Scintillator structure and X-ray detector

Abstract

To improve the reliability of scintillator structures. [Solution] The scintillator structure for X-ray detection that constitutes the X-ray detector includes a resin and a phosphor. The phosphor includes gadolinium sulfide. The resin is an epoxy resin comprising a main component, a curing agent, and a curing catalyst. The curing agent is a phthalic anhydride-based curing agent. The resin has an isocyanurate ring as its backbone, and after irradiation with X-rays at a dose of 100 kGy, the total light transmittance of the resin for light with a wavelength of 542 nm is 80% or more.

Description

Technical Field

[0001] The present invention relates to a scintillator structure, and more particularly to a technique effective when applied to a scintillator structure having a plurality of cells each containing a resin and a phosphor.

Background Art

[0002] Japanese Patent Laid-Open No. 63-100391 (Patent Document 1) describes a technique related to a phosphor molded body containing a bisphenol A type epoxy resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0006] Furthermore, when the scintillator is constructed from "GOS" alone, "GOS" is made of ceramic. On the other hand, as will be described later, it is also being considered to construct the scintillator from a mixture of "GOS" and resin, in which case "GOS" is made of powder. Therefore, in this specification, unless it is necessary to specifically indicate ceramic or powder, it will simply be referred to as "GOS". Conversely, when it is necessary to specify ceramic, it will be called "GOS" ceramic. On the other hand, when it is necessary to specify powder, it will be called "GOS" powder.

[0007] While "GOS" has the advantage of higher visible light emission output than cadmium tungstate (CdWO4), it has a higher manufacturing cost.

[0008] Therefore, in order to reduce the manufacturing cost of scintillator structures, the use of a mixture of "GOS" powder and resin as the scintillator is being considered.

[0009] In this regard, improving reliability is a high-priority requirement for scintillator structures. This is because improving the reliability of the scintillator structure can extend the lifespan of the radiation detector. Therefore, scintillators are required to have high radiation resistance in order to improve reliability. In particular, as mentioned above, when the scintillator is composed of a mixture of "GOS" powder and resin, it is desirable that the resin does not deteriorate or change in quality when irradiated with radiation.

[0010] The objective of this invention is to improve the reliability of scintillator structures. [Means for solving the problem]

[0011] In one embodiment, the scintillator structure comprises a plurality of cells and a reflective layer covering the plurality of cells. Here, each of the plurality of cells contains a resin and a phosphor, and the resin has a reduction rate of less than 8% in total light transmittance for light with a wavelength of 542 nm after irradiation with X-rays at a dose of 100 kGy. [Effects of the Invention]

[0012] According to one embodiment, the reliability of the scintillator structure can be improved. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of an X-ray detector. [Figure 2] This is a flowchart illustrating the manufacturing process of scintillator structures. [Figure 3] This diagram schematically shows the process from the dicing process to the reflective material coating process. [Modes for carrying out the invention]

[0014] In all the drawings for explaining the embodiments, the same members are generally denoted by the same reference numerals, and repeated explanations thereof are omitted. Note that, in order to make the drawings easy to understand, hatching may be added even to a plan view.

[0015] <Overview of X-ray Detector> FIG. 1 is a diagram schematically showing an X-ray detector.

[0016] In FIG. 1, the X-ray detector 100 has a scintillator structure 10 and a light receiving element 20. The scintillator structure 10 is composed of a plurality of scintillators 11 that generate visible light from the X-rays incident on the X-ray detector 100, and a reflective layer 12 that covers each of these plurality of scintillators 11. On the other hand, the light receiving element 20 has a function of generating a current from the visible light generated by the scintillator 11, and is composed of, for example, a photoelectric conversion element typified by a photodiode. This light receiving element 20 is provided, for example, on a support 30 and is provided corresponding to each of the plurality of scintillators 11.

[0017] The scintillator 11 has a function of absorbing X-rays and generating visible light, and is composed of a phosphor 11a and a resin 11b. Here, in this specification, a material obtained by mixing the "GOS" powder constituting the phosphor 11a and the resin 11b may also be referred to as "resin GOS". That is, the scintillator 11 in the present embodiment is composed of "resin GOS". The phosphor 11a is a gadolinium oxysulfide containing praseodymium, terbium, etc., and the resin 11b is, for example, an epoxy resin. The reflective layer 12 is composed of a resin 12b containing reflective particles 12a made of titanium oxide.

[0018] In recent years, as shown in FIG. 1, in the scintillator structure 10, the scintillator 11 is divided into a plurality of cells (CL). That is, from the viewpoint of improving the resolution of an X-ray image, the scintillator 11 is divided into a plurality of cells CL in accordance with each of the plurality of light-receiving elements 20 (arraying of the scintillator 11). Thus, the scintillator structure 10 includes a plurality of cells CL and a reflective layer 12 covering the plurality of cells CL. Specifically, the upper surface and the four side surfaces of the cell CL are covered with the reflective layer 12. On the other hand, since the lower surface of the cell CL needs to be in contact with the light-receiving element 20, it is not covered with the reflective layer 12.

[0019] The X-ray detector configured as described above operates as follows.

[0020] That is, when X-rays enter the scintillator 11 of the scintillator structure 10, electrons in the phosphor 11a constituting the scintillator 11 receive the energy of the X-rays and transition from the ground state to the excited state. Thereafter, the excited electrons transition to the ground state. At this time, visible light corresponding to the energy difference between the excited state and the ground state is emitted. By such a mechanism, the scintillator 11 absorbs X-rays and generates visible light.

[0021] Then, a part of the visible light generated from the scintillator 11 directly enters the light-receiving element 20, and another part of the visible light generated from the scintillator 11 is condensed on the light-receiving element 20 while being repeatedly reflected by the reflective layer 12 covering the scintillator 11. Subsequently, for example, when visible light enters the light-receiving element 20 composed of a photodiode, electrons in the semiconductor material constituting the photodiode are excited from the valence band to the conduction band by the energy of this visible light. As a result, a current caused by the electrons excited to the conduction band flows through the photodiode. Then, an X-ray image is acquired based on the current output from the photodiode. In this way, according to the X-ray detector 100, an X-ray image can be acquired.

[0022] For example, as shown in Figure 1, the scintillator structure 10 is composed of a rectangular parallelepiped scintillator 11 and a reflective layer 12 covering the scintillator 11. Here, the rectangular parallelepiped scintillator 11 is formed through processing processes such as dicing and grinding, so a processed surface is formed on the surface of the rectangular parallelepiped. In other words, a "processed surface" refers to a surface that has been mechanically processed. Specifically, a "processed surface" includes a surface ground with a grinding wheel when performing workpiece thickness adjustment, or a surface cut with a slicing blade when performing dicing.

[0023] For example, in a scintillator 11 using "resin GOS," the "processed surface" is defined as a surface where the resin is exposed and the "GOS" powder has been fractured are mixed. For example, Figure 1 schematically shows a scintillator 11 using "resin GOS" where the interface between the scintillator 11 and the reflective layer 12 is the "processed surface." In this case, it can be seen that the "processed surface" contains a mixture of areas where the resin 11b is cut and areas where the phosphor 11a ("GOS" powder) is fractured. The X-ray detector 100 is constructed in this manner.

[0024] <Reasons for adopting "Resin GOS"> As described above, in this embodiment, "resin GOS" is used as the scintillator 11. The reason for this will be explained below.

[0025] For example, cadmium tungstate (hereinafter referred to as "CWO") is used as the scintillator 11 that makes up the scintillator structure 10, but this "CWO" contains cadmium, which is a substance subject to the RoHS Directive / REACH Regulation. For this reason, "GOS" ceramic has been used as a substitute for "CWO" which contains cadmium as the scintillator 11. While this "GOS" ceramic has the advantage of higher visible light emission output compared to "CWO", it has the disadvantage of higher manufacturing costs.

[0026] Therefore, from the perspective of reducing manufacturing costs, instead of the "GOS" ceramic, the scintillator 11 was replaced with "Resin GO," which is a mixture of a resin made of epoxy resin and "GOS" powder. The adoption of "S" is being considered. In other words, in order to suppress the increase in manufacturing costs due to "GOS" ceramic, the cheaper "resin GOS" is being considered. There is a movement involved in using the intilizer 11.

[0027] Here, "resin GOS" includes "first resin GOS," which is a mixture of epoxy resin and "GOS" powder,.

[0028] Furthermore, both the "first resin GOS" and the "second resin GOS" have the advantage of higher luminescence output compared to "CWO". In addition, the "first resin GOS" has the advantage of having afterglow characteristics equivalent to those of "CWO". In other words, the performance of the scintillator structure 10 requires not only high luminescence output but also good afterglow characteristics.

[0029] Next, let's explain the afterglow characteristics. The scintillator 11 that makes up the scintillator structure 10 is a material that generates visible light when irradiated with X-rays. The mechanism by which the scintillator 11 generates visible light when irradiated with X-rays is as follows.

[0030] In other words, when X-rays are irradiated onto the scintillator 11, electrons within the scintillator 11 receive energy from the X-rays and transition from a low-energy ground state to a high-energy excited state. Then, the electrons in the excited state transition back to the low-energy ground state. At this time, most of the excited electrons immediately transition back to the ground state. On the other hand, some of the excited electrons transition back to the ground state after a certain amount of time has elapsed.

[0031] The visible light generated by the transition from the excited state to the ground state of electrons that occurs after a certain amount of time has elapsed is called afterglow. In other words, afterglow is visible light generated because the transition from the excited state to the ground state occurs a certain amount of time after the X-ray irradiation. A large afterglow means that the intensity of the visible light generated remains high for a certain amount of time after the X-ray irradiation. In this case, the afterglow generated by the previous X-ray irradiation will remain until the next X-ray irradiation, and this remaining afterglow will become noise. For this reason, a small afterglow is desirable. In other words, good afterglow characteristics mean that the afterglow is small. In this respect, the afterglow characteristics of "GOS No. 1 Resin" are equivalent to those of "CWO".

[0032] Therefore, "resin GOS" has the following advantages compared to "CWO," making it an excellent scintillator 11 that can balance performance and manufacturing cost. (1) "Resin GOS" has a higher luminescence output compared to "CWO". (2) The afterglow characteristics of "GOS first resin" are equivalent to those of "CWO". (3) Cadmium is not used in "Resin GOS". (4) "Resin GOS" has lower manufacturing costs compared to "CWO".

[0033] Furthermore, while cesium iodide (CsI) is used as scintillator 11, "resin GOS" has the following advantages compared to "CsI". (1) "Second resin GOS" has better X-ray stopping characteristics compared to "CsI". (2) The afterglow characteristics of "Second Resin GOS" are approximately 1 / 70th of those of "CsI". (3) "Resin GOS" is a stable substance that does not deliquesce.

[0034] Furthermore, "resin GOS" has the following advantages compared to "GOS" ceramic. Specifically, "resin GOS" and "GOS" ceramic contain heavy metals such as "Gd," "Ga," or "Bi." These heavy metals are relatively expensive, and there are concerns about their adverse effects on living organisms and the environment if they leak out. Therefore, it is desirable that the amount of heavy metals contained in the scintillator 11 be as small as possible. In this regard, "resin GOS," which is composed of a mixture of "GOS" powder and resin, uses less "GOS" than bulk "GOS" ceramic. This means that with "resin GOS," it is possible to construct a scintillator 11 with a lower heavy metal content than with "GOS" ceramic. From this, it can be said that "resin GOS" is superior to "GOS" ceramic in that it can provide a scintillator 11 with a low heavy metal content.

[0035] Based on the above, "resin GOS" is considered a promising scintillator 11 that can achieve both good performance and low manufacturing costs.

[0036] <Specific materials> Next, we will describe the specific materials of the constituent elements that make up the scintillator structure 10.

[0037] <<Phosphor 11a>> The phosphor 11a used in this embodiment is composed of, for example, gadolinium sulfide or gadolinium-aluminum-gallium garnet (GGAG). For example, the composition of "Gd2O2S" obtained by activating gadolium sulfide with at least one selected from praseodium (Pr), cerium (Ce), or terbium (Tb) is It possesses. On the other hand, "GGAG" is activated with at least one of the following elements, such as cerium (Ce) or praseodymium (Pr) (Gd 1-x Lu x ) 3+a (Ga u Al 1-u ) 5-a O 12The main composition is (x=0~0.5, u=0.2~0.6, a=-0.05~0.15). However, the phosphor 11a is not limited to a specific composition.

[0038] <<Resin 11b and Resin 12b>> Resins 11b and 12b are made of materials that are resistant to deterioration when irradiated with radiation. The materials of these resins 11b and 12b are characteristic features of this embodiment, and these characteristics will be described later.

[0039] <<Reflective particle 12a>> Examples of constituent materials for the reflective particles 12a include white particles such as "TiO2" (titanium oxide), "Al2O3" (aluminum oxide), and "ZrO2" (zirconium oxide). Here, the reflective particles 12a can be, for example, a mixture of bulk or powder and resin. In particular, reflective particles 12a made of "rutile-type TiO2" are desirable particles because they have excellent light reflection efficiency. From the viewpoint of improving the light reception efficiency of the photodetector 20, the light reflectance of the reflective particles 12a is preferably 80% or more, and furthermore, it is desirable that the light reflectance of the reflective particles 12a be 90% or more.

[0040] <<Other additives>> The reflective material constituting the scintillator 11 and the reflective layer 12 may contain other additives in addition to the components described above. For example, it is desirable to include a curing catalyst to shorten the curing time of the resin.

[0041] <Consideration of improvements> For example, epoxy resin is used as the resin contained in "Resin GOS". This epoxy resin contains at least a main component and a curing agent as constituent materials. For example, bisphenol A type epoxy resin is often used as the main component, and an amine-based curing agent is often used as the curing agent. However, the inventors have newly discovered that when a general epoxy resin is used as the resin constituting "Resin GOS", with bisphenol A type epoxy resin as the main component and an amine-based curing agent as the curing agent, it deteriorates and discolors when repeatedly exposed to radiation (X-rays) over a long period of time.

[0042] Furthermore, the discoloration of a translucent resin means that light absorption increases, which in turn means that the light transmittance decreases. As a result, light generated from a scintillator made of "resin GOS" has difficulty reaching the photodetector (photodiode), leading to a decrease in the detection performance of the X-ray detector.

[0043] In other words, the inventors have found that using a general epoxy resin, primarily composed of bisphenol A type epoxy resin and using an amine-based curing agent, as the resin constituting "Resin GOS" makes it difficult to achieve stable detection performance over a long period of time in an X-ray detector. To put it another way, the inventors have gained novel knowledge that using the above-mentioned general epoxy resin as the resin constituting "Resin GOS" makes it difficult to ensure the reliability of the X-ray detector over a long period of time.

[0044] Therefore, based on the novel findings described above, in order to ensure the reliability of the X-ray detector over a long period of time, it is desirable to use a resin that does not easily discolor even when exposed to X-rays for a long period of time as the resin constituting the "resin GOS," instead of the general epoxy resin described above. Accordingly, the inventors have found a resin with excellent radiation resistance that does not easily discolor even when exposed to X-rays for a long period of time, and this point will be explained below.

[0045] <Features of the Embodiment> A key feature of this embodiment is that, as the epoxy resin containing at least a main component and a curing agent, the epoxy resin described below is used for both the resin contained in "Resin GOS" and the resin contained in the reflector. This ensures the reliability of the X-ray detector, which uses the scintillator structure in this embodiment as a component, over a long period of time.

[0046] <<Main ingredient>> The main component is a triazine derivative epoxy resin. An example of a triazine derivative epoxy resin is 1,3,5-triazine derivative epoxy resin. Furthermore, it is desirable that the 1,3,5-triazine derivative epoxy resin is an epoxy resin having an "isocyanurate ring". This is because epoxy resins having an "isocyanurate ring" in their backbone have excellent stability against radiation and heat, and are resistant to discoloration.

[0047] In particular, epoxy resins having an "isocyanurate ring" as their backbone are desirable to have multiple epoxy groups per isocyanurate ring from the viewpoint of suppressing discoloration. For example, it is desirable to have three epoxy groups per isocyanurate ring. This is because when multiple epoxy groups are bonded to an isocyanurate ring, it becomes highly reactive and has robust stability, making it less susceptible to discoloration even when irradiated with X-rays.

[0048] Examples of epoxy resins having an "isocyanurate ring" include 1,3,5-triglycidyl isocyanurate, tris(2,3-epoxypropyl) isocyanurate, tris(α-methylglycidyl) isocyanurate, tris(1-methyl-2,3-epoxypropyl) isocyanurate, 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and 1,3,5-tris(3,4-epoxypropyl) Examples include xybutyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1,3,5-tris(5,6-epoxybutyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and tris{2,2-bis[(oxiran-2-ylmethoxy)methyl]butyl}-3,3´,3´´-[1,3,5-triazine-2,4,6(1H,3H,5H)-trione-1,3,5-triyl]tripropanoate.

[0049] Commercially available triazine derivative epoxy resins (epoxy resins having an "isocyanurate ring") include, for example, Nissan Chemical Industries' "TEPIC-G," "TEPIC-S," "TEPIC-SS," "TEPIC-HP," "TEPIC-L," and "TEPIC-PAS," which are commercially available 1,3,5-tris(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione products. Examples include Nissan Chemical Industries' "TEPIC-VL," a commercially available product; Nissan Chemical Industries' "TEPIC-FL," a commercially available product of 1,3,5-tris(5,6-epoxybutyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; and Nissan Chemical Industries' "TEPIC-UC," a commercially available product of tris{2,2-bis[(oxiran-2-ylmethoxy)methyl]butyl}-3,3´,3´´-[1,3,5-triazine-2,4,6(1H,3H,5H)-trione-1,3,5-triyl]tripropanoate.

[0050] <<Hardening agent>> To suppress discoloration caused by X-ray irradiation, it is desirable to use a curing agent that does not contain carbon double bonds. This is because carbon double bonds have weaker bond strength than carbon single bonds, and X-ray irradiation easily breaks the carbon double bonds, resulting in discoloration of the material. For example, acid anhydride-based curing agents, such as phthalic anhydride-based curing agents, can be used as curing agents. In particular, from the viewpoint of effectively suppressing discoloration caused by X-ray irradiation, one type of polybasic acid carboxylic acid anhydride that is non-aromatic and chemically does not contain carbon double bonds may be used, or two or more types may be used in combination.

[0051] Specifically, examples of curing agents include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, and dodecenyl succinic anhydride. In particular, the use of methylhexahydrophthalic anhydride is desirable.

[0052] Specific examples of acid anhydride compounds include "Ricacid TH," "TH-1A," "HH," "MH," "MH-700," and "MH-700G" (all manufactured by Shin-Nippon Rika Co., Ltd.).

[0053] <<Curing catalyst>> While a curing catalyst is not an essential component, its addition is desirable from the standpoint of accelerating the curing reaction of the main component. As the curing catalyst, it is desirable to use an organophosphorus compound that does not easily discolor when irradiated with X-rays. Specifically, examples of curing catalysts include tetrabutylphosphonium 0,0-diethylphosphodithioate (Hishiko-Rin PX-4ET, manufactured by Nippon Chemical Industries, Ltd.) and methyltributylphosphonium dimethyl phosphate (Hishiko-Rin PX-4MP, manufactured by Nippon Chemical Industries, Ltd.).

[0054] <Verification of effectiveness> This section explains the verification results showing that the "Resin GOS" containing the aforementioned triazine derivative epoxy resin can suppress the decrease in "total light transmittance" even after X-ray irradiation.

[0055] In this specification, "total light transmittance" is used with the intention of including transmitted light that has been scattered within the scintillator and whose transmission direction has shifted from the incident direction. In other words, "total light transmittance" represents the transmittance when it includes not only transmitted light that travels in a straight line from the incident direction, but also transmitted light that has been scattered within the scintillator and whose transmission direction has shifted from the straight line. The reason for using "total light transmittance" in this way is that, in a scintillator structure, the cell made of scintillator is covered with a reflective layer, and as a result, the light scattered within the cell is repeatedly reflected and finally incident on the photodetector placed on the bottom surface of the cell. Therefore, the light scattered within the cell also contributes to the detection of radiation by the photodetector. In short, "total light transmittance" is used to evaluate by taking into account all transmitted light that contributes to the detection of radiation.

[0056] Furthermore, in this specification, "total light transmittance" refers to the total light transmittance measured using light with a wavelength of 542 nm for a sample with a thickness of 1.5 mm. For measuring "light transmittance," a sample with dimensions of 15mm x 15mm x 1.5mm (length x width x thickness) was prepared, and the surface of the sample was polished to a mirror finish. The "total light transmittance" is being measured.

[0057] [Table 1]

[0058] Table 1 shows the verification results for Sample A and Sample B.

[0059] In Table 1, Sample A represents the "resin GOS" in this embodiment, which uses a triazine derivative epoxy resin as the main component and "Me-HHPA" (material name: methylhexahydrophthalic anhydride, product name: "Ricacid MH-T" manufactured by Shin Nippon Rika Co., Ltd.) as the curing agent. On the other hand, Sample B represents the "resin GOS" in related technology, which uses a bisphenol A type epoxy resin as the main component and an amine compound as the curing agent.

[0060] As shown in Table 1, in Sample A, the initial "total light transmittance (0 kGy)" before X-ray irradiation was "91.358", while the "total light transmittance (100 kGy)" after X-ray irradiation with a dose of 100 kGy was "87.425", and the "difference in total light transmittance" was "3.933".

[0061] In contrast, in sample B, the initial "total light transmittance (0 kGy)" before X-ray irradiation was "90.902", while the "total light transmittance (100 kGy)" after X-ray irradiation with a dose of 100 kGy was "78.361", resulting in a "difference in total light transmittance" of "12.541".

[0062] As a result, the "total light transmittance reduction rate" for sample A was "4.5%", while the "total light transmittance reduction rate" for sample B was "16%". Therefore, the results in Table 1 confirm that the "resin GOS" in this embodiment can suppress the decrease in "total light transmittance" even after X-ray irradiation.

[0063] In particular, as shown in Table 1, the "resin GOS" in this embodiment achieves excellent performance, with an initial total light transmittance of 90% or more for light with a wavelength of 542 nm before irradiation with X-rays, and a decrease in total light transmittance for light with a wavelength of 542 nm of less than 8% after irradiation with X-rays at a dose of 100 kGy. Therefore, by using the "resin GOS" in this embodiment, a scintillator structure with high emission output and excellent radiation resistance can be provided. As a result, by using the scintillator structure in this embodiment, a highly reliable X-ray detector that can maintain stable detection performance over a long period of time can be provided.

[0064] In particular, the verification results in this embodiment have significant technical importance because they confirm the suppression of the decrease in total light transmittance of "Resin GOS" containing triazine derivative epoxy resin, even after irradiation with a high dose of X-rays of 100 kGy.

[0065] For example, even if a material is known to be radiation-resistant, if it is unknown how much X-ray radiation it can withstand, it is impossible to say whether the reliability of the X-ray detector can be ensured over a long period of time. In other words, simply because a material is qualitatively radiation-resistant does not necessarily guarantee the reliability of an X-ray detector that uses high doses of X-rays over a long period of time. In this regard, this embodiment shows verification results after irradiation with a high dose of X-rays of 100 kGy, and based on these verification results, it is stated that the radiation resistance of "Resin GOS" containing triazine derivative epoxy resin is excellent. The significant technical aspect here is that it is verified that "Resin GOS" containing triazine derivative epoxy resin can suppress the decrease in "total light transmittance" even after irradiation with 100 kGy of X-rays. This is because, since the verification results are based on data from a high dose of 100 kGy, it provides highly reliable data as a basis for guaranteeing the reliability of X-ray detectors that use high doses of X-rays over a long period of time.

[0066] <Method for manufacturing scintillator structures> Next, we will explain the manufacturing method of the scintillator structure.

[0067] Figure 2 is a flowchart illustrating the manufacturing process of the scintillator structure.

[0068] In Figure 2, first, predetermined amounts of raw material powder and flux components are weighed and mixed (S101). This mixture is then packed into a crucible and fired in an atmospheric furnace at 1300°C to 1400°C for 7 to 9 hours (S102) to produce "GOS" powder. Next, flux components and impurities contained in the "GOS" powder are removed by washing with hydrochloric acid and hot water (S103). Then, epoxy resin is dropped onto the "GOS" powder to impregnate it with epoxy resin (S104). After the epoxy resin has hardened (S105), the epoxy resin that has not been mixed with the "GOS" powder is removed (S106). This allows for the formation of a scintillator made of "resin GOS".

[0069] Next, the substrate on which the scintillator is formed is diced to separate it into multiple cells (S107). The separated cells are rearranged (S108), and then a reflective material is applied to cover the cells (S109). After the unnecessary parts of the scintillator structure 10A are cut off (S110), the scintillator structures that have passed inspection are shipped (S111).

[0070] Figure 3 is a schematic diagram showing the process from the dicing process to the reflective material coating process.

[0071] As shown in Figure 3, the substrate WF on which a scintillator made of "resin GOS" is formed is diced, thereby separating the substrate WF into multiple cells CL. The separated cells CL are then rearranged, for example, into a line. Subsequently, an outer frame FR is positioned to enclose the rearranged cells CL. Next, a reflective material, for example, an epoxy resin containing titanium dioxide, is applied to cover the cells CL arranged within the outer frame FR. After that, the outer frame FR is removed. In this way, the scintillator structure 10A is manufactured.

[0072] Although Figure 3 illustrates a linear scintillator structure 10A using 1 × n cells as an example, the technical concept in this embodiment is not limited to this and can also be applied to array-shaped (matrix-shaped) scintillator structures using n × n cells, for example.

[0073] <Examples> The following describes detailed verification results supporting the effectiveness of the technical concept in this embodiment, based on the examples. Note that the technical concept in this embodiment is not limited to these examples.

[0074] [Table 2]

[0075] Table 2 shows the evaluation results based on the sample.

[0076] First, let me explain the sample.

[0077] <<Materials>> "GOS" powder: Gadolinium sulfide (Gd2O2S) Main component: Example 1 Triazine derivative epoxy resin (TEPIC-PAS B22) Example 2: Triazine derivative epoxy resin (TEPIC-VL) Example 3: Triazine derivative epoxy resin (TEPIC-FL) Comparative example: Hydrogenated bisphenol A diglycidyl ether epoxy resin (Epiclon 840 (DIC)) Hardener: Acid anhydride (Licacid MH-T) Curing catalyst: Organophosphorus compound (Hishiko-Phosphorus PX-4ET)

[0078] <<Sample Preparation>> Samples were prepared using the formulations shown in Table 2 (stoichiometric amount:equivalent ratio) under primary curing conditions (90°C, 15 hours) and secondary curing conditions (120°C, 2.5 hours).

[0079] The dimensions of this sample are 15mm x 15mm x 1.5mm (length x width x thickness), and the surface of the sample has a mirror finish.

[0080] <<Evaluation Method>> After irradiating the sample with 100 kGy of X-rays, the "total light transmittance" for light with a wavelength of 542 nm was measured using a JASCO V-570 ultraviolet-visible-near-infrared spectrophotometer.

[0081] Here, an integrating sphere apparatus and a reflector were used to collect diffusely transmitted light and linearly transmitted light at a detector and measure the total light transmittance.

[0082] <<Evaluation Results>> As shown in Table 2, the initial "total light transmittance" before X-ray irradiation was 90% or higher in all of Examples 1 to 3 and the Comparative Example. On the other hand, when examining the "total light transmittance" after irradiation with a dose of 100 kGy of X-rays, Examples 1 to 3 showed values ​​of 80% or higher, while the Comparative Example did not reach 80%. Converting these results to a "total light transmittance reduction rate," Examples 1 to 3 showed a reduction rate of less than 5%, while the Comparative Example showed a reduction rate of 14% or more.

[0083] From the above, it can be seen that the "resin GOS" in Examples 1 to 3 can suppress the decrease in "total light transmittance" even after X-ray irradiation.

[0084] In particular, the results in Table 2 show that the "resin GOS" in Examples 1 to 3 achieves excellent performance, with an initial total light transmittance of 90% or more for light with a wavelength of 542 nm before X-ray irradiation, and a decrease in total light transmittance for light with a wavelength of 542 nm of less than 5% after irradiation with a dose of 100 kGy of X-rays. Therefore, by using the "resin GOS" in Examples 1 to 3, a scintillator structure with high emission output and excellent radiation resistance can be provided. Furthermore, by using this scintillator structure, a highly reliable X-ray detector that can maintain stable detection performance over a long period of time can be provided.

[0085] The present invention has been described in detail above based on its embodiments, but it goes without saying that the present invention is not limited to the above embodiments and can be modified in various ways without departing from its essence. [Explanation of Symbols]

[0086] 10 Scintillator Structure 11 Scintillator 11a Phosphor 11b Resin 12 Reflective layer 12a reflective particles 12b Resin 20 Photodetectors 30 Support 100 X-ray detectors CL Cell

Claims

1. A scintillator structure for X-ray detection applications, The scintillator structure comprises a resin and a phosphor. The phosphor comprises a gadolinium sulfide activated with at least one selected from praseodium (Pr) or terbium (Tb). The aforementioned resin is an epoxy resin comprising a main component, a curing agent, and a curing catalyst. The curing agent is non-aromatic and does not chemically contain a carbon double bond. The curing agent is a phthalic anhydride-based curing agent. Scintillator structure.

2. A scintillator structure for X-ray detection applications, The scintillator structure comprises a resin and a phosphor. The phosphor comprises a gadolinium sulfide activated with at least one selected from praseodium (Pr) or terbium (Tb). The aforementioned resin is an epoxy resin comprising a main component, a curing agent, and a curing catalyst. The curing agent is non-aromatic and does not chemically contain a carbon double bond. The curing catalyst is an organophosphorus compound. Scintillator structure.

3. A scintillator structure for X-ray detection applications, The scintillator structure comprises a resin and a phosphor. The aforementioned resin is an epoxy resin comprising a main component, a curing agent, and a curing catalyst. The aforementioned resin has an isocyanurate ring as its backbone. Scintillator structure.

4. A scintillator structure according to any one of claims 1 to 3, The aforementioned resin is rutile-type TiO ２ Further includes reflective particles consisting of Scintillator structure.

5. A scintillator structure according to any one of claims 1 to 3, After irradiation with X-rays at a dose of 100 kGy, the total light transmittance of the resin to light with a wavelength of 542 nm is 80% or more. Scintillator structure.

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