JP2022147170A - Scintillator panel, radiation detector, and method of manufacturing radiation detector - Google Patents

Abstract

To provide a scintillator panel which enables easy and accurate alignment with a light-receiving substrate and offers a large detection area.SOLUTION: A scintillator panel 1 is provided, comprising a base material 2, grid-like partition walls 3 formed on the base material 2, and a phosphor layer 4 in cells partitioned by the partition walls 3, where the base material 2 has a total light transmittance of 30% or greater in the visible light region, and the partition walls 3 are formed all the way to an outermost periphery of the base material 2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a scintillator panel, a radiation detector, and a method for manufacturing a radiation detector.

Conventionally, film-based X-ray images have been widely used in medical practice. However, since X-ray images using film are analog image information, in recent years, digital methods such as computed radiography (CR), flat panel X-ray detectors (FPD), line sensors, etc. of radiation detectors are widely developed and manufactured.

For example, FPDs use a scintillator panel, which is a phosphor panel that converts radiation into visible light. The scintillator panel contains an X-ray phosphor such as cesium iodide (CsI), and the X-ray phosphor emits visible light in response to irradiated X-rays. , a charge-coupled device (CCD), a complementary metal oxide semiconductor (CMOS), or the like to convert X-ray information into digital image information. However, such an indirect conversion type detection device has a problem of low image resolution. This is because visible light is scattered by the phosphor itself when the X-ray phosphor emits light. In order to reduce the influence of this light scattering, methods have been proposed in which pixels partitioned by partition walls are filled with a phosphor (Patent Documents 1 to 4).

In order to maximize the advantages of a scintillator panel in which a pixel structure (cell) is formed by partition walls, photoelectric conversion elements arranged on a light-receiving substrate facing the scintillator panel and grid-shaped partition walls are formed. It is important to align and bond the cells without misalignment. If there is a positional deviation between the light emitting portion and the photoelectric conversion element due to scintillation, the partition wall that does not emit light will be present in the light receiving area, resulting in a decrease in the light receiving efficiency. In addition, since emitted light leaks into adjacent photoelectric conversion elements, there is a problem that high image sharpness cannot be obtained. In order to avoid this, a technique for aligning the scintillator panel and the photoelectric conversion element and adhering them accurately is required.

As a method for attaching them accurately, there is a method in which alignment marks are provided outside the respective display areas of the scintillator panel and the light-receiving substrate and aligned coaxially.

JP-A-5-60871 JP-A-5-188148 JP 2011-7552 A WO2012/161304

However, in order to form an alignment mark that maintains a high-precision positional relationship with the pixels in the display area, the method is limited to the photolithography method or the like, and the processing method is restricted. In addition, when the thickness of the partition wall is large, it is necessary to align the marks in a state that the marks are spaced apart from each other.

Further, when forming alignment marks on the scintillator panel positioned above the photoelectric conversion elements of the light-receiving substrate, there are areas in the scintillator panel that are not filled with phosphor. It could not be used as a valid display area of the device.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a scintillator panel that can be easily and accurately aligned with a light receiving substrate and has a wide detection area.

That is, the present invention has a base material, grid-like partition walls formed on the base material, and phosphor layers in cells partitioned by the partition walls, and the total light transmittance in the visible light region of the base material is 30% or more, and the partition wall is formed up to the outermost periphery of the base material.

Further, the present invention provides a pixel pitch of a scintillator panel having a substrate, grid-like partition walls formed on the substrate, phosphor layers in cells partitioned by the partition walls, and a light-receiving substrate having a photoelectric conversion element. A method for manufacturing a radiation detector, comprising a step of bonding the substrates of the scintillator panel in correspondence with the pixel pitch of the scintillator panel, wherein the total light transmittance in the visible light region of the base material of the scintillator panel is 30% or more, and the partition wall is the base material. A method for manufacturing a radiation detector formed up to the outermost periphery of a material.

According to the present invention, a scintillator panel having a pixel structure formed of partition walls and a light-receiving substrate having a photoelectric conversion element can be bonded together with their pixels aligned with each other with high precision. In addition, the pixels can be aligned and pasted together by a relatively simple method without providing a dedicated alignment mark, and the entire area where the photoelectric conversion elements are formed can be used as the effective display area of the radiation detector. can do. Further, by combining with a light-receiving substrate on which photoelectric conversion elements are arranged up to the edge, it is possible to connect a plurality of radiation detectors and expand the detection area.

1 is a perspective view schematically showing a scintillator panel of the present invention; FIG. (Light emitting surface is up) 1 is a perspective view schematically showing a scintillator panel of the present invention; FIG. (light-emitting surface down) 1 is a cross-sectional view schematically showing a radiation detector formed by laminating a scintillator panel and a light receiving substrate according to the present invention; FIG. 1 is a cross-sectional view schematically showing a radiation detector formed by laminating a scintillator panel and a light receiving substrate according to the present invention; FIG. It is the figure which illustrated the manufacturing process of the scintillator panel of this invention. FIG. 4 is a diagram schematically showing a state in which the scintillator panel and the light receiving substrate of the present invention are bonded together; It is a figure which illustrates the alignment method of the scintillator panel of this invention, and a light receiving substrate. It is a figure which illustrates the alignment method of the scintillator panel of this invention, and a light receiving substrate. FIG. 2 is a diagram showing a radiation detector in which a scintillator panel and a light receiving substrate of the present invention are bonded together to form a radiation detector. FIG. 4 is a diagram illustrating a method of cutting out a scintillator panel in an example;

(scintillator panel)
The present invention will be described below with reference to the drawings, but the present invention should not be construed as being limited to the aspects shown in the drawings.

Electromagnetic radiation such as X-rays and γ-rays and particle radiation such as α-rays, β-rays and neutron beams can be used as the radiation used to emit light from the scintillator panel. Among them, X-rays are preferably used.

FIG. 1 is a perspective view schematically showing the scintillator panel 1. FIG. Grid-like partition walls 3 are formed on a substrate 2, and phosphor layers 4 are arranged in spaces partitioned by the partition walls. The phosphor absorbs the energy of incident radiation such as X-rays and emits light in the range from ultraviolet light to infrared light, mainly visible light, upward on the plane of FIG. FIG. 2 shows the scintillator panel of FIG. 1 turned upside down. By using a transparent material as described later for the substrate 2, the pixel structure formed by the partition walls can be visually recognized from the substrate side. can.

FIG. 3 is a sectional view showing one end of a radiation detector in which the scintillator panel 1 and the light receiving substrate 5 are bonded together. Photoelectric conversion elements 6 are arranged on the light-receiving substrate, and an X-ray image can be obtained by receiving the light emitted from the phosphor which is excited by X-rays and converting it into electric charges. On the other hand, the partition walls of the scintillator panel are designed to have the same pitch as the pixel pitch of the photoelectric conversion elements or a pitch that is an integral multiple thereof, and are bonded together in correspondence with the pixel pitch of the photoelectric conversion elements of the light receiving substrate (the same as in FIG. 3). indicates the shape of the pitch). In this way, by matching the pixel pitches to each other over the entire detection surface, the light emitted in the pixels partitioned by the partition walls of the scintillator can be extracted to the light-receiving substrate side without diffusing into adjacent pixels, resulting in very clear and blurred images. It is possible to obtain an X-ray image with less

The pixel pitch is determined by the resolution required for the object to be imaged. The smaller the pitch, the higher the resolution, but the ratio of barrier ribs that do not contribute to light emission in the entire scintillator layer increases. On the other hand, if the pitch is too large, the resolution will decrease and it will be difficult to obtain a clear image. In general, a pixel pitch of about 70 to 800 μm is often used.

The scintillator panel 1 and the light-receiving substrate 5 are bonded together with a transparent adhesive or the like (not shown), and the thickness thereof should be as thin as possible. This is because if the adhesive is thick, the light emitted from the phosphor may diffuse out of the pixels through the adhesive, impairing the sharpness of the image.

(Base material)
The base material 2 is a support for the scintillator layer including the partition walls 3 and the phosphor layer 4 . In the present invention, alignment with the light-receiving substrate can be easily performed by visually recognizing the pixel structure of the scintillator layer from the substrate side, as will be described later. Therefore, it is necessary to use a transparent material for the base material. As an index of transparency, the total light transmittance in the visible light region (400 to 780 nm) is 30% or more, and the higher the better. If the total light transmittance is less than 30%, it becomes difficult to visually recognize the pixel structure through the substrate, and accurate alignment becomes difficult. It is preferable that the total light transmittance is 40% or more because the shading of the pixel structure can be clearly visually recognized. The total light transmittance is obtained by extracting the transmittance in the visible light region from the transmittance data of the substrate measured with a spectrophotometer.

A polymer film or glass can be used as the transparent material used for the base material. Since glass has a higher X-ray absorption rate than a polymer film, it is preferable to make the thickness as thin as possible when glass is used. However, if the thickness is too thin, the strength will decrease, making it difficult to function as a support.

From the viewpoint of strength and X-ray absorption, it is preferable to use a polymer film. Even when a polymer film is used, it is necessary to select an appropriate thickness because if the thickness is too thick, the X-ray absorbance increases. A thickness of about 25 to 200 μm is preferable in order to suppress X-ray absorption and obtain appropriate rigidity as a support.

When a polymer film is used as the base material, a material with a small coefficient of thermal expansion is preferable in consideration of dimensional changes due to temperature in order to minimize the dimensional difference from the light receiving substrate. A material with a small coefficient of thermal expansion has excellent dimensional stability even when passing through a thermal process such as a drying process during processing of a scintillator panel, and is easy to process. The coefficient of thermal expansion is preferably 30×10 ⁻⁶ /° C. or less. Specific examples include PET (polyester) film, PP (polypropylene) film, polyamide film, and polyimide film, but polyimide film is preferred because of its excellent dimensional stability. Among them, a polyimide film having a thickness of 25 to 200 μm is preferred.

(Partition wall)
The partition wall 3 is a partition that partitions the phosphor in correspondence with the photoelectric conversion element of the light receiving substrate, and various materials such as metal, resin, glass, and ceramic can be used.

The width of the partition wall is preferably 5 to 150 μm. When the width is 5 μm or more, the strength is improved and defects in the lattice pattern are less likely to occur. On the other hand, when the width is 150 μm or less, the amount of phosphors that can be arranged in the space partitioned by the partition walls is increased, and the emission luminance of the obtained scintillator panel is improved.

Since the thickness of the barrier ribs is approximately equal to the thickness of the phosphor layer, it can be optimized according to the energy band of the X-rays used. In general, in the field using low-energy X-rays (soft X-rays), the thickness is about 50 to 200 μm. Partition walls having a thickness of up to several millimeters are used.

The aspect ratio (thickness/width) of the partition walls is preferably 1.0 to 50.0. The larger the aspect ratio of the partition, the wider the space per pixel partitioned by the partition, and the more phosphors can be arranged. As a method for processing the partition walls, a method suitable for the material, such as etching, photolithography, dicing, screen printing, or sandblasting, may be used. Among them, photolithography using a photosensitive paste is preferable because a large area can be processed with high precision. The partition walls may be directly formed on the transparent base material, or a partition pattern formed in a separate process may be attached to the transparent base material.

It is important that the partition walls are formed up to the outermost periphery of the substrate. Since the partition walls are formed up to the outermost periphery of the base material, the detection area of the scintillator panel can be widened. Moreover, a detection area can be expanded by connecting a plurality of radiation detectors using this. Here, the “outermost peripheral portion” means a region within 20 μm from the edge of the substrate in the width direction and the depth direction. The distance from the edge of the base material to the edge of the partition wall should be less than the interval between adjacent photoelectric conversion elements of the light receiving substrate to be bonded (dead region. Although it depends on the light receiving substrate, specifically about 20 μm). is preferred, and it is more preferred that the edge of the substrate and the edge of the partition wall match. When aligning the light-receiving substrate and the scintillator panel, the outermost partition wall can be visually recognized through the base material having a total light transmittance of 30% or more in the visible light region as described above, and the light-receiving substrate side is based on this partition wall. This is for alignment with the photoelectric conversion element.

(reflective layer)
In order to efficiently reflect the visible light emitted by the phosphor layer 4 in the pixel toward the light receiving substrate, it is preferable to have a reflective layer 7 on the surface of the partition that is in contact with the phosphor layer. Moreover, in addition to the effect of increasing the reflectance of emitted light, there is also the effect of making it easier to visually recognize the arrangement of partition walls (pixels) from the substrate side. That is, by forming the reflective layer after forming the barrier ribs on the transparent substrate as described above, the light reflection of the reflective layer makes the positional relationship of the pixels in the scintillator panel clearer even when viewed from the substrate side. can be visually recognized. On the other hand, in the case where the barrier ribs are provided after the reflective layer is formed over the entire surface of the substrate, the position of the barrier ribs can be visually recognized even when viewed from the substrate side because the reflective layer is formed over the entire surface. becomes difficult.

The reflective layer is made of a material that has a higher reflectance than the barrier ribs and transmits X-rays. The reflective layer preferably has metal and/or white pigments. Au, Ag, Al, Ni and the like are used as metals, and metal oxides such as TiO ₂ , ZrO ₂ , Al ₂ O ₃ and ZnO are preferably used as white pigments. It is preferable that the reflective layer is formed on all the surfaces of the pixels partitioned by the partition wall that are in contact with the phosphor layer in order to improve the light extraction efficiency.

The thickness of the reflective layer should be as thin as possible within the range where the reflectance of the material used can be maximized. If it is too thick, the amount of phosphor in the pixel will decrease as in the case of the partition wall. In order to increase the reflection efficiency, the reflective layer may be formed so that the corners of the pixels on the substrate side are curved.

As a method for forming the reflective layer, in the case of metal, a film can be formed by vacuum deposition, plating, or the like. When a white pigment is used, a film can be formed by making the pigment into a paste, applying it inside the pixel by a vacuum printing method or a spray method, and drying it.

(Phosphor layer)
A phosphor layer is provided in each cell partitioned by the barrier ribs described above. As phosphors, CsI, _Gd2O2S , _Lu2O2S , _Y2O2S , _LaCl3 , _{LaBr3 , LaI3 , CeBr3} , _{CeI3 ,} which have a high conversion rate from radiation to visible light. , LuSiO ₅ or Ba(Br, F) can be used. An activator may be added to the phosphor in order to increase the luminous efficiency. Examples of activators include sodium (Na), indium (In), thallium (Tl), lithium (Li), potassium (K), rubidium (Rb), sodium (Na), terbinium (Tb), cerium (Ce ), europium (Eu), or praseodymium (Pr), but a phosphor obtained by adding Tb to Gd ₂ O ₂ S is preferable because of its high chemical stability and high luminous efficiency.

As a method of forming the phosphor layer, a method of filling the pixels with a paste prepared by mixing a powdery phosphor with a binder resin, a solvent, etc., and a method of pressing a sheet-like molded phosphor into the pixels by pressurizing it. A method of filling by The thickness of the phosphor is preferably formed so as not to exceed the thickness of the partition wall. If the thickness is greater than that of the barrier ribs, the phosphors cannot be completely separated by the barrier ribs, and the sharpness of the image that should be originally obtained tends to decrease.

(adhesion layer)
It is preferable that the substrate and the partition walls are adhered with a transparent resin. FIG. 4 shows an embodiment in which a transparent resin 8 is arranged as an adhesive layer between the base material 2 and the partition walls 3 . When the barrier ribs are not formed directly on the base material, the barrier ribs formed in a separate step and the base material can be bonded together by an adhesive layer. The adhesive layer used for bonding must be transparent in order to ensure pixel visibility from the substrate side. Moreover, it may be as thin as possible and have a total light transmittance of 30% or more in the visible region when bonded to the base material, similarly to the base material. As the transparent resin, a double-sided pressure-sensitive adhesive sheet and a heat- or ultraviolet-curing adhesive can be used. The double-sided pressure-sensitive adhesive sheet can be attached to the substrate by using a laminator or the like, and the barrier ribs can be laminated thereon in the same manner. In the case of an adhesive, it can be pasted together by applying the adhesive to one surface of the substrate, laminating the partition walls, and curing the adhesive. In either case, it is sufficient to use a material that is resistant to the environment of the post-process.

(Manufacturing method of scintillator panel)
FIG. 5 shows an example of a method for manufacturing a scintillator panel according to the present invention. Here, an example is shown in which only the partition pattern is peeled off from the substrate after the partition is formed by the photolithography method using a photosensitive glass paste, and is attached to the transparent substrate.

As a substrate for forming the barrier ribs, a glass substrate 9 is used so as to have resistance even at the firing temperature (approximately 500 to 600° C.) of the low softening point glass used for the glass paste.

First, as shown in FIG. 5A, a release layer 10 is formed on a glass substrate. The release layer is a layer for separating the partition wall pattern from the glass substrate in a post-process, and is mainly composed of a high softening point glass with a sintering temperature higher than that used for the partition walls. By setting the temperature in the firing process to be equal to or higher than the sintering temperature of the glass for partition walls and lower than or equal to the sintering temperature of the release layer glass, it is possible to peel off only the partition pattern after the baking process.

The release layer is formed by applying a photosensitive glass paste to one surface using a screen printer, die coater, or the like and drying it. The thickness of the dry film is preferably about 10 to 100 μm. If the thickness is less than 10 μm, the barrier ribs and the glass substrate are bound together, making it difficult to peel off.

Next, as shown in FIG. 5B, a partition layer 11 is formed on the release layer. It can be obtained by applying a photosensitive glass paste to one surface using a screen printer or die coater and drying it. Since the thickness of the partition layer is approximately the same as the thickness of the phosphor layer, the thickness is determined in consideration of the thickness required for the characteristics of the scintillator panel and the dimensional change due to firing shrinkage.

Next, as shown in FIG. 5(c), the partition wall layer is exposed with an exposure pattern corresponding to the pixel pitch of the light-receiving substrate to harden the photosensitive portion, and the soluble portion is washed away by development to form a grid pattern. is obtained. As for the size of the exposure pattern, it is preferable to design the pattern so that a plurality of surfaces can be obtained on the premise that the scintillator panel is cut into a predetermined size after formation. Since the width of the pattern approximately corresponds to the width of the partition, it is preferable to make it as narrow as possible.

Next, as shown in FIG. 5D, firing at the firing temperature described above burns off the organic components in the barrier rib layer and sinters the glass to obtain strong barrier ribs. Here, the peeling layer, in which the glass is not sintered, becomes powdery, and the grid-like partition walls can be peeled off using this as a starting point.

Next, as shown in FIG. 5(e), the separated partition wall pattern is adhered through the transparent resin 8 applied on the base material 2 and cured to bond them together.

Thereafter, as shown in FIG. 5(f), a reflective layer 7 is formed on the surfaces of the barrier ribs and the transparent resin using a sputtering device or the like. At this point, the adhesive portion of the partition wall and the reflective layer can be distinguished from each other when viewed from the substrate side, so the pixel position of the scintillator panel can be specified.

Next, as shown in FIG. 5(g), a scintillator panel is obtained by filling the phosphor layer 4 into the pixels partitioned by the partition walls. If the scintillator panel has a non-uniform shape around it, and if there is a portion that poses a quality problem, it is removed by cutting it with a dicing machine or the like.

Next, as shown in FIG. 5(h), it is cut according to the size of the corresponding light-receiving substrate. As a result, the peripheries of the base material and the partition walls are matched, and a scintillator panel in which the partition walls are formed up to the outermost periphery of the base material is obtained. The display area of the scintillator panel can be expanded by forming the pixel structure so that it extends to the outer periphery of the base material. If a plurality of scintillator panels can be cut out from one panel that is collectively formed in this way, production efficiency will be excellent.

(radiation detector)
A radiation detector of the present invention has a light receiving substrate having a photoelectric conversion element and the scintillator panel described above, and the pixel pitch of the photoelectric conversion element corresponds to the pixel pitch of the scintillator panel. By combining a radiation detector, a control circuit, a power supply, etc., the scintillator converts the strength of the X-rays that pass through the subject into visible light, and the visible light is further converted into electrical signals by photoelectric conversion elements to produce an X-ray image. Obtainable. It is common to select and bond scintillator panels according to the type of subject, the pixels of the light-receiving substrate, and the size of the substrate. Since a scintillator panel in which pixels are formed by partition walls is used, a sharp X-ray image can be obtained by laminating the panels in correspondence with the pixel pitch of the photoelectric conversion elements on the light receiving substrate.

Preferably, the radiation detector of the present invention is composed of two or more of the radiation detectors described above. The detection area can be expanded by connecting two or more radiation detectors.

(Method for manufacturing radiation detector)
A method for manufacturing a radiation detector according to the present invention comprises a scintillator panel having a base material, grid-like partition walls formed on the base material, phosphor layers in cells partitioned by the partition walls, and a pixel pitch of the scintillator panel. A method for manufacturing a radiation detector comprising a step of bonding a light receiving substrate having a conversion element in correspondence with a pixel pitch, wherein the base material of the scintillator panel has a total light transmittance of 30% or more in the visible light region. , the partition wall is formed up to the outermost periphery of the base material. A method for bonding the scintillator panel and the light receiving substrate together will be described in detail below.

FIG. 6 shows a schematic diagram of manufacturing a radiation detector by aligning and bonding the scintillator panel and the light receiving substrate of the present invention. A one-dimensional array of photoelectric conversion elements 6 was used as the light-receiving substrate 5 . FIG. 6 shows a leftmost portion of the entire object. A wiring 12, which is a lead electrode from the photoelectric conversion element, is arranged in the center of the element. For the scintillator panel, the pixel pitches of the photoelectric conversion elements and the partition walls are the same or integral multiples (FIG. 6 shows the form of the same pitch). A scintillator panel is prepared so that the light-emitting surface of the phosphor faces the detection side of the light-receiving substrate. They are laminated with a transparent adhesive or the like, aligned and pasted so that the pixels correspond to each other.

An example of alignment method is shown in FIG. Since the pixel structure of the scintillator panel can be visually recognized from the substrate side as described above, this is used for alignment. Although the positions of the photoelectric conversion elements are indicated by dotted lines in FIG. 7, they are actually hidden behind the scintillator panel and cannot be seen. Based on an image obtained by enlarging the end portion (the left end in FIG. 7) with a CCD camera or the like, it is possible to use, for example, the wiring 12 whose positional relationship with the photoelectric conversion element is determined in terms of design as a reference.

Since the wiring 12 is positioned at the center of each photoelectric conversion element in the X direction (horizontal direction in FIG. 7), the pixels in the X direction can be aligned by aligning them so that A=B in the drawing. In the Y direction (vertical direction in FIG. 7), assuming that the distance from each photoelectric conversion element to the bent portion of the wiring 12 is the same, C: the distance from the scintillator end surface to the partition pixel edge (the middle point of the partition width) (design value) and D: the distance from the bent portion of the wiring to the element (design value), and E: the distance from the bent portion of the wiring to the end surface of the scintillator (actual value). This also allows pixels in the Y direction to be aligned. By carrying out this process not only on the left edge of the panel but also on the right edge, alignment can be performed easily and accurately. Here, there is a slight deviation in the mutual panel dimensions especially in the X direction, and there are cases where the center of the pixel of the partition wall and the center of the wiring of the photoelectric conversion element cannot both be aligned at the left and right ends. The misalignment can be evenly distributed by aligning so that the amounts are even.

In this method, in addition to the fact that the pixels can be visually recognized from the side of the substrate, the pixel structure with the partition wall extending to the outermost periphery of the substrate is a condition for easy alignment. In addition, since the distance between the partition wall and the wiring (which has a clear positional relationship with the photoelectric conversion element) can be measured after alignment, the amount of misalignment can be quantified, which is excellent in terms of quality assurance.

Another example of the alignment method is shown in FIG. In this method, a reference line is drawn on a screen captured by a camera, and the position is indirectly aligned using this reference line. This method can be suitably used when it is difficult to use a pattern that serves as a guideline for alignment, such as electrode wiring of a photoelectric conversion element.

First, an image of the edge on the light-receiving substrate side (the left edge in FIG. 8) is picked up, and a reference line is drawn in the screen of the picked-up image as a reference indicating the positional information of the photoelectric conversion element. In FIG. 8, a cross line (reference line 13) is drawn on the upper end of the element between the first element and the second element from the left. In this state, the positions of the light receiving substrate and the camera are fixed. It is assumed that the reference line is displayed as it is on the screen.

Next, place the scintillator panels on top of each other and position the scintillator panels so that the part located between the first pixel and the second pixel of the scintillator panel and located at the upper end of the pixel (the middle point of the partition wall width) is in the center of the displayed reference line. to align. Accordingly, the pixels can be matched with each other without using a reference such as wiring. By carrying out this process not only on the left edge of the panel but also on the right edge, alignment can be performed easily and accurately. Also, the method for evenly distributing the dimensional deviation on the left and right is as described above.

In addition, as a simple alignment method (not shown), there is a method of aligning the outer shape of the scintillator with the outer shape of the light receiving substrate. The scintillator panel is cut so that the position of the photoelectric conversion element from the end face of the light receiving substrate and the pixel position from the end face of the scintillator panel are the same, and the scintillator panel is aligned by abutting on the end face reference. In this case, the accuracy of alignment is low because an error is likely to occur depending on the cut state of the end face. Therefore, it is preferable to carry out in combination with the method of identifying pixels from the substrate side as described above.

A scintillator panel provided with partition walls up to the outermost periphery of the base material and a light receiving substrate having photoelectric conversion elements arranged up to the edge of the base material, as in the present invention, were bonded together by the method described above to manufacture a radiation detector. In this case, a plurality of radiation detectors can be combined with a few joints to form one radiation detector as shown in the schematic diagram of the surface in FIG. 9(a) and the cross section in FIG. 9(b). In this case as well, the jointed portion of the radiation detector a14 and the radiation detector b15 is imaged by a CCD camera or the like, and the distance between the pixels of the scintillator is measured so that the pixels of the scintillator are arranged at a predetermined interval, and the pixels are aligned and joined together. be able to. As a result, it is possible to image a large object that cannot be imaged in one time with a single radiation detector, by enlarging the detection area, so that it can be imaged in one time or less times than before. By using a scintillator panel in which pixels are formed with partition walls, it is possible to reduce the luminance difference between pixels at the joints of radiation detectors, which has been a problem in scintillator panels without partition walls. That is, in the absence of partition walls, the amount of light diffused inside the phosphor layer is different between the edges of the scintillator panel and the other parts of the scintillator panel. On the other hand, in the case of using a scintillator panel in which phosphors are partitioned by barrier ribs, the diffusion state of light is the same in the end portions and other portions, so that luminance differences are less likely to occur. Therefore, when combining radiation detectors into one detector, it is preferable to use the scintillator panel of the present invention.

EXAMPLES The present invention will be specifically described below with reference to examples. The gist of the present invention should not be construed as being limited to this example. Raw materials used to prepare each paste material are as follows.

(paste raw material)
・Photosensitive monomer M-1: trimethylolpropane triacrylate ・Photosensitive monomer M-2: tetrapropylene glycol dimethacrylate ・Photosensitive polymer: methacrylic acid/methyl methacrylate/styrene = 40/40/30 mass ratio 0.4 equivalent of glycidyl methacrylate is added to the carboxyl group of the copolymer (weight average molecular weight: 43,000; acid value: 100)
· Binder resin: 100 cP ethyl cellulose · Photoinitiator: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone-1 (IC369; manufactured by BASF)
- Polymerization inhibitor: 1,6-hexanediol-bis [(3,5-di-t-butyl-4-hydroxyphenyl) propionate])
・Ultraviolet absorber solution: Sudan IV (manufactured by Tokyo Ohka Kogyo Co., Ltd.) γ-butyrolactone 0.3% by mass solution ・Viscosity modifier: Flownon EC121 (manufactured by Kyoeisha Chemical Co., Ltd.)
・Solvent A: γ-butyrolactone ・Solvent B: terpineol ・Low softening point glass powder: SiO ₂ 27% by mass, B ₂ O ₃ 31% by mass, ZnO 6% by mass, Li ₂ O 7% by mass, MgO 2% by mass, CaO 2% by mass, BaO 2% by mass, Al ₂ O ₃ 23% by mass, refractive index (ng): 1.56, glass softening temperature 588°C, linear expansion coefficient 70 × 10 ^-7 (K ^-1 ), average particle diameter 2.3 μm
High softening point glass powder: SiO ₂ 30% by mass, B ₂ O ₃ 31% by mass, ZnO 6% by mass, MgO 2% by mass, CaO 2% by mass, BaO 2% by mass, Al ₂ O ₃ 27% by mass, refraction Modulus (ng): 1.55, softening temperature 790°C, thermal expansion coefficient 32 × 10 ^-7 (K ^-1 ), average particle size 2.3 µm
· Phosphor powder: 3010-54TOR (manufactured by Nichia Corporation, average particle size 10 μm).

(Evaluation of total light transmittance of substrate)
The total light transmittance of the substrate in the visible light region was measured using a spectrophotometer (Hitachi U-4100). The base material was used after being cut into 5×5 cm. The transmittance of each light is measured with and without the substrate, and the ratio of the integral value of transmittance in the visible light region of 400 to 780 nm (integral value of substrate transmittance/integral transmittance without substrate) value).

(Preparation of release layer paste)
4.0 parts by weight of photosensitive monomer M-1, 6.0 parts by weight of photosensitive monomer M-2, 24.0 parts by weight of photosensitive polymer, 6.0 parts by weight of photoinitiator, 0.2 A polymerization inhibitor of 12.8 parts by mass and an ultraviolet absorber solution of 12.8 parts by mass were heated and dissolved in solvent A of 38.0 parts by mass at a temperature of 80°C. After cooling the resulting solution, 9.0 parts by mass of a viscosity modifier was added to prepare an organic solution 1 . After adding 5.0 parts by mass of low softening point glass powder and 35.0 parts by mass of high softening point glass powder to 60.0 parts by mass of organic solution 1, the mixture was kneaded with a three-roller kneader and separated. A layer paste was made.

(Preparation of partition layer paste)
After adding 40.0 parts by mass of low softening point glass powder to 60.0 parts by mass of organic solution 1, the mixture was kneaded with a three-roller kneader to prepare a partition layer paste.

(Preparation of phosphor paste)
3.0 parts by mass of binder resin was heated and dissolved in 20.0 parts by mass of solvent B at a temperature of 60°C. After cooling the obtained organic solution 2, 77.0 parts by mass of phosphor powder was added, and the mixture was stirred with a stirring mixer to prepare a phosphor paste.

(Preparation of partition wall)
A release layer paste is applied to an area of 280 x 280 mm using a die coater on a soda glass substrate of 300 x 300 mm and a thickness of 1.1 mm, dried at 100 ° C. for 30 minutes in a drying oven, and the dried film of the release layer ( thickness of 50 μm). A barrier rib layer paste was coated on the release layer over an area of 270×270 mm using a die coater and dried at 100° C. for 60 minutes in a drying oven to obtain a dry barrier rib layer film (thickness: 400 μm). Next, exposure is performed using a lattice pattern (exposure width: 30 μm, X-direction pitch: 400 μm, Y-direction pitch: 600 μm, pattern area: 250×250 mm) with an exposure device (wavelength: h-line, exposure amount: 500 mJ/cm ² ), A grid-like pattern of partition walls was obtained by removing unexposed portions with an alkaline developer (0.5% aqueous sodium carbonate solution). This was fired in a firing furnace at 595° C. for 10 minutes to burn off the organic components in the release layer and barrier rib layer, and to sinter the low softening point glass powder in the barrier ribs to obtain a strong barrier rib pattern. The partition walls after sintering had a width of 25 μm and a thickness of 300 μm due to shrinkage during sintering. Here, since the peeling layer is mainly composed of unsintered high-softening-point glass powder, only the partition wall pattern could be peeled off from the glass substrate.

(Example 1)
(Formation of partition walls on base material)
A thermosetting adhesive is applied onto a polyimide film (Kapton 200EN manufactured by Toray DuPont Co., Ltd.: 270 x 270 mm, thickness 50 µm, total visible light transmittance of 48%) as a base material, and the separated partition wall pattern is attached. , 190° C. for 60 minutes to thermally cure and adhere. The total visible light transmittance of the portion where the adhesive was applied to the substrate was 45%.

(Formation of reflective layer)
A 100 nm-thick aluminum film was formed on the pixel surface using an aluminum target set in a sputtering apparatus to form a reflective layer. Here, it was confirmed that the partition wall and the reflective layer were visible when viewed from the substrate side.

(Formation of phosphor layer)
Phosphor paste is filled in the pixels formed by the partition walls using a vacuum printer, excess phosphor overflowing from the partition walls is removed with a rubber squeegee, and dried at 120° C. for 30 minutes to form a phosphor layer, which is then used as a scintillator. manufactured the panel.

(dicing)
A dicing device was used to cut out a scintillator panel corresponding to the number of pixels corresponding to the light-receiving substrate. Specifically, as shown in FIG. 10, a sheet-like scintillator panel was cut along the dotted line to obtain a size of 51225×625 μm, 128 pixels in the X direction×1 pixel in the Y direction. The light-receiving substrate uses a line sensor type substrate with a size of 300 μm in the X direction, 600 μm in the Y direction, 128 elements arranged in a row at a pitch of 400 μm in the X direction, and a total width of 51.25 mm in the X direction. board. Electrode wiring was pulled out in the Y direction from the center portion in the X direction from each photoelectric conversion element, and was bent at a position of 300 μm.

(Fabrication of radiation detector)
A thermosetting transparent adhesive was applied onto the photoelectric conversion element of the light receiving substrate, and the scintillator panel cut out through this adhesive was installed at a roughly aligned position so that the light emitting surface faced the light receiving substrate. Although detailed alignment was not carried out at this point, the edges of the scintillator panel and the light-receiving substrate were roughly aligned with each other, so that there was no deviation of more than one pixel.

Next, the left end of the scintillator panel was imaged with a camera, and an enlarged image was displayed on the monitor for alignment. At this point, the scintillator panel could be freely adjusted in position because the adhesive was not cured. Alignment in the X direction was carried out by moving the center of the pixels of the partition walls in the X direction, which can be seen from the substrate side of the scintillator panel, to be positioned at the center of the wiring of the photoelectric conversion element. In the Y direction, the distance from the bent portion of the electrode wiring to the edge of the scintillator panel is 300 μm, and the distance from the edge of the pixel of the photoelectric conversion element to the bent portion of the electrode wiring is 300 μm. The distance to point): Aligned so as to be 287.5 μm, which is the difference from 12.5 μm. By performing this operation in the same way on the right edge of the panel, it was possible to match the pixels with each other with high accuracy.

After that, in order to fix the positional relationship between the scintillator panel and the light-receiving substrate, the scintillator panel and the light-receiving substrate were heated under a load to cure the adhesive to complete one radiation detector. After completion, the pixels of the scintillator and the wiring of the photoelectric conversion element were imaged again with the CCD camera, and it was confirmed that there was no deviation in the mutual positional relationship. The remaining 4 detectors were created in the same manner, and the pixels of each detector were arranged in one row in the X direction to connect 5 detectors, and a radiation detector with a detection width of 256 mm (640 pixels) was created. manufactured.

(Comparative example 1)
Work up to dicing in the same manner as in Example 1 except that a polyimide film (PIF200, thickness 200 μm) with a total visible light transmittance of 26% was used as the base material instead of the polyimide film (Kapton 200EN). was performed to fabricate a scintillator panel. Next, in (Fabrication of Radiation Detector), after the light-receiving substrate and the scintillator panel were pasted together with an adhesive, the edge of the scintillator panel was imaged with a camera for alignment. Due to the shortage, the boundaries between the partition walls and the pixels were unclear. This makes it impossible to perform alignment using the wiring of the photoelectric conversion elements as described above. When the characteristics of one completed radiation detector were evaluated, the MTF, which is an index of image sharpness, decreased to 75% of that of Example 1, and the original performance could not be obtained. It is presumed that the misalignment between the photoelectric conversion element and the partition due to the deterioration of the alignment accuracy is the cause of the decrease in MTF.

(Comparative example 2)
A base material having a pattern of partition walls was produced in the same manner as in Example 1 up to (formation of partition walls on base material). Next, in the step of forming the reflective layer and the fluorescent material, masking is performed with tape on portions corresponding to three pixels at both ends of the scintillator panel in the X direction, and then (formation of the reflective layer) to (dicing) are performed to form the reflective layer and the phosphor. A scintillator panel having pixels with no body layer was fabricated. As a result, the space between the three pixels at both ends has no shielding, and the opposite side can be seen through the transparent substrate. Subsequently, when aligning with the light-receiving substrate in (Fabrication of Radiation Detector), using this characteristic, three pixels on both ends of the photoelectric conversion element and a scintillator panel on which no reflective layer and phosphor layer are formed. Alignment was performed so that three pixels at both ends were aligned. When the characteristics of one completed radiation detector were evaluated, it was confirmed that the MTF, which is an index of image sharpness, was equivalent to that of Example 1, and that the alignment was performed with good precision. However, since the three pixels at both ends are used as pixels for alignment, this portion becomes a non-detection area, and the effective detection area is narrower than that of the first embodiment by six pixels. In addition, when a plurality of such radiation detectors are joined together, non-detection areas are positioned at the joints, making it unsuitable for jointing.

REFERENCE SIGNS LIST 1 scintillator panel 2 substrate 3 partition 4 phosphor layer 5 light receiving substrate 6 photoelectric conversion element 7 reflective layer 8 transparent resin 9 glass substrate 10 peeling layer 11 partition layer 12 wiring 13 reference line 14 radiation detector a
15 radiation detector b

The scintillator panel of the present invention is used for medical diagnostic equipment, non-destructive testing equipment, and the like.

Claims (8)

It has a base material, grid-like partition walls formed on the base material, and phosphor layers in cells partitioned by the partition walls, and the base material has a total light transmittance of 30% or more in the visible light region. A scintillator panel, wherein the partition walls are formed up to the outermost periphery of the base material. 2. The scintillator panel according to claim 1, further comprising a reflective layer on a surface of said barrier ribs in contact with the phosphor layer. 3. The scintillator panel according to claim 1, wherein said reflective layer contains metal and/or white pigment. The scintillator panel according to any one of claims 1 to 3, wherein said base material is a polyimide film having a thickness of 25 to 200 µm. 5. The scintillator panel according to any one of claims 1 to 4, wherein said base material and said partition walls are bonded with a transparent resin. A radiation detector comprising a light receiving substrate having a photoelectric conversion element and the scintillator panel according to any one of claims 1 to 5, wherein the pixel pitch of the photoelectric conversion element corresponds to the pixel pitch of the scintillator panel. A radiation detector comprising two or more of the radiation detectors according to claim 6 joined together. A pixel pitch of a scintillator panel having a base material, grid-like partition walls formed on the base material, and phosphor layers in cells partitioned by the partition walls, and a pixel pitch of a light-receiving substrate having a photoelectric conversion element. A method for manufacturing a radiation detector comprising a step of matching and bonding together, wherein the total light transmittance in the visible light region of the base material of the scintillator panel is 30% or more, and the partition wall is the outermost peripheral portion of the base material. A method of manufacturing a radiation detector, comprising:

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