectric conversion element. Crystalline Si shows a broad light receiving sensitivity distribution having a light receiving peak at 700 to 800 nm. Therefore, when using such a photoelectric conversion element, it is preferable to use a phosphor that can efficiently convert X-rays into visible light in the above wavelength region. Examples of phosphors with high luminous efficiency that match this include rare earth oxychalcogenide phosphors and europium activated rare earth oxysulfide phosphors, more preferably europium activated gadolinium oxysulfide phosphors and europium activated lutetium. Examples thereof include oxysulfide phosphors and europium activated lanthanum oxysulfide phosphors.

  It is particularly suitable when using a phosphor that has high luminous efficiency as described above and matches the photosensitivity distribution of the photoelectric conversion element, but is mixed with the terbium-activated gadolinium oxysulfide phosphor that has been used in the past. May be.

  The average particle size of the phosphor powder is 25 μm or more and 50 μm or less, preferably 25 μm or more and 40 μm or less, and particularly preferably 28 μm or more and 40 μm or less. When the average particle size is less than 25 μm, it is not preferable because sufficient sensitivity cannot be obtained. In addition, since it is difficult to manufacture a phosphor having an average particle size exceeding 50 μm, it cannot be said that it is preferable from the viewpoint of manufacturability.

  The filling rate of the fluorescent powder is 30% to 65%, preferably 40% to 60%, particularly preferably 45% to 55%. If this filling rate is less than 30%, the presence of the phosphor becomes too sparse, and sufficient light emission cannot be obtained and the sensitivity becomes insufficient. On the other hand, if it exceeds 65%, the phosphor is not preferred. This is not preferable because the presence of light becomes too dense and light emitted by X-rays is not transmitted and sensitivity is insufficient.

  The layer thickness of the scintillator according to the present invention is 400 μm or more and 1000 μm or less, preferably 400 μm or more and 800 μm or less, particularly preferably 450 μm or more and 650 μm or less. When the layer thickness is less than 400 μm, it is too thin, and the amount of light emitted from the phosphor is not sufficient and the sensitivity becomes insufficient, which is not preferable. On the other hand, when it exceeds 1000 μm, the layer is too thick and emitted by X-rays. Since light does not transmit and sensitivity becomes insufficient, it is not preferable.

Organic polymer material As the organic polymer material, the above-mentioned phosphor powder can be dispersed and this dispersed state can be satisfactorily maintained in the use environment of the X-ray detector, and any scintillator according to the present invention can be formed. Materials can be used. Preferable specific examples of such organic polymer materials include nitrified cotton (nitrocellulose), cellulose acetate, ethyl cellulose, polyvinyl butyral, cotton-like polyester, polyvinyl acetate, vinylidene chloride-vinyl chloride polymer, vinyl chloride-vinyl acetate. Examples include copolymers, polyalkyl (meth) acrylates, polycarbonates, polyurethanes, cellulose acetate butyrate, polyvinyl alcohol, acrylic resins, and the like. Of these, polyvinyl butyral and acrylic resin are particularly preferable.

  Each of the above organic polymer materials can be used alone or in combination of two or more. Furthermore, various organic solvents can be used in combination as required.

  Preferable organic solvents used for the phosphor coating solution include, for example, ethanol, methyl ethyl ether, butyl acetate, ethyl acetate, ethyl ether, xylene and the like. If necessary, a dispersant such as phthalic acid or stearic acid or a plasticizer such as triphenyl phosphate or diethyl phthalate may be added.

Production of scintillator As a preferred production method of the scintillator according to the present invention, (a) the phosphor and the organic polymer material are mixed in a powder state, pressed at a temperature near the melting point of the organic polymer material, and subjected to photoelectric conversion. Examples thereof include a method of processing into a shape that matches the element, and (b) a general phosphor plate manufacturing method in which a phosphor coating solution is coated on a support (for example, a film that becomes a reflective layer).

At this time, various production conditions and the like can be determined so that the scintillator according to the present invention having a filling rate of the phosphor powder of 30% to 65% and a layer thickness of 400 μm to 1000 μm can be obtained.
Here, the filling rate (P) P of the phosphor powder is a value obtained based on the following equation.
P = V _P / V = W / V / ρ _P
(Wherein the V _P volume of the phosphor material, V is the volume of the scintillator layer, W is the mass of the phosphor material, RoP is the density of the phosphor material.)

<Fluorescent screen>
The fluorescent plate according to the present invention comprises at least one layer of the above scintillator and a support.
The material of the support and the formation position thereof are arbitrary, and can be appropriately determined in consideration of the purpose and function of the X-ray inspection apparatus according to the present invention. Specific examples of the support that is particularly preferable in the present invention include a reflector having a reflectance of 80% or more, particularly 90% or more.

The reflective material can be formed of any material. In the present invention, particularly preferred reflectors include, for example, (a) various resin materials, preferably polyesters such as cellulose acetate, cellulose propionate, cellulose acetate butyrate, polyethylene terephthalate, polystyrene, polymethacrylate, polyamide, vinyl chloride Examples thereof include those obtained by forming a resin such as vinyl acetate copolymer and polycarbonate into a film and provided with a reflective material, and (b) those obtained by attaching paper or an aluminum plate to (b) above. (C) The above-mentioned plastic film or paper containing light reflecting substances such as titanium dioxide and calcium carbonate or bubbles can also be used. Further, (d) a metal vapor deposition film such as Al, Ag, Cr, Cu, Ni, Ti, Mg, Rh, Pt, or Au may be directly formed on the scintillator surface, or vapor deposition may be performed on the film. In addition, (e) a light reflecting substance can be prepared as a coating solution and applied to the scintillator surface.
The reflective layer thus provided preferably has a reflectance of 80% or more.

As described above, in the present invention, a protective layer can be formed as necessary. Various transparent resins can be used as the protective film. Specifically, a protective film can be formed by laminating a transparent resin film made of polyethylene terephthalate, polyethylene, polyvinylidene chloride, polyamide or the like on the phosphor layer. Alternatively, a transparent resin such as cellulose derivative, polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polycarbonate, polyvinyl butyral, polymethyl methacrylate, polyvinyl formal, and polyurethane is dissolved to obtain a protective film coating solution having an appropriate viscosity. A protective film can be formed by preparing, applying this on a scintillator, and drying.

<X-ray detector>
An X-ray detector according to the present invention comprises the above scintillator and a plurality of photoelectric conversion films and pixel electrodes arranged on the scintillator.

The photoelectric conversion film and the pixel electrode itself are known, and in the present invention, an appropriate one can be appropriately selected from such known various photoelectric conversion films and pixel electrodes.
Arrangement of the photoelectric conversion film and the pixel electrode is also arbitrary. For example, the photoelectric conversion film and the pixel electrode can be arranged in a line shape or a two-dimensional lattice shape.
A linear X-ray detector in which photoelectric conversion films and pixel electrodes are arranged in a line or a plurality of examples are arranged in parallel is a specific example of a preferable X-ray detector of the present invention. Such a line-shaped X-ray detector is capable of continuously inspecting the object to be inspected in a transported state at the production site or final inspection process of various articles.

Next, specific examples of the present invention will be described.
<Example 1>
A Gd ₂ O ₂ S: Eu phosphor having an average particle size of 25 μm is prepared, and 0.9 part by weight of polyvinyl butyral resin as a binder and an appropriate amount of methyl ethyl ketone as an organic solvent are mixed with 10 parts by weight of the phosphor powder. A phosphor coating solution was prepared. This phosphor coating solution is uniformly coated and dried with a knife coater on a sheet made of polyethylene terephthalate film with a reflectance of 95% as a reflection layer so that the thickness of the scintillator after drying is 500 μm. A target scintillator was produced. The filling rate of the scintillator at this time was 50%. In addition, since the solvent etc. volatilize and shrink | contract in the scintillator after drying compared with before drying, the gap of the knife coater was adjusted in consideration of it.

<Example 2>
A scintillator was produced in the same manner as in Example 1 except that the phosphor had an average particle diameter of 50 μm.

<Example 3>
A scintillator was produced in the same manner as in Example 1 except that the amount was 1.5 parts by weight of polyvinyl butyral resin.

<Example 4>
A scintillator was produced in the same manner as in Example 1 except that the content was 0.5 part by weight of polyvinyl butyral resin.

<Example 5>
A scintillator was produced in the same manner as in Example 1 except that the thickness of the scintillator was adjusted to 400 μm by adjusting the gap of the knife coater.

<Example 6>
A scintillator was produced in the same manner as in Example 1 except that the thickness of the scintillator was adjusted to 1000 μm by adjusting the gap of the knife coater.

<Example 7>
A scintillator was produced in the same manner as in Example 1 except that the phosphor material was Lu ₂ O ₂ S: Eu.

<Example 8>
A scintillator was produced in the same manner as in Example 1 except that a white polyethylene terephthalate film having a reflectance of 80% serving as a reflective layer was used.

<Example 9>
A scintillator was produced in the same manner as in Example 1 except that a Gd ₂ S: Tb phosphor having an average particle diameter of 30 μm was used and the thickness was 350 μm.

<Comparative Example 1>
A scintillator was produced in the same manner as in Example 1 except that it was a Gd ₂ O ₂ S: Eu phosphor having an average particle diameter of 20 μm and the thickness was 350 μm.

<Comparative Example 2>
A scintillator was produced in the same manner as in Example 1 except that a Gd ₂ O ₂ S: Eu phosphor having an average particle diameter of 20 μm was used.

<Comparative Example 3>
A scintillator was produced in the same manner as in Example 1 except that it was 2 parts by weight of polyvinyl butyral resin.

<Comparative example 4>
A scintillator was produced in the same manner as in Example 1 except that the content was 0.3 parts by weight of polyvinyl butyral resin.

<Comparative Example 5>
A scintillator was produced in the same manner as in Example 1 except that the thickness of the scintillator was adjusted to 300 μm by adjusting the gap of the knife coater.

<Comparative Example 6>
A scintillator was produced in the same manner as in Example 1, except that the thickness of the scintillator was adjusted to 1200 μm by adjusting the gap of the knife coater.

<Comparative Example 7>
A scintillator was produced in the same manner as in Example 1 except that the reflectance of the reflective layer was 65%.

X-ray detectors were produced using the scintillators according to the examples and comparative examples, and the sensitivity was measured. The results are as shown in Table 1. In Table 1, the sensitivity [%] in each example is the value when the sensitivity in Comparative Example 1 is evaluated as 100%.

  As can be seen from Table 1, the X-ray detector using the scintillator according to the present example was found to have good sensitivity.

The figure which shows the conceptual diagram of the system using X-ray imaging apparatus The figure which shows the schematic sectional drawing of a scintillator and an X-ray detector The figure which shows distribution of the light reception sensitivity of an a-Si photoelectric conversion element and a single crystal Si photoelectric conversion element

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray imaging device 2 X-ray detector 3 X-ray generator 4 Subject 5 Digital image processing means 6 Monitor 7 Scintillator 7a Organic polymer material 7b Phosphor powder 8 Photoelectric conversion element 9 Support body 10 Wiring 11 12 13 14 Reflection Material

Claims (7)

  A layered scintillator which is attached to a photoelectric conversion element and is composed of an organic polymer material and a phosphor powder, wherein the phosphor powder has an average particle size of 25 μm or more and 50 μm or less, and a filling ratio of the phosphor powder is 30 % Scintillator, wherein the layer thickness is 400 μm or more and 1000 μm or less.   The scintillator according to claim 1, wherein the phosphor is a rare earth oxychalcogenide phosphor.   A fluorescent plate comprising at least one scintillator according to claim 1 or 2 and a support.   The fluorescent plate according to claim 3, wherein the support is a reflective material having a reflectance of 80% or more.   An X-ray detector comprising: the scintillator according to claim 1; and a plurality of photoelectric conversion films and pixel electrodes disposed on the scintillator.   The X-ray detector according to claim 5, wherein the scintillator or the fluorescent plate according to any one of claims 1 to 4 and a reflective layer having a reflectance of 80% or more are provided on a surface other than the scintillator surface.   The X-ray detector according to claim 5 or 6, wherein the X-ray detector is an X-ray line sensor.

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