WO2012026223A1 - Grid for capturing radiation image, method for manufacturing same, and radiation image capturing system - Google Patents

Grid for capturing radiation image, method for manufacturing same, and radiation image capturing system Download PDF

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Publication number
WO2012026223A1
WO2012026223A1 PCT/JP2011/065574 JP2011065574W WO2012026223A1 WO 2012026223 A1 WO2012026223 A1 WO 2012026223A1 JP 2011065574 W JP2011065574 W JP 2011065574W WO 2012026223 A1 WO2012026223 A1 WO 2012026223A1
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Prior art keywords
grid
small
grids
radiation
small grids
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PCT/JP2011/065574
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French (fr)
Japanese (ja)
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金子 泰久
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富士フイルム株式会社
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/48Diagnostic techniques
    • A61B6/484Diagnostic techniques involving phase contrast X-ray imaging
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/42Arrangements for detecting radiation specially adapted for radiation diagnosis
    • A61B6/4291Arrangements for detecting radiation specially adapted for radiation diagnosis the detector being combined with a grid or grating
    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21KTECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K1/00Arrangements for handling particles or ionising radiation, e.g. focusing or moderating
    • G21K1/06Arrangements for handling particles or ionising radiation, e.g. focusing or moderating using diffraction, refraction or reflection, e.g. monochromators
    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21KTECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K2201/00Arrangements for handling radiation or particles
    • G21K2201/06Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
    • G21K2201/064Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements having a curved surface
    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21KTECHNIQUES FOR HANDLING PARTICLES OR IONISING RADIATION NOT OTHERWISE PROVIDED FOR; IRRADIATION DEVICES; GAMMA RAY OR X-RAY MICROSCOPES
    • G21K2201/00Arrangements for handling radiation or particles
    • G21K2201/06Arrangements for handling radiation or particles using diffractive, refractive or reflecting elements
    • G21K2201/067Construction details

Definitions

  • the present invention relates to a radiographic imaging grid used for radiographic imaging, a manufacturing method thereof, and a radiographic imaging system using the radiographic imaging grid.
  • a radiation imaging system using the Talbot interference effect is known as a kind of radiation phase imaging that obtains an image (hereinafter referred to as a phase contrast image) based on a phase change (angle change) when radiation passes through a subject.
  • An X-ray imaging system that uses, for example, X-rays as radiation, includes a first grid disposed behind the subject, and a Talbot interference distance determined by the grid pitch and X-ray wavelength of the first grid, and the X-ray irradiation direction. And a second grid disposed downstream of the X-ray image detector and an X-ray image detector disposed behind the second grid.
  • the X-rays that have passed through the first grid form a self-image (stripe image) at the position of the second grid due to the Talbot interference effect. This self-image is modulated by the X-ray phase change by the subject.
  • the X-ray imaging system acquires a phase contrast image of a subject from a change (phase shift) caused by the subject of a stripe image whose intensity is modulated by superimposing the self-image of the first grid and the second grid. .
  • This is called a fringe scanning method.
  • imaging is performed by an X-ray image detector at each scanning position while moving the second grid with respect to the first grid, and the above-described scanning of pixel data of each pixel obtained by the X-ray image detector is performed.
  • a phase differential image (corresponding to the angular distribution of X-rays refracted by the subject) is acquired from the amount of phase shift in intensity change with respect to the position.
  • translational movement is performed at a scanning pitch obtained by equally dividing the grid pitch in a direction substantially parallel to the plane of the first grid and substantially perpendicular to the grid direction of the first grid. ing.
  • a phase contrast image of the subject is obtained by integrating the obtained phase differential image along the fringe scanning direction.
  • the first and second grids are striped (striped) in which X-ray absorbers stretched in a direction perpendicular to the X-ray irradiation direction are arranged at a predetermined pitch in a direction orthogonal to the X-ray irradiation direction and the stretching direction. It has the following structure.
  • the arrangement pitch of the X-ray absorbers is determined by the distance from the X-ray focal point to the first grid and the distance between the first grid and the second grid, and is approximately 2 to 20 ⁇ m.
  • the line absorption part of the second grid requires high X-ray absorption, it requires a high aspect ratio structure in which the X-ray traveling direction thickness is about 100 ⁇ m.
  • FIG. 15A a technique is known in which a plurality of small grids 90 having a small size are arranged to form a grid 91 having a large area as a whole (see, for example, Patent Documents 1 and 2).
  • a small grid manufactured using a silicon semiconductor process has a rectangular shape with the outer periphery cut.
  • the outer periphery to be cut coincides with the end portion of the grid portion 93 that is provided with an X-ray absorption portion and actually functions as a grid.
  • the cut end portion 94 may be inclined with respect to the end portion of the grid portion 93 as shown in FIG. 16B.
  • the end portion 95 may be uneven as a result of chipping that occurs during cutting, chipping that occurs during handling after cutting, and the like. Accordingly, as shown in FIG. 15A, the actual small grid 90 needs to be provided with a non-grid portion 96 as a cutting margin that does not function as a grid outside the grid portion 93.
  • This distance DS is preferably short. More specifically, the interval DS is more preferably less than or equal to the size of one pixel (for example, 150 ⁇ m or less) of an X-ray image detector used for capturing a phase contrast image. This is because when the interval DS becomes larger than the pixel size, the portion becomes an area where a phase contrast image cannot be acquired, and the image quality is deteriorated.
  • Patent Documents 1 and 2 do not disclose a method for arranging the small grids 90 by narrowing the interval DS between the grid portions 93.
  • An object of the present invention is to arrange a plurality of small grids so that the interval between the grid portions of adjacent small grids is less than the size of one pixel of the X-ray image detector.
  • a grid for radiographic imaging includes N (N is an integer of 2 or more) small grids, and each small grid has a grid portion in which radiation absorbing portions are arranged at a predetermined pitch. And a radiation transmissive non-grid portion provided on the outer periphery of the grid portion. Between the adjacent small grids, the grid portion of one small grid and the non-grid portion of the other small grid are overlapped so as to face each other.
  • the boundary between the grid portion and the non-grid portion of one small grid and the boundary between the grid portion and the non-grid portion of the other small grid coincide.
  • N N small grids may be stacked alternately one above the other. Thereby, even when a plurality of small grids are overlapped, it is possible to suppress the thickness of the radiation image capturing grid from being increased.
  • N small grids may be stacked in a staircase pattern. At this time, it is preferable to bond a radiation-transmitting dummy substrate under a plurality of small grids. Further, instead of the dummy substrate, it may be held by a concave support substrate. Further, the N small grids may be arranged so as to be inclined so as to form a substantially concave or substantially spherical grid surface.
  • the method for manufacturing a radiographic imaging grid according to the present invention includes N grids each including a grid part in which radiation absorbing parts are arranged at a predetermined pitch and a radiation transmissive non-grid part provided on the outer periphery of the grid part ( N is an integer greater than or equal to 2), and the adjacent small grids are superposed so that the grid portion of one small grid and the non-grid portion of the other small grid face each other. And a joining step for joining.
  • an alignment mark forming step for forming an alignment mark having visibility and radiation transparency by visible light on the non-grid portion, and a position for detecting the position of the alignment mark and adjusting the position of the adjacent small grid It is also preferable to further include an adjustment step. Further, in the position adjustment step, adjacent small grids are arranged so that the surfaces provided with the alignment marks face each other with a space therebetween, and a position detection device is inserted into this space to detect the position of the alignment mark. The position may be adjusted accordingly.
  • the radiographic imaging system of the present invention includes a radiation source that emits radiation, a first grid that transmits radiation and generates a fringe image, a second grid that applies intensity modulation to the fringe image, a radiation source, A third grid which is arranged between the first grid and shields the radiation emitted from the radiation source in a selective manner and detects a plurality of line light sources, and a fringe image whose intensity is modulated by the second grid is detected.
  • At least one of the first to third grids includes N pieces of grid portions in which radiation absorbing portions are arranged at a predetermined pitch and radiation transmissive non-grid portions provided on the outer periphery of the grid portion ( N is an integer of 2 or more). Between the adjacent small grids, the grid portion of one small grid and the non-grid portion of the other small grid are overlapped so as to face each other.
  • the interval between the grid portions is not affected by the size of the non-grid portion.
  • a plurality of small grids can be arranged to be narrow.
  • FIG. 2B is a cross-sectional view showing a cross section taken along the line IIB-IIB in FIG. 2A. It is sectional drawing which shows the structure of the grid part of a small grid. It is sectional drawing which shows the manufacture procedure 1 of a small grid. It is sectional drawing which shows the manufacturing procedure 2 of a small grid. It is sectional drawing which shows the manufacturing procedure 3 of a small grid. It is sectional drawing which shows the manufacture procedure 4 of a small grid. It is sectional drawing which shows the manufacturing procedure 5 of a small grid.
  • FIG. 9B is a cross-sectional view showing a cross section taken along line IXB-IXB in FIG. 9A. It is a top view of the grid which piled up the three or more small grids in the step shape.
  • FIG. 10B is a sectional view showing a section taken along line XB-XB in FIG. 10A. It is sectional drawing of the grid which joined the 3 or more small grid to the concave-shaped support substrate. It is sectional drawing of the grid which inclined the small grid and made it concave. It is a perspective view of the grid which piled up the small grid in a plurality of directions. It is a disassembled perspective view of the grid which piled up the small grid in two directions.
  • FIG. 15B is a cross-sectional view showing a cross section taken along line XVB-XVB in FIG. 15A. It is a top view which illustrates the small grid where the perimeter was cut ideally. It is a top view which illustrates the small grid by which the outer periphery was cut diagonally. It is a top view which illustrates the small grid by which the outer periphery was cut in the uneven
  • the X-ray imaging system 10 of the present invention includes an X-ray source 11, a source grid 12, a first grid 13, a second grid 14, and an X-ray image detector 15. .
  • the X-ray source 11 emits X-rays toward the subject H arranged in the Z direction.
  • the radiation source grid 12 is disposed opposite to the X-ray source 11 in the Z direction.
  • the first grid 13 is arranged in parallel at a position away from the radiation source grid 12 by a predetermined distance in the Z direction.
  • the second grid 14 is arranged in parallel at a position away from the first grid 13 by a predetermined distance in the Z direction.
  • the X-ray image detector 15 is disposed so as to face the second grid 14.
  • a flat panel detector using a semiconductor circuit is used as the X-ray image detector 15, for example.
  • the radiation source grid 12, the first grid 13, and the second grid 14 are absorption grids, and a plurality of X-ray absorption parts 17, 18, and 19 are provided in a striped pattern.
  • the X-ray absorbers 17, 18, and 19 are linearly extended in the X direction orthogonal to the Z direction, and are periodically arranged at a predetermined pitch along the Y direction orthogonal to the Z direction and the X direction. Yes.
  • the radiation source grid 12, the first grid 13, and the second grid 14 absorb X-rays by the X-ray absorption units 17, 18, and 19, and X-rays are transmitted by the X-ray transmission unit provided between the X-ray absorption units. Make lines transparent.
  • the first grid 13 does not generate a Talbot interference effect, and the grating pitch is relative to the wavelength of the X-ray so that X-rays are projected linearly (geometrically) onto the second grid 14. Is set.
  • the source grid 12 and the first grid 13 have substantially the same configuration as the second grid 14 except that the widths, pitches, thicknesses in the X-ray irradiation direction, and the like of the X-ray absorbers 17 and 18 are different. Therefore, detailed description is omitted.
  • the small grids 21 and 22 include grid portions 21a and 22a that function as grids, and non-grid portions 21b and 22b that are provided on the outer periphery of the grid portions 21a and 22a and do not function as grids, respectively. ing.
  • the small grids 21 and 22 are joined so that the grid part 21a and the non-grid part 22b overlap with the non-grid part 21b and the grid part 22a, and each grid part and the non-grid part when viewed from the Z direction. And the two grid portions 21a and 22a are joined together so as to form one large grid portion.
  • the small grids 21 and 22 include an X-ray transparent substrate 24 formed of a material having X-ray transparency such as silicon, and the X-rays.
  • the X-ray absorber 19 is provided on the transparent substrate 24.
  • the X-ray absorber 19 is provided in the grid portions 21a and 22a.
  • the X-ray absorber 19 is provided in the X-ray transparent substrate 24 along the X direction and is provided in a plurality of grooves 25 arranged along the Y direction, and is a metal having excellent X-ray absorption. For example, it is composed of gold or platinum.
  • the plurality of partition walls 26 separating the X-ray absorption parts 19 function as X-ray transmission parts.
  • the width W 2 is about 2 to 20 ⁇ m
  • the pitch P 2 is about 4 to 40 ⁇ m.
  • the thickness T 2 in the X direction of the X-ray absorption unit 19 is preferably as thick as possible in order to obtain high X-ray absorption, but vignetting of cone-beam X-rays radiated from the X-ray source 11 is considered. And it is preferable that it is about 100 micrometers.
  • the width W 2 is 2.5 ⁇ m
  • the pitch P 2 is 5 ⁇ m
  • the thickness T 2 is 100 ⁇ m.
  • the grid manufacturing method of the present invention will be described using the second grid 14 as an example.
  • the radiation source grid 12 and the first grid 13 are also manufactured by the same manufacturing method, and detailed description thereof is omitted.
  • the small grid 22 is manufactured in the same procedure, detailed description is abbreviate
  • the support substrate 28 is bonded to the lower surface of the X-ray transparent substrate 24 made of silicon.
  • the support substrate 28 is made of a material having low X-ray absorption, and is preferably borosilicate glass, soda lime glass, quartz, alumina, GaAs, Ge, or the like, and more preferably the same silicon as the X-ray transparent substrate 24.
  • borosilicate glass for example, Pyrex (registered trademark) glass, Tempax (registered trademark) glass, or the like can be used.
  • a conductive sheath layer 30 is provided on the surface of the support substrate 28 bonded to the X-ray transparent substrate 24.
  • the seed layer 30 is made of, for example, Au or Ni, or a metal film formed of Al, Ti, Cr, Cu, Ag, Ta, W, Pb, Pd, Pt, or a metal film formed of an alloy thereof. Preferably there is. Further, the seeds layer 30 may be provided on the X-ray transparent substrate 24 or may be provided on both the X-ray transparent substrate 24 and the support substrate 28.
  • an etching mask 32 is formed on the X-ray transparent substrate 24 by using a general photolithography technique.
  • the etching mask 32 has a striped pattern that extends linearly in the X direction and is periodically arranged at a predetermined pitch in the Y direction.
  • a plurality of grooves 25 are formed in the X-ray transparent substrate 24 by dry etching using the etching mask 32.
  • the groove 25 requires a high aspect ratio of, for example, a width of several ⁇ m and a depth of about 100 ⁇ m. Therefore, a Bosch process, a cryo process, or the like is used for dry etching for forming the groove 25.
  • a groove may be formed by using a photosensitive resist instead of the silicon substrate and exposing with synchrotron radiation.
  • the groove 25 is filled with an X-ray absorber such as gold by electrolytic plating to form an X-ray absorber 19.
  • the X-ray transparent substrate 24 to which the support substrate 28 is bonded is immersed in a plating solution with a current terminal connected to the sheath layer 30.
  • the other electrode anode
  • gold is embedded in the groove 25.
  • the filling of the X-ray absorbing material into the groove 25 is not limited to the electrolytic plating method, and may be performed by applying a paste-like or colloidal X-ray absorbing material.
  • the outer periphery of the X-ray transparent substrate 24 and the like on which the X-ray absorbing portion 19 is formed is cut into a rectangular shape by dicing or the like, and a small grid 21 is formed.
  • a non-grid portion 21b having a width that can be used as a joining margin when joining the small grids is formed on the outer periphery of the grid portion 21a.
  • the support substrate 28, the seed layer 30 and the etching mask 32 are removed by polishing or the like.
  • the support substrate 28 and the seed layer 30 may be left on the small grid 21.
  • two alignment marks 34 and 35 are used for alignment when joining the non-grid portions 21 b and 22 b of the small grids 21 and 22. Individually formed.
  • the alignment marks 34 and 35 are provided at positions that overlap when the grid portions 19 of the small grids 21 and 22 are joined.
  • the alignment marks 34 and 35 are formed by, for example, forming a thin film used for the alignment mark on the small grids 21 and 22 and partially removing the thin film using etching or a photolithography technique.
  • the alignment marks 34 and 35 are made of an X-ray transmissive material such as Al, Ti, Cr, resist or the like.
  • the thickness of the alignment marks 34 and 35 may be such that it can be identified during alignment, for example, 0.01 to 1 ⁇ m.
  • the size of the alignment marks 34 and 35 is preferably not more than one pixel of the X-ray image detector 15 in consideration of the effect on the grid performance, and is preferably about 50 to 100 ⁇ m, for example.
  • the shape of the alignment marks 34 and 35 is a cross shape, it may be any shape as long as it is easy to align. Further, although two alignment marks 34 and 35 are provided, three or more alignment marks may be provided.
  • the small grids 21 and 22 are positioned and joined to each other by the alignment device. As shown in FIG. 6, in the alignment apparatus, the small grids 21 and 22 are held by a position adjusting mechanism (not shown) so that the alignment marks 34 and 35 of the small grids 21 and 22 face each other. For example, the small grid 21 is disposed such that the alignment mark 34 faces downward, and the small grid 22 is disposed such that the alignment arc 35 faces upward.
  • the position adjustment mechanism is configured so that each of the small grids 21 and 22 has an extending direction (X direction) of the X-ray absorber 19, an arrangement direction of the X-ray absorber 19 (Y direction), and ⁇ around the Z direction orthogonal to the grid surface. It can be moved in three directions of Z.
  • two sets of position detection units 39 having a pair of alignment cameras 37 and 38 arranged back to back so as to photograph the upper side and the lower side are inserted,
  • the alignment marks 34 and 35 are photographed by the respective cameras. Images taken by the alignment cameras 37 and 38 of each position detection unit 39 are processed by an image processing device (not shown), and the amount of positional deviation between the alignment mark 34 and the alignment mark 35 is detected.
  • the position adjustment mechanism adjusts the positions of the small grids 21 and 22 based on the detected displacement amount.
  • the adhesive preferably has X-ray permeability and does not deform such as shrinkage when solidified.
  • a thermosetting adhesive or an instantaneous adhesive can be used.
  • the X-rays emitted from the X-ray source 11 are partially shielded by the X-ray absorber 17 of the source grid 12, thereby reducing the effective focus size in the Y direction, and a large number of lines in the Y direction.
  • a light source (dispersed light source) is formed.
  • the X-rays of a large number of line light sources formed by the radiation source grid 12 cause a phase difference when passing through the subject H, and the X-rays pass through the first grid 13 to refract the subject H.
  • a fringe image reflecting the transmission phase information of the subject H determined from the rate and the transmission optical path length is formed.
  • the fringe image of each line light source is projected onto the second grid 14 and coincides (overlaps) at the position of the second grid 14, so that the image quality of the phase contrast image can be improved without reducing the X-ray intensity. it can.
  • the intensity of the fringe image is modulated by the second grid 14 and, for example, a phase differential image is generated by a fringe scanning method.
  • the fringe scanning method translates in the Y direction at a scanning pitch in which the second grid 14 is equally divided (for example, divided into five) with respect to the first grid 13. This is a method of shooting while moving.
  • the subject H is irradiated with X-rays from the X-ray source 11 and detected by the X-ray image detector 15, and the pixel data of each pixel of the X-ray image detector 15 is detected.
  • a phase differential image is obtained by calculating the phase shift amount (phase shift amount with and without the subject H). By integrating this phase differential image along the fringe scanning direction (Y direction), a phase contrast image of the subject H is obtained.
  • the grid for radiographic imaging according to the present embodiment is configured by joining the small grids 21 and 22, a large area can be obtained and the imaging area of the phase contrast image can be increased. Can do.
  • the small grids 21 and 22 are joined so that the grid part 21a and the non-grid part 22b overlap the non-grid part 21b and the grid part 22a. Since the boundary with the grid portion coincides and the two grid portions 21a and 22a are joined to form one large grid portion in succession, the grid portions 21a and 22a of the small grids 21 and 22 The interval between them becomes smaller than the pixel size, and a high-quality phase contrast image can be obtained.
  • the alignment marks 34 and 35 are provided after the small grids 21 and 22 are manufactured.
  • the alignment marks may be formed during the manufacturing of the small grids 21 and 22.
  • a bridge portion 40 that connects the partition walls 26 may be formed on the X-ray transparent substrate 24, and one or a plurality of the bridge portions 40 may be used as an alignment mark.
  • the formation process of the alignment mark performed after manufacture of a small grid in the said embodiment can be abolished.
  • the bridge portion 40 has an effect of reinforcing the partition wall 26, it is possible to prevent a sticking phenomenon in which the partition walls 26 stick to each other when the groove 25 is filled with gold by an electrolytic plating method.
  • the boundaries between the grid portions and the non-grid portions are made to coincide with each other, but as shown in FIG. You may make a part overlap. In this case, it is necessary to perform alignment so that the X-ray absorption part 19 of the grid part 21a and the X-ray absorption part 19 of the grid part 22a overlap in the overlapping part.
  • the boundary between the respective grid portions and the non-grid portions may not be matched, and a gap DS may be provided between them. According to this, since the alignment accuracy can be lowered, the manufacturing cost and the manufacturing throughput can be reduced.
  • the interval DS is preferably set to a size (150 ⁇ m) or less of one pixel of the X-ray image detector 15.
  • the small grids 21 and 22 from which the support substrate 28 is removed are used.
  • the surfaces provided with the grid portions 43a and 44a of the small grids 43 and 44 may be joined to each other, or as shown in FIG. 8D, the surface provided with the support substrate 42 and the grid portion 42a. You may join the surface provided with.
  • the second grid 14 is configured by the two small grids 21 and 22, but a large area grid may be configured by using three or more small grids.
  • a large area grid 46 may be formed by joining four small grids 45a to 45d.
  • FIG. 9B if the small grids 45a to 45d are alternately overlapped, the thickness of the grid 46 can be suppressed even if the number of small grids increases.
  • the gap CL generated between the small grids may be left as it is when used as an absorption grid.
  • the X-ray transmissive substrate used for the small grids 45a to 45d is made of a material having the same X-ray permeability, It is preferable to fill the gap CL.
  • the small grids 51a to 51e may be overlapped and joined in a staircase pattern.
  • dummy substrates 52a to 52d having X-ray transparency are provided under the small grids 51a, 51b, 51d, and 51e as shown by two-dot chain lines. It is preferable to join.
  • a concave support substrate 54 may be used instead of the dummy substrate.
  • the small grids 51a to 51e are temporarily fixed with an adhesive in order, and all the small grids are temporarily fixed, and then the adhesive for main bonding is small with the support substrate 54. What is necessary is just to fill between the grids 51a to 51e.
  • the small grids 51a, 51b, 51d and 51e of the grid 50 are inclined so as to be directed to the X-ray focal point.
  • a grid may be configured. When the grid is enlarged using a plurality of small grids, vignetting of cone-beam X-rays occurs. However, since a grid with a converging structure is obtained by tilting the small grids, X-rays are obtained. Vignetting can be reduced. Further, each small grid may be inclined using a concave support substrate.
  • the small grids are arranged only in one direction (Y direction) and overlap each other.
  • the small grids are arranged in two directions (X direction and Y direction). They may be arranged together and overlap each other.
  • the grid 60 is formed by first joining the four sides of the lowermost small grid 61 with the second small grids 62a to 62d being overlapped, and then joining the three stages.
  • the small grids 63a to 63d of the eyes are joined around the small grids 62a to 62d in the second stage. According to this, the area of the grid can be increased in the two-dimensional direction. If the grid portion of each small grid is replaced by a cross-shaped grid instead of a striped grid, and each small grid is inclined toward the X-ray focal point, a spherical grid can be obtained.
  • the X-rays that have passed through the first and second grids 13 and 14 are linearly projected.
  • the Talbot interference is performed by diffracting the X-rays by the grid. It is good also as a structure (structure described in patent 44459797) which produces an effect.
  • a phase-type grid can be used as the first grid 13, and the phase-type grid used in place of the first grid 13 is a fringe image (self-image) generated by the Talbot interference effect. )
  • the second grid 14 At the position of the second grid 14.
  • the above embodiment has been described by taking X-rays as an example of radiation, but it can also be applied to grids used for radiation such as ⁇ rays, ⁇ rays, ⁇ rays, electron beams, and ultraviolet rays.
  • the present invention can also be applied to a scattered radiation removal grid that removes radiation scattered by a subject when the radiation passes through the subject.
  • the above embodiments can be implemented in combination with each other within a consistent range.

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Abstract

A grid for capturing a radiation image, wherein a plurality of small grids are arranged such that the interval between grid parts of adjacent small grids is smaller than or equal to the size of one pixel of an X-ray image detector. A second grid serving as a grid for capturing a radiation image is configured from at least two small grids. Each of the small grids comprises a grid part that functions as a grid, and a non-grid part that is provided at the outer periphery of the grid part and does not function as the grid. Two adjacent small grids are joined such that the grid part of one small grid and the non-grid part of the other small grid overlap each other, and the boundary between the grid part and the non-grid part of the one small grid and the boundary of the grid part and the non-grid part of the other small grid match. Consequently, the grid parts of the adjacent small grids are continuous to thereby constitute one large grid part.

Description

放射線画像撮影用グリッド及びその製造方法、並びに放射線画像撮影システムRadiation imaging grid, manufacturing method thereof, and radiation imaging system
 本発明は、放射線画像の撮影に用いられる放射線画像撮影用グリッド及びその製造方法と、この放射線画像撮影用グリッドを用いた放射線画像撮影システムとに関する。 The present invention relates to a radiographic imaging grid used for radiographic imaging, a manufacturing method thereof, and a radiographic imaging system using the radiographic imaging grid.
 放射線が被検体を透過する際の位相変化(角度変化)に基づいた画像(以下、位相コントラスト画像という)を得る放射線位相イメージングの一種として、タルボ干渉効果を用いた放射線画像撮影システムが知られている。放射線として、例えばX線を用いるX線画像撮影システムは、被検体の背後に配置した第1のグリッドと、第1のグリッドのグリッドピッチとX線波長で決まるタルボ干渉距離だけX線の照射方向の下流に配置した第2のグリッドと、その背後に配置したX線画像検出器とを有する。第1のグリッドを通過したX線は、タルボ干渉効果により第2のグリッドの位置で自己像(縞画像)を形成する。この自己像は、被検体によるX線の位相変化により変調を受ける。 A radiation imaging system using the Talbot interference effect is known as a kind of radiation phase imaging that obtains an image (hereinafter referred to as a phase contrast image) based on a phase change (angle change) when radiation passes through a subject. Yes. An X-ray imaging system that uses, for example, X-rays as radiation, includes a first grid disposed behind the subject, and a Talbot interference distance determined by the grid pitch and X-ray wavelength of the first grid, and the X-ray irradiation direction. And a second grid disposed downstream of the X-ray image detector and an X-ray image detector disposed behind the second grid. The X-rays that have passed through the first grid form a self-image (stripe image) at the position of the second grid due to the Talbot interference effect. This self-image is modulated by the X-ray phase change by the subject.
 上記X線画像撮影システムは、第1のグリッドの自己像と第2のグリッドとの重ね合わせにより強度変調された縞画像の被検体による変化(位相ズレ)から被検体の位相コントラスト画像を取得する。これは縞走査法と呼ばれている。縞走査法では、第1のグリッドに対して第2のグリッドを移動させながら各走査位置でX線画像検出器により撮影を行い、X線画像検出器で得られる各画素の画素データの上記走査位置に対する強度変化の位相のズレ量から位相微分像(被検体で屈折したX線の角度分布に対応)を取得する。この第2のグリッドの移動では、第1のグリッドの面にほぼ平行で、かつ第1のグリッドのグリッド方向にほぼ垂直な方向に、グリッドピッチを等分割した走査ピッチで並進移動(走査)させている。得られた位相微分像を、縞走査方向に沿って積分することにより被検体の位相コントラスト画像が得られる。 The X-ray imaging system acquires a phase contrast image of a subject from a change (phase shift) caused by the subject of a stripe image whose intensity is modulated by superimposing the self-image of the first grid and the second grid. . This is called a fringe scanning method. In the fringe scanning method, imaging is performed by an X-ray image detector at each scanning position while moving the second grid with respect to the first grid, and the above-described scanning of pixel data of each pixel obtained by the X-ray image detector is performed. A phase differential image (corresponding to the angular distribution of X-rays refracted by the subject) is acquired from the amount of phase shift in intensity change with respect to the position. In the movement of the second grid, translational movement (scanning) is performed at a scanning pitch obtained by equally dividing the grid pitch in a direction substantially parallel to the plane of the first grid and substantially perpendicular to the grid direction of the first grid. ing. A phase contrast image of the subject is obtained by integrating the obtained phase differential image along the fringe scanning direction.
 第1及び第2のグリッドは、X線の照射方向に直交する方向に延伸されたX線吸収部をX線照射方向及び延伸方向に直交する方向に所定ピッチで配列した縞状(ストライプ状)の構造を有する。X線吸収部の配列ピッチは、X線焦点から第1のグリッドまでの距離と、第1のグリッドと第2のグリッドとの距離によって決定され、およそ2~20μmである。また、第2のグリッドの線吸収部は、高いX線吸収性を必要とするため、X線の進行方向の厚みが100μm程度という高アスペクト比の構造を必要とする。 The first and second grids are striped (striped) in which X-ray absorbers stretched in a direction perpendicular to the X-ray irradiation direction are arranged at a predetermined pitch in a direction orthogonal to the X-ray irradiation direction and the stretching direction. It has the following structure. The arrangement pitch of the X-ray absorbers is determined by the distance from the X-ray focal point to the first grid and the distance between the first grid and the second grid, and is approximately 2 to 20 μm. Moreover, since the line absorption part of the second grid requires high X-ray absorption, it requires a high aspect ratio structure in which the X-ray traveling direction thickness is about 100 μm.
 グリッドの構造は微細であるため、グリッドの製作には微細な加工が可能なシリコン半導体プロセスが用いられている。しかし、シリコン半導体プロセスでは、加工可能なサイズがウエハのサイズに制限されるため、大きなサイズのグリッドを製造することはできない。そのため、図15Aに示すように、サイズの小さな小グリッド90を複数枚並べ、全体として大きな面積のグリッド91を構成する手法が知られている(例えば、特許文献1、2参照)。 Since the grid structure is fine, a silicon semiconductor process capable of fine processing is used for the production of the grid. However, in the silicon semiconductor process, the size that can be processed is limited to the size of the wafer, and thus a large-size grid cannot be manufactured. For this reason, as shown in FIG. 15A, a technique is known in which a plurality of small grids 90 having a small size are arranged to form a grid 91 having a large area as a whole (see, for example, Patent Documents 1 and 2).
特開2007-203061号公報JP 2007-203061 A 特開平09-304738号公報JP 09-304738 A
 シリコン半導体プロセスを用いて製造された小グリッドは、外周がカットされて矩形状となる。カットされる外周は、図16Aに示すように、X線吸収部が設けられて実際にグリッドとして機能するグリッド部93の端部と一致しているのが理想的である。しかし、外周をカットする精度によっては、図16Bに示すように、カットした端部94がグリッド部93の端部に対して斜めになることがある。また、カット時に発生するチッピング、カット後の取り扱い中に発生する欠け等により、図16Cに示すように、端部95が凹凸状になることもある。したがって、実際の小グリッド90は、図15Aに示すように、グリッド部93の外側に、グリッドとして機能しない切り代としての非グリッド部96を設ける必要がある。 A small grid manufactured using a silicon semiconductor process has a rectangular shape with the outer periphery cut. Ideally, as shown in FIG. 16A, the outer periphery to be cut coincides with the end portion of the grid portion 93 that is provided with an X-ray absorption portion and actually functions as a grid. However, depending on the accuracy of cutting the outer periphery, the cut end portion 94 may be inclined with respect to the end portion of the grid portion 93 as shown in FIG. 16B. Further, as shown in FIG. 16C, the end portion 95 may be uneven as a result of chipping that occurs during cutting, chipping that occurs during handling after cutting, and the like. Accordingly, as shown in FIG. 15A, the actual small grid 90 needs to be provided with a non-grid portion 96 as a cutting margin that does not function as a grid outside the grid portion 93.
 非グリッド部96は、例えばダイシングによってカットする場合に、50μmの幅が必要である。また、小グリッド90を並べる際に、各小グリッド90を平行にアライメントするためには、小グリッド90間にある程度の隙間が必要である。そのため、小グリッド90を並べると、図15A及び図15Bに示すように、隣接する小グリッド90のグリッド部93との間に間隔DSが生じてしまう。 When the non-grid portion 96 is cut by, for example, dicing, a width of 50 μm is necessary. In order to align the small grids 90 in parallel when the small grids 90 are arranged, a certain amount of gap is required between the small grids 90. Therefore, when the small grids 90 are arranged, as shown in FIG. 15A and FIG. 15B, an interval DS occurs between the grid portions 93 of the adjacent small grids 90.
 この間隔DSは短いことが望ましい。具体的には、この間隔DSは、位相コントラスト画像の撮影に用いられるX線画像検出器の1画素のサイズ以下(例えば、150μm以下)であることがより望ましい。これは、間隔DSが画素サイズよりも大きくなると、その部分が位相コントラスト画像を取得できない領域となり、画像品質を劣化させるためである。なお、特許文献1、2には、グリッド部93の間隔DSを狭くして小グリッド90を配列するための手法は開示されていない。 This distance DS is preferably short. More specifically, the interval DS is more preferably less than or equal to the size of one pixel (for example, 150 μm or less) of an X-ray image detector used for capturing a phase contrast image. This is because when the interval DS becomes larger than the pixel size, the portion becomes an area where a phase contrast image cannot be acquired, and the image quality is deteriorated. Patent Documents 1 and 2 do not disclose a method for arranging the small grids 90 by narrowing the interval DS between the grid portions 93.
 本発明の目的は、隣接する小グリッドのグリッド部の間隔が、X線画像検出器の1画素のサイズ以下となるように、複数枚の小グリッドを配列することにある。 An object of the present invention is to arrange a plurality of small grids so that the interval between the grid portions of adjacent small grids is less than the size of one pixel of the X-ray image detector.
 上記課題を解決するために、本発明の放射線画像撮影用グリッドは、N個(Nは2以上の整数)の小グリッドを備え、各小グリッドは放射線吸収部が所定ピッチで配列されたグリッド部と、グリッド部の外周に設けられた放射線透過性の非グリッド部とにより構成されている。隣接する小グリッドの間では、一方の小グリッドのグリッド部と、他方の小グリッドの非グリッド部とが対面するように重ね合わされている。 In order to solve the above problems, a grid for radiographic imaging according to the present invention includes N (N is an integer of 2 or more) small grids, and each small grid has a grid portion in which radiation absorbing portions are arranged at a predetermined pitch. And a radiation transmissive non-grid portion provided on the outer periphery of the grid portion. Between the adjacent small grids, the grid portion of one small grid and the non-grid portion of the other small grid are overlapped so as to face each other.
 隣接する小グリッドの間では、一方の小グリッドのグリッド部と非グリッド部との境界と、他方の小グリッドのグリッド部と非グリッド部との境界とが一致していることが好ましい。 Between adjacent small grids, it is preferable that the boundary between the grid portion and the non-grid portion of one small grid and the boundary between the grid portion and the non-grid portion of the other small grid coincide.
 N個の小グリッドを上下交互に重ね合わせてもよい。これにより、複数枚の小グリッドを重ね合わせたときでも、放射線画像撮影用グリッドの厚みが厚くならないように抑制することができる。 N N small grids may be stacked alternately one above the other. Thereby, even when a plurality of small grids are overlapped, it is possible to suppress the thickness of the radiation image capturing grid from being increased.
 また、N個の小グリッドを階段状に重ね合わせてもよい。このときには、複数枚の小グリッドの下に、放射線透過性を有するダミー基板を接合することが好ましい。また、ダミー基板に代えて、凹面状の支持基板により保持してもよい。更に、N個の小グリッドを、略凹状または略球面状のグリッド面を構成するように傾斜して配置させてもよい。 Also, N small grids may be stacked in a staircase pattern. At this time, it is preferable to bond a radiation-transmitting dummy substrate under a plurality of small grids. Further, instead of the dummy substrate, it may be held by a concave support substrate. Further, the N small grids may be arranged so as to be inclined so as to form a substantially concave or substantially spherical grid surface.
 本発明の放射線画像撮影用グリッドの製造方法は、放射線吸収部が所定ピッチで配列されたグリッド部と、グリッド部の外周に設けられた放射線透過性の非グリッド部とにより構成されたN個(Nは2以上の整数)の小グリッドを製造する小グリッド製造工程と、隣接する小グリッドについて、一方の小グリッドのグリッド部と、他方の小グリッドの非グリッド部とが対面するように重ね合わせて接合する接合工程とを備える。 The method for manufacturing a radiographic imaging grid according to the present invention includes N grids each including a grid part in which radiation absorbing parts are arranged at a predetermined pitch and a radiation transmissive non-grid part provided on the outer periphery of the grid part ( N is an integer greater than or equal to 2), and the adjacent small grids are superposed so that the grid portion of one small grid and the non-grid portion of the other small grid face each other. And a joining step for joining.
 また、非グリッド部に、可視光による視認性と放射線透過性とを備えたアライメントマークを形成するアライメントマーク形成工程と、アライメントマークの位置を検出して、隣接する小グリッドの位置を調整する位置調整工程と、を更に備えることも好ましい。更に、位置調整工程では、隣接する小グリッドを、アライメントマークが設けられた面同士が空間を空けて対面するように配置し、この空間に位置検出装置を挿入してアライメントマークの位置を検出することにより位置調整を行ってもよい。 In addition, an alignment mark forming step for forming an alignment mark having visibility and radiation transparency by visible light on the non-grid portion, and a position for detecting the position of the alignment mark and adjusting the position of the adjacent small grid It is also preferable to further include an adjustment step. Further, in the position adjustment step, adjacent small grids are arranged so that the surfaces provided with the alignment marks face each other with a space therebetween, and a position detection device is inserted into this space to detect the position of the alignment mark. The position may be adjusted accordingly.
 本発明の放射線画像撮影システムは、放射線を放射する放射線源と、放射線を通過させて縞画像を生成する第1のグリッドと、縞画像に強度変調を与える第2のグリッドと、放射線源と第1のグリッドとの間に配置され、放射線源から照射された放射線を領域選択的に遮蔽して多数の線光源とする第3のグリッドと、第2のグリッドにより強度変調された縞画像を検出する放射線画像検出器とを備えている。第1~第3のグリッドの少なくとも1つは、放射線吸収部が所定ピッチで配列されたグリッド部と、グリッド部の外周に設けられた放射線透過性の非グリッド部とにより構成されたN個(Nは2以上の整数)の小グリッドを備えている。隣接する小グリッドの間では、一方の小グリッドのグリッド部と、他方の小グリッドの非グリッド部とが対面するように重ね合わされている。 The radiographic imaging system of the present invention includes a radiation source that emits radiation, a first grid that transmits radiation and generates a fringe image, a second grid that applies intensity modulation to the fringe image, a radiation source, A third grid which is arranged between the first grid and shields the radiation emitted from the radiation source in a selective manner and detects a plurality of line light sources, and a fringe image whose intensity is modulated by the second grid is detected. A radiation image detector. At least one of the first to third grids includes N pieces of grid portions in which radiation absorbing portions are arranged at a predetermined pitch and radiation transmissive non-grid portions provided on the outer periphery of the grid portion ( N is an integer of 2 or more). Between the adjacent small grids, the grid portion of one small grid and the non-grid portion of the other small grid are overlapped so as to face each other.
 本発明では、一方の小グリッドのグリッド部と他方の小グリッドの非グリッド部とが対面するように重ね合わせているので、非グリッド部の大きさに影響されることなく、グリッド部の間隔が狭くなるように複数枚の小グリッドを配列することができる。これにより、本発明では、複数枚の小グリッドのグリッド部間で位相コントラスト画像が取得できなくなるような事態が発生せず、高画質の位相コントラスト画像得ることができる。 In the present invention, since the grid portion of one small grid and the non-grid portion of the other small grid are overlapped with each other, the interval between the grid portions is not affected by the size of the non-grid portion. A plurality of small grids can be arranged to be narrow. As a result, in the present invention, a situation in which a phase contrast image cannot be acquired between the grid portions of a plurality of small grids does not occur, and a high-quality phase contrast image can be obtained.
本発明のX線画像撮影システムの構成を示す説明図である。It is explanatory drawing which shows the structure of the X-ray imaging system of this invention. 第2のグリッドをX線画像検出器の側から見た平面図である。It is the top view which looked at the 2nd grid from the X-ray image detector side. 図2AのIIB-IIB線に沿う断面を示す断面図である。FIG. 2B is a cross-sectional view showing a cross section taken along the line IIB-IIB in FIG. 2A. 小グリッドのグリッド部の構成を示す断面図である。It is sectional drawing which shows the structure of the grid part of a small grid. 小グリッドの製造手順1を示す断面図である。It is sectional drawing which shows the manufacture procedure 1 of a small grid. 小グリッドの製造手順2を示す断面図である。It is sectional drawing which shows the manufacturing procedure 2 of a small grid. 小グリッドの製造手順3を示す断面図である。It is sectional drawing which shows the manufacturing procedure 3 of a small grid. 小グリッドの製造手順4を示す断面図である。It is sectional drawing which shows the manufacture procedure 4 of a small grid. 小グリッドの製造手順5を示す断面図である。It is sectional drawing which shows the manufacturing procedure 5 of a small grid. 小グリッドのアライメントマークを示す平面図である。It is a top view which shows the alignment mark of a small grid. 小グリッドのアライメントマークの別の例を示す平面図である。It is a top view which shows another example of the alignment mark of a small grid. 小グリッドのアライメント工程を示す説明図である。It is explanatory drawing which shows the alignment process of a small grid. アライメントマークとして用いるブリッジ部を有する小グリッドを示す平面図である。It is a top view which shows the small grid which has a bridge part used as an alignment mark. 2枚の小グリッドの接合例1を示す断面図である。It is sectional drawing which shows the example 1 of joining of two small grids. 2枚の小グリッドの接合例2を示す断面図である。It is sectional drawing which shows the example 2 of joining of two small grids. 2枚の小グリッドの接合例3を示す断面図である。It is sectional drawing which shows the example 3 of joining of two small grids. 2枚の小グリッドの接合例4を示す断面図である。It is sectional drawing which shows the example 4 of joining of two small grids. 3枚以上の小グリッドを上下交互に重ね合わせたグリッドの平面図である。It is a top view of the grid which piled up three or more small grids alternately up and down. 図9AのIXB-IXB線に沿う断面を示す断面図である。FIG. 9B is a cross-sectional view showing a cross section taken along line IXB-IXB in FIG. 9A. 3枚以上の小グリッドを階段状に重ね合わせたグリッドの平面図である。It is a top view of the grid which piled up the three or more small grids in the step shape. 図10AのXB-XB線に沿う断面を示す断面図である。FIG. 10B is a sectional view showing a section taken along line XB-XB in FIG. 10A. 凹面状の支持基板に3枚以上の小グリッドを接合したグリッドの断面図である。It is sectional drawing of the grid which joined the 3 or more small grid to the concave-shaped support substrate. 小グリッドを傾斜させて凹面状にしたグリッドの断面図である。It is sectional drawing of the grid which inclined the small grid and made it concave. 小グリッドを複数方向において重ね合わせたグリッドの斜視図である。It is a perspective view of the grid which piled up the small grid in a plurality of directions. 小グリッドを2方向に重ね合わせたグリッドの分解斜視図である。It is a disassembled perspective view of the grid which piled up the small grid in two directions. 従来の放射線画像撮影用グリッドを示す平面図である。It is a top view which shows the conventional grid for radiographic imaging. 図15AのXVB-XVB線に沿う断面を示す断面図である。FIG. 15B is a cross-sectional view showing a cross section taken along line XVB-XVB in FIG. 15A. 外周が理想的にカットされた小グリッドを例示する平面図である。It is a top view which illustrates the small grid where the perimeter was cut ideally. 外周が斜めにカットされた小グリッドを例示する平面図である。It is a top view which illustrates the small grid by which the outer periphery was cut diagonally. 外周が凹凸状にカットされた小グリッドを例示する平面図である。It is a top view which illustrates the small grid by which the outer periphery was cut in the uneven | corrugated shape.
 図1に示すように、本発明のX線画像撮影システム10は、X線源11、線源グリッド12、第1のグリッド13、第2のグリッド14、X線画像検出器15を備えている。X線源11は、Z方向に配置された被検体Hに向けてX線を放射する。線源グリッド12は、Z方向においてX線源11に対向配置されている。第1のグリッド13は、線源グリッド12からZ方向に所定距離離れた位置に平行に配置されている。第2のグリッド14は、第1のグリッド13からZ方向に所定距離離れた位置に平行に配置されている。X線画像検出器15は、第2のグリッド14に対向配置されている。このX線画像検出器15は、例えば、半導体回路を用いたフラットパネル検出器が用いられる。 As shown in FIG. 1, the X-ray imaging system 10 of the present invention includes an X-ray source 11, a source grid 12, a first grid 13, a second grid 14, and an X-ray image detector 15. . The X-ray source 11 emits X-rays toward the subject H arranged in the Z direction. The radiation source grid 12 is disposed opposite to the X-ray source 11 in the Z direction. The first grid 13 is arranged in parallel at a position away from the radiation source grid 12 by a predetermined distance in the Z direction. The second grid 14 is arranged in parallel at a position away from the first grid 13 by a predetermined distance in the Z direction. The X-ray image detector 15 is disposed so as to face the second grid 14. As the X-ray image detector 15, for example, a flat panel detector using a semiconductor circuit is used.
 線源グリッド12、第1のグリッド13及び第2のグリッド14は、吸収型グリッドであり、複数のX線吸収部17、18、19がそれぞれ縞状に設けられている。このX線吸収部17、18、19は、Z方向に直交するX方向に直線状に延伸され、かつZ方向及びX方向に直交するY方向に沿って所定のピッチで周期的に配列されている。線源グリッド12、第1のグリッド13及び第2のグリッド14は、X線吸収部17、18、19によってX線を吸収し、X線吸収部の間に設けられたX線透過部によってX線を透過させる。本実施形態では、第1のグリッド13は、タルボ干渉効果を発生せず、X線を線形的(幾何光学的)に第2のグリッド14に投影するように格子ピッチがX線の波長に対して設定されている。 The radiation source grid 12, the first grid 13, and the second grid 14 are absorption grids, and a plurality of X-ray absorption parts 17, 18, and 19 are provided in a striped pattern. The X-ray absorbers 17, 18, and 19 are linearly extended in the X direction orthogonal to the Z direction, and are periodically arranged at a predetermined pitch along the Y direction orthogonal to the Z direction and the X direction. Yes. The radiation source grid 12, the first grid 13, and the second grid 14 absorb X-rays by the X-ray absorption units 17, 18, and 19, and X-rays are transmitted by the X-ray transmission unit provided between the X-ray absorption units. Make lines transparent. In the present embodiment, the first grid 13 does not generate a Talbot interference effect, and the grating pitch is relative to the wavelength of the X-ray so that X-rays are projected linearly (geometrically) onto the second grid 14. Is set.
 以下、第2のグリッド14を例にして、本発明の放射線画像撮影用グリッドの構成を説明する。なお、線源グリッド12及び第1のグリッド13は、X線吸収部17、18の幅、ピッチ、X線照射方向の厚さ等が異なる以外は第2のグリッド14とほぼ同様の構成であるため、詳しい説明は省略する。 Hereinafter, the configuration of the grid for radiographic imaging of the present invention will be described using the second grid 14 as an example. The source grid 12 and the first grid 13 have substantially the same configuration as the second grid 14 except that the widths, pitches, thicknesses in the X-ray irradiation direction, and the like of the X-ray absorbers 17 and 18 are different. Therefore, detailed description is omitted.
 図2A及び図2Bにおいて、小グリッド21、22は、グリッドとして機能するグリッド部21a,22aと、グリッド部21a,22aの外周に設けられてグリッドとして機能しない非グリッド部21b,22bとをそれぞれ備えている。小グリッド21、22は、グリッド部21a及び非グリッド部22bと、非グリッド部21b及びグリッド部22aとが重なり合うように接合されており、Z方向から見たときにそれぞれのグリッド部と非グリッド部との境界が一致し、かつ2つのグリッド部21a、22aが連続して1枚の大きなグリッド部を構成するように接合されている。 2A and 2B, the small grids 21 and 22 include grid portions 21a and 22a that function as grids, and non-grid portions 21b and 22b that are provided on the outer periphery of the grid portions 21a and 22a and do not function as grids, respectively. ing. The small grids 21 and 22 are joined so that the grid part 21a and the non-grid part 22b overlap with the non-grid part 21b and the grid part 22a, and each grid part and the non-grid part when viewed from the Z direction. And the two grid portions 21a and 22a are joined together so as to form one large grid portion.
 図2Bのグリッド部を拡大して表した図3に示すように、小グリッド21、22は、シリコン等のX線透過性を有する材質で形成されたX線透過性基板24と、このX線透過性基板24に設けられたX線吸収部19とで構成されている。X線吸収部19は、グリッド部21a,22a内に設けられている。X線吸収部19は、X線透過性基板24にX方向に沿って設けられ、Y方向に沿って配列された複数の溝25の中に設けられており、X線吸収性に優れた金属、例えば金やプラチナ等から構成されている。各X線吸収部19を隔てている複数の隔壁26は、X線透過部として機能する。 As shown in FIG. 3 in which the grid portion of FIG. 2B is enlarged, the small grids 21 and 22 include an X-ray transparent substrate 24 formed of a material having X-ray transparency such as silicon, and the X-rays. The X-ray absorber 19 is provided on the transparent substrate 24. The X-ray absorber 19 is provided in the grid portions 21a and 22a. The X-ray absorber 19 is provided in the X-ray transparent substrate 24 along the X direction and is provided in a plurality of grooves 25 arranged along the Y direction, and is a metal having excellent X-ray absorption. For example, it is composed of gold or platinum. The plurality of partition walls 26 separating the X-ray absorption parts 19 function as X-ray transmission parts.
 X線吸収部19の幅W2及びピッチPは、線源グリッド12と第1のグリッド13との間の距離、第1のグリッド13と第2のグリッド14との距離、及び第1のグリッド13のX線吸収部18のピッチ等によって決まる。幅Wはおよそ2~20μm、ピッチPは4~40μm程度である。また、X線吸収部19のX方向への厚みTは、高いX線吸収性を得るためには厚いほどよいが、X線源11から放射されるコーンビーム状のX線のケラレを考慮して、100μm程度であることが好ましい。本実施形態では、例えば、幅Wを2.5μm、ピッチPを5μm、厚みTを100μmとする。 Width W2 and the pitch P 2 of the X-ray absorbing portion 19, the distance between the source grid 12 and the first grid 13, the distance between the first grid 13 and second grid 14, and the first grid It is determined by the pitch of the 13 X-ray absorbers 18. The width W 2 is about 2 to 20 μm, and the pitch P 2 is about 4 to 40 μm. Further, the thickness T 2 in the X direction of the X-ray absorption unit 19 is preferably as thick as possible in order to obtain high X-ray absorption, but vignetting of cone-beam X-rays radiated from the X-ray source 11 is considered. And it is preferable that it is about 100 micrometers. In the present embodiment, for example, the width W 2 is 2.5 μm, the pitch P 2 is 5 μm, and the thickness T 2 is 100 μm.
 次に、図4A~図4Eを参照し、第2のグリッド14を例にして、本発明のグリッドの製造方法について説明する。なお、線源グリッド12及び第1のグリッド13も同様の製造方法により製造されるため、詳しい説明は省略する。なお、小グリッド22も同様の手順で製造されるため、詳しい説明は省略する。 Next, with reference to FIGS. 4A to 4E, the grid manufacturing method of the present invention will be described using the second grid 14 as an example. The radiation source grid 12 and the first grid 13 are also manufactured by the same manufacturing method, and detailed description thereof is omitted. In addition, since the small grid 22 is manufactured in the same procedure, detailed description is abbreviate | omitted.
 図4Aに示すように、小グリッド21を製造する最初の工程では、シリコン製のX線透過性基板24の下面に支持基板28が接合される。支持基板28には、X線吸収性の低い材料が用いられており、ホウケイ酸ガラス、ソーダライムガラス、石英、アルミナ、GaAs、Ge等が望ましく、X線透過性基板24と同じシリコンがより望ましい。ホウケイ酸ガラスとしては、例えばパイレックス(登録商標)ガラス、テンパックス(登録商標)ガラス等を用いることができる。 As shown in FIG. 4A, in the first step of manufacturing the small grid 21, the support substrate 28 is bonded to the lower surface of the X-ray transparent substrate 24 made of silicon. The support substrate 28 is made of a material having low X-ray absorption, and is preferably borosilicate glass, soda lime glass, quartz, alumina, GaAs, Ge, or the like, and more preferably the same silicon as the X-ray transparent substrate 24. . As the borosilicate glass, for example, Pyrex (registered trademark) glass, Tempax (registered trademark) glass, or the like can be used.
 支持基板28のX線透過性基板24に接合された面には、導電性を有するシーズ層30が設けられている。シーズ層30は、例えば、AuまたはNi、もしくはAl、Ti、Cr、Cu、Ag、Ta、W、Pb、Pd、Pt等により形成された金属膜、あるいはそれらの合金により形成された金属膜であることが好ましい。また、シーズ層30は、X線透過性基板24に設けてもよいし、X線透過性基板24と支持基板28との両方に設けてもよい。 A conductive sheath layer 30 is provided on the surface of the support substrate 28 bonded to the X-ray transparent substrate 24. The seed layer 30 is made of, for example, Au or Ni, or a metal film formed of Al, Ti, Cr, Cu, Ag, Ta, W, Pb, Pd, Pt, or a metal film formed of an alloy thereof. Preferably there is. Further, the seeds layer 30 may be provided on the X-ray transparent substrate 24 or may be provided on both the X-ray transparent substrate 24 and the support substrate 28.
 図4Bに示すように、一般的なフォトリソグラフィ技術を用いて、X線透過性基板24の上にエッチングマスク32が形成される。エッチングマスク32は、X方向に直線状に延伸され、かつY方向に所定ピッチで周期的に配列された縞模様のパターンを有する。 As shown in FIG. 4B, an etching mask 32 is formed on the X-ray transparent substrate 24 by using a general photolithography technique. The etching mask 32 has a striped pattern that extends linearly in the X direction and is periodically arranged at a predetermined pitch in the Y direction.
 図4Cに示すように、エッチングマスク32を用いたドライエッチングにより、X線透過性基板24に複数の溝25が形成される。溝25は、例えば、幅が数μm、深さ100μm程度の高いアスペクト比を必要とするため、溝25を形成するドライエッチングには、ボッシュプロセス、クライオプロセス等が用いられる。なお、シリコン基板に代えて感光性レジストを使用し、シンクロトロン放射光で露光することにより溝を形成してもよい。 As shown in FIG. 4C, a plurality of grooves 25 are formed in the X-ray transparent substrate 24 by dry etching using the etching mask 32. The groove 25 requires a high aspect ratio of, for example, a width of several μm and a depth of about 100 μm. Therefore, a Bosch process, a cryo process, or the like is used for dry etching for forming the groove 25. Note that a groove may be formed by using a photosensitive resist instead of the silicon substrate and exposing with synchrotron radiation.
 図4Dに示すように、電解メッキにより溝25内に金などのX線吸収材が充填され、X線吸収部19が形成される。支持基板28が接合されたX線透過性基板24は、シーズ層30に電流端子が接続されて、メッキ液中に浸漬される。X線透過性基板24と対向させた位置には、もう一方の電極(陽極)が用意され、この問に電流が流されてメッキ液中の金属イオンがパターン加工されたX線透過性基板24へ析出されることにより、溝25内に金が埋め込まれる。なお、溝25に対するX線吸収材の充填は、電解メッキ法に限定されるものではなく、ペースト状やコロイド状のX線吸収材を塗布することにより行ってもよい。 As shown in FIG. 4D, the groove 25 is filled with an X-ray absorber such as gold by electrolytic plating to form an X-ray absorber 19. The X-ray transparent substrate 24 to which the support substrate 28 is bonded is immersed in a plating solution with a current terminal connected to the sheath layer 30. The other electrode (anode) is prepared at a position facing the X-ray transparent substrate 24, and an electric current is passed through this electrode to pattern the metal ions in the plating solution. By depositing into the groove 25, gold is embedded in the groove 25. The filling of the X-ray absorbing material into the groove 25 is not limited to the electrolytic plating method, and may be performed by applying a paste-like or colloidal X-ray absorbing material.
 図4Eに示すように、X線吸収部19が形成されたX線透過性基板24等の外周がダイシング等によって矩形状にカットされ、小グリッド21が形成される。このカット工程により、グリッド部21aの外周に、小グリッド同士を接合する際の接合代として用いることが可能な幅を有した非グリッド部21bが形成される。この後、支持基板28、シーズ層30及びエッチングマスク32は、研磨等により除去される。なお、支持基板28及びシーズ層30を小グリッド21に残存させてもよい。 As shown in FIG. 4E, the outer periphery of the X-ray transparent substrate 24 and the like on which the X-ray absorbing portion 19 is formed is cut into a rectangular shape by dicing or the like, and a small grid 21 is formed. By this cutting step, a non-grid portion 21b having a width that can be used as a joining margin when joining the small grids is formed on the outer periphery of the grid portion 21a. Thereafter, the support substrate 28, the seed layer 30 and the etching mask 32 are removed by polishing or the like. The support substrate 28 and the seed layer 30 may be left on the small grid 21.
 小グリッド21、22の製造後に、図5A及び図5Bに示すように、小グリッド21、22の非グリッド部21b、22bに、両者を接合する際のアライメントに用いられるアライメントマーク34、35が2個ずつ形成される。アライメントマーク34、35は、小グリッド21、22のグリッド部19が接合されたときに重なり合う位置に設けられる。アライメントマーク34、35の形成は、例えば、小グリッド21、22上にアライメントマークに用いる薄膜を形成し、この薄膜をエッチングやフォトリソグラフィ技術などを用いて部分的に除去することにより形成される。アライメントマーク34、35は、Al、Ti、Cr、レジスト等のX線透過性を有する材質で形成されている。 After the small grids 21 and 22 are manufactured, as shown in FIGS. 5A and 5B, two alignment marks 34 and 35 are used for alignment when joining the non-grid portions 21 b and 22 b of the small grids 21 and 22. Individually formed. The alignment marks 34 and 35 are provided at positions that overlap when the grid portions 19 of the small grids 21 and 22 are joined. The alignment marks 34 and 35 are formed by, for example, forming a thin film used for the alignment mark on the small grids 21 and 22 and partially removing the thin film using etching or a photolithography technique. The alignment marks 34 and 35 are made of an X-ray transmissive material such as Al, Ti, Cr, resist or the like.
 アライメントマーク34、35の厚さは、アライメント時に識別できる程度でよく、例えば0.01~1μmとする。アライメントマーク34、35のサイズは、グリッドの性能に対する影響を考慮した場合、X線画像検出器15の1画素以下であることが好ましく、例えば50~100μm程度が好ましい。また、アライメントマーク34、35の形状を十字形状としたが、アライメントしやすい形状であればどのような形状であってもよい。また、アライメントマーク34、35を2個ずつ設けたが、3個以上ずつ設けてもよい。 The thickness of the alignment marks 34 and 35 may be such that it can be identified during alignment, for example, 0.01 to 1 μm. The size of the alignment marks 34 and 35 is preferably not more than one pixel of the X-ray image detector 15 in consideration of the effect on the grid performance, and is preferably about 50 to 100 μm, for example. Moreover, although the shape of the alignment marks 34 and 35 is a cross shape, it may be any shape as long as it is easy to align. Further, although two alignment marks 34 and 35 are provided, three or more alignment marks may be provided.
 小グリッド21、22は、アライメント装置により、小グリッド21と小グリッド22との位置決めと、接合とが行なわれる。図6に示すように、アライメント装置では、小グリッド21及び22のアライメントマーク34、35が対向するように、小グリッド21及び22が図示しない位置調整機構により保持される。例えば、小グリッド21は、アライメントマーク34が下方を向くように配置され、小グリッド22は、アライメントアーク35が上方を向くように配置される。位置調整機構は、小グリッド21、22をそれぞれX線吸収部19の延伸方向(X方向)と、X線吸収部19の配列方向(Y方向)と、グリッド面に直交するZ方向周りのθの3方向に移動させることができる。 The small grids 21 and 22 are positioned and joined to each other by the alignment device. As shown in FIG. 6, in the alignment apparatus, the small grids 21 and 22 are held by a position adjusting mechanism (not shown) so that the alignment marks 34 and 35 of the small grids 21 and 22 face each other. For example, the small grid 21 is disposed such that the alignment mark 34 faces downward, and the small grid 22 is disposed such that the alignment arc 35 faces upward. The position adjustment mechanism is configured so that each of the small grids 21 and 22 has an extending direction (X direction) of the X-ray absorber 19, an arrangement direction of the X-ray absorber 19 (Y direction), and θ around the Z direction orthogonal to the grid surface. It can be moved in three directions of Z.
 小グリッド21と小グリッド22との間の空間には、上方と下方とを撮影するように背中合わせに配置された一対のアライメント用カメラ37、38を有する2組の位置検出ユニット39が挿入され、アライメントマーク34、35がそれぞれのカメラにより撮影される。各位置検出ユニット39のアライメント用カメラ37、38により撮影された画像は、図示しない画像処理装置によって処理され、アライメントマーク34とアライメントマーク35の位置ずれ量が検出される。位置調整機構は、検出された位置ずれ量に基づいて小グリッド21、22の位置を調整する。 In the space between the small grid 21 and the small grid 22, two sets of position detection units 39 having a pair of alignment cameras 37 and 38 arranged back to back so as to photograph the upper side and the lower side are inserted, The alignment marks 34 and 35 are photographed by the respective cameras. Images taken by the alignment cameras 37 and 38 of each position detection unit 39 are processed by an image processing device (not shown), and the amount of positional deviation between the alignment mark 34 and the alignment mark 35 is detected. The position adjustment mechanism adjusts the positions of the small grids 21 and 22 based on the detected displacement amount.
 小グリッド21、22の位置調整後、小グリッド21、22の間から2組の位置検出ユニット39が退避される。次いで、小グリッド21、22の接合部分に接着剤が塗布され、小グリッド21と小グリッド22とが当接されることにより、小グリッド21、22は接合される。接着剤は、X線透過性を有し、固化時に収縮等の変形をしないものが好ましく、例えば、熱硬化接着剤、瞬間接着剤等を用いることができる。また、接着剤の代わりに、X線透過性を有する低融点金属(例えば、ハンダ、インジウム等)を用いてもよい。 After the position adjustment of the small grids 21 and 22, two sets of position detection units 39 are retracted from between the small grids 21 and 22. Next, an adhesive is applied to the joining portion of the small grids 21 and 22, and the small grids 21 and 22 are joined by contacting the small grid 21 and the small grid 22. The adhesive preferably has X-ray permeability and does not deform such as shrinkage when solidified. For example, a thermosetting adhesive or an instantaneous adhesive can be used. Moreover, you may use the low melting metal (for example, solder | pewter, indium, etc.) which has X-ray permeability instead of an adhesive agent.
 次に、図1に示すX線画像撮影システムの作用について説明する。X線源11から放射されたX線は、線源グリッド12のX線吸収部17によって部分的に遮蔽されることにより、Y方向に関する実効的な焦点サイズが縮小され、Y方向に多数の線光源(分散光源)が形成される。線源グリッド12により形成された多数の線光源のX線は、被検体Hを通過することにより位相差が生じ、このX線が第1のグリッド13を通過することにより、被検体Hの屈折率と透過光路長とから決定される被検体Hの透過位相情報を反映した縞画像が形成される。各線光源の縞画像は、第2のグリッド14に投影され、第2のグリッド14の位置で一致する(重なり合う)ので、X線強度を低下させずに、位相コントラスト画像の画質を向上させることができる。 Next, the operation of the X-ray imaging system shown in FIG. 1 will be described. The X-rays emitted from the X-ray source 11 are partially shielded by the X-ray absorber 17 of the source grid 12, thereby reducing the effective focus size in the Y direction, and a large number of lines in the Y direction. A light source (dispersed light source) is formed. The X-rays of a large number of line light sources formed by the radiation source grid 12 cause a phase difference when passing through the subject H, and the X-rays pass through the first grid 13 to refract the subject H. A fringe image reflecting the transmission phase information of the subject H determined from the rate and the transmission optical path length is formed. The fringe image of each line light source is projected onto the second grid 14 and coincides (overlaps) at the position of the second grid 14, so that the image quality of the phase contrast image can be improved without reducing the X-ray intensity. it can.
 縞画像は、第2のグリッド14により強度変調され、例えば、縞走査法により位相微分像が生成される。縞走査法とは、段落[0003]に記載してあるように、第1のグリッド13に対し第2のグリッド14をグリッドピッチを等分割(例えば、5分割)した走査ピッチでY方向に並進移動させながら撮影する方法である。第2のグリッド14の並進移動を行うたびにX線源11から被検体HにX線を照射してX線画像検出器15により検出し、X線画像検出器15の各画素の画素データの位相のズレ量(被検体Hがある場合とない場合とでの位相のズレ量)を算出することにより位相微分像が得られる。この位相微分像を縞走査方向(Y方向)に沿って積分することにより、被検体Hの位相コントラスト画像が得られる。 The intensity of the fringe image is modulated by the second grid 14 and, for example, a phase differential image is generated by a fringe scanning method. As described in paragraph [0003], the fringe scanning method translates in the Y direction at a scanning pitch in which the second grid 14 is equally divided (for example, divided into five) with respect to the first grid 13. This is a method of shooting while moving. Each time the second grid 14 is translated, the subject H is irradiated with X-rays from the X-ray source 11 and detected by the X-ray image detector 15, and the pixel data of each pixel of the X-ray image detector 15 is detected. A phase differential image is obtained by calculating the phase shift amount (phase shift amount with and without the subject H). By integrating this phase differential image along the fringe scanning direction (Y direction), a phase contrast image of the subject H is obtained.
 以上説明したように、本実施形態の放射線画像撮影用グリッドは、小グリッド21、22を接合して構成しているので、大きな面積を得ることができ、位相コントラスト画像の撮影面積を大きくすることができる。また、小グリッド21、22は、グリッド部21a及び非グリッド部22bと、非グリッド部21b及びグリッド部22aとが重なり合うように接合されており、Z方向から見たときにそれぞれのグリッド部と非グリッド部との境界が一致し、かつ2つのグリッド部21a、22aが連続して1枚の大きなグリッド部を構成するように接合されているので、小グリッド21、22のグリッド部21a,22aの間の間隔が画素サイズ以下となり、高画質の位相コントラスト画像を得ることができる。 As described above, since the grid for radiographic imaging according to the present embodiment is configured by joining the small grids 21 and 22, a large area can be obtained and the imaging area of the phase contrast image can be increased. Can do. In addition, the small grids 21 and 22 are joined so that the grid part 21a and the non-grid part 22b overlap the non-grid part 21b and the grid part 22a. Since the boundary with the grid portion coincides and the two grid portions 21a and 22a are joined to form one large grid portion in succession, the grid portions 21a and 22a of the small grids 21 and 22 The interval between them becomes smaller than the pixel size, and a high-quality phase contrast image can be obtained.
 上記実施形態では、小グリッド21、22の製造後にアライメントマーク34、35を設けたが、小グリッド21、22の製造中にアライメントマークを造り込んでもよい。例えば、図7に示すように、X線透過性基板24に隔壁26の間を連結するブリッジ部40を形成し、このブリッジ部40を1個、または複数個用いてアライメントマークとしてもよい。これにより、上記実施形態において小グリッドの製造後に行われるアライメントマークの形成工程を廃することができる。また、ブリッジ部40は、隔壁26を補強する作用を有するので、電解メッキ法によって溝25内に金を充填する際に、隔壁26同士がくっついてしまうスティッキング現象を防止することができる。 In the above embodiment, the alignment marks 34 and 35 are provided after the small grids 21 and 22 are manufactured. However, the alignment marks may be formed during the manufacturing of the small grids 21 and 22. For example, as shown in FIG. 7, a bridge portion 40 that connects the partition walls 26 may be formed on the X-ray transparent substrate 24, and one or a plurality of the bridge portions 40 may be used as an alignment mark. Thereby, the formation process of the alignment mark performed after manufacture of a small grid in the said embodiment can be abolished. Further, since the bridge portion 40 has an effect of reinforcing the partition wall 26, it is possible to prevent a sticking phenomenon in which the partition walls 26 stick to each other when the groove 25 is filled with gold by an electrolytic plating method.
 また、上記実施形態では、小グリッド21、22を重ね合わせる際にそれぞれのグリッド部と非グリッド部との境界を一致させているが、図8Aに示すように、グリッド部21aと22aとを一部重複させてもよい。この場合、重複部分において、グリッド部21aのX線吸収部19とグリッド部22aのX線吸収部19とが重なり合うようにアライメントを行なう必要がある。 Further, in the above embodiment, when the small grids 21 and 22 are overlapped, the boundaries between the grid portions and the non-grid portions are made to coincide with each other, but as shown in FIG. You may make a part overlap. In this case, it is necessary to perform alignment so that the X-ray absorption part 19 of the grid part 21a and the X-ray absorption part 19 of the grid part 22a overlap in the overlapping part.
 図8Bに示すように、小グリッド21、22を重ね合わせる際に、それぞれのグリッド部と非グリッド部との境界を一致させず、両者の間に間隔DSを設けてもよい。これによれば、アライメント精度を低くすることができるので、製造コスト及び製造スループットを下げることができる。なお、間隔DSは、X線画像検出器15の1画素のサイズ(150μm)以下にすることが好ましい。 As shown in FIG. 8B, when the small grids 21 and 22 are overlapped, the boundary between the respective grid portions and the non-grid portions may not be matched, and a gap DS may be provided between them. According to this, since the alignment accuracy can be lowered, the manufacturing cost and the manufacturing throughput can be reduced. Note that the interval DS is preferably set to a size (150 μm) or less of one pixel of the X-ray image detector 15.
 上記実施形態では、支持基板28を除去した小グリッド21、22を用いたが、図8Cに示すように、小基板の製造時に使用した支持基板42が接合された状態の小グリッド43、44を使用してグリッドを構成してもよい。この場合、小グリッド43、44のグリッド部43a、44aが設けられている面同士を接合してもよいし、図8Dに示すように、支持基板42が設けられている面と、グリッド部42aが設けられている面とを接合してもよい。 In the above embodiment, the small grids 21 and 22 from which the support substrate 28 is removed are used. However, as shown in FIG. 8C, the small grids 43 and 44 in a state in which the support substrate 42 used in manufacturing the small substrate is bonded. It may be used to construct a grid. In this case, the surfaces provided with the grid portions 43a and 44a of the small grids 43 and 44 may be joined to each other, or as shown in FIG. 8D, the surface provided with the support substrate 42 and the grid portion 42a. You may join the surface provided with.
 また、上記実施形態では、2枚の小グリッド21、22により第2のグリッド14を構成したが、3枚以上の小グリッドを用いて大面積のグリッドを構成してもよい。例えば、図9Aに示すように、4枚の小グリッド45a~45dを接合して大面積のグリッド46を構成してもよい。この場合、図9Bに示すように、小グリッド45a~45dを上下交互に重ね合わせれば、小グリッドの枚数が多くなってもグリッド46の厚みを抑えることができる。小グリッドの間に生じる隙間CLは、吸収グリッドとして使用する場合にはそのまま残しておいてもよい。しかし、位相グリッドとして使用する場合には、隙間CLでX線が回折を起こすため、小グリッド45a~45dに使用しているX線透過性基板と同程度のX線透過性を有する材料により、隙間CLを埋めておくことが好ましい。 In the above embodiment, the second grid 14 is configured by the two small grids 21 and 22, but a large area grid may be configured by using three or more small grids. For example, as shown in FIG. 9A, a large area grid 46 may be formed by joining four small grids 45a to 45d. In this case, as shown in FIG. 9B, if the small grids 45a to 45d are alternately overlapped, the thickness of the grid 46 can be suppressed even if the number of small grids increases. The gap CL generated between the small grids may be left as it is when used as an absorption grid. However, when used as a phase grid, X-rays are diffracted in the gap CL, so that the X-ray transmissive substrate used for the small grids 45a to 45d is made of a material having the same X-ray permeability, It is preferable to fill the gap CL.
 図10A及び図10Bに示すグリッド50のように、小グリッド51a~51eを階段状に重ね合わせて接合してもよい。このような接合を行う場合、グリッド50の強度を向上させるため、2点鎖線で示すように、小グリッド51a、51b、51d、51eの下に、X線透過性を有するダミー基板52a~52dを接合するのが好ましい。 As in the grid 50 shown in FIGS. 10A and 10B, the small grids 51a to 51e may be overlapped and joined in a staircase pattern. When such bonding is performed, in order to improve the strength of the grid 50, dummy substrates 52a to 52d having X-ray transparency are provided under the small grids 51a, 51b, 51d, and 51e as shown by two-dot chain lines. It is preferable to join.
 また、図11に示すように、ダミー基板に代えて、凹状の支持基板54を用いてもよい。支持基板54に対する小グリッド51a~51eの接合は、例えば、下段の小グリッドから順に接着剤で仮止めし、全ての小グリッドを仮止めした後に、本接着用の接着剤を支持基板54と小グリッド51a~51eの間に充填すればよい。 Further, as shown in FIG. 11, a concave support substrate 54 may be used instead of the dummy substrate. For joining the small grids 51a to 51e to the support substrate 54, for example, the small grids in the lower stage are temporarily fixed with an adhesive in order, and all the small grids are temporarily fixed, and then the adhesive for main bonding is small with the support substrate 54. What is necessary is just to fill between the grids 51a to 51e.
 図12に示すように、上面が傾斜されたダミー基板56a~56dを使用してグリッド50の小グリッド51a、51b、51d、51eをX線焦点に向かうように傾斜させ、擬似的に凹面状のグリッドを構成してもよい。複数枚の小グリッドを用いてグリッドを大面積化した場合、コーンビーム状のX線のケラレが発生するが、小グリッドを傾けて凹状にすることにより収束構造のグリッドが得られるので、X線のケラレを少なくすることができる。また、凹面状の支持基板を用いて各小グリッドを傾斜させてもよい。 As shown in FIG. 12, by using dummy substrates 56a to 56d whose upper surfaces are inclined, the small grids 51a, 51b, 51d and 51e of the grid 50 are inclined so as to be directed to the X-ray focal point. A grid may be configured. When the grid is enlarged using a plurality of small grids, vignetting of cone-beam X-rays occurs. However, since a grid with a converging structure is obtained by tilting the small grids, X-rays are obtained. Vignetting can be reduced. Further, each small grid may be inclined using a concave support substrate.
 上記各実施形態では、小グリッドを1方向(Y方向)にのみで配列して互いに重ね合わせているが、図13に示すグリッド60のように、小グリッドを2方向(X方向及びY方向)に配列して互いに重ねて合わせてもよい。この実施形態では、図14に示すように、グリッド60は、まず、最下段の小グリッド61の4辺に2段目の小グリッド62a~62dをそれぞれ重ね合わせて接合し、次に、3段目の小グリッド63a~63dを2段目の小グリッド62a~62dの周囲に接合している。これによれば、グリッドを二次元方向に大面積化することができる。なお、各小グリッドのグリッド部を縞状グリッドに代えて十字状グリッドとし、各小グリッドをX線焦点に向けて傾斜させれば、球面状のグリッドが得られる。 In each of the above embodiments, the small grids are arranged only in one direction (Y direction) and overlap each other. However, like the grid 60 shown in FIG. 13, the small grids are arranged in two directions (X direction and Y direction). They may be arranged together and overlap each other. In this embodiment, as shown in FIG. 14, the grid 60 is formed by first joining the four sides of the lowermost small grid 61 with the second small grids 62a to 62d being overlapped, and then joining the three stages. The small grids 63a to 63d of the eyes are joined around the small grids 62a to 62d in the second stage. According to this, the area of the grid can be increased in the two-dimensional direction. If the grid portion of each small grid is replaced by a cross-shaped grid instead of a striped grid, and each small grid is inclined toward the X-ray focal point, a spherical grid can be obtained.
 上記各実施形態では、第2のグリッド14を例にして構造、製造方法、効果等を説明したが、線源グリッド12及び第1のグリッド13にも同様に適用可能である。 In each of the above-described embodiments, the structure, manufacturing method, effects, and the like have been described using the second grid 14 as an example, but the present invention can be similarly applied to the source grid 12 and the first grid 13.
 上記実施形態では、第1及び第2のグリッド13,14を通過したX線を線形的に投影するように構成しているが、この代わりに、グリッドによりX線を回折させることにより、タルボ干渉効果を生じさせる構成(特許第4445397号公報に記載の構成)としてもよい。ただし、この場合には、第1及び第2のグリッド13,14の間の距離をタルボ干渉距離に設定する必要がある。また、この場合には、第1のグリッド13に、位相型グリッドを用いることが可能であり、第1のグリッド13に代えて用いた位相型グリッドは、タルボ干渉効果により生じる縞画像(自己像)を、第2のグリッド14の位置に形成する。 In the above embodiment, the X-rays that have passed through the first and second grids 13 and 14 are linearly projected. Instead, however, the Talbot interference is performed by diffracting the X-rays by the grid. It is good also as a structure (structure described in patent 44459797) which produces an effect. However, in this case, it is necessary to set the distance between the first and second grids 13 and 14 as the Talbot interference distance. In this case, a phase-type grid can be used as the first grid 13, and the phase-type grid used in place of the first grid 13 is a fringe image (self-image) generated by the Talbot interference effect. ) At the position of the second grid 14.
 上記実施形態は、放射線としてX線を例に説明したが、α線、β線、γ線、電子線、紫外線などの放射線に用いるグリッドにも適用可能である。また、本発明は、放射線が被検体を透過する際に、被検体によって散乱された放射線を除去する散乱線除去用グリッドにも適用可能である。更に、上記各実施形態は、矛盾しない範囲で互いに組み合わせて実施することも可能である。 The above embodiment has been described by taking X-rays as an example of radiation, but it can also be applied to grids used for radiation such as α rays, β rays, γ rays, electron beams, and ultraviolet rays. The present invention can also be applied to a scattered radiation removal grid that removes radiation scattered by a subject when the radiation passes through the subject. Furthermore, the above embodiments can be implemented in combination with each other within a consistent range.

Claims (11)

  1.  放射線画像撮影用グリッドは、以下を備える:
     N個(Nは2以上の整数)の小グリッド;
     前記各小グリッドは放射線吸収部が所定ピッチで配列されたグリッド部と、前記グリッド部の外周に設けられた放射線透過性の非グリッド部とにより構成されている;及び
     隣接する前記小グリッドの間では、一方の前記小グリッドの前記グリッド部と、他方の前記小グリッドの前記非グリッド部とが対面するように重ね合わされている。
    The radiographic grid includes:
    N small grids (N is an integer greater than or equal to 2);
    Each of the small grids includes a grid portion in which radiation absorbing portions are arranged at a predetermined pitch, and a radiation transmissive non-grid portion provided on an outer periphery of the grid portion; and between adjacent small grids Then, the grid portion of one of the small grids and the non-grid portion of the other small grid are overlapped with each other.
  2.  隣接する前記小グリッドの間では、一方の前記小グリッドの前記グリッド部と前記非グリッド部との境界と、他方の前記小グリッドの前記グリッド部と前記非グリッド部との境界とが一致していることを特徴とする請求の範囲第1項記載の放射線画像撮影用グリッド。 Between the adjacent small grids, the boundary between the grid part and the non-grid part of one small grid coincides with the boundary between the grid part and the non-grid part of the other small grid. The grid for radiographic imaging according to claim 1, wherein the grid is provided.
  3.  前記N個の小グリッドを上下交互に重ね合わせたことを特徴とする請求の範囲第1項記載の放射線画像撮影用グリッド。 The radiographic imaging grid according to claim 1, wherein the N small grids are alternately superposed on each other.
  4.  前記N個の小グリッドを階段状に重ね合わせたことを特徴とする請求の範囲第1項記載の放射線画像撮影用グリッド。 The radiographic imaging grid according to claim 1, wherein the N small grids are superposed in a staircase pattern.
  5.  前記小グリッドの下に、放射線透過性を有するダミー基板を接合したことを特徴とする請求の範囲第4項記載の放射線画像撮影用グリッド。 The radiographic imaging grid according to claim 4, wherein a dummy substrate having radiation transparency is bonded under the small grid.
  6.  前記N個の小グリッドは、凹面状の支持基板により保持されていることを特徴とする請求の範囲第4項記載の放射線画像撮影用グリッド。 The radiographic imaging grid according to claim 4, wherein the N small grids are held by a concave support substrate.
  7.  前記N個の小グリッドは、略凹状または略球面状のグリッド面を構成するように傾斜して配置されていることを特徴とする請求の範囲第4項記載の放射線画像撮影用グリッド。 The radiographic imaging grid according to claim 4, wherein the N small grids are arranged so as to form a substantially concave or substantially spherical grid surface.
  8.  放射線画像撮影用グリッドの製造方法は、以下を備える:
     放射線吸収部が所定ピッチで配列されたグリッド部と、前記グリッド部の外周に設けられた放射線透過性の非グリッド部とにより構成されたN個(Nは2以上の整数)の小グリッドを製造する小グリッド製造工程;及び
     隣接する前記小グリッドについて、一方の前記小グリッドの前記グリッド部と、他方の前記小グリッドの前記非グリッド部とが対面するように重ね合わせて接合する接合工程。
    A method for manufacturing a grid for radiographic imaging comprises the following:
    Manufacture N small grids (N is an integer of 2 or more) composed of a grid part in which radiation absorbing parts are arranged at a predetermined pitch and a radiation transmissive non-grid part provided on the outer periphery of the grid part. A small grid manufacturing step; and a joining step of joining adjacent small grids so that the grid portion of one small grid and the non-grid portion of the other small grid face each other.
  9.  前記非グリッド部に、可視光による視認性と放射線透過性とを備えたアライメントマークを形成するアライメントマーク形成工程と、
     前記アライメントマークの位置を検出して、隣接する前記小グリッドの位置を調整する位置調整工程と、
     を更に備えることを特徴とする請求の範囲第8項の放射線画像撮影用グリッドの製造方法。
    An alignment mark forming step for forming an alignment mark having visibility and radiation transparency with visible light on the non-grid portion;
    A position adjusting step of detecting the position of the alignment mark and adjusting the position of the adjacent small grid;
    The manufacturing method of the grid for radiographic imaging of Claim 8 further equipped with these.
  10.  前記位置調整工程では、隣接する前記小グリッドを、前記アライメントマークが設けられた面同士が空間を空けて対面するように配置し、この空間に位置検出装置を挿入して前記アライメントマークの位置を検出することにより位置調整を行うことを特徴とする請求の範囲第9項の放射線画像撮影用グリッドの製造方法。 In the position adjusting step, the adjacent small grids are arranged so that the surfaces provided with the alignment marks face each other with a space between them, and a position detection device is inserted into the space to position the alignment marks. 10. The method for manufacturing a radiographic imaging grid according to claim 9, wherein the position adjustment is performed by detection.
  11.  放射線画像撮影システムは、以下を備える:
     放射線を放射する放射線源;
     前記放射線を通過させて縞画像を生成する第1のグリッド;
     前記縞画像に強度変調を与える第2のグリッド;
     前記放射線源と前記第1のグリッドとの間に配置され、前記放射線源から照射された放射線を領域選択的に遮蔽して多数の線光源とする第3のグリッド;
     前記第2のグリッドにより強度変調された縞画像を検出する放射線画像検出器;及び
     前記第1~第3のグリッドの少なくとも1つは、放射線吸収部が所定ピッチで配列されたグリッド部と、前記グリッド部の外周に設けられた放射線透過性の非グリッド部とにより構成されたN個(Nは2以上の整数)の小グリッドを備え、隣接する前記小グリッドの間では、一方の前記小グリッドの前記グリッド部と、他方の前記小グリッドの前記非グリッド部とが対面するように重ね合わされている。
    The radiographic imaging system comprises:
    A radiation source that emits radiation;
    A first grid that passes the radiation to produce a fringe image;
    A second grid for applying intensity modulation to the fringe image;
    A third grid disposed between the radiation source and the first grid, wherein the radiation emitted from the radiation source is area-selectively shielded to form a plurality of line light sources;
    A radiation image detector for detecting a fringe image intensity-modulated by the second grid; and at least one of the first to third grids includes a grid portion in which radiation absorbing portions are arranged at a predetermined pitch; N small grids (N is an integer greater than or equal to 2) formed by a radiation transmissive non-grid part provided on the outer periphery of the grid part, and between the adjacent small grids, one of the small grids The grid portion and the non-grid portion of the other small grid are overlapped with each other.
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