JP6956700B2 - Radiation detector - Google Patents

Description

The present invention relates to a radiation detector.

Patent Documents 1 to 3 are known as techniques in this field.

Patent Document 1 discloses a scintillator panel. The scintillator panel has a metal film provided between the resin substrate and the phosphor layer.

Patent Document 2 discloses a radiation detection device including a scintillator panel. The scintillator panel has a scintillator layer containing cesium iodide as a main component. The scintillator layer is doped with thallium. The concentration of thallium in the scintillator layer is high near the interface with the substrate. According to this thallium concentration distribution, the light output is improved.

Patent Document 3 discloses a radiation detector including a phosphor layer. This radiation detector also has a scintillator layer containing cesium iodide as a main component, and the scintillator layer is doped with thallium. Further, the concentration of thallium in the scintillator layer is higher on the substrate side. According to this thallium concentration distribution, the adhesion between the sensor substrate and the phosphor layer is improved.

International Publication No. 2011/065302 Japanese Unexamined Patent Publication No. 2008-51793 Japanese Unexamined Patent Publication No. 2012-98110

The growth substrate on which the scintillator layer is grown may have moisture permeability to allow moisture to permeate. Moisture that has passed through the growth substrate reaches the root of the scintillator layer. The scintillator layer formed by cesium iodide is known to have deliquescent properties. Then, the moisture supplied from the growth substrate causes deliquescent at the root of the scintillator layer, which in turn deteriorates the characteristics of the scintillator panel. Therefore, in this field, it is desired to improve the moisture resistance of a scintillator panel having a scintillator layer formed of cesium iodide.

For example, Patent Document 1 aims to prevent the movement of water from the resin substrate to the phosphor layer by providing a metal film between the substrate and the phosphor layer.

Therefore, an object of the present invention is to provide a radiation detector capable of improving moisture resistance.

The photodetector, which is one embodiment of the present invention, is formed on a sensor substrate containing an organic material as a main component, a sensor substrate, a resin protective layer made of an organic material, and a resin protective layer, to which thallium is added. The sensor substrate includes a scintillator layer composed of a plurality of columnar crystals containing cesium iodide as a main component, and the sensor substrate has a photodetection surface provided with a photoelectric conversion element that receives light generated in the scintillator layer. Further, the scintillator panel, which is one embodiment of the present invention, has a substrate, an intermediate layer formed on the substrate and made of an organic material, a barrier layer formed on the intermediate layer and containing thallium iodide as a main component, and a barrier. It includes a scintillator layer formed on the layer and composed of a plurality of columnar crystals containing cesium iodide to which thallium is added as a main component.

In this scintillator panel, the scintillator layer is formed on the substrate via an intermediate layer and a barrier layer. The barrier layer contains thallium iodide as a main component. Such a barrier layer has a property that it is difficult for moisture to permeate. Then, the barrier layer can block the moisture that tends to move from the intermediate layer made of the organic material to the scintillator layer. As a result, deliquescent at the root of the scintillator layer is suppressed, and as a result, deterioration of the characteristics of the scintillator panel can be suppressed. Therefore, the moisture resistance of the scintillator panel can be improved.

In the above scintillator panel, the substrate may contain any one of a metal material, a carbon material, a glass material and a resin material as a main component. According to this configuration, it is possible to impart properties based on material properties to the substrate.

In the above scintillator panel, the organic material may contain any one of xylylene-based resin, acrylic-based resin, silicone-based resin, polyimide or polyester-based resin. According to this configuration, it is possible to impart properties based on material properties to the intermediate layer.

The photodetector, which is another embodiment of the present invention, has a substrate, an intermediate layer formed on the substrate and made of an organic material, a barrier layer formed on the intermediate layer and containing thallium iodide as a main component, and a barrier. A scintillator panel having a scintillator layer formed on the layer and composed of a plurality of columnar crystals containing thallium-added cesium iodide as a main component, and a photoelectric conversion element that receives light generated in the scintillator panel are provided. A sensor substrate including the light detection surface is provided, and the light detection surface of the sensor substrate faces the scintillator layer.

In this radiation detector, light is generated by the radiation incident on the scintillator panel, and the light is detected by a photoelectric conversion element provided on the photodetection surface. Here, the radiation detector has an intermediate layer made of an organic material and a barrier layer containing thallium iodide as a main component between the substrate and the scintillator layer. According to this barrier layer, it becomes possible to prevent the movement of water from the intermediate layer to the scintillator layer. Therefore, since the deliquescent at the root of the scintillator layer is suppressed, it is possible to suppress the deterioration of the characteristics of the scintillator panel. As a result, the radiation detector can improve the moisture resistance because the deterioration of the radiation detection characteristic is suppressed.

In the above radiation detector, the substrate may contain any one of a metal material, a carbon material, a glass material and a resin material as a main component. According to this configuration, it is possible to impart properties based on material properties to the substrate.

In the above radiation detector, the organic material may contain any one of xylylene-based resin, acrylic-based resin, silicone-based resin, polyimide and polyester-based resin. According to this configuration, it is possible to impart properties based on material properties to the intermediate layer.

The photodetector, which is still another form of the present invention, includes a substrate, an intermediate layer formed on the substrate and made of an organic material, and a barrier layer formed on the intermediate layer containing thallium iodide as a main component. A scintillator layer formed on the barrier layer and composed of a plurality of columnar crystals containing thallium-added cesium iodide as a main component is provided, and the substrate is a photoelectric conversion element that receives light generated in the scintillator layer. It has a provided light detection surface.

In this radiation detector, light is generated by the radiation incident on the scintillator panel, and the light is detected by a photoelectric conversion element provided on the photodetection surface. Here, the radiation detector has an intermediate layer made of an organic material and a barrier layer containing thallium iodide as a main component between the substrate and the scintillator layer. According to this barrier layer, it becomes possible to prevent the movement of water from the intermediate layer to the scintillator layer. Therefore, since the deliquescent at the root of the scintillator layer is suppressed, it is possible to suppress the deterioration of the characteristics of the scintillator panel. As a result, the radiation detector can improve the moisture resistance because the deterioration of the radiation detection characteristic is suppressed.

In the above radiation detector, the substrate may contain any one of a metal material, a carbon material and a glass material as a main component. According to this configuration, it is possible to impart properties based on material properties to the substrate.

In the above radiation detector, the organic material may contain any one of xylylene-based resin, acrylic-based resin, silicone-based resin, polyimide, polyester-based resin, siloxane resin, and epoxy resin. According to this configuration, it is possible to impart properties based on material properties to the intermediate layer.

According to the present invention, a scintillator panel and a radiation detector capable of improving moisture resistance are provided.

FIG. 1 is a cross-sectional view showing a scintillator panel according to the first embodiment. FIG. 2 is a cross-sectional view showing a radiation detector according to the second embodiment. Part (a) of FIG. 3 is a cross-sectional view showing the scintillator panel according to the modified example 1, and part (b) of FIG. 3 is a cross-sectional view showing the scintillator panel according to the modified example 2. Part (a) of FIG. 4 is a cross-sectional view showing the scintillator panel according to the modified example 3, and part (b) of FIG. 4 is a cross-sectional view showing a radiation detector according to the modified example 4. Part (a) of FIG. 5 is a cross-sectional view showing the radiation detector according to the modified example 5, and part (b) of FIG. 5 is a cross-sectional view showing the radiation detector according to the modified example 6. The part (a) of FIG. 6 is a cross-sectional view showing the radiation detector according to the modified example 7, and the part (b) of FIG. 6 is a cross-sectional view showing the radiation detector according to the modified example 8. Part (a) of FIG. 7 is a cross-sectional view showing the radiation detector according to the modified example 9, and part (b) of FIG. 7 is a cross-sectional view showing the radiation detector according to the modified example 10. FIG. 8 is a graph showing the results of the experimental example.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

<First Embodiment>
As shown in FIG. 1, the scintillator panel 1 according to the first embodiment has a substrate 2, a resin protective layer 5 (intermediate layer), a barrier layer 3, a scintillator layer 4, and a protective film 6. .. The scintillator panel 1 having such a configuration is used as a radiation image sensor in combination with a photoelectric conversion element (not shown).

The substrate 2, the resin protective layer 5, the barrier layer 3, and the scintillator layer 4 are laminated bodies 7 laminated in this order along the respective thickness directions. Specifically, the resin protective layer 5 is formed on the substrate 2. Next, the barrier layer 3 is formed on the resin protective layer 5. Then, the scintillator layer 4 is formed on the barrier layer 3. That is, since the resin protective layer 5 and the barrier layer 3 exist between the substrate 2 and the scintillator layer 4, the substrate 2 and the scintillator layer 4 do not come into direct contact with each other. The laminate 7 is covered with the protective film 6.

The substrate 2 forms the substrate of the scintillator panel 1. The substrate 2 has a rectangular shape, a polygonal shape, or a circular shape in a plan view, and its thickness is 10 micrometers or more and 5000 micrometers or less, and 100 micrometers as an example. The substrate 2 has a substrate front surface 2a, a substrate back surface 2b, and a substrate side surface 2c. The substrate 2 is made of a metal material, a carbon material, a ceramic material or a resin material. Examples of the metal material include aluminum, stainless steel (SUS), and copper. Further, examples of the carbon material include amorphous carbon, examples of the ceramic material include glass and alumina, and examples of the resin material include polyethylene terephthalate, polyethylene naphthalate, polyimide, and polyetheretherketone.

When the substrate 2 is made of a metal material, the resin protective layer 5 prevents the substrate 2 from directly contacting the scintillator layer 4 to prevent corrosion of the metal substrate 2 due to the substrate 2 coming into direct contact with the scintillator layer 4. do. Therefore, the resin protective layer 5 has at least an area larger than that of the scintillator layer 4. When the substrate 2 is made of a carbon material, a ceramic material, or a resin material, by providing the resin protective layer 5 on the substrate 2, a film is attached to the substrate 2 at the base of the scintillator layer 4 composed of a plurality of columnar crystals. It will improve and you will be able to grow clean columnar crystals. The resin protective layer 5 has a protective layer surface 5a, a protective layer back surface 5b, and a protective layer side surface 5c. The protective layer surface 5a faces the barrier layer 3. The back surface 5b of the protective layer faces the surface surface 2a of the substrate. The protective layer side surface 5c is flush with the substrate side surface 2c. In the present embodiment, the resin protective layer 5 is formed on the entire surface of the substrate surface 2a. Further, the resin protective layer 5 may cover not only the substrate surface 2a but also the substrate back surface 2b and the substrate side surface 2c. That is, the resin protective layer 5 may cover the entire substrate 2. The resin protective layer 5 is made of a resin material. Examples of the resin material include xylylene-based resins such as polyparaxylylene, acrylic resins, silicone-based resins, polyimides, and polyester-based resins.

The barrier layer 3 inhibits the movement of water from the resin protective layer 5 to the scintillator layer 4. The barrier layer 3 is formed on a part of the protective layer surface 5a. That is, when viewed from the thickness direction, the barrier layer 3 is smaller than the resin protective layer 5 and the substrate 2. The thickness of the barrier layer 3 is 0.001 micrometer or more and 1.0 micrometer or less, and 0.06 micrometer (600 angstrom) as an example. The barrier layer 3 has a barrier layer surface 3a, a barrier layer back surface 3b, and a barrier layer side surface 3c. The barrier layer surface 3a faces the scintillator layer 4. The back surface 3b of the barrier layer faces the surface 5a of the protective layer. The barrier layer 3 contains thallium iodide (TlI) as a main component. For example, the TlI content of the barrier layer 3 may be 90% or more and 100% or less. In other words, when the TlI content in the barrier layer 3 is 90% or more, it can be said that the barrier layer 3 contains TlI as a main component. Such a barrier layer 3 can be formed by, for example, a two-source vapor deposition method. Specifically, a first vapor deposition source containing cesium iodide (CsI) and a second thin-film deposition source containing thallium iodide (TlI) are used. The barrier layer 3 is formed by depositing TlI on the substrate before CsI. Its thickness is, for example, about 600 angstroms. The film thickness of the barrier layer can be measured by peeling the scintillator layer and the substrate with a strong adhesive tape or the like and analyzing the interface between the substrates with a fluorescent X-ray analysis (XRF) apparatus. Examples of the device include ZSX Primus manufactured by Rigaku.

The scintillator layer 4 receives radiation and generates light corresponding to the radiation. The scintillator layer 4 has a thickness of 10 micrometers or more and 3000 micrometers or less, and is 600 micrometers as an example. The scintillator layer 4 is a fluorescent material and contains cesium iodide to which thallium is added as a main component. That is, cesium iodide contains thallium as a dopant (CsI: Tl). For example, the CsI content of the scintillator layer 4 may be 90% or more and 100% or less. In other words, when the CsI content of the scintillator layer 4 is 90% or more, it can be said that the scintillator layer 4 contains CsI as a main component. Further, since the scintillator layer 4 is composed of a plurality of columnar crystals, each columnar crystal has a light guide effect, which is suitable for high-resolution imaging. Such a scintillator layer 4 can be formed, for example, by a vapor deposition method.

The scintillator layer 4 has a scintillator layer surface 4a, a scintillator layer back surface 4b, and a scintillator layer side surface 4c. The scintillator layer 4 is formed on the barrier layer 3 so that the back surface 4b of the scintillator layer faces the surface 3a of the barrier layer. That is, the barrier layer 3 exists between the scintillator layer 4 and the resin protective layer 5. Therefore, the scintillator layer 4 does not come into direct contact with the resin protective layer 5. Further, the barrier layer 3 is smaller than the substrate 2 and the resin protective layer 5 when viewed from the thickness direction. Therefore, similarly, the scintillator layer 4 is smaller than the substrate 2 and the resin protective layer 5 when viewed from the thickness direction.

The scintillator layer 4 contains a plurality of columnar crystals extending in the thickness direction thereof. The roots of the plurality of columnar crystals form the back surface 4b of the scintillator layer and are in contact with the surface 3a of the barrier layer of the barrier layer 3. Further, the tip portions of the plurality of columnar crystals form the scintillator layer surface 4a.

Further, the scintillator layer 4 has a pyramidal trapezoidal shape, and the side surface 4c of the scintillator layer is inclined with respect to the thickness direction thereof. In other words, the scintillator layer side surface 4c has a slope. Specifically, when the scintillator layer 4 is viewed in cross section from a direction orthogonal to the thickness direction, the cross section exhibits a trapezoidal shape. That is, one side on the surface 4a side of the scintillator layer is shorter than one side on the back surface 4b side of the scintillator layer.

The protective film 6 protects the laminated body 7 from moisture by covering the laminated body 7. The protective film 6 covers the back surface 2b of the substrate, the side surface 2c of the substrate, the side surface 5c of the protective layer, the side surface 3c of the barrier layer, the side surface 4c of the scintillator layer, and the surface 4a of the scintillator layer. Further, the thickness of the protective film 6 may be substantially the same at all the formed portions, or may be different for each portion. For example, according to the protective film 6, for example, the film portion formed on the scintillator layer surface 4a is a film portion formed on the substrate back surface 2b, the substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c. Thicker than. The protective film 6 contains polyparaxylylene as a main component. Such a protective film 6 can be formed by, for example, chemical vapor deposition (CVD).

In the scintillator panel 1, a barrier layer 3 is provided between the resin protective layer 5 and the scintillator layer 4. The barrier layer 3 contains thallium iodide as a main component. Such a barrier layer 3 has a property that it is difficult for moisture to permeate. Then, the moisture that tends to move from the resin protective layer 5 to the scintillator layer 4 can be blocked by the barrier layer 3. As a result, deliquescent at the root of the scintillator layer 4 is suppressed, and thus deterioration of the characteristics of the scintillator panel 1 can be suppressed. Therefore, the moisture resistance of the scintillator panel 1 can be improved.

<Second Embodiment>
Next, the radiation detector according to the second embodiment will be described. Actually, a region (side) for taking conduction is provided on the sensor panel 11, but it is not shown for convenience.

As shown in FIG. 2, the radiation detector 10 includes a sensor panel 11 (sensor substrate), a resin protective layer 5, a barrier layer 3, a scintillator layer 4, and a sealing portion 12. The radiation received from the sealing plate 14 enters the scintillator layer 4. The scintillator layer 4 generates light corresponding to radiation. The light passes through the resin protective layer 5 and the barrier layer 3 and enters the sensor panel 11. The sensor panel 11 generates an electric signal according to the incident light. The electric signal is output through a predetermined electric circuit. According to this electric signal, a radiation image can be obtained.

The sensor panel 11 has a panel front surface 11a, a panel back surface 11b, and a panel side surface 11c. The sensor panel 11 is a CCD sensor, CMOS sensor, or TFT panel having a photoelectric conversion element 16, and includes a semiconductor such as silicon or glass as a main component. The sensor panel 11 may contain an organic material as a main component. Examples of the organic material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI). The plurality of photoelectric conversion elements 16 are arranged two-dimensionally on the panel surface 11a. The region on the panel surface 11a in which the plurality of photoelectric conversion elements 16 are arranged is the photodetection region S1 (photodetection surface). Then, the panel surface 11a includes a peripheral region S2 surrounding the light detection region S1 in addition to the light detection region S1. A resin protective layer 5 is provided to protect the photoelectric conversion element 16. The resin protective layer 5 is, for example, a polyimide, a siloxane resin, or an epoxy resin. Further, in order to enhance the crystallinity of the scintillator layer composed of a plurality of columnar crystals, the same resin protective layer 5 as in the first embodiment may be provided.

The sealing portion 12 covers a part of the back surface 5b of the protective layer of the sensor panel 11, the barrier layer 3, and the scintillator layer 4. The sealing portion 12 is fixed to the peripheral region S2 on the back surface 5b of the protective layer. Then, the internal space formed by the sealing portion 12 and the resin protective layer 5 is kept airtight. With this configuration, the scintillator layer 4 is protected from moisture.

The sealing portion 12 has a sealing frame 13 and a sealing plate 14. The sealing frame 13 has a frame front surface 13a, a frame back surface 13b, and a frame wall portion 13c. The frame wall portion 13c connects the frame front surface 13a and the frame back surface 13b. The height of the frame wall portion 13c (that is, the length from the frame front surface 13a to the frame back surface 13b) is higher than the height from the protective layer back surface 5b to the scintillator layer back surface 4b. Therefore, a gap is formed between the back surface 4b of the scintillator layer and the sealing plate 14. The sealing frame 13 may be made of, for example, a resin material, a metal material, or a ceramic material. The sealing frame 13 may be solid or hollow. The frame front surface 13a and the plate back surface 14b, and the frame back surface 13b and the resin protective layer 5 may be bonded with an adhesive.

The sealing plate 14 is a plate material having a rectangular shape in a plan view. The sealing plate 14 has a plate surface 14a, a plate back surface 14b, and a plate side surface 14c. The plate back surface 14b is fixed to the frame surface 13a. The plate side surface 14c may be flush with the outer surface of the frame wall portion 13c. The sealing plate 14 may be made of, for example, a glass material, a metal material, a carbon material, or a barrier film. Aluminum is exemplified as a metal material. CFRP is exemplified as a carbon material. Examples of the barrier film include a laminate of an organic material layer (PET or PEN) and an inorganic material layer (SiN).

In the radiation detector 10, light is generated by the radiation incident on the scintillator layer 4, and the light is detected by the photoelectric conversion element 16 provided in the photodetection region S1. Here, the radiation detector 10 has a barrier layer 3 containing thallium iodide as a main component between the resin protective layer 5 and the scintillator layer 4. According to the barrier layer 3, it is possible to prevent the movement of water from the resin protective layer 5 to the scintillator layer 4. Therefore, since the deliquescent at the root of the scintillator layer 4 is suppressed, the deterioration of the characteristics of the radiation detector 10 can be suppressed.

Although the embodiment of the present invention has been described above, the embodiment is not limited to the above embodiment and may be implemented in various forms. Modifications 1 to 3 are modifications of the first embodiment. Further, the modified examples 4 to 9 are modified examples of the second embodiment.

<Modification example 1>
Part (a) of FIG. 3 shows the scintillator panel 1A according to the first modification. The scintillator panel 1A according to the first modification has a substrate 2A, a resin reflective layer 5A, a barrier layer 3, a scintillator layer 4, and a protective film 6. The constituent material of the substrate 2A is not particularly limited. The substrate 2A may be further composed of a glass material or a resin material in addition to the metal material and the carbon material. Examples of the metal material include aluminum and stainless steel (SUS). Examples of the carbon material include amorphous carbon and carbon fiber reinforced plastic (CFRP). Examples of the resin material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI). The resin reflective layer 5A reflects the light generated in the scintillator layer 4. The resin reflective layer 5A may be composed of, for example, a mixed material of a white pigment and a binder resin. Examples of the white pigment include alumina, titanium oxide, yttrium oxide, and zirconium oxide. The protective film 6 may be composed of polyparaxylylene. The protective film 6 is formed by a chemical vapor deposition method (CVD method).

<Modification 2>
Part (b) of FIG. 3 shows the scintillator panel 1B according to the second modification. The scintillator panel 1B according to the second modification has a substrate 2, an inorganic reflective layer 8, a resin protective layer 5, a barrier layer 3, a scintillator layer 4, and a protective film 6. That is, the scintillator panel 1B according to the second modification is the scintillator panel 1 according to the first embodiment to which the inorganic reflective layer 8 is added. The inorganic reflective layer 8 is formed between the substrate 2 and the resin protective layer 5. Specifically, the inorganic reflective layer 8 has a reflective layer surface 8a, a reflective layer back surface 8b, and a reflective layer side surface 8c. Then, the reflective layer surface 8a faces the protective layer back surface 5b. The back surface 8b of the reflective layer faces the surface surface 2a of the substrate. The inorganic reflective layer 8 may be made of, for example, a metal material. Examples of the metal material include aluminum and silver. Further, the inorganic reflective layer 8 may be a dielectric multilayer film. The dielectric multilayer film is a laminated film of _{silicon oxide (SiO 2} ) and titanium oxide (TiO _2). Examples of the resin protective layer 5 include polyimide (PI) and polyparaxylylene. According to the scintillator panel 1B, the inorganic reflective layer 8 can reflect the light generated in the scintillator layer 4. Further, a resin protective layer 5 is formed between the scintillator layer 4 and the inorganic reflective layer 8. According to the resin protective layer 5, the direct contact of the inorganic reflective layer 8 made of a metal material with the scintillator layer 4 is hindered. Therefore, it is possible to suppress the occurrence of corrosion of the inorganic reflective layer 8 due to the direct contact of the inorganic reflective layer 8 with the scintillator layer 4. Further, when the inorganic reflective layer 8 is made of a dielectric multilayer film, the resin protective layer 5 can suppress the occurrence of corrosion of the metal substrate when the dielectric multilayer film has pinholes.

<Modification example 3>
Part (a) of FIG. 4 shows the scintillator panel 1C according to the third modification. The scintillator panel 1C has a substrate 2B, a resin reflective layer 5A, a barrier layer 3, a scintillator layer 4, and a resin film 9. The substrate 2B is made of a thin glass material (for example, a thickness of 150 μm or less) or a carbon material such as CFRP. Such a substrate 2B has a property of being easily warped. Therefore, the resin film 9 is formed in order to suppress the warp of the substrate 2B when the scintillator layer is formed. Specifically, the resin film 9 is formed on the entire surface of the back surface 2b of the substrate 2B. The resin film 9 is a sheet member made of a resin material, and the sheet member may be attached to the back surface 2b of the substrate. Further, the resin film 9 may be formed by applying a resin material and then drying it. According to this configuration, the occurrence of warpage of the substrate 2B can be suppressed.

<Modification example 4>
Part (b) of FIG. 4 shows the radiation detector 10A according to the modified example 4. The radiation detector 10A has a sealing portion 12A different from that of the radiation detector 10 according to the second embodiment. The configurations of the other barrier layer 3, the scintillator layer 4, the resin protective layer 5, and the sensor panel 11 are the same as those of the radiation detector 10 according to the second embodiment. The sealing portion 12A includes a sealing plate 14 and a sealing frame 13A, and the sealing frame 13A further includes an inner sealing frame 17 and an outer sealing frame 18. That is, the sealing frame 13 has a double structure. The inner sealing frame 17 may be made of, for example, a resin material. Further, the outer sealing frame 18 may be made of, for example, a coating layer formed of an inorganic material or an inorganic solid material such as a glass rod. According to this configuration, the scintillator layer 4 can be suitably protected from moisture.

<Modification 5>
Part (a) of FIG. 5 shows the radiation detector 10B according to the modified example 5. The radiation detector 10B does not have a sealing portion 12 with respect to the radiation detector 10 according to the second embodiment, and has a protective film 6A instead of the sealing portion 12. The configurations of the other barrier layer 3, the scintillator layer 4, and the sensor panel 11 are the same as those of the radiation detector 10 according to the second embodiment. The protective film 6A covers the back surface 5b of the protective layer, the side surface 3c of the barrier layer, the side surface 4c of the scintillator layer, and the back surface 4b of the scintillator layer. According to this configuration, the protective film 6A can protect the scintillator layer 4A from moisture. The protective film 6A can be selected from the same materials as the protective film 6.

<Modification 6>
Part (b) of FIG. 5 shows the radiation detector 10C according to the modified example 6. The radiation detector 10C is obtained by further adding a sealing frame 13B to the radiation detector 10B according to the modified example 5. Therefore, the scintillator layer 4, the barrier layer 3, the resin protective layer 5, the sensor panel 11, and the protective film 6A are the same as the radiation detector 10B according to the modified example 5. The sealing frame 13B is formed so as to close the joint portion between the resin protective layer 5 and the protective film 6A. Therefore, the sealing frame 13B is formed along the outer edge of the protective film 6A when viewed in a plan view from the thickness direction. The sealing frame 13B may be made of, for example, a UV curable resin. According to this configuration, the intrusion of moisture from the joint portion between the sensor panel 11 and the protective film 6A is suppressed, so that the moisture resistance can be further improved.

<Modification 7>
Part (a) of FIG. 6 shows the radiation detector 10D according to the modified example 7. The radiation detector 10D does not have the sealing portion 12 of the radiation detector 10 according to the second embodiment, and has a sealing sheet 12B instead of the sealing portion 12. The configurations of the other barrier layer 3, the scintillator layer 4, the resin protective layer 5, and the sensor panel 11 are the same as those of the radiation detector 10 according to the second embodiment. The sealing sheet 12B has a rectangular shape, a polygonal shape, or a circular shape when viewed in a plan view in the thickness direction. The sealing sheet 12B may be made of, for example, a metal sheet such as a metal foil or an aluminum sheet, or a barrier film. The sealing sheet 12B covers the scintillator layer 4 and the barrier layer 3. Specifically, it covers a part of the back surface 4b of the scintillator layer, the side surface 4c of the scintillator layer, the side surface 3c of the barrier layer, and the back surface 5b of the protective layer. That is, when viewed in a plan view, the sealing sheet 12B is larger than the scintillator layer 4 and the barrier layer 3. Then, the outer peripheral edge 12a of the sealing sheet 12B is adhered to the back surface 5b of the protective layer by the adhesive 15. Therefore, the sealing sheet 12B and the resin protective layer 5 form an airtight region for accommodating the scintillator layer 4 and the barrier layer 3. Therefore, the scintillator layer 4 can be protected from moisture. The adhesive 15 may contain a filler material. This filler material has a particle size less than the thickness of the adhesive layer.

<Modification 8>
Part (b) of FIG. 6 shows the radiation detector 10E according to the modified example 8. The radiation detector 10E has a sealing frame 12C having a structure different from that of the sealing sheet 12B according to the modified example 7. The sealing frame 12C has a box shape and has an opening on the bottom surface. That is, the sealing sheet 12B according to the modified example 7 has flexibility, but the sealing frame 12C according to the modified example 8 is different in that it maintains a predetermined shape and is hard. Therefore, the sealing frame 12C may be made of, for example, a glass material, a metal material, or a carbon material. The bottom surface of the sealing frame 12C is adhered to the back surface 5b of the protective layer by the adhesive 15. According to this configuration, since the scintillator layer 4 is arranged in the airtight region formed by the sealing frame 12C and the resin protective layer 5, the scintillator layer 4 can be protected from moisture. Further, since the sealing frame 12C is hard, the scintillator layer 4 can be mechanically protected.

<Modification example 9>
Part (a) of FIG. 7 shows the radiation detector 10F according to the modified example 9. The radiation detector 10F has a barrier layer 3A, a scintillator layer 4A, and a resin protective layer 5B, which are different from the radiation detector 10 according to the second embodiment. The barrier layer 3A has a barrier layer surface 3a, a barrier layer back surface 3b, and a barrier layer side surface 3c. The scintillator layer 4A has a scintillator layer surface 4a, a scintillator layer back surface 4b, and a scintillator layer side surface 4c. The resin protective layer 5B has a protective layer surface 5a, a protective layer back surface 5b, and a protective layer side surface 5c. The single configuration of the sensor panel 11 is the same as that of the radiation detector 10 according to the second embodiment. The scintillator layer 4A is formed on one side surface of the sensor panel 11 so as to protrude from the light detection region S1. Specifically, first, the resin protective layer 5B is formed on the light detection region S1 and one peripheral region S2a. Next, the barrier layer 3A covers the light detection region S1, one panel side surface 11c, and the peripheral region S2a between the light detection region S1 and one panel side surface 11c so as to cover the resin protective layer 5B. Formed on top. Then, the scintillator layer 4A is formed on the entire surface of the barrier layer 3A so as to cover the barrier layer 3A. The radiation detector 10F having this configuration can be suitably used as a radiation detector for mammography by arranging, for example, a side formed so that the scintillator layer 4A protrudes from the photodetection region S1 on the chest wall side.

<Modification example 10>
Part (b) of FIG. 7 shows the radiation detector 10G according to the modified example 10. The radiation detector 10G according to the modified example 10 has a substrate 2, a resin protective layer 5, a barrier layer 3, a scintillator layer 4, and a sensor panel 11.

In this radiation detector 10G, the scintillator layer surface 4a is attached to the sensor panel 11 so as to face the panel surface 11a. According to this configuration, the exposed region S3 on the substrate surface 2a also faces the peripheral region S2 on the panel surface 11a. The protective layer surface 5a is separated from the panel surface 11a by the heights of the scintillator layer 4 and the barrier layer 3. Therefore, the sealing frame 13 is sandwiched between the protective layer surface 5a and the panel surface 11a. The sealing frame 13 and the resin protective layer 5 are fixed to each other by adhesion. Similarly, the sealing frame 13 and the sensor panel 11 are fixed to each other by adhesion (when the sealing frame 13 is adhesive, they are adhered by bonding, and when the sealing frame 13 is non-adhesive, an adhesive is provided at the interface). .. According to this configuration, the substrate 2 having the resin protective layer 5 can function as a growth substrate for the barrier layer 3 and the scintillator layer 4 and as a sealing plate in the radiation detector 10G. Therefore, the number of parts constituting the radiation detector 10G can be reduced.

<Experimental example>
In the experimental example, the effect of improving the moisture resistance of the barrier layer was confirmed. Moisture resistance as used in this experimental example refers to the relationship between the time of exposure to an environment having a predetermined humidity and the degree of change in resolution indicated by the scintillator panel. That is, high humidity resistance means that the degree of decrease in resolution indicated by the scintillator panel is small even when exposed to a humidity environment for a long time. On the contrary, low humidity resistance means that the resolution of the scintillator panel is greatly reduced when exposed to a humidity environment for a long time.

In the experimental example, first, three test pieces (scintillator panels) were prepared. Each test piece has a scintillator layer and a substrate. Each scintillator layer contains CsI as a main component and has a thickness of 600 micrometers. The first and second test pieces have a barrier layer containing TlI as a main component between the substrate and the scintillator layer. On the other hand, the third test piece does not have a barrier layer. That is, the third test piece is a comparative example in which the scintillator layer is directly formed on the substrate. The substrate of the first test piece is an organic substrate containing an organic material as a main component. That is, the first test piece corresponds to the scintillator panel according to the reference example. In the second test piece, a resin protective film containing an organic material as a main component was formed on an aluminum substrate. That is, the second test piece corresponds to the scintillator panel according to the first embodiment. The substrate of the third specimen is the same as the substrate of the second specimen.

In short, the configurations of the first to third test pieces are as follows.
First test piece: Substrate made of organic material, barrier layer, scintillator layer.
Second test piece: a substrate having an organic layer, a barrier layer, and a scintillator layer.
Third specimen: a substrate with an organic layer, a scintillator layer (without a barrier layer).

Next, the respective resolutions of the first to third test pieces were obtained. This resolution was used as a reference value. Next, the first to third test pieces were installed in an environmental tester having a temperature of 40 ° C. and a humidity of 90%. Next, the resolution was obtained for each test piece every predetermined time from the start of installation. Then, the ratio of the resolution obtained for each predetermined time to the resolution which is the reference value was calculated. That is, the relative value with respect to the resolution before installation in the environmental tester was obtained. For example, when the relative value is 100%, the resolution obtained after the lapse of a predetermined time has not changed with respect to the resolution before installation in the environmental tester, indicating that the performance has not deteriorated. Therefore, it is shown that the characteristics of the scintillator panel decrease as the relative value decreases.

The graph shown in FIG. 8 shows the relationship between the time of exposure to the environment (horizontal axis) and the relative value (vertical axis). The resolution of the first test piece was measured 1 hour, 72 hours, and 405 hours after the start of installation. The respective results are shown as plots P1a, P1b, P1c. The resolution of the second test piece was measured 1 hour, 20.5 hours, 84 hours, and 253 hours after the start of installation. The respective results are shown as plots P2a, P2b, P2c, P2d. The resolution of the third test piece was measured 1 hour, 24 hours, 71 hours, and 311 hours after the start of installation. The respective results are shown as plots P3a, P3b, P3c, P3d.

When each plot was confirmed, among the first to third test specimens, the performance deterioration of the third test specimen (plots P3a, P3b, P3c, P3d) having no barrier layer was the largest. That is, in the third test piece, it is considered that the performance deteriorated because the water permeated from the organic layer into the scintillator layer and the deliquescent of the scintillator layer proceeded with the passage of time. On the other hand, the relative values of the first and second test pieces (plots P1a, P1b, P1c, plots P2a, P2b, P2c, P2d) tended to decrease as time passed. However, the degree of decrease in the relative value indicated by the first and second specimens was clearly suppressed more than the degree of decrease in the relative value indicated by the third specimen. Therefore, it was found that the deterioration of the characteristics of the scintillator panel can be suppressed by providing the barrier layer containing TlI as a main component. That is, it was found that the barrier layer containing TlI as a main component can contribute to the improvement of the moisture resistance of the scintillator panel.

1,1A, 1B, 1C ... scintillator panel, 2,2A, 2B ... substrate, 2a ... substrate surface, 2b ... substrate back surface, 2c ... substrate side surface, 3,3A ... barrier layer, 3a ... barrier layer surface, 3b ... barrier Layer back surface, 3c ... Barrier layer side surface, 4, 4A ... Scintillator layer, 4a ... Scintillator layer surface, 4b ... Scintillator layer back surface, 4c ... Scintillator layer side surface, 5, 5B ... Resin protective layer, 5A ... Resin reflection layer, 5a ... Protective layer front surface, 5b ... Protective layer back surface, 5c ... Protective layer side surface, 6, 6A ... Protective film, 7 ... Laminate, 8 ... Inorganic reflective layer, 8a ... Reflective layer surface, 8b ... Reflective layer back surface, 8c ... Reflective layer Side surface, 9 ... Resin film, 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G ... Radiation detector, 11 ... Sensor panel, 11a ... Panel surface, 11b ... Panel back surface, 11c ... Panel side surface, 12, 12A ... Sealing part, 12a ... Outer peripheral edge, 12B ... Sealing sheet, 12C ... Sealing frame, 13, 13A, 13B ... Sealing frame, 13a ... Frame surface, 13b ... Frame back surface, 13c ... Frame wall part, 14 ... Sealing plate, 14a ... Plate front surface, 14b ... Plate back surface, 14c ... Plate side surface, 15 ... Adhesive, 16 ... Photoelectric conversion element, 17 ... Inner sealing frame, 18 ... Outer sealing frame, S1 ... Light detection area, S2 ... peripheral area, S2a ... peripheral area, S3 ... exposed area.

Claims (5)

A sensor substrate containing organic materials as the main component,
A resin protective layer formed on the sensor substrate and made of an organic material,
A barrier layer formed on the resin protective layer and containing thallium iodide as a main component,
A scintillator layer formed on the barrier layer and composed of a plurality of columnar crystals containing cesium iodide to which thallium is added as a main component is provided.
The sensor substrate is a radiation detector having a photodetector surface provided with a photoelectric conversion element that receives light generated in the scintillator layer. The radiation detector according to claim 1, wherein the organic material contained in the sensor substrate as a main component is any one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and polyimide (PI). The organic material forming the resin protective layer according to claim 1 or 2, which comprises any one of a xylylene-based resin, an acrylic resin, a silicone-based resin, a polyimide, a polyester-based resin, a siloxane resin, and an epoxy resin. Radiation detector. The radiation detector according to any one of claims 1 to 3, further comprising a protective film that covers the main surface of the resin protective layer, the side surface of the scintillator layer, and the main surface of the scintillator layer. The radiation detector according to claim 4, wherein the protective film is formed of polyparaxylylene.

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