JP3997134B2 - Fiber plate and manufacturing method thereof, radiation imaging apparatus, and radiation imaging system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fiber plate (also referred to as a fiber optic plate), a manufacturing method thereof, a radiation imaging apparatus, and a radiation imaging system, and in particular, a large-area fiber plate joined with a small fiber plate and a manufacturing method thereof, The present invention relates to a radiation imaging apparatus using a fiber plate, and a radiation imaging system using the radiation imaging apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is a need for a radiation imaging apparatus, particularly an X-ray imaging apparatus for medical purposes, which can capture an X-ray moving image, has excellent image quality, is thin, and has a large area input range. In addition, not only for medical use but also for industrial nondestructive inspection machines and the like, there is a demand for a thin and inexpensive large-area X-ray imaging apparatus.
[0003]
In such an X-ray imaging apparatus, when X-rays are directly incident on the photoelectric conversion element, noise may occur during reading, and the semiconductor crystal in the photoelectric conversion element may be destroyed to deteriorate the characteristics.
[0004]
Therefore, a fiber plate is used to shield X-rays. If a fiber plate is used, X-rays can be shielded without blurring the captured optical image.
[0005]
As such an X-ray imaging apparatus, for example, (1) The fiber fiber of the fiber plate is inclined, and the end of the fiber plate avoids the inactive part of the connected photoelectric conversion element (imaging element). Larger device (for example, US Pat. No. 5,563,414), (2) The fiber plate thickness is stepped so that the end of the fiber plate avoids the inactive portion of each photoelectric conversion element (imaging device). And an apparatus with a large area (for example, US Pat. No. 5,834,782).
[0006]
FIG. 15 is a schematic cross-sectional view of the X-ray imaging apparatus (1). The X-ray imaging apparatus includes a scintillator 3 made of a phosphor that converts X-rays into visible light, and an individual fiber plate 2 such as an optical fiber that guides the visible light converted by the scintillator 3 to the photoelectric conversion element 1 such as a CCD sensor. And a photoelectric conversion element 1 that converts visible light guided by the individual fiber plate 2 into an electrical signal.
[0007]
In this X-ray imaging apparatus, the individual fiber plate 2 is inclined with respect to the photoelectric conversion element 1, and a processing circuit for processing an electrical signal from each photoelectric conversion element 1 is provided between the individual fiber plates 2. ing.
[0008]
FIG. 16 is a schematic perspective view of the X-ray imaging apparatus (2). In FIG. 16 , the same parts as those in FIG. 15 are denoted by the same reference numerals. As shown in FIG. 16 , the length of the fiber plate 2 is partially changed, and, for example, the photoelectric conversion elements 1 such as three CCD sensors are provided as a set to provide a step for each set. Are provided with a processing circuit and the like.
[0009]
[Problems to be solved by the invention]
However, the configuration of (1) has a light guide surface (light incident / exit surface) that obliquely intersects the axis of the optical fiber, and is arranged so that the optical fiber axes of the respective fiber plates intersect each other. Has been. With this configuration, it is difficult to further reduce the size of the X-ray imaging apparatus.
[0010]
On the other hand, the configuration (2) further increases the size of the X-ray imaging apparatus. Further, since the alignment accuracy between each stepped portion and the photoelectric conversion element is severe, the number of manufacturing steps is increased and a highly accurate alignment apparatus is required. In view of these, the configuration (2) is not realistic.
[0011]
As described above, the conventional X-ray imaging apparatus is not always sufficient in terms of size increase, cost reduction, workability in the manufacturing process, and the like.
[0012]
Accordingly, an object of the present invention is to provide a large-area fiber plate that is suitable for downsizing and cost reduction, and is more excellent in workability in the manufacturing process, and a method for manufacturing the same. An object of the present invention is to provide a radiation imaging apparatus and a radiation imaging system that are inexpensive and have excellent image quality by using a fiber plate.
[0013]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, in the present invention, in a large-area fiber plate in which a plurality of individual fiber plates having upper and lower light guide surfaces and having the same thickness are adjacently arranged and joined, the plurality of individual fiber plates included in the individual fiber plate The two individual fiber plates sequentially cut from the same block including a plurality of fibers in which the fiber axes intersect each other and the fiber axes intersect each other are guided by one of the individual fiber plates. Bonded with the light surface upside down.
[0014]
Further, in the method of manufacturing a large-area fiber plate in which a plurality of individual fiber plates having upper and lower light guide surfaces and having the same thickness are adjacently arranged and joined, the plurality of fibers included in the individual fiber plate include a fiber axes intersect with each other, successively cut two individual fiber plates were from the same block including a plurality of fibers the fiber axis intersect each other, bonding the light guide surface of one of the individual fiber plates upside down on to To do.
[0015]
Further, in the radiation imaging apparatus, a wavelength converter that converts radiation into light, a photoelectric conversion element that converts light into an electrical signal, and the large-area fiber provided between the wavelength converter and the photoelectric conversion element A plate.
[0016]
Further, in the radiation imaging system, the radiation imaging apparatus, a signal processing means for processing a signal from the radiation imaging apparatus, a recording means for recording a signal from the signal processing means, and a signal processing means A radiation source for displaying the signal.
[0017]
In other words, a fiber plate in which a plurality of photoelectric conversion elements are arranged adjacent to each other under a single large-area fiber plate to solve a conventional problem, and a plurality of individual fiber plates are enlarged by side bonding, Since the fiber directions of the individual fiber plates cut out from the same block are aligned, the light that was generated at the fiber joints by joining the light guide surfaces of the same side in the block upside down. It is possible to improve so as to reduce the area not propagating.
[0018]
In addition, a fiber plate with a large area by joining multiple individual fiber plates can be removed by double-side polishing after joining to eliminate the occurrence of steps during joining and the sticking out of adhesive. It is easy to obtain characteristics when bonding.
[0019]
In addition, by mixing the X-ray shielding material in the adhesive, X-rays harmful to the photoelectric conversion element leaking from the fiber plate joint can be absorbed, and X with excellent noise characteristics and reliability A line imaging apparatus can be provided.
[0020]
Therefore, by using the large-area fiber plate manufactured by this method for the radiation imaging apparatus, it is possible to provide a large-area and low-cost radiation imaging apparatus with excellent seamless image quality.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1-10 is a figure which shows the manufacturing method of the fiber plate by this invention.
[0022]
Before making the fiber plate, first make a single fiber. FIG. 1 is a diagram showing a method for producing a single fiber. The single fiber 1 is formed of a central core glass 21, a clad glass 22 covering the periphery thereof, and an absorber glass 23. The composite of core glass 21 + cladding glass 22 + absorber glass 23 is stretched through a heating device to obtain a single fiber 1 having a cross section similar to that of the composite.
[0023]
Next, a multi-fiber is manufactured using the single fiber 1. 2 and 3 are diagrams showing a method for producing a multi-fiber, in which a single fiber 1 is laminated and heated and stretched to produce a multi-fiber 3.
[0024]
Reference numeral 2 denotes a laminate in which single fibers 1 are laminated. As shown in FIG. 2A, the single fiber 1 is aligned in the length direction to form the laminate 2. Here, the laminated body 2 is laminated so as to have a hexagonal cross section as shown in FIG. 2B, but may have other shapes as long as the multi-fibers 3 can be laminated without a gap.
[0025]
As shown in FIG. 3, the single fiber laminate 2 is heated and stretched in the same manner as in FIG. FIG. 3B shows the AA ′ cross section of FIG.
[0026]
Next, the fiber block 4 is manufactured using the multifiber 3.
[0027]
FIG. 4 is a diagram showing a fiber block manufacturing method, in which multi-fibers 3 are stacked in a mold 100 of a hot press apparatus and hot-pressed. In order to prevent welding of the mold 100 and the multi-fiber 3, a metal foil is put inside the mold 100 to complete the fiber block 4.
[0028]
FIG. 5 is a view showing the appearance of the completed fiber block 4. At this time, the fiber block 4 is slightly deformed due to the load distribution of the temperature distribution press, the unevenness of the outer shape of the multi-fiber 3, or deformation.
[0029]
At this time, it is very difficult to produce a defect in which the fiber does not transmit light due to temperature distribution and load distribution, and to manufacture a large fiber block 4 due to residual stress and temperature difference in the block.
[0030]
FIG. 6 is a diagram showing a method for slicing the fiber block 4. The fiber block 4 is first cut using a slicing device along the block outer shape to obtain the individual fiber plate 5.
[0031]
FIG. 7 is a diagram showing a method of aligning the outer shape of the individual fiber plate 5 and the fiber fiber direction. Since the individual fiber plate 5 is not aligned in its outer shape and fiber direction as it is, the individual fiber plate 5 and fiber fiber direction are aligned using a side polishing apparatus. Polishing is performed while the individual fiber plate 5 is fixed on the stage 200 of the polishing apparatus in which the stage angle can be arbitrarily set and the polishing grindstone 201 is rotated.
[0032]
FIG. 8 is a diagram illustrating a method of bonding the individual fiber plates 5 to each other. At this time, the fiber block 4 is deformed as shown in FIGS. That is, as shown in FIG. 8 (a), the fiber fibers are not parallel in the fiber block 4, and the individual fiber plates 5 cut out from the fiber block 4 have the same fiber fibers. It becomes. As shown in FIG. 8B, when the two individual fiber plates 5 are bonded to each other, the fiber direction of the fibers is not aligned at the joint 7, so that a region where light does not propagate is generated.
[0033]
Therefore, in the present invention, as shown in FIG. 8C, another individual fiber plate 5b is joined upside down to one individual fiber plate 5a taken from the same block. That is, when joining the sequentially cut individual fiber plates 5, one is turned over and joined. Since the direction of strain of the fiber fibers is almost the same in the same fiber block 4, when the individual fiber plates 5 are bonded to each other upside down, the region that does not transmit light is the thickness of only the adhesive 7 of the bonding portion 6. Since it becomes very small, about 5-15 micrometers, the area | region which does not propagate the light which generate | occur | produced in the junction part 6 can be made small. In this way, distortion generated during the manufacture of the fiber block 4 can be absorbed.
[0034]
Specific examples of the adhesive 7 include an epoxy resin, a polyurethane resin, a silicone resin, and an acrylic resin. These are used alone or in combination of two or more. Further, as an additive, at least one material or alloy or compound such as iron, cobalt, nickel, copper, zinc, silver, tin, gadolinium, tungsten, lead, gold, lanthanum or the like, which is an X-ray shielding material, is used.
[0035]
Further, as the adhesive 7, a low melting point glass having a melting point lower than that of the fiber plate material and shielding X-rays, which contains a large amount of heavy metals such as lead, lanthanum, gadolinium, gadolinium, etc. An alloy containing two or more metals such as zinc, indium and silver may be used. For example, bonding by soldering or brazing may be used.
[0036]
FIG. 9 is a diagram illustrating a polishing method for a large-area fiber plate. Finally, the thickness variation and steps when the individual fiber plates are bonded to each other by the double-side polishing apparatus 300, or the protrusion of the adhesive are removed by polishing to complete the fiber plate 8 having a large area.
[0037]
FIG. 10 is an external view showing the large-area fiber plate 8 manufactured by the manufacturing method described above. The large-area fiber plate 8 has a size of, for example, 30 cm × 30 cm and a thickness of about 3 mm. This size is preferably slightly larger than the effective area of the X-ray imaging apparatus to be configured.
[0038]
The thickness is required to sufficiently shield X-rays. For example, when lanthanum-based glass is used, if the thickness is 3 mm, the X-rays attenuate from 1/10 to 1/1000. Since this value varies depending on the wavelength of the X-ray used, the thickness of the fiber plate may be determined in accordance with the X-ray wavelength used by the apparatus.
[0039]
The large-area fiber plate 8 is combined as shown in FIGS. 11 and 12 to constitute an X-ray imaging apparatus.
[0040]
FIG. 11 is a schematic diagram showing a basic configuration of an X-ray imaging apparatus using the fiber plate 8 described above. Reference numeral 9 denotes a photoelectric conversion element (imaging element) composed of an integrated circuit chip such as a CCD image sensor, a CMOS image sensor, a bipolar image sensor, a CMD image sensor, or a thin film transistor image sensor, and a plurality of photoelectric conversion elements 9a. A large-area photoelectric conversion element 9 in which is arranged is configured.
[0041]
Reference numeral 8 denotes the large-area fiber plate shown in FIG. 10, but here, the joint portion between the fiber plates 5 is omitted, and only the large-area fiber plate 8 is shown. The light guide surfaces of the large-area fiber plate 8 are upper and lower main surfaces (light incident / exit surfaces).
[0042]
Reference numeral 10 denotes a scintillator for converting radiation into visible light, gadolinium sulfide oxide such as Gd ₂ O ₂ S (Tb), alkali metal halide represented by cesium iodide such as CsI (TI), and the like. This is a layered member made of the above material.
[0043]
The light guide area of the bonded large-area fiber plate 8 is the same as or larger than the effective light receiving area of the bonded large-area photoelectric conversion element 9, and the effective area of the scintillator 10 is bonded. The light guide area of the large area fiber plate 8 should be the same or larger.
[0044]
When radiation enters the upper surface of the scintillator 10, the scintillator 10 emits light in the visible light range. A fiber plate 8 disposed between the scintillator 10 and the photoelectric conversion element 9 guides this light to the light receiving portion of the photoelectric conversion element 9. The light incident on the light receiving unit is photoelectrically converted for each pixel and read out as an electric signal.
[0045]
Here, since the large-area fiber plate 8 prevents radiation from entering the photoelectric conversion element 9, malfunction of the photoelectric conversion element 9 and generation of noise can be suppressed.
[0046]
Although the imaging apparatus of the present invention can be suitably used for an X-ray imaging apparatus, its use is not particularly limited to X-rays, and the radiation imaging apparatus detects a radiation image such as α, β, γ rays, etc. Can also be used. Light is an electromagnetic wave in a wavelength region that can be detected by a pixel, and includes visible light.
[0047]
FIG. 12 is a cross-sectional view of a specific configuration example of the X-ray imaging apparatus according to the present invention. The X-ray imaging apparatus includes a scintillator 10 that converts X-rays into light having a wavelength that can be detected by a photoelectric conversion element such as visible light, and a plurality of fiber plates that guide light converted by the scintillator 10 to the photoelectric conversion element 9 side. It has a bonded large-area fiber plate 8 and a plurality of photoelectric conversion elements 9a each including a photoelectric conversion light-receiving element that converts light into an electrical signal.
[0048]
This apparatus has the following elements as required. That is, it has a transparent adhesive 16 excellent in elasticity for bonding the large-area fiber plate 8 and the photoelectric conversion element 9 having a plurality of pixels, and wiring for outputting an electrical signal from each photoelectric conversion element 9a to the outside. Flexible substrate 19, bump 15 that electrically connects flexible substrate 19 and each photoelectric conversion element 9a, printed circuit board 20 that is a drive circuit substrate to which flexible substrate 19 is connected, aluminum protective sheet 11 that protects scintillator 10, photoelectric A base substrate 13 on which the conversion element 9 is mounted, a case 14 for holding the base substrate 13, a case cover 12 provided in the case 14, and a constant provided between the photoelectric conversion element 9 and the fiber plate 8. A spacer 17 and a transparent adhesive 16 for maintaining a gap are interposed between the fiber plate 8 and each photoelectric conversion element 9a. With the order of the joint plum agent 18.
[0049]
The large-area fiber plate 8 is bonded by the above method, and the width of the region where light is not propagated at the joint is finished to 5 to 15 μm. Further, the pixel pitch of the photoelectric conversion element 9 is 160 μm, and even if a region where light does not propagate is applied to the pixel, image data based on light can be obtained sufficiently in the portion where the remaining light propagates. Further, since the output is lower than other pixels, a better image can be obtained by correcting by image processing.
[0050]
As described above, according to this embodiment, since a large-area fiber plate can be manufactured seamlessly and inexpensively, it is possible to configure a radiation imaging apparatus that combines a large-area effective light-receiving unit, high image quality, and low cost. .
[0051]
The radiation imaging system described below is a system using the above-described radiation imaging apparatus.
[0052]
FIG. 13 is a conceptual diagram showing a configuration of a nondestructive inspection system including the X-ray imaging apparatus according to the present invention. The nondestructive inspection system includes an X-ray imaging apparatus 1000 according to the above-described embodiment, a subject 2000, a microfocus X-ray generator 3000 that irradiates the subject 2000 with X-rays, and an image that processes signals from the X-ray imaging apparatus 1000. The image processing apparatus has a processing device 6000, a monitor 4000 that displays an image subjected to image processing, and a controller 5000 that controls them.
[0053]
In the nondestructive inspection system, when X-rays generated by the microfocus X-ray generator 3000 are irradiated to the subject 2000 to be nondestructively inspected, information on the presence or absence of defects inside the subject 2000 is transmitted to the image processing device 6000 through the X-ray imaging device 1000. Is output. In the image processing device 6000, the output signal is corrected at a portion where the output is reduced at the above-described fiber plate connecting portion, and an image is displayed on the monitor 4000 by performing dark signal correction as necessary.
[0054]
The image displayed on the monitor 4000 can be controlled by, for example, enlargement / reduction and shading by the controller 5000. Thus, a defect inside the subject 2000 is found through the image displayed on the monitor 4000 and is excluded from the manufacturing process as a defective product.
[0055]
FIG. 14 is a conceptual diagram illustrating a configuration of an X-ray diagnostic system including the X-ray imaging apparatus according to the above-described embodiment. The X-ray diagnostic system includes a bed equipped with an X-ray imaging apparatus 1000, an X-ray generation apparatus 7000 for irradiating an object 2000 with X-rays, processing of image signals output from the X-ray imaging apparatus 1000, and X-rays An image processor 8000 that controls the timing of X-ray irradiation from the generator 7000 and a monitor 4000 that displays an image signal processed by the image processor 8000 are included. In FIG. 13, the same parts as those shown in FIG.
[0056]
In the X-ray diagnostic system, the X-ray generator 7000 generates X-rays based on an instruction from the image processor 8000. When the X-ray is applied to the subject 2000 on the bed, the X-ray imaging device 1000 converts the X-ray image information of the subject 2000. To the image processor 8000. In the image processor 8000, the output signal is corrected at the portion where the output is reduced at the above-described fiber plate connecting portion, and a dark signal correction is performed as necessary to display an image on the monitor 4000.
[0057]
The image displayed on the monitor 4000 can be controlled to be enlarged / reduced and shaded by the controller, for example. A doctor or the like diagnoses the lesion of the subject 2000 through the image displayed on the monitor 4000 in this way. Further, the X-ray information of the subject 2000 after the doctor examines may be recorded on a disk-shaped recording medium or the like by providing a recording unit in the system.
[0058]
【The invention's effect】
As described above, according to the large-area fiber plate and the manufacturing method thereof of the present invention, the small fiber plate is aligned in the fiber fiber direction, and the adjacent fiber is cut from the same ingot with the light guide surface. By joining them upside down, a large-area fiber plate that does not have a joint between the plates can be manufactured at low cost.
[0059]
Further, by using this large-area fiber plate for a radiation imaging apparatus, it is possible to provide a high-quality image and a large-area radiation imaging apparatus and radiation imaging system at a low price.
[Brief description of the drawings]
FIG. 1 is a diagram showing a manufacturing method of a single fiber. FIG. 2 is a diagram showing a manufacturing method of a multi-fiber. FIG. 3 is a diagram showing a manufacturing method of a multi-fiber. 5] Diagram showing the appearance of the fiber block. [Fig. 6] Diagram showing the fiber block slicing method. [Fig. 7] Diagram showing the method for aligning the outer shape of the individual fiber plate and the fiber fiber direction. [Fig. FIG. 9 is a diagram showing a method for polishing a large-area fiber plate. FIG. 10 is an external view showing a large-area fiber plate. FIG. 11 is a basic configuration of an X-ray imaging apparatus using a large-area fiber plate. FIG. 12 is a cross-sectional view of a specific configuration example of the X-ray imaging apparatus according to the present invention. FIG. 13 is a conceptual diagram illustrating the configuration of a nondestructive inspection system. 14 is a conceptual diagram showing the configuration of the X-ray diagnostic system. FIG. 15 is a schematic cross-sectional view of the X-ray imaging apparatus of the conventional example (1). FIG. 16 is a schematic perspective view of the X-ray imaging apparatus of the conventional example (2). [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Single fiber 2 Single fiber laminated body 3 Multi fiber 4 Fiber block 5 Individual fiber plate 6 Joint part 7 Adhesive 8 Large area fiber plate 9 Photoelectric conversion element 10 Scintillator 100 Die press 200 Polishing device stage 201 Polishing stone 300 Double-side polishing device 1000 X-ray imaging device 2000 Subject 3000 Microfocus X-ray generator 4000 Monitor 5000 Controller 6000 Image processing device 7000 X-ray generator 8000 Image processor

Claims (7)

In a large-area fiber plate in which a plurality of individual fiber plates having equal thicknesses having upper and lower light guide surfaces are adjacently arranged and joined,
The plurality of fibers included in the individual fiber plate have fiber axes intersecting each other ,
The two individual fiber plates sequentially cut out from the same block including a plurality of fibers whose fiber axes intersect each other are joined with the light guide surfaces of one of the individual fiber plates turned upside down. And fiber plate. The fiber plate according to claim 1, wherein at least one of the light guide surface and the side surface of the individual fiber plate is a polished surface. By at least one of the adhesive or metal, the have a joint side faces of the individual fiber plates are joined, the junction according to claim 1, characterized in that it comprises a radiation shielding material Fiber plate. 4. The fiber according to claim 3 , wherein the two individual fiber plates sequentially cut out from the block are joined with the light guide surfaces of the same side in the block being turned upside down. 5. plate. In a method for manufacturing a large-area fiber plate in which a plurality of individual fiber plates having equal thicknesses having upper and lower light guide surfaces are arranged adjacent to each other and joined together,
The plurality of fibers included in the individual fiber plate have fiber axes intersecting each other ,
A fiber plate characterized by joining two individual fiber plates sequentially cut from the same block including a plurality of fibers whose fiber axes intersect with each other, with the light guide surfaces of one individual fiber plate turned upside down. Manufacturing method.   The fiber according to claim 1, which is provided between a wavelength converter that converts radiation into light, a photoelectric conversion element that converts light into an electrical signal, and the wavelength converter and the photoelectric conversion element. A radiation imaging apparatus comprising a plate.   7. The radiation imaging apparatus according to claim 6, a signal processing means for processing a signal from the radiation imaging apparatus, a recording means for recording a signal from the signal processing means, and a signal from the signal processing means. A radiation imaging system comprising a radiation source for display.

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