JP2012149982A - Lattice unit for radiological imaging, radiological imaging system and manufacturing method for lattice body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool a central portion of a lattice without disturbing radiography.SOLUTION: A second lattice unit 14 has a lattice body 23 including a lattice substrate 31 made of a radiolucent material. The lattice substrate 31 has a plurality of grooves 34a functioning as a lattice for X-ray phase contrast imaging by allowing an X-ray absorbing lattice medium 22 in a fluid state to flow in the grooves. The X-ray absorbing lattice medium 22 is stored in a storage tank 26, supplied to the lattice body 23 by a circulation pump 27 through a supply passage 24, and recovered to the storage tank 26 through a recovery passage 25. The X-ray absorbing lattice medium 22 in the storage tank 26 is cooled by a cooler 28.

Description

  The present invention relates to a radiographic imaging grid unit used for radiographic imaging, a radiographic imaging system using the same, and a method of manufacturing a grid constituting the radiographic imaging grid unit.

  It is known that X-rays change in intensity and phase due to interaction when incident on an object, and the change in phase exhibits an interaction higher than the change in intensity. Using this X-ray property, based on the phase change (angle change) of the X-ray by the subject, a high-contrast image (hereinafter referred to as a phase contrast image) is obtained from the subject having a low X-ray absorption capability. Research on line phase imaging has been actively conducted.

  An X-ray imaging system that performs X-ray phase imaging using a Talbot interference effect by two transmission diffraction gratings has been devised (see, for example, Patent Document 1 and Non-Patent Document 1). In this X-ray imaging system, the first grating is arranged behind the subject as viewed from the X-ray source, and the second grating is arranged downstream from the first grating by the Talbot interference distance. Behind the second grating, an X-ray image detector (FPD: Flat Panel Detector) that detects X-rays and generates an image is arranged. The first grating and the second grating are striped one-dimensional gratings in which X-ray absorption parts and X-ray transmission parts extended in one direction are alternately arranged along an arrangement direction orthogonal to the extension direction. . The Talbot interference distance is a distance at which X-rays that have passed through the first grating form a self-image (stripe image) due to the Talbot interference effect.

  In the X-ray imaging system, a fringe image generated by superimposing (intensity modulation) the self-image of the first grating and the second grating is detected by the fringe scanning method, and the object is detected from the change in the fringe image by the subject. Obtain sample phase information. In the fringe scanning method, the second grating is arranged in parallel to the first grating surface in a direction substantially parallel to the plane of the first grating and substantially perpendicular to the grating direction (strip direction) of the first grating. The image is taken a plurality of times while being translated at a scanning pitch obtained by equally dividing the lattice pitch, and the angle distribution of X-rays refracted by the subject (differentiating the phase shift) from the change in each pixel value obtained by the X-ray image detector. Image), and a phase contrast image of the subject is obtained based on this angular distribution. This fringe scanning method is also used in an imaging apparatus using laser light (see, for example, Non-Patent Document 2).

  The first and second gratings require a fine structure in which the width and pitch of the X-ray absorber are several μm. Moreover, the X-ray absorption part of the first and second gratings is required to have high X-ray absorption. In particular, the second grating requires higher X-ray absorption than the first grating in order to surely modulate the intensity of the fringe image. For this reason, the X-ray absorption portions of the first and second lattices are formed of gold (Au) having a heavy atomic weight, and the X-ray absorption portions of the second lattice have a relatively large thickness with respect to the X-ray traveling direction. And so-called aspect ratio (a value obtained by dividing the thickness of the portion that absorbs X-rays by the width) is required.

  The temperature of the lattice rises due to X-ray irradiation, but the temperature rise and temperature distribution are affected by the dose and intensity distribution of the X-ray, so that the central portion of the lattice is mainly hotter than the peripheral portion. . When the temperature of the lattice rises, the X-ray absorption part and the X-ray transmission part may thermally expand and the pitch may change. Further, when the X-ray absorption part (for example, Au) and the X-ray transmission part (for example, Si) have different coefficients of thermal expansion, the lattice is distorted due to the temperature rise of the lattice. When the pitch of the grating changes or distortion occurs in the grating, there is a problem that the image quality of the phase contrast image is deteriorated.

  Patent Document 1 describes that the temperature of a grating is measured by a temperature sensor, and the temperature of the grating is controlled using a Peltier element or the like based on the measurement result. Japanese Patent Laid-Open No. 2004-228561 includes a lattice that includes a case body, a lattice medium made of liquid or gas contained in the case body, and an ultrasonic generator attached to the case body. It is described that it is vibrated like a wave by a sound wave generator to function as a lattice.

JP 2008-200320 A JP 2007-203060 A

C. David, et al., Applied Physics Letters, Vol. 81, No. 17, October 2002, p. 3287 Hector Canabal, et al., Applied Optics, Vol.37, No.26, September 1998, 6227

  In Patent Document 1, if a cooling means such as a Peltier element is attached to the central portion of the grating, the photographing is hindered. Therefore, the cooling means can only be attached to the end of the grating. Therefore, Patent Document 1 is considered to have a low effect on cooling the central portion of the lattice. Further, since the lattice medium of Patent Document 2 moves the lattice medium in the case body, it can prevent the lattice from being locally heated, but cannot cool the lattice.

  An object of the present invention is to enable cooling of the central portion of the grating so as not to hinder X-ray imaging.

  In order to solve the above-described problems, a grid unit for radiographic imaging according to the present invention includes a lattice substrate provided with a lattice portion including a plurality of grooves, and each groove is joined to the lattice substrate as an individual flow path. A grid body having a sealing plate, a flow means for flowing a fluid grid medium having a different radiation absorption from the grid substrate in the groove, and a cooling means for cooling the grid medium outside the grid body. ing.

  The lattice substrate is provided with a first channel for distributing the lattice medium in the plurality of grooves on one end side of the lattice portion, and the lattice medium flowing out from the plurality of grooves is collected on the other end side of the lattice portion. Two flow paths are provided.

  The flow means includes a supply path whose one end is connected to the first flow path, a recovery path whose one end is connected to the second flow path, a storage tank whose other end is connected to the supply path and the recovery path, A circulation pump for circulating the grid medium stored in the storage tank in the order of the supply path, the grid body, the recovery path, and the storage tank.

  The lattice body may have a radiation transparency, and the lattice medium may have a higher radiation absorption than the lattice body. Moreover, the partition which comprises a groove | channel is comprised with a radiation absorber, and a grating | lattice medium is good also as a structure which has a higher radiation transmittance than a grating | lattice board | substrate. Furthermore, a fluidity improving film for improving the fluidity of the lattice medium may be provided on the inner walls of the plurality of grooves.

  The X-ray imaging system of the present invention detects at least one grating unit constituted by the above-described grating unit for radiographic imaging, a radiation source that emits radiation toward the grating unit, and detects radiation via the grating unit. A radiographic image detector that generates image data, a control unit that controls the flow unit and cooling unit of the lattice unit, and an image processing unit that generates a phase contrast image based on image data obtained by the radiographic image detector. ing.

  A temperature sensor that measures the temperature of the grid body may be provided, and the control unit may control the cooling unit of the grid unit based on the measurement result of the temperature sensor.

  As the grating unit, a first grating unit and a second grating unit which are disposed to face each other between the radiation source and the radiation image detector may be provided. In this case, the image processing unit includes a scanning unit that moves one of the lattices of the first lattice unit or the second lattice unit to a plurality of positions at a predetermined pitch with respect to the other, and the image processing unit detects a radiation image at each position. A phase contrast image may be generated based on a plurality of image data obtained by the device.

  A third grating unit disposed between the radiation source and the first grating unit, and having a third grating unit that partially shields the radiation emitted from the radiation source to form a plurality of line light sources; Any one of the above radiographic imaging grid units may be used as the unit.

  The method for manufacturing a lattice body according to the present invention includes a step of forming a plurality of grooves in a lattice substrate having radiation transparency, and a step of sealing each groove by bonding a sealing plate to the lattice substrate.

  Another method for manufacturing a lattice body includes a step of forming a plurality of recesses in a lattice substrate, a step of filling a radiation absorbing material in each recess to form a plurality of radiation absorbing portions, and a space between each radiation absorbing portion. A step of forming grooves, and a step of sealing each groove by bonding a sealing plate to the lattice substrate.

  A step of forming a fluidity improving film for improving the fluidity of the lattice medium on the inner walls of the plurality of grooves may be included. In addition, when the grooves are formed, a first flow path for distributing the lattice medium in the plurality of grooves and a second flow path for collecting the lattice medium flowing out from the plurality of grooves may be formed.

  According to the grid unit for radiographic imaging of the present invention, by cooling the grid medium flowing in the grid body, it is possible to suppress the central portion of the grid body from becoming extremely hot and cool it. Thereby, it is possible to suppress the pitch deviation of the grooves and the distortion of the lattice body due to the thermal expansion of the lattice body. In addition, according to the radiographic image capturing system of the present invention, it is possible to use a lattice unit that does not cause pitch shift or distortion due to thermal expansion, so that a high-quality phase contrast image can be captured. Furthermore, according to the method for manufacturing a lattice body of the present invention, a lattice body in which a lattice medium can flow can be relatively easily and accurately manufactured.

It is the schematic which shows typically the structure of the X-ray imaging system of this invention. It is the schematic which shows typically the structure of the 2nd grating | lattice unit of 1st Embodiment. It is a disassembled perspective view which shows the structure of the lattice body of 1st Embodiment. It is sectional drawing which shows the structure of the lattice part of the lattice body of 1st Embodiment. It is sectional drawing which shows the structure of the grid | lattice body which provided the fluid improvement film | membrane in the groove | channel. It is sectional drawing which shows the manufacture procedure of the lattice body of 1st Embodiment. It is the schematic which shows typically the structure of the 2nd grating | lattice unit of 2nd Embodiment. It is a disassembled perspective view which shows the structure of the lattice body of 2nd Embodiment. It is sectional drawing which shows the manufacture procedure of the lattice body of 2nd Embodiment.

[First Embodiment]
As shown in FIG. 1, the X-ray imaging system 10 includes an X-ray source 11, a source grid unit 12, a first grid unit 13, and a second grid arranged along the z direction that is the X-ray irradiation direction. A lattice unit 14 and an X-ray image detector 15, a scanning mechanism 16, an image processing unit 17, a console 18, and a system control unit 19 are provided.

  The X-ray source 11 includes, for example, a rotary anode type X-ray tube and a collimator that limits the X-ray irradiation field, and emits cone beam-shaped X-rays to the subject H. The X-ray image detector 15 is, for example, a flat panel detector (FPD) using a semiconductor circuit, and is disposed behind the second grating unit 14. The X-ray image detector 15 is connected to an image processing unit 17 that generates a phase contrast image from the image data detected by the X-ray image detector 15.

  The console 18 has an operation unit that enables selection of a shooting type for which phase contrast image or absorption image is shot, an input of a shooting start instruction, and a display unit that displays an image obtained by shooting. Is provided. The system control unit 19 comprehensively controls each unit of the X-ray imaging system 10 in accordance with an input signal from the operation unit of the console 18.

  The radiation source grating unit 12, the first grating unit 13, and the second grating unit 14 each include a grating that absorbs X-rays, and is disposed to face the X-ray source 11 in the z direction. An interval in which the subject H can be arranged is provided between the radiation source lattice unit 12 and the first lattice unit 13. The distance between the first grating unit 13 and the second grating unit 14 is set to be equal to or shorter than the minimum Talbot interference distance. That is, the X-ray image capturing system 10 of the present embodiment captures a phase contrast image by projecting X-rays without using the Talbot interference effect.

  The scanning mechanism 16 is a mechanism that translates the grating pitch of the second grating unit 14 in the grating pitch direction (x direction) at a scanning pitch obtained by equally dividing the grating pitch of the second grating unit 14 (for example, five divisions) at the time of capturing a phase contrast image.

  The configuration of the second lattice unit 14 will be described. FIG. 2 is a front view of the second grating unit 14 as viewed from the X-ray image detector 15 side. The second lattice unit 14 includes an X-ray absorbing lattice medium (hereinafter abbreviated as an absorption medium) 22, a lattice body 23, a supply path 24, a recovery path 25, a storage tank 26, a circulation pump 27, a cooler 28, and a temperature. A sensor 29 is provided.

  The absorption medium 22 is made of a fluid having X-ray absorption, and is, for example, a liquid at normal temperature (for example, a melting point of 0 ° C. or less). As the absorption medium 22, mercury (Hg) or a liquid in which X-ray absorbing fine particles are dispersed (for example, a gold colloid solution in which gold colloid particles are dispersed in water or an organic solvent) is used.

  As shown in FIG. 3, the lattice body 23 includes a lattice substrate 31 and a sealing plate 32 formed of a material having X-ray transparency. In the concave portion on one surface of the lattice substrate 31, a lattice portion 34, a supply-side collective flow channel 35 that is a first collective flow channel, and a recovery-side collective flow channel 36 that is a second collective flow channel are provided. ing. The lattice portion 34 is formed by arranging grooves 34a extending in the y direction perpendicular to the z direction and the x direction at a predetermined pitch in the x direction. A supply-side collective flow path 35 is connected to one end of each groove 34a, and a recovery-side collective flow path 36 is connected to the other end. The supply path 24 is connected to the supply side collective flow path 35. The collection path 25 is connected to the collection side collecting flow path 36.

  The sealing plate 32 is bonded to the lattice substrate 31 with an adhesive or the like so as to cover the lattice portion 34, the supply-side collective flow channel 35, and the recovery-side collective flow channel 36. Similar to the lattice substrate 31, the sealing plate 32 is made of a flat plate-like X-ray transparent substrate such as silicon. As shown in FIG. 4, the sealing plate 32 seals the upper portion of each groove 34 a of the lattice portion 34, and each of the grooves 34 a serves as a flow path for the absorbing medium 22.

  The material of the lattice substrate 31 and the sealing plate 32 needs to have low X-ray absorption, high strength, and easy processing. As a material satisfying such characteristics, for example, silicon (Si) is desirable, but GaAs, Ge, quartz, or the like may be used.

  The lattice portion 34 functions as an absorption lattice by filling the groove 34 a with the absorbing medium 22 from the supply path 24 through the supply side collecting flow path 35. The width of the grooves 34a in the x direction is about 2 to 20 μm, and the arrangement pitch of the grooves 34a is about twice the width. On the other hand, the pixel size in the x direction and the y direction of the X-ray image detector 15 is about 150 μm. The thickness of the groove 34a in the z direction is about 100 to 200 μm in consideration of vignetting of cone-beam X-rays emitted from the X-ray source 11. 2 and 3 show only a few grooves 34 a, a large number of grooves 34 a are actually formed in the lattice portion 34.

  In order to facilitate the flow of the absorbing medium 22 through the lattice 23, a fluidity improving film 38 made of metal (for example, Au) or the like may be formed on the side surface and the bottom surface of the groove 34a as shown in FIG. The fluidity improving film 38 can be formed by, for example, vapor deposition.

  The absorption medium 22 is stored in the storage tank 26, is pumped up from the storage tank 26 by a circulation pump 27 provided in the supply path 24, flows in the lattice body 23, and is stored again through the recovery path 25. 26 is stored. The storage tank 26 is made of, for example, a metal having high thermal conductivity. A cooler 28 for cooling the absorption medium 22 in the storage tank 26 is disposed on the outer periphery of the storage tank 26 via the storage tank 26. As the cooler 28, for example, a Peltier element or the like is used.

  A temperature sensor 29 for measuring the temperature of the lattice body 23 when the X-ray image is taken is attached to the lattice body 23. The temperature of the lattice body 23 measured by the temperature sensor 29 is input to the system control unit 19 that controls the entire X-ray imaging system 10. The system control unit 19 controls the cooler 28 based on the measured temperature of the grid body 23 input from the temperature sensor 29, and the interval between the grooves 34 a of the grid body 23 changes due to thermal expansion, or the grid body 23 The temperature of the lattice body 23 is adjusted so that no distortion occurs.

  Next, a method for manufacturing the lattice body 23 will be described. As shown in FIG. 6A, in the first step, an etching mask 40 is formed on one surface of the lattice substrate 31 using a general photolithography technique. The etching mask 40 is composed of a plurality of line-shaped patterns extending in the y direction and arranged at a predetermined pitch along the x direction, and inverted patterns of the supply-side collective flow channel 35 and the recovery-side collective flow channel 36. .

  As shown in FIG. 6B, in the next step, the lattice substrate 31 is dry-etched using the etching mask 40, the lattice portion 34 including the plurality of grooves 34a, the supply-side collective flow path 35, and the recovery-side assembly. A flow path 36 is formed. For this dry etching, dry etching for deep trenching capable of forming the groove 34a having a high aspect ratio is used. For dry etching for deep digging, for example, a Bosch process in which etching and protective film formation are alternately repeated is used.

  As shown in FIG. 6C, in the next step, the etching mask 40 is removed from the lattice substrate 31, and the sealing plate 32 is coated on the surface from which the etching mask 40 has been removed with an adhesive having X-ray transparency. Are joined, and the grid portion 34, the supply-side collective flow path 35, and the recovery-side collective flow path 36 are sealed. For joining the lattice substrate 31 and the sealing plate 32, other joining methods such as direct joining may be used.

  The source grid unit 12 and the first grid unit 13 are composed of an absorption medium, a grid, a supply path, a recovery path, a storage tank, a circulation pump, a cooler, a temperature sensor, and the like, similarly to the second grid unit 14. Has been. Similar to the lattice body 23 of the second lattice unit 14, the lattice bodies of the source lattice unit 12 and the first lattice unit 13 are formed from a plurality of grooves extending in the y direction and alternately arranged along the x direction. An absorption type grating is configured by flowing an absorption medium in the grating part. As described above, the source grid unit 12 and the first grid unit 13 are the same as the second grid unit 14 except that the width and pitch in the x direction of the grooves of the grid body and the thickness in the z direction are different. Since it is a structure, detailed description is abbreviate | omitted. Further, since the source grating unit 12 and the first grating unit 13 are manufactured in the same manner as the second grating unit 14, detailed description thereof is omitted.

  Next, the operation of the X-ray imaging system 10 will be described. The X-rays emitted from the X-ray source 11 are partially shielded by the grid of the source grid unit 12, thereby reducing the effective focal size in the x direction, and a large number of line light sources (in the x direction ( A distributed light source) is formed. The X-rays of a large number of line light sources formed by the source grid unit 12 cause a phase difference by passing through the subject H, and this X-ray passes through the grid body of the first grid unit 13, A fringe image (first periodic pattern image) reflecting the transmission phase information of the subject H determined from the refractive index of the subject H and the transmitted optical path length is formed. The fringe image of each line light source is projected onto the second grating unit 14 and coincides (overlaps) at the position of the grating 23, so that the image quality of the phase contrast image can be improved without reducing the X-ray intensity. .

  The fringe image is intensity-modulated by the second grating unit 14. The intensity-modulated fringe image (second periodic pattern image) is detected by, for example, a fringe scanning method. In the fringe scanning method, the grating pitch is equally divided (for example, divided into five) into the first grating unit 13 in the direction along the grating surface with the X-ray focal point as the center by using the scanning mechanism 16 for the second grating unit 14. ) The X-ray source 11 irradiates the subject H with X-rays while performing translational movement at the scanning pitch, and the X-ray image detector 15 detects the X-rays, and the X-ray image detector 15 detects the X-rays. Corresponds to the phase differential image (angle distribution of X-rays refracted by the subject) from the phase shift amount (the amount of phase shift with and without the subject H) of the pixel data of each pixel of the image detector 15 ).

  The image processing unit 17 generates a phase contrast image of the subject H by integrating the phase differential image along the stripe scanning direction. The phase contrast image generated by the image processing unit 17 is displayed on the display unit of the console 18. For a detailed method of generating a phase contrast image using the fringe scanning method, refer to Japanese Patent No. 4445397.

  During the X-ray imaging performed as described above, the system control unit 19 measures the temperature of the grid body 23 by the temperature sensor 29 of each grid unit 12 to 14, and based on the measurement result, the circulation pump 27 and the cooler 28. And the absorption medium 22 is cooled. Thereby, since the temperature rise of the center part of the grid | lattice body 23 can be suppressed, the pitch shift of the groove | channel 34a by the thermal expansion of the grid | lattice board | substrate 31 and generation | occurrence | production of the distortion of the grid | lattice body 23 can be suppressed. Thereby, in the X-ray imaging system 10 using the source grating unit 12, the first grating unit 13, and the second grating unit 14 of the present embodiment, the image quality of the phase contrast image can be improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In addition, about the same structure as 1st Embodiment, detailed description is abbreviate | omitted using a same sign. In FIG. 7, the second lattice unit 50 according to the second embodiment includes an X-ray transmissive lattice medium (hereinafter abbreviated as a transmissive medium) 51, a lattice body 52, a supply passage 24, a recovery passage 25, and a storage tank 26. A circulation pump 27, a cooler 28, and a temperature sensor 29.

  The transmission medium 51 is made of a fluid having X-ray transparency, and is, for example, a liquid at a normal temperature (for example, a melting point of 0 ° C. or less) or a gas. As the transmission medium 51, a fluorine-based solvent, a liquid such as water or oil, or a gas such as air is used.

  As shown in FIG. 8, the lattice body 52 includes a lattice substrate 54 and a sealing plate 32 that are made of a material having X-ray transparency. In the concave portion on one surface of the lattice substrate 54, a lattice portion 55, a supply-side collective flow channel 35 that is a first collective flow channel, and a recovery-side collective flow channel 36 that is a second collective flow channel are provided. ing.

  The lattice portion 55 extends in the y direction orthogonal to the z direction and the x direction, and is disposed between the plurality of X-ray absorption portions 56 arranged at a predetermined pitch in the x direction, and the plurality of X-ray absorption portions 56. Groove 57. The X-ray absorption part 56 is made of a material having high X-ray absorption, and for example, gold, platinum, silver, lead or the like is used. One end of each groove 57 is connected to the supply side collective flow path 35, and the other end is connected to the recovery side collective flow path 36. As shown in FIG. 9E, the sealing plate 32 seals the upper portions of the grooves 57 of the lattice portion 55, and each of the grooves 57 serves as a flow path for the transmission medium 51.

  Next, a method for manufacturing the lattice body 52 will be described. As shown in FIG. 9A, the lattice substrate 54 includes an X-ray transmissive substrate 60, a support substrate 61 bonded to the X-ray transmissive substrate 60, and the X-ray transmissive substrate 60 and the support substrate 61. It consists of a seeds layer 62 provided therebetween.

  As the material of the X-ray transparent substrate 60, Si, GaAs, Ge, quartz, or the like is used as in the lattice substrate 31 of the first embodiment. The support substrate 61 is a substrate for reinforcing the X-ray transmissive substrate 60, and is made of a material having strength capable of supporting the X-ray transmissive substrate 60 and high X-ray transmittance. As the material of the support substrate 61, for example, glass, carbon, acrylic, aluminum, titanium, or the like is used. Note that the support substrate 61 may be omitted if sufficient rigidity can be obtained with only the X-ray transparent substrate 60.

  The seed layer 62 is made of, for example, Au or Ni, or a metal film made of Al, Ti, Cr, Cu, Ag, Ta, W, Pb, Pd, Pt, or a metal film made of an alloy thereof. preferable. The seed layer 62 may be provided on one of the X-ray transparent substrate 60 and the support substrate 61 or may be provided on both. Since the seed layer 62 has a thickness of about several μm, it does not affect the X-ray transmission even when a material having high X-ray absorption such as Au is used.

  As shown in FIG. 9B, in the next step, a plurality of recesses 64 are formed in the X-ray transmissive substrate 60 as in the first embodiment. The recess 64 is formed by forming an etching mask (not shown) on one surface of the X-ray transparent substrate 60 using a general photolithography technique, and performing dry etching through the etching mask. It is formed by.

  As shown in FIG. 9C, in the next step, an X-ray absorbing material such as gold is filled in the recess 64 by electrolytic plating, and an X-ray absorbing portion 56 is formed. In this electrolytic plating, the grid substrate 54 is immersed in the plating solution with the current terminals connected to the sheath layer 62. The other electrode (anode) is prepared at a position facing the lattice substrate 54, and an electric current is applied to this electrode to deposit metal ions in the plating solution on the patterned X-ray transparent substrate 60. As a result, gold is embedded in the recess 64. The filling of the X-ray absorbing material into the concave portion 64 is not limited to electrolytic plating. For example, a paste-like or colloidal X-ray absorbing material may be filled. It is unnecessary.

  As shown in FIG. 9D, in the next step, an X-ray absorber 56 and an etching mask (not shown) composed of a reverse pattern of the supply side collecting channel 35 and the recovery side collecting channel 36 are formed. Then, dry etching is performed on the X-ray transparent substrate 60. Thereby, the lattice part 55 provided with the several groove | channel 57 between the X-ray absorption parts 56, the supply side collection flow path 35, and the collection | recovery side collection flow path 36 are formed. As shown in FIG. 5E, in the next step, the sealing plate 32 is joined to the lattice substrate 54, and each groove 57 is sealed.

  In the second lattice unit 50 of the present embodiment, an absorption lattice is constituted by the lattice body 52 by filling the groove 57 with the transmission medium 51 from the supply passage 24 through the supply-side collective passage 35. Like the absorption medium 22 of the first embodiment, the transmission medium 51 is circulated by the circulation pump 27 and is cooled by the cooler 28 when stored in the storage tank 26. It is possible to suppress an extreme rise. Thereby, it is possible to suppress the occurrence of a pitch shift of the X-ray absorption unit 56 due to the thermal expansion of the lattice body 52 and the distortion of the lattice body 52.

  In each of the above embodiments, the second grating unit is translated by the scanning mechanism. However, the second grating unit may be moved. Moreover, you may move only a lattice body instead of the whole lattice unit. In this case, the supply path and the recovery path may be made of a flexible material such as rubber.

  In each of the above embodiments, the grating unit of the present invention is used for the source grating unit 12, the first grating unit 13, and the second grating unit 14, but the distance from the X-ray source 11 is short and the highest temperature is obtained. The grating unit of the present invention may be used only for the source grating unit 12 that is likely to become.

  Moreover, in the said embodiment, the striped one-dimensional grating | lattice which has the X-ray absorption part and X-ray transmission part which were extended | stretched in one direction and was alternately arrange | positioned along the sequence direction orthogonal to the extending | stretching direction was demonstrated to the example. However, the present invention can also be applied to a two-dimensional lattice in which an X-ray absorption part and an X-ray transmission part are arranged in two directions. Further, in the above embodiment, the subject H is arranged between the X-ray source and the first lattice unit, but the subject H is arranged between the first lattice unit and the second lattice unit. In this case, a phase contrast image can be generated in the same manner. Moreover, although the X-ray imaging system provided with the source grid unit has been described, the present invention can also be applied to an X-ray imaging system that does not use the source grid unit. The above embodiments can be combined with each other within a consistent range.

  In the above embodiment, the first and second grating units are configured to linearly project the X-rays that have passed through the X-ray transmission part, but the present invention is not limited to this configuration. Alternatively, a configuration in which a so-called Talbot interference effect is generated by diffracting X-rays by the first and second grating units (configuration described in International Publication WO 2004/058070) may be employed. In this case, it is necessary to set the distance between the first and second grating units to the Talbot interference distance. Further, the type of the first grating unit can be a phase type grating having a relatively low aspect ratio instead of an absorption type grating.

  Moreover, in the said embodiment, the fringe image intensity-modulated by the 2nd grating | lattice unit is detected by the fringe scanning method, and the phase contrast image is produced | generated, However, X-ray which produces | generates a phase contrast image by one imaging | photography Image capturing systems are also known. For example, in the X-ray imaging system described in International Publication WO2010 / 050484, the moire generated by the first and second grating units is detected by an X-ray image detector, and the detected moire is detected. A spatial frequency spectrum is obtained by Fourier transforming the intensity distribution, and a differential phase image is obtained by performing inverse Fourier transform by separating the spectrum corresponding to the carrier frequency from the spatial frequency spectrum. The lattice unit of the present invention may be used for at least one of the first and second lattice units of such an X-ray imaging system.

  In addition, in an X-ray imaging system that generates a phase contrast image by one imaging, a conversion layer that converts X-rays into electric charges and a conversion layer are used as intensity modulation means instead of the second grating unit. There is one using a direct conversion type X-ray image detector having a charge collecting electrode for collecting the generated charge. In this X-ray imaging system, for example, the linear electrodes in which the charge collection electrodes of each pixel are arranged with a period substantially matching the period pattern of the fringe image formed by the first lattice unit are electrically connected to each other. These linear electrode groups are arranged so that their phases are different from each other, and each stripe electrode group is individually controlled to collect charges, thereby acquiring a plurality of fringe images by one photographing. A phase contrast image is generated based on the plurality of fringe images (configuration described in JP 2009-133823 A). You may use the grating | lattice unit of this invention for the 1st grating | lattice unit of such an X-ray imaging system.

  Further, as another X-ray imaging system that generates a phase contrast image by one imaging, the first and second grating units are configured such that the extending directions of the X-ray absorbing unit and the X-ray transmitting unit are relatively predetermined. A plurality of fringe images with different relative positions of the first and second lattice units are obtained by dividing and shooting the section of the moire cycle that occurs in the stretching direction due to this inclination, and so as to incline by an angle. It is also possible to generate a phase contrast image from these plurality of fringe images. The lattice unit of the present invention may be used for at least one of the first and second lattice units of such an X-ray imaging system.

  Further, an X-ray imaging system in which the second grating unit is omitted by using an optical reading type X-ray image detector can be considered. In this system, a first electrode layer that transmits a periodic pattern image formed by a first grating unit, a photoconductive layer that generates charges upon irradiation of the periodic pattern image transmitted through the first electrode layer, and A charge accumulation layer for accumulating charges generated in the photoconductive layer and a second electrode layer in which a large number of linear electrodes that transmit the reading light are stacked in this order, and each line is scanned by the reading light. An optical reading type X-ray image detector that reads out the image signal for each pixel corresponding to the electrode is used as the intensity modulation means, and the charge storage layer is formed in a grid pattern with a pitch finer than the arrangement pitch of the linear electrodes As a result, the charge storage layer can function as the second lattice unit. You may use the grating | lattice unit of this invention for the 1st grating | lattice unit of such an X-ray imaging system.

  The embodiment described above can be applied not only to a radiographic imaging system for medical diagnosis but also to other radiographic systems for industrial use and nondestructive inspection. The present invention is also applicable to a scattered radiation removal grating unit that removes scattered radiation in X-ray imaging. Furthermore, in the present invention, gamma rays or the like can be used in addition to X-rays as radiation.

DESCRIPTION OF SYMBOLS 10 X-ray imaging system 11 X-ray source 12 Source grating | lattice unit 13 1st grating | lattice unit 14,50 2nd grating | lattice unit 15 X-ray image detector 18 Scanning mechanism 22 X-ray-absorbing grating | lattice medium 23,52 Grid 24 Supply path 25 Recovery path 26 Storage tank 27 Circulation pump 28 Cooling unit 29 Temperature sensor 31, 54 Lattice substrate 32 Sealing plate 34, 55 Lattice part 34 a, 57 Groove 35 Supply side collective flow path 36 Recovery side collective flow path 38 Flow 20 Improving film 20 Grid substrate 21 Support substrate 24 X-ray absorbing portion 25 X-ray transmitting portion 27 Hole 29 Insulating layer 32 Recessed portion 51 X-ray transmitting lattice medium 56 X-ray absorbing portion

Claims (15)

A lattice body having a lattice substrate provided with a lattice portion composed of a plurality of grooves, and a sealing plate bonded to the lattice substrate and having each of the grooves as individual flow paths;
In the groove, a flow means for flowing a fluid lattice medium having a different radiation absorption from the lattice substrate,
Cooling means for cooling the lattice medium outside the lattice body;
A grid unit for radiographic imaging, comprising:   The lattice substrate is provided with a first flow path for distributing the lattice medium in the plurality of grooves on one end side of the lattice portion, and flows out of the plurality of grooves on the other end side of the lattice portion. The radiation image capturing lattice unit according to claim 1, further comprising a second flow path for collecting the lattice medium.   The flow means includes a supply path having one end connected to the first flow path, a recovery path having one end connected to the second flow path, and the other ends of the supply path and the recovery path. 3. A storage tank, and a circulation pump that circulates the grid medium stored in the storage tank in the order of the supply path, the grid body, the recovery path, and the storage tank. The lattice unit for radiographic imaging as described.   The radiographic imaging lattice unit according to any one of claims 1 to 3, wherein the lattice body has radiation transparency, and the lattice medium has higher radiation absorption than the lattice body.   The lattice unit for radiographic imaging according to any one of claims 1 to 3, wherein the partition walls constituting the groove are made of a radiation absorbing material, and the lattice medium has higher radiation transmittance than the lattice substrate. .   6. The radiographic imaging lattice unit according to claim 1, wherein a fluidity improving film for improving fluidity of the lattice medium is provided on inner walls of the plurality of grooves. At least one lattice unit constituted by the lattice unit for radiographic imaging according to any one of claims 1 to 6;
A radiation source that emits radiation toward the grating unit;
A radiation image detector for detecting radiation via the lattice unit and generating image data;
A controller for controlling the flow means and the cooling means of the lattice unit;
An image processing unit that generates a phase contrast image based on image data obtained by the radiation image detector;
A radiographic imaging system comprising:   The radiation according to claim 7, further comprising: a temperature sensor that measures a temperature of the lattice body, wherein the control unit controls the cooling unit of the lattice unit based on a measurement result of the temperature sensor. Image shooting system.   9. The radiographic imaging according to claim 7, further comprising: a first grating unit and a second grating unit which are arranged to face each other between the radiation source and the radiation image detector as the grating unit. system. Scanning means for moving one of the lattice bodies of the first lattice unit or the second lattice unit to a plurality of positions at a predetermined pitch with respect to the other,
The radiographic image capturing system according to claim 9, wherein the image processing unit generates a phase contrast image based on a plurality of image data obtained by the radiographic image detector at each position.   A third grating unit disposed between the radiation source and the first grating unit and partially shielding the radiation emitted from the radiation source to form a plurality of line light sources; The radiographic imaging system according to any one of claims 7 to 10, wherein the grid unit for radiographic imaging according to any one of claims 1 to 6 is used as the grid unit. Forming a plurality of grooves in a lattice substrate having radiation transparency;
Bonding a sealing plate to the lattice substrate and sealing the grooves,
A method for manufacturing a lattice body comprising the steps of: Forming a plurality of recesses in the lattice substrate;
Filling each of the concave portions with a radiation absorbing material to form a plurality of radiation absorbing portions;
Forming a groove between the radiation absorbing parts;
Bonding a sealing plate to the lattice substrate and sealing the grooves,
A method for manufacturing a lattice body comprising the steps of:   14. The method for manufacturing a lattice body according to claim 12, further comprising a step of forming a fluidity improving film for improving fluidity of the lattice medium on inner walls of the plurality of grooves.   When forming the groove, a first flow path for distributing the lattice medium in the plurality of grooves and a second flow path for collecting the lattice medium flowing out from the plurality of grooves are formed. The manufacturing method of the lattice body in any one of Claims 12-14.

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