Radiation imaging device, radiation imaging system, and method for manufacturing a radiation imaging device

Abstract

To provide a technique advantageous for suppressing a reduction in image quality.SOLUTION: A radiation imaging apparatus includes a sensor substrate and a scintillator, which are coupled to each other by a coupling member. The scintillator includes: a first surface opposed to the sensor substrate through the coupling member and covered with a first protective layer; a second surface arranged on a side opposed to the first surface and covered with a second protective layer; and a third surface connecting the first surface with the second surface and covered with a third protective layer. Each of the first protective layer, the second protective layer and the third protective layer is configured of one or more layers, and the number of layers of the first protective layer is equal to or less than the number of layers of each of the second protective layer and the third protective layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a radiation imaging apparatus, a radiation imaging system, and a method for manufacturing a radiation imaging apparatus. [Background Art]

[0002] Radiation imaging apparatuses are widely used in medical image diagnosis and non-destructive inspection. Patent Document 1 discloses that after a scintillator is formed on a substrate for scintillator formation, the formed scintillator is fixed to a sensor substrate, and then the substrate for scintillator formation is separated from the scintillator. According to Patent Document 1, since the substrate for scintillator formation is not used in the radiation imaging apparatus, a material suitable for forming the scintillator can be selected as the material of the substrate without considering radiation transmittance, light reflectivity, or the like. [Prior Art Document] [Patent Document]

[0003] [Patent Document 1] International Publication No. 2020 / 229499 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Since a scintillator may deliquesce due to moisture contained in ambient air, a protective layer is formed after the scintillator is formed. In the process disclosed in Patent Document 1, when the scintillator is formed, a protective layer can be formed on the upper surface and side surfaces of the scintillator. Further, when the substrate for scintillator formation is separated from the scintillator, a protective layer can be formed on the surface of the scintillator separated from the substrate for scintillator formation. If the number of protective layers arranged between the scintillator and the sensor substrate increases due to multiple formations of protective layers, light emitted by the scintillator may scatter in the protective layers, potentially leading to a decrease in the image quality of the obtained image.

[0005] The present invention aims to provide a technology that is advantageous in suppressing the degradation of image quality. [Means for solving the problem]

[0006] In view of the above problems, a radiation imaging apparatus according to an embodiment of the present invention is a radiation imaging apparatus in which a sensor substrate and a scintillator are coupled by a coupling member, wherein the scintillator comprises a first surface facing the sensor substrate via the coupling member and covered by a first protective layer, a second surface positioned on the opposite side of the first surface and covered by a second protective layer, and a third surface connecting the first surface and the second surface and covered by a third protective layer, wherein each of the first protective layer, the second protective layer and the third protective layer is composed of one or more layers, and the number of layers of the first protective layer is such that the second protective layer Layers Less than or equal to the number of layers Furthermore, the number of layers is less than that of the third protective layer, and the outermost layer of the third protective layer and the first protective layer are formed integrally. It is characterized by the following. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technology that is advantageous in suppressing the deterioration of image quality. [Brief explanation of the drawing]

[0008] [Figure 1] A cross-sectional view showing an example of the manufacturing process for the radiation imaging device of this embodiment. [Figure 2] A cross-sectional view showing an example of the manufacturing process for the radiation imaging device of this embodiment. [Figure 3] A cross-sectional view showing an example of the manufacturing process for the radiation imaging device of this embodiment. [Figure 4] This figure shows an example configuration of a radiation imaging system using the radiation imaging device of this embodiment. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] Furthermore, the radiation in this disclosure may include not only alpha rays, beta rays, and gamma rays, which are beams created by particles (including photons) emitted by radioactive decay, but also beams with energy of equal or greater magnitude, such as X-rays, particle beams, and cosmic rays.

[0011] Referring to Figures 1(a) to 1(d), a radiation imaging apparatus and a method for manufacturing a radiation imaging apparatus according to embodiments of the present disclosure will be described. Figures 1(a) to 1(d) are cross-sectional views showing examples of the manufacturing process for the radiation imaging apparatus 100 of the present disclosure.

[0012] As shown in Figure 1(d), the radiation imaging device 100 has a sensor substrate 330 and a scintillator 110 connected by a coupling member 130. Multiple pixels are arranged on the sensor substrate 330. Each of the multiple pixels is sensitive to light converted from radiation by the scintillator 110 and generates an electric charge corresponding to the incident light. Multiple pixels on the sensor substrate 330 may be arranged in rows and columns. The sensor substrate 330 may have a semiconductor layer such as silicon on which multiple pixels are arranged on an insulating base made of glass or the like. Alternatively, for example, a flexible resin base such as polyimide may be used for the sensor substrate 330. Alternatively, the sensor substrate 330 may have multiple pixels formed on a silicon substrate.

[0013] The scintillator 110 converts radiation incident on the scintillator 110 into light that is sensitive to pixels arranged on the sensor substrate 330. The scintillator 110 may have a needle-shaped crystalline structure containing an alkali metal halide compound. The scintillator 110 having a needle-shaped crystalline structure mainly composed of an alkali metal halide compound may be, for example, cesium iodide (CsI:Tl) with thallium added as an activator. However, it is not limited to this, and the scintillator 110 may also be sodium-activated cesium iodide (CsI:Na), cesium bromide (CsBr), etc. However, it is not limited to this, and other materials may be used. In the following explanation, it will be assumed that CsI:Tl is used for the scintillator 110.

[0014] Here, as shown in Figure 1(d), the surface of the scintillator 110 that faces the sensor substrate 330 via the coupling member 130 is called surface 111. The surface of the scintillator 110 that is located on the opposite side from surface 111 is called surface 112. Furthermore, the side surface of the scintillator 110 that connects surface 111 and surface 112 is called surface 113.

[0015] Surface 111 of the scintillator 110 is covered by protective layer 210. Surface 112 of the scintillator 110 is covered by protective layer 220. Surface 113 of the scintillator 110 is covered by protective layer 230. It can also be said that the scintillator 110 is sealed by protective layers 210, 220, and 230. Each of the protective layers 210, 220, and 230 is formed through a process described later and consists of one or more layers.

[0016] The bonding member 130 is a component such as an adhesive that bonds the sensor substrate 330 and the scintillator 110. Various resin materials can be used for the bonding member 130. For example, a thermoplastic resin may be used for the bonding member 130. For example, a hot melt resin such as a polyester-based, polyolefin-based, or polyamide-based resin may be used for the bonding member 130. For example, the sensor substrate 330 and the scintillator 110 can be bonded via the bonding member 130 by thermocompression bonding.

[0017] Next, a method for manufacturing the radiation imaging apparatus 100 will be described. First, as shown in FIG. 1(a), a substrate 310 is prepared. In the present embodiment, the substrate 310 used when forming the scintillator 110 is separated from the scintillator 110 in a subsequent process. Therefore, a material suitable for forming the scintillator 110 can be used for the substrate 310. Any material may be used for the substrate 310 as long as it can withstand the scintillator forming process, such as the temperature applied when forming the scintillator 110. For example, a resin material such as PET, polyurethane, polyimide, or polyamideimide may be used for the substrate 310. Alternatively, beryllium, magnesium, aluminum, titanium, iron, or an alloy containing any of these as a main component may be used for the substrate 310.

[0018] The scintillator 110 is formed on the substrate 310. The scintillator 110 may be formed on the substrate 310 by a vapor deposition method. Alternatively, the scintillator 110 may be formed by any method, such as a sublimation method, a plasma deposition method, a spray method, or growth in a liquid medium accompanied by solvent evaporation.

[0019] Subsequent to the step of forming the scintillator 110, a protective layer 201 is formed so as to cover the scintillator 110 disposed on the substrate 310. More specifically, the protective layer 201 is formed so as to cover the top surface and side surfaces of the scintillator 110 formed on the substrate 310. As shown in FIG. 1(d), in the radiation imaging apparatus 100, the protective layer 201 constitutes the layer in contact with the scintillator 110 among the protective layer 220 and the protective layer 230 that cover the surface 112 and the surface 113 of the scintillator 110.

[0020] For the protective layer 201, for example, a monomolecular layer containing silicon oxide, which is a polycondensate obtained by hydrolysis using a metal alkoxide such as ethyl silicate or methoxysilane as a raw material, may be used. Further, for example, for the protective layer 201, silicon oxide produced from a polysilazane-based inorganic polymer composed of silicon, nitrogen and hydrogen including perhydropolysilazane may be used as a raw material. Furthermore, for example, for the protective layer 201, polyparaxylene produced from parylene dimer as a raw material may be used. A material having moisture resistance is used for the protective layer 201. Further, the protective layer 201 may be a combination of two or more of the materials described above. By forming the protective layer 201 promptly after forming the scintillator 110, exposure of the scintillator 110 to the open air can be suppressed. Further, for example, the substrate 310 on which the scintillator 110 is formed may be transported from an apparatus for forming the scintillator 110 to an apparatus for forming the protective layer 201 in a vacuum or under an inert gas atmosphere, and the protective layer 201 may be formed there.

[0021] The protective layer 201 may be formed, for example, by a method using a liquid material such as spin coating, spray coating, dip coating, flow coating, or bar coating. Further, for example, the protective layer 201 may be formed by supplying a raw material gas through a vapor phase growth method. By selecting an appropriate method, it is possible to form the protective layer 201 having a desired thickness on the scintillator 110. With any of these methods, the raw material for the protective layer 201 can be uniformly supplied even when the substrate has a large area. If necessary, the chemical reaction may be promoted by raising the temperature or heating during or after the formation of the protective layer 201, or supplying water vapor in an amount that does not cause deliquescence of the columnar crystals of the scintillator 110.

[0022] The thickness of the protective layer 201 may be 1 / 50 or less of the columnar diameter of the columnar crystals of the scintillator 110. Alternatively, the thickness of the protective layer 201 (the layer in contact with the scintillator 110) may be 1 / 50 or less of the columnar diameter of the columnar crystals of the scintillator 110. If the protective layer 201 is thick, the gaps between the columnar crystals of the scintillator 110 may be filled, potentially causing light to be guided or scattered from one columnar crystal to another. This could result in a decrease in the spatial resolution of the radiation imaging device 100.

[0023] After the protective layer 201 is formed, the scintillator 110 is transferred to the substrate 320, as shown in Figure 1(b). First, a bonding process is performed to bond the scintillator 110 to the substrate 320 so that the scintillator 110 is positioned between the substrate 310 and the substrate 320. The scintillator 110 and the substrate 320 may be bonded via a bonding member 120 made of a resin material such as an adhesive. The bonding member 120 may be made of the same material as the bonding member 130 described above.

[0024] Next, a separation step is performed to separate the substrate 320 from the scintillator 110 bonded to the substrate 320. The separation step may be performed using chemical or mechanical methods. For example, the separation step may be performed by applying force to separate the substrate 310 from the substrate 320. In this case, the bonding force between the substrate 320 and the scintillator 110 (protective layer 201) via the bonding member 120 must be greater than the bonding force between the substrate 310 and the scintillator 110. Alternatively, for example, a step to weaken the bonding force between the substrate 310 and the scintillator 110 may be added before separating the substrate 310 from the scintillator 110. For example, the substrate 310 may be processed to weaken its adhesion to the scintillator 110 before the scintillator 110 is formed.

[0025] Once the separation process of the substrate 310 is complete, as shown in Figure 1(b), the surface of the scintillator 110 that was in contact with the substrate 310 is exposed, so it is necessary to prevent the scintillator 110 from being exposed to the outside air. For this reason, as shown in Figure 1(c), a protective layer 202 is formed to cover the scintillator 110 placed on the substrate 320. As shown in Figure 1(d), the protective layer 202 constitutes one of the protective layers 210 and 230 that cover the surfaces 111 and 113 of the scintillator 110 in the radiation imaging apparatus 100. The protective layer 202 may also constitute a part of the protective layer 220 by covering a part of the surface 112 of the scintillator 110.

[0026] The protective layer 202 may be formed using the same material as the protective layer 201. In this case, the protective layer 202 may be formed using the same method as the protective layer 201. By forming the protective layer 201 and the protective layer 202 using the same material and method, it becomes possible to share the forming equipment for the protective layers 201 and 202 in the manufacturing process of the radiation imaging device 100, thereby reducing manufacturing costs. However, this is not the only option, and the protective layer 201 and the protective layer 202 may be formed using different materials. Furthermore, the protective layer 201 and the protective layer 202 may be formed using different methods.

[0027] After forming the protective layer 202, the scintillator 110 is transferred to the sensor substrate 330, as shown in Figure 1(d). A bonding step is performed to bond the scintillator 110 to the sensor substrate 330 via a bonding member 130, so that the scintillator 110 is positioned between the substrate 320 and the sensor substrate 330. The radiation imaging device 100 is obtained by including the above steps. The substrate 320 does not undergo the process of forming the scintillator 110 as the substrate 310. Therefore, any suitable material that can be incorporated into the radiation imaging device 100 can be used as long as it can support the scintillator 110 in the steps shown in Figures 1(b) and 1(c). Thus, the substrate 320 may remain bonded to the scintillator 110, as shown in Figure 1(d). However, it is not limited to this, and the substrate 320 may be separated from the scintillator 110.

[0028] Here, we will explain the number of layers in the protective layers 210, 220, and 230 that cover the scintillator 110 of the radiation imaging device 100. As described above, the protective layer 210 that covers the surface 111 of the scintillator 110 facing the sensor substrate 330 is composed of one layer of protective layer 202. The protective layer 220 that covers the surface 112 of the scintillator 110 is composed of protective layer 201 (and the bonding member 120 and substrate 320). The protective layer 230 that covers the surface 113 of the scintillator 110 is composed of protective layer 201 and protective layer 202. In other words, the number of layers in protective layer 210 is less than or equal to the number of layers in protective layers 220 and 230, respectively.

[0029] As described above, if a protective layer is formed each time the surface of the scintillator 110 is exposed, the number of protective layers will increase due to the formation of multiple layers. When the number of protective layers increases, there is a possibility that the light generated by the scintillator 110 will be scattered at the interface between the protective layers. Also, when the number of protective layers increases, the thickness of the protective layers may increase. When the thickness of the protective layers increases, the distance between the scintillator 110 and the sensor substrate 330 increases, and there is a possibility that the light generated by the scintillator 110 will be scattered within the protective layer. If light is scattered in the protective layer, the image quality obtained by the radiation imaging device 100 may decrease. Therefore, by using the process described above, the number of protective layers placed between the scintillator 110 and the sensor substrate 330 is suppressed. This makes it possible to seal the scintillator 110 with a protective layer to increase reliability while suppressing the decrease in image quality obtained by the radiation imaging device 100.

[0030] In the process shown in Figures 1(a) to 1(d), protective layers are formed multiple times on the side surface (face 113) of the scintillator 110 (protective layers 201, 202). Therefore, the number of layers of protective layer 210 may be less than the number of layers of protective layer 230. Also, from the viewpoint of image quality obtained by the radiation imaging device 100, the thickness of protective layer 210 may be less than or equal to the thickness of protective layer 220 and protective layer 230, respectively. Furthermore, the thickness of protective layer 210 may be thinner than the thickness of protective layer 230.

[0031] Furthermore, in the process shown in Figures 1(a) to 1(d), the scintillator 110 formed on the substrate 310 is first transferred to the substrate 320, and then to the sensor substrate 330. However, it is not limited to this, and the substrate 320 may be the sensor substrate. In that case, the radiation imaging device 100 is obtained in the process shown in Figure 1(c). In this case, the scintillator 110 is coupled to the substrate 320 (sensor substrate) via the coupling member 120. Also, the surface of the scintillator 110 facing the substrate 320 (sensor substrate) via the coupling member 120 is covered with a protective layer 201. The surface of the scintillator 110 opposite to the surface facing the substrate 320 (sensor substrate) is covered with a protective layer 202. The sides of the scintillator 110 are covered with protective layers 201 and 202. In other words, even in this case, the number of protective layers covering the surface of the scintillator 110 facing the substrate 320 (sensor substrate) is less than or equal to the number of protective layers covering the other surfaces. As a result, the above-mentioned effect can be obtained even if the substrate 320 is a sensor substrate.

[0032] Next, a modified example of the manufacturing method of the radiation imaging apparatus 100 described above will be explained using Figures 2(a) to 2(f). The process shown in Figure 2(a) is the same as the process shown in Figure 1(a) described above. A scintillator 110 is formed on the substrate 310. Then, a protective layer 203 is formed so as to cover the scintillator 110 placed on the substrate 310. For example, the material described in the protective layer 201 described above may be used for the protective layer 203.

[0033] After the protective layer 203 is formed, a planarization process is performed to flatten the surface of the scintillator 110 opposite to the surface in contact with the substrate 310, as shown in Figure 2(b). During the formation of the scintillator 110, columnar crystals may grow abnormally, resulting in increased surface irregularities. The planarization process is performed to suppress surface irregularities of the scintillator 110. The planarization process may be carried out by applying pressure to the surface of the scintillator 110 using a flat plate or roller. Alternatively, for example, the planarization process may involve removing the abnormally grown portion of the columnar crystals of the scintillator 110 by cutting or other means. Any planarization method can be used as long as the surface roughness of the scintillator 110 is reduced.

[0034] As shown in Figure 2(b), the planarized surface of the scintillator 110 may be exposed by the planarization process. Therefore, after the planarization process, a layer formation process is performed to form a protective layer 204 so as to cover the scintillator 110 placed on the substrate 310, as shown in Figure 2(c). The protective layer 204 may be formed using the same material as the protective layer 203. In this case, the protective layer 204 may be formed using the same method as the protective layer 203. However, it is not limited to this, and the protective layer 203 and the protective layer 204 may be formed using different materials. Also, the protective layer 203 and the protective layer 204 may be formed using different methods.

[0035] After forming the protective layer 204, the radiation imaging device 100 may be manufactured by carrying out the steps shown in Figure 1(b) and subsequent steps described above. Alternatively, the radiation imaging device 100 may be manufactured using the steps described below.

[0036] After the protective layer 204 is formed, a bonding step is performed in which the scintillator 110 is bonded to the sensor substrate 330 via the bonding member 130, as shown in Figure 2(d). At this time, as shown in Figure 2(d), the bonding member 130 is positioned so that a portion of the scintillator 110 is bonded to the sensor substrate 330.

[0037] Next, a separation process is performed to separate the scintillator 110 bonded to the sensor substrate 330 from the substrate 310. In this separation process, as shown in Figure 2(e), the portion of the scintillator 110 bonded to the sensor substrate 330 is separated from the substrate 310, while the other portion of the scintillator 110 not bonded to the sensor substrate 330 remains on the substrate 310.

[0038] As shown in Figure 2(e), the central portion of the scintillator 110 formed on the substrate 310 can be transferred to the sensor substrate 330. This prevents the use of portions of the scintillator 110 with reduced crystallinity or thinner film thickness in the outer edge of the scintillator 110 in the radiation imaging device 100. In this embodiment, a portion of the scintillator 110 formed on the substrate 310 is transferred to the sensor substrate 330, which is smaller than the substrate 310. As a result, narrowing the bezel, which increases the proportion of the scintillator 110 on the sensor substrate 330, can be easily achieved.

[0039] After separating a portion of the scintillator 110 from the substrate 310, the surface of the scintillator 110 that was in contact with the substrate 310 is exposed. Therefore, as shown in Figure 2(f), a protective layer 205 is formed to cover the scintillator 110 placed on the sensor substrate 330. The protective layer 205 may be formed using the same material as the protective layer 203. In this case, the protective layer 205 may be formed using the same method as the protective layer 203. Also, protective layers 203, 204, and 205 may be formed using the same material. In this case, protective layers 203, 204, and 205 may be formed using the same method. However, this is not limited to the above, and protective layers 203, 204, and 205 may be formed using different materials. Also, protective layers 203, 204, and 205 may be formed using different methods.

[0040] Including the above steps, the radiation imaging device 100 shown in Figure 2(f) is obtained. When using the steps shown in Figures 2(a) to 2(f), the protective layer 210 covering the surface 111 of the scintillator 110 facing the sensor substrate 330 is composed of protective layer 204. The protective layer 220 covering the surface 112 of the scintillator 110 opposite to surface 111 is composed of protective layer 205. The protective layer 230 covering the surface 113, which is the side surface connecting surfaces 111 and 112 of the scintillator 110, is composed of protective layer 203 and protective layer 205. In other words, in this embodiment as well, the number of layers in protective layer 210 is less than or equal to the number of layers in protective layer 220 and protective layer 230, respectively. Also, the number of layers in protective layer 210 is less than the number of layers in protective layer 230. Furthermore, the thickness of the protective layer 210 may be less than or equal to the thickness of the protective layers 220 and 230, respectively, and the thickness of the protective layer 210 may be thinner than the thickness of the protective layer 230. As described above, by limiting the number of layers and thickness of the protective layer 210 placed between the scintillator 110 and the sensor substrate 330, scattering of light generated by the scintillator 110 within the protective layer 210 can be suppressed. As a result, the degradation of image quality obtained by the radiation imaging device 100 is suppressed.

[0041] Using Figures 3(a) to 3(c), a modified example of the manufacturing method of the radiation imaging device 100 described using Figures 2(a) to 2(f) will be explained. The process up to the step shown in Figure 2(c) is the same as described above. After forming the protective layer 204, in the step shown in Figure 2(d), the sensor substrate 330 and the scintillator 110 are bonded together. On the other hand, in the step shown in Figure 3(a), similar to the step described using Figure 1(b), the scintillator 110 is bonded to the substrate 320 via the bonding member 120, and then the scintillator 110 is separated from the substrate 310. At this time, a part of the surface of the scintillator 110 that was in contact with the substrate 310 may be removed. Generally, in the CsI deposition process, fine crystal nuclei are formed on the substrate in the initial stages of film formation, and columnar crystals grow on them. By removing the initial layer that is prone to light scattering in the early stages of growth of the scintillator 110 formed on the substrate 310, the properties of the scintillator 110 can be improved.

[0042] After the initial layer of scintillator 110 is removed, a protective layer 207 is formed as shown in Figure 3(b). The protective layer 207 may be formed using the same material as the protective layer 203. In this case, the protective layer 207 may be formed using the same method as the protective layer 203. Alternatively, protective layers 203, 204, and 207 may be formed using the same material. In this case, protective layers 203, 204, and 207 may be formed using the same method. However, the invention is not limited to these examples, and protective layers 203, 204, and 207 may be formed using different materials. Alternatively, protective layers 203, 204, and 207 may be formed using different methods.

[0043] After the protective layer 207 is formed, a bonding step is performed in which the scintillator 110 is bonded to the sensor substrate 330 via a bonding member 130, as shown in Figure 3(b). At this time, similar to the step shown in Figure 2(d), the bonding member 130 is positioned so that a portion of the scintillator 110 is bonded to the sensor substrate 330.

[0044] Next, as shown in Figure 3(c), the outer edge of the scintillator 110 and the substrate 320 are cut and removed using a rotary cutting machine or the like. As a result, as shown in Figure 3(c), the central portion of the scintillator 110 formed on the substrate 310 is transferred to the sensor substrate 330. This prevents the use of portions of the scintillator 110 with reduced crystallinity or thin film thickness in the outer edge from being used in the radiation imaging device 100. In this embodiment, a portion of the scintillator 110 formed on the substrate 310 is transferred to the sensor substrate 330, which is smaller than the substrate 310. As a result, narrowing the bezel, which increases the proportion of the scintillator 110 on the sensor substrate 330, can be easily achieved.

[0045] After the outer edge of the scintillator 110 is cut and removed, the cut surface of the scintillator 110 may be exposed. In Figure 3(c), the columnar crystals of the scintillator 110 are depicted as being covered by the protective layer 203, but this is because the outer edge of the scintillator 110 may be cut not only between the columnar crystals of the scintillator 110, but also in a way that cuts the columnar crystals. Therefore, as shown in Figure 3(c), the protective layer 208 is formed to cover the side surface (face 113) of the scintillator 110. In this embodiment, the central part of the scintillator 110 is transferred to the sensor substrate 330 by removing the outer edge of the scintillator 110 together with the substrate 320. However, this is not the only way, and a part of the scintillator 110 may be transferred to the sensor substrate 330 using a process such as the one shown in Figure 2(e) above. In that case, the protective layer 208 will cover not only face 113 but also face 112 in the radiation imaging device 100.

[0046] The protective layer 208 may be formed using the same material as the protective layer 203. In this case, the protective layer 208 may be formed using the same method as the protective layer 203. Also, protective layers 203, 204, 207, and 208 may be formed using the same material. In this case, protective layers 203, 204, 207, and 208 may be formed using the same method. However, the invention is not limited to these, and protective layers 203, 204, 207, and 208 may be formed using different materials. Also, protective layers 203, 204, 207, and 208 may be formed using different methods.

[0047] Including the above steps, the radiation imaging device 100 shown in Figure 3(c) is obtained. When using the steps shown in Figures 2(a) to 2(c) and Figures 3(a) to 3(c), the protective layer 210 covering the surface 111 of the scintillator 110 facing the sensor substrate 330 is composed of protective layer 207. The protective layer 220 covering the surface 112 of the scintillator 110 opposite to surface 111 is composed of protective layer 204. The protective layer 230 covering the surface 113, which is the side surface connecting surfaces 111 and 112 of the scintillator 110, is composed of protective layer 203 and protective layer 208. In other words, in this embodiment as well, the number of layers in protective layer 210 is less than or equal to the number of layers in protective layer 220 and protective layer 230, respectively. Also, the number of layers in protective layer 210 is less than the number of layers in protective layer 230. Furthermore, the thickness of the protective layer 210 may be less than or equal to the thickness of the protective layers 220 and 230, respectively, and the thickness of the protective layer 210 may be thinner than the thickness of the protective layer 230. Similar to the above configurations, by limiting the number of layers and thickness of the protective layer 210 placed between the scintillator 110 and the sensor substrate 330, scattering of light generated by the scintillator 110 within the protective layer 210 can be suppressed. As a result, the degradation of image quality obtained by the radiation imaging device 100 is suppressed.

[0048] Next, we will describe the examples.

[0049] Example 1 A radiation imaging device 100 was constructed as shown in Figure 1(d). CsI:Tl was formed as a scintillator 110 on a glass substrate 310. More specifically, a material supply source filled with cesium iodide as the deposition matrix material, a material supply source filled with thallium iodide as the deposition activator material, and the glass substrate 310 were placed inside the vacuum deposition apparatus. The inside of the deposition apparatus was evacuated to a vacuum of 0.01 Pa or less. Next, current was gradually passed through each material supply source to heat them, and when the set temperature was reached, the deposition of the scintillator 110 was started by opening a shutter provided between the substrate and the material supply source while rotating the substrate 310. The substrate temperature was gradually raised from 80°C to 160°C. While monitoring the progress of film deposition, the shutter was closed and the film deposition was terminated when the scintillator 110 had been deposited to the desired film thickness. After the substrate 310 and the material supply source were cooled to room temperature, ethyl silicate was quickly brought into contact with the scintillator 110 by vapor phase growth to form a protective layer 201.

[0050] Next, the scintillator 110 was bonded to the amorphous carbon substrate 320 using a resin adhesive as a bonding member 120. Then, the substrate 310 was separated from the scintillator 110 to form a protective layer 202. The protective layer 202 was formed by spray coating a solution raw material containing a small amount of perhydropolysilazane in a dibutyl ether solvent using a spray coating method, and drying it at 50°C for 3 hours. After the formation of the protective layer 202, the sensor substrate 330 equipped with an array of pixels (optical sensors) and the scintillator 110 with the protective layer 202 formed on it were bonded together using a resin adhesive as a bonding member 130 to obtain the radiation imaging device 100 shown in Figure 1(d).

[0051] Spatial resolution characteristics can be quantitatively compared by measuring the modulation transfer function (MTF). In the radiation imaging device 100 shown in Figure 1(d), images were acquired by irradiating the substrate 320 with X-rays conforming to the international standard RQA5 beam quality. The MTF(2) at a spatial frequency of 2 Lp / mm, which is an indicator of the spatial resolution of the radiation imaging device 100, was determined by the edge method using a tungsten knife edge. The device was stored in an environment of 25°C and 50% humidity, and the MTF was measured every few days. Comparing the initial MTF(2) value with that after 30 days, almost no degradation in spatial resolution was observed, indicating that high spatial resolution and moisture resistance can be achieved simultaneously. Furthermore, because the scintillator can be uniformly arranged up to the outer edge of the sensor substrate 330, the in-plane distribution of the obtained image was reduced, and the effect of narrowing the frame was confirmed.

[0052] Example 2 A radiation imaging device 100 was constructed as shown in Figure 3(c). CsI:Tl was used as the scintillator 110, as in Example 1. Next, ethyl silicate was contacted with the scintillator 110 by vapor phase growth to form a protective layer 201.

[0053] After the formation of the protective layer 201, the scintillator 110 was planarized by polishing the columnar crystals from the tip side to a thickness of 10 μm using a dry planar polishing apparatus. After planarizing the surface of the scintillator 110, methoxysilane was brought into contact with the planarized surface by vapor deposition to form the protective layer 204.

[0054] After the protective layer 204 was formed, the scintillator 110 was bonded to the aluminum substrate 320 using a resin adhesive as a bonding member 120. Next, the substrate 310 was separated from the scintillator 110. Since the surface of the scintillator 110 that had been in contact with the substrate 310 was exposed, a protective layer 207 was formed by contacting the scintillator 110, which was placed on the substrate 320, with methoxysilane using vapor phase growth.

[0055] After forming the protective layer 207, the sensor substrate 330, which has an array of pixels (optical sensors), and the scintillator 110 were bonded together using a resin adhesive as a bonding member 130. Next, the outer edge portion of the scintillator 110, including the aluminum substrate 320, was cut and removed using a rotary cutting machine. After removing the outer edge portion of the scintillator 110, the protective layer 208 was formed. The protective layer 205 was formed by applying a solution raw material containing a small amount of perhydropolysilazane in a dibutyl ether solvent using a spray coating method, and drying it at 50°C for 3 hours. Through these steps, a radiation imaging device 100 as shown in Figure 3(c) was obtained.

[0056] In the radiographic imaging device 100 shown in Figure 3(c), images were acquired by irradiating the substrate 320 with X-rays conforming to the international standard RQA5 beam quality. The MTF(2) at a spatial frequency of 2 Lp / mm, which is an indicator of the spatial resolution of the radiographic imaging device 100, was determined by the edge method using a tungsten knife edge. The device was stored in an environment of 25°C and 50% humidity, and MTF measurements were taken at regular intervals. Comparing the initial MTF(2) values ​​with those after 30 days, almost no degradation in spatial resolution was observed, indicating that high spatial resolution and moisture resistance could be achieved simultaneously. Furthermore, because the scintillator could be uniformly arranged up to the outer edge of the sensor substrate 330, the in-plane distribution of the obtained image was reduced, confirming the effect of narrowing the frame.

[0057] The following describes an exemplary radiation imaging system incorporating the above-described radiation imaging device 100 with reference to Figure 4. X-rays 6060 generated by the X-ray tube 6050, which is a radiation source for irradiating the radiation imaging device 100, pass through the chest 6062 of the patient or subject 6061 and enter the radiation imaging device 100. These incident X-rays contain information about the inside of the patient or subject 6061's body. In the radiation imaging device 100, the scintillator 110 emits light in response to the incidence of X-rays 6060, which is photoelectrically converted by a photoelectric conversion element to obtain electrical information. This information is converted digitally and output to the image processor 6070, which acts as a signal processing unit, and is processed as an image by the image processor 6070, which can then be observed on the display 6080, which acts as a display unit in the control room.

[0058] Furthermore, this information can be transmitted to a remote location by a transmission processing unit such as a telephone line 6090. This allows it to be displayed on a display unit 6081, such as a doctor's room in another location, enabling a doctor in that location to make a diagnosis. This information can also be recorded on a recording medium such as an optical disc, or on a film 6110, which is a recording medium, by a film processor 6100.

[0059] This disclosure includes the following methods for manufacturing a radiographic imaging device.

[0060] (Item 1) A radiation imaging device in which a sensor substrate and a scintillator are coupled by a coupling member, The scintillator comprises a first surface facing the sensor substrate via the coupling member and covered by a first protective layer, a second surface positioned on the opposite side of the first surface and covered by a second protective layer, and a third surface connecting the first surface and the second surface and covered by a third protective layer. Each of the first protective layer, the second protective layer, and the third protective layer is composed of one or more layers. A radiation imaging apparatus characterized in that the number of layers of the first protective layer is less than or equal to the number of layers of the second protective layer and the third protective layer, respectively.

[0061] (Item 2) The radiation imaging apparatus according to item 1, characterized in that the number of layers of the first protective layer is less than the number of layers of the third protective layer.

[0062] (Item 3) The radiation imaging apparatus according to item 1 or 2, characterized in that the thickness of the first protective layer is less than or equal to the thickness of the second protective layer and the third protective layer, respectively.

[0063] (Item 4) A radiation imaging apparatus according to any one of items 1 to 3, characterized in that the thickness of the first protective layer is thinner than the thickness of the third protective layer.

[0064] (Item 5) A radiation imaging apparatus according to any one of items 1 to 4, characterized in that the layers constituting each of the first protective layer, the second protective layer, and the third protective layer are composed of the same material.

[0065] (Item 6) The scintillator has columnar crystals, A radiation imaging apparatus according to any one of items 1 to 5, characterized in that the thickness of the third protective layer in contact with the scintillator is 1 / 50 or less of the columnar diameter of the columnar crystal.

[0066] (Item 7) A radiation imaging apparatus according to any one of items 1 to 6, characterized in that the scintillator contains an alkali metal halide compound.

[0067] (Item 8) A radiographic imaging device described in any one of items 1 through 7, A signal processing unit that processes signals output from the aforementioned radiation imaging device, A radiation imaging system characterized by having the following features.

[0068] (Item 9) A method for manufacturing a radiation imaging apparatus, comprising a sensor substrate and a scintillator sealed by a protective layer consisting of one or more layers, coupled by a coupling member, A scintillator formation step in which a scintillator is formed on a first substrate, A first layer formation step is to form a first protective layer so as to cover the scintillator placed on the first substrate, A first bonding step involves bonding the scintillator to the second substrate such that the scintillator is positioned between the first substrate and the second substrate, A first separation step of separating the first substrate from the scintillator bonded to the second substrate, A second layer formation step is performed after the first separation step, in which a second layer of the protective layer is formed so as to cover the scintillator placed on the second substrate, A manufacturing method characterized by including the following.

[0069] (Item 10) The manufacturing method according to item 9, characterized in that the second substrate is the sensor substrate.

[0070] (Item 11) The manufacturing method according to item 9, characterized in that, after the second layer formation step, the scintillator is bonded to the sensor substrate via a bonding member so that the scintillator is positioned between the second substrate and the sensor substrate.

[0071] (Item 12) In the first bonding step, a portion of the scintillator is bonded to the second substrate. In the first separation step, a portion of the scintillator is separated from the first substrate, and the other portion of the scintillator remains on the first substrate. The manufacturing method according to item 10, further comprising a third layer formation step, in which, after the first separation step, a third layer of the protective layer is formed so as to cover a portion of the scintillator disposed on the second substrate.

[0072] (Item 13) After the first layer formation step and before the first bonding step, A planarization step is performed to flatten the surface of the scintillator opposite to the surface in contact with the first substrate, A fourth layer formation step is performed after the planarization step, in which a fourth layer of the protective layer is formed so as to cover the scintillator placed on the first substrate, A manufacturing method according to any one of items 9 to 12, further comprising the above.

[0073] (Item 14) The manufacturing method according to any one of items 9 to 13, characterized in that the protective layer is formed using at least one method from spin coating, spray coating, dip coating, flow coating, bar coating, and vapor phase growth.

[0074] (Item 15) The manufacturing method according to item 14, characterized in that each of the layers constituting the protective layer is formed using the same method.

[0075] (Item 16) The manufacturing method according to any one of items 9 to 15, characterized in that the layers constituting the protective layer are each formed using the same material.

[0076] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0077] 100: Radiation imaging device, 110: Scintillator, 111, 112, 113: Surface, 130: Connecting member, 210, 220, 230: Protective layer, 330: Sensor substrate

Claims

1. A radiation imaging device in which a sensor substrate and a scintillator are coupled by a coupling member, The scintillator comprises a first surface facing the sensor substrate via the coupling member and covered by a first protective layer, a second surface positioned on the opposite side of the first surface and covered by a second protective layer, and a third surface connecting the first surface and the second surface and covered by a third protective layer. Each of the first protective layer, the second protective layer, and the third protective layer is composed of one or more layers. The number of layers of the first protective layer is less than or equal to the number of layers of the second protective layer, and less than the number of layers of the third protective layer. A radiation imaging apparatus characterized in that the outermost layer of the third protective layer and the first protective layer are formed integrally.

2. The radiation imaging apparatus according to claim 1, characterized in that the thickness of the first protective layer is less than or equal to the thickness of the second protective layer and the third protective layer, respectively.

3. The radiation imaging apparatus according to claim 1, characterized in that the thickness of the first protective layer is thinner than the thickness of the third protective layer.

4. The radiation imaging apparatus according to claim 1, characterized in that the layers constituting each of the first protective layer, the second protective layer, and the third protective layer are composed of the same material.

5. The scintillator has columnar crystals, The radiation imaging apparatus according to claim 1, characterized in that the thickness of the third protective layer in contact with the scintillator is 1 / 50 or less of the columnar diameter of the columnar crystal.

6. The radiation imaging apparatus according to claim 1, characterized in that the scintillator contains an alkali metal halide compound.

7. A radiation imaging apparatus according to any one of claims 1 to 6, A signal processing unit that processes signals output from the aforementioned radiation imaging device, A radiation imaging system characterized by having the following features.

8. A method for manufacturing a radiation imaging apparatus, comprising a sensor substrate and a scintillator sealed by a protective layer consisting of one or more layers, coupled by a coupling member, A scintillator formation step in which a scintillator is formed on a first substrate, A first layer forming step in which a first layer of the protective layer is formed so as to cover the scintillator placed on the first substrate, A first bonding step involves bonding the scintillator to the second substrate such that the scintillator is positioned between the first substrate and the second substrate, A first separation step of separating the first substrate from the scintillator bonded to the second substrate, A second layer formation step is performed after the first separation step, in which a second layer of the protective layer is formed so as to cover the scintillator placed on the second substrate, A second bonding step is performed in which, after the second layer formation step, the scintillator is bonded to the sensor substrate via a bonding member so that the scintillator is positioned between the second substrate and the sensor substrate, A manufacturing method characterized by including the following.

9. After the first layer formation step and before the first bonding step, A planarization step is performed to flatten the surface of the scintillator opposite to the surface in contact with the first substrate, A fourth layer formation step is performed after the planarization step, in which a fourth layer of the protective layer is formed so as to cover the scintillator placed on the first substrate, The manufacturing method according to claim 8, further comprising:

10. The manufacturing method according to claim 8, characterized in that the protective layer is formed using at least one of the following methods: spin coating, spray coating, dip coating, flow coating, bar coating, and vapor phase growth.

11. The manufacturing method according to claim 10, characterized in that each of the layers constituting the protective layer is formed using the same method.

12. The manufacturing method according to claim 8, characterized in that each of the layers constituting the protective layer is formed using the same material.

Images