WO2019207860A1 - Dispositif optique d'imagerie et procédé de traitement d'images - Google Patents

Dispositif optique d'imagerie et procédé de traitement d'images Download PDF

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Publication number
WO2019207860A1
WO2019207860A1 PCT/JP2019/001921 JP2019001921W WO2019207860A1 WO 2019207860 A1 WO2019207860 A1 WO 2019207860A1 JP 2019001921 W JP2019001921 W JP 2019001921W WO 2019207860 A1 WO2019207860 A1 WO 2019207860A1
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Prior art keywords
phase distribution
phase
image
images
pixel
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PCT/JP2019/001921
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English (en)
Japanese (ja)
Inventor
直樹 森本
木村　健士
太郎 白井
貴弘 土岐
哲 佐野
日明 堀場
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株式会社島津製作所
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Priority to JP2020516026A priority Critical patent/JP7060090B2/ja
Publication of WO2019207860A1 publication Critical patent/WO2019207860A1/fr

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
    • A61B6/06—Diaphragms
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T7/00—Details of radiation-measuring instruments

Definitions

  • the present invention relates to an optical imaging apparatus and an image processing method, and more particularly to an optical imaging apparatus and an image processing method for generating a phase distribution image.
  • an optical imaging apparatus and an image processing method for generating a phase distribution image are known.
  • Such an optical imaging apparatus and an image processing method are disclosed in, for example, International Publication No. 2014/030115.
  • the X-ray phase difference imaging system disclosed in International Publication No. 2014/030115 is configured to perform X-ray imaging by a Talbot-Lau interferometer and generate a phase distribution image by a fringe scanning method.
  • the fringe scanning method is a method of generating a phase contrast image based on the intensity change of the pixel value of each pixel of an X-ray image captured a plurality of times while translating the lattice. Specifically, the fringe scanning method determines the waveform of the function, assuming that the intensity change of the pixel value of each pixel of the moire fringe that appears in the X-ray image is data in each phase of the function of the grating period.
  • the phase distribution image generated by the fringe scanning method includes a phase differential image.
  • an image including an absorption image and a dark field image can be generated.
  • the phase differential image is an image formed based on the phase shift of the X-ray generated when the X-ray passes through the subject.
  • An absorption image is an image formed based on the attenuation of X-rays generated when X-rays pass through a subject.
  • a dark field image is a Visibility image obtained by a change in Visibility based on small-angle scattering of an object.
  • a dark field image is also called a small angle scattered image. “Visibility” means sharpness.
  • the time for X-ray irradiation is set. It needs to be long.
  • the lattice fluctuates due to heat generated from an X-ray source or the like, thereby causing a positional shift in the relative position of each lattice. If a positional shift occurs in the relative position of each grating, the phase of the moire fringe changes, resulting in artifacts in the obtained phase distribution image.
  • a method of generating a phase distribution image by combining a plurality of phase distribution images picked up with a short X-ray irradiation time is conceivable.
  • the irradiation time of X-rays is short, it is possible to suppress the influence of the thermal fluctuation of the grating when generating each phase distribution image as much as possible. Therefore, it is possible to suppress the change in the phase of the moire fringes due to the thermal fluctuation of the grating.
  • the plurality of phase distribution images are integrated or averaged, noise in the finally obtained phase distribution image can be reduced.
  • phase value in the same pixel region between the phase distribution images changes due to the thermal fluctuation of the lattice. Therefore, when one phase distribution image is generated based on a plurality of phase distribution images in which the phase values in the same pixel region between the phase distribution images are changed, in the generated phase distribution image, between the phase distribution images There is a problem in that an artifact based on the change of the phase value in the pixel region occurs, and the image quality of the phase distribution image deteriorates.
  • an apparatus that generates a plurality of images from a phase distribution and combines the plurality of images to generate a single phase distribution image. Has the same problem.
  • the present invention has been made to solve the above-described problems.
  • One object of the present invention is to generate a single phase distribution image based on a plurality of phase distribution images.
  • the phase distribution image it is possible to suppress the occurrence of artifacts due to the change of the phase value in the pixel area between the phase distribution images, and to suppress the deterioration of the image quality of the generated phase distribution image
  • an optical imaging apparatus includes a light source that irradiates a subject with light, a detector that detects light emitted from the light source, and a signal detected by the detector.
  • An image processing unit that generates a phase distribution image based on the image processing unit, wherein the image processing unit is a phase value between images of pixel regions of a plurality of phase distribution images acquired based on images captured at different timings, respectively.
  • the phase value of the pixel area is corrected based on the change in the pixel area, and one phase distribution image is generated based on the plurality of phase distribution images that have been corrected for the phase value of the pixel area.
  • a plurality of phase distributions in which the phase values of the pixel regions are corrected based on changes in the phase values between the pixel regions of the plurality of phase distribution images.
  • An image processing unit that generates one phase distribution image according to the image is provided.
  • the image processing unit is configured to correct the phase value of the pixel region by shifting the phase value between the images of each pixel of the plurality of phase distribution images by one period.
  • An unwrapping process is performed to correct the phase value of the discontinuous wrapping region so as to be a continuous change. If comprised in this way, the position of the wrapping area
  • the image processing unit includes phase values between the images of the pixels of the plurality of phase distribution images arranged in the imaging order of the plurality of phase distribution images or in the order opposite to the imaging. It is configured to perform an unwrapping process based on the change in.
  • the thermal fluctuation of the lattice occurs in a specific direction with time. Therefore, if configured as described above, a change in phase value between images of each pixel can be acquired in time series. As a result, it is possible to obtain time-series phase value changes, so that each image can accurately grasp phase value changes due to the effects of lattice thermal fluctuations that occur in a specific direction over time. Thus, an accurate unwrapping process can be performed.
  • the image processing unit performs the unwrapping process as the correction process of the phase value of the pixel region
  • the image processing unit applies a pixel in the vicinity of the boundary where the phase value is discontinuous in the plurality of phase distribution images.
  • an unwrapping process is performed. If comprised in this way, it can suppress performing an unwrapping process with respect to the area
  • the pixels near the boundary where the phase value becomes discontinuous include the pixel itself at the boundary position where the phase value becomes discontinuous and the pixel adjacent to the boundary position where the phase value becomes discontinuous. .
  • the light source is configured to emit X-rays
  • the detector detects the X-rays.
  • a plurality of gratings including a first grating that is disposed between the light source and the detector and that is irradiated with X-rays from the light source, and a second grating that is irradiated with X-rays from the first grating.
  • the image processing unit obtains a plurality of phase distribution images, and based on a change in phase value between the images of each pixel of the plurality of phase distribution images, the phase value between the images of the plurality of phase distribution images
  • the unwrapping process is performed, and a plurality of phase distribution images subjected to the unwrapping process are integrated or averaged to generate one phase distribution image.
  • phase distribution image even in the phase distribution image, it is possible to suppress the occurrence of artifacts due to the change in the phase value in each pixel between the phase distribution images in the generated phase distribution image and the generated phase distribution image. It is possible to suppress deterioration of the image quality of the phase distribution image.
  • the image processing unit further includes a grating moving mechanism that moves any of the plurality of gratings, and the image processing unit 1 based on the plurality of phase distribution images captured while moving any of the plurality of gratings.
  • a single phase distribution image is generated.
  • the plurality of gratings include a light source, a first grating, and the like.
  • the image processing units are preferably captured at different timings.
  • a plurality of phase distribution images are generated by performing Fourier transform processing and inverse Fourier transform processing on the obtained image.
  • An image processing method includes a step of acquiring a plurality of phase distribution images acquired based on images captured at different timings, and an image between pixel regions of the plurality of phase distribution images.
  • One phase distribution image is generated based on the step of correcting the phase value of the pixel area based on the change of the phase value and a plurality of phase distribution images on which the phase value of the pixel area is corrected. Steps.
  • the image processing method includes a step of performing a process of correcting the phase value of the pixel region based on a change in the phase value between the pixel regions of the plurality of phase distribution images. Generating a single phase distribution image based on a plurality of phase distribution images subjected to correction of the phase value of the pixel region.
  • each phase An image processing method capable of suppressing an artifact based on a change in phase value in a pixel area between distribution images and suppressing deterioration in image quality of a generated phase distribution image Can be provided.
  • the phase values in the pixel regions between the phase distribution images are generated in the generated phase distribution image. It is possible to provide an optical imaging apparatus and an image processing method capable of suppressing the occurrence of artifacts based on the change in image quality and suppressing the deterioration of the image quality of the generated phase distribution image. .
  • 1 is a schematic diagram illustrating an overall configuration of an optical imaging apparatus according to a first embodiment. It is a schematic diagram for demonstrating the structure of the lattice position adjustment mechanism by 1st Embodiment. It is a schematic diagram for demonstrating the process in which the image process part by 1st Embodiment produces
  • the optical imaging apparatus 100 is an apparatus that images the inside of the subject Q using the Talbot effect.
  • the optical imaging apparatus 100 can be used for imaging the inside of the subject Q, for example, in nondestructive inspection applications.
  • FIG. 1 is a view of the optical imaging apparatus 100 as viewed from the X direction.
  • the optical imaging apparatus 100 includes an X-ray source 1, a first grating 2, a second grating 3, a detector 4, an image processing unit 5, a control unit 6, and a storage unit 7. And a lattice moving mechanism 8.
  • the X-ray source 1 is an example of the “light source” in the claims.
  • the direction from the X-ray source 1 toward the first grating 2 is the Z2 direction, and the opposite direction is the Z1 direction.
  • the vertical direction in the plane orthogonal to the Z direction is the Y direction
  • the upper direction is the Y1 direction
  • the lower direction is the Y2 direction.
  • the left-right direction in the plane orthogonal to the Z direction is defined as the X direction
  • the direction toward the back of the paper surface in FIG. 1 is defined as the X2 direction
  • the X-ray source 1 generates X-rays when a high voltage is applied.
  • the X-ray source 1 is configured to irradiate the generated X-rays in the Z2 direction.
  • the first grating 2 has a plurality of slits 2a arranged in a fixed direction with a predetermined period (pitch) p1 and an X-ray phase change portion 2b. Each slit 2a and X-ray phase change portion 2b are formed to extend linearly. Each slit 2a and X-ray phase change portion 2b are formed to extend in parallel. In the example shown in FIG. 1, each slit 2 a and X-ray phase change portion 2 b are arranged in a predetermined cycle (pitch) p ⁇ b> 1 in the Y direction and are formed to extend in the X direction.
  • the first grating 2 is a so-called phase grating.
  • the first grating 2 is disposed between the X-ray source 1 and the second grating 3 and is irradiated with X-rays from the X-ray source 1.
  • the first grating 2 is provided for forming a self-image (not shown) of the first grating 2 by the Talbot effect.
  • Talbot distance a predetermined distance
  • the second grating 3 has a plurality of X-ray transmission parts 3a and X-ray absorption parts 3b arranged in a predetermined direction with a predetermined period (pitch) p2.
  • Each X-ray transmission part 3a and X-ray absorption part 3b are each formed so as to extend linearly.
  • Each X-ray transmission part 3a and X-ray absorption part 3b are formed so as to extend in parallel.
  • each X-ray transmission part 3 a and X-ray absorption part 3 b are arranged in a predetermined cycle (pitch) p ⁇ b> 2 in the Y direction and are formed to extend in the X direction.
  • the second grating 3 is a so-called absorption grating.
  • lattice 2 has a function which changes the phase of X-ray
  • lattice 3 has a function which shields a part of X-ray
  • the second grating 3 is disposed between the first grating 2 and the detector 4 and is irradiated with X-rays that have passed through the first grating 2.
  • the second grating 3 is disposed at a position away from the first grating 2 by the Talbot distance.
  • the second grating 3 interferes with the self-image of the first grating 2 to form moire fringes mf (see FIG. 3) on the detection surface of the detector 4.
  • the detector 4 is configured to detect X-rays, convert the detected X-rays into electric signals, and read the converted electric signals as image signals.
  • the detector 4 is, for example, an FPD (Flat Panel Detector).
  • the detector 4 includes a plurality of conversion elements (not shown) and pixel electrodes (not shown) arranged on the plurality of conversion elements.
  • the plurality of conversion elements and pixel electrodes are arranged in an array in the X direction and the Y direction at a predetermined period (pixel pitch).
  • the detector 4 is configured to output the acquired image signal to the image processing unit 5.
  • the image processing unit 5 is configured to generate an integrated phase distribution image 14 (see FIG. 11) based on the image signal output from the detector 4.
  • the image processing unit 5 includes, for example, a processor such as a GPU (Graphics Processing Unit) or an FPGA (Field-Programmable Gate Array) configured for image processing.
  • the image processing unit 5 is configured to generate an average value image 11 (see FIG. 3) and a visibility image 15 (see FIG. 3) based on the image signal output from the detector 4.
  • the control unit 6 is configured to move the first lattice 2 by controlling the lattice moving mechanism 8.
  • the controller 6 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
  • the storage unit 7 is configured to store the X-ray image 10, the average value image 11, the integrated phase distribution image 14, the visibility image 15 and the like generated by the image processing unit 5.
  • the storage unit 7 includes, for example, an HDD (Hard Disk Drive) and a nonvolatile memory.
  • the lattice moving mechanism 8 is configured to be able to move the first lattice 2 under the control of the control unit 6.
  • the lattice moving mechanism 8 holds the first lattice 2.
  • the lattice moving mechanism 8 includes a rotation direction Rz around the X-axis, Y-direction, Z-direction, Z-axis axis, a rotation direction Rx around the X-axis axis, and a Y-axis rotation axis.
  • the first grating 2 is configured to be movable in the rotation direction Ry.
  • the lattice movement mechanism 8 includes an X-direction linear motion mechanism 80, a Y-direction linear motion mechanism 81, a Z-direction linear motion mechanism 82, a linear motion mechanism connection portion 83, and a stage support portion drive portion 84. , Stage support portion 85, stage drive portion 86, and stage 87.
  • the X direction linear motion mechanism 80 is configured to be movable in the X direction.
  • the X direction linear motion mechanism 80 includes, for example, a motor.
  • the Y direction linear motion mechanism 81 is configured to be movable in the Y direction.
  • the Y direction linear motion mechanism 81 includes, for example, a motor.
  • the Z direction linear motion mechanism 82 is configured to be movable in the Z direction.
  • the Z direction linear motion mechanism 82 includes, for example, a motor.
  • the lattice moving mechanism 8 is configured to move the first lattice 2 in the X direction by the operation of the X direction linear motion mechanism 80. Further, the lattice moving mechanism 8 is configured to move the first lattice 2 in the Y direction by the operation of the Y direction linear motion mechanism 81. The lattice moving mechanism 8 is configured to move the first lattice 2 in the Z direction by the operation of the Z-direction linear movement mechanism 82.
  • the stage support unit 85 supports the stage 87 from below (Y1 direction).
  • the stage drive unit 86 is configured to reciprocate the stage 87 in the X direction.
  • the stage 87 is formed in a convex curved surface toward the stage support portion 85, and is configured to rotate around the axis line in the Z direction (Rz direction) by reciprocating in the X direction.
  • the stage support unit drive unit 84 is configured to reciprocate the stage support unit 85 in the Z direction.
  • the stage support portion 85 is formed with a convex curved surface at the bottom toward the linear motion mechanism connection portion 83, and is rotated around the axis line in the X direction (Rx direction) by reciprocating in the Z direction. It is configured as follows.
  • the linear motion mechanism connecting portion 83 is provided in the X-direction linear motion mechanism 80 so as to be rotatable around an axis line in the Y direction (Ry direction). Therefore, the lattice moving mechanism 8 can rotate the lattice around the central axis in the Y direction.
  • the optical imaging apparatus 100 performs the integrated average value image 12 (see FIG. 3), the integrated phase distribution image 14 (see FIG. 3), and the integrated visibility image 16.
  • generates (refer FIG. 3) is demonstrated.
  • an image 10 acquired by the optical imaging apparatus 100 according to the first embodiment and a plurality of average value images 11, a phase distribution image 13 and a visibility image 15 to be generated will be described with reference to FIG.
  • the average value image 11, the phase distribution image 13, and the visibility image 15 respectively correspond to changes in the pixel value of each pixel in the plurality of images 10 obtained by translating the second grating 3 in the fringe scanning method.
  • This is an image obtained by mapping an average value, a phase value, and a visibility value of a function that has been fitted with a sine function.
  • the example shown in FIG. 3 is based on four images 10 (an image set including an image 10a, an image 10b, an image 10c, and an image 10d) captured by translating the second lattice 3 four times by the lattice moving mechanism 8.
  • the average value image 11, the phase distribution image 13, and the visibility image 15 are generated.
  • the image processing unit 5 has a plurality of average value images 11, phase distribution images 13, and visibility images 15 based on each set of images 10 (images 10a to 10d) captured at different timings. To get. Further, the image processing unit 5 generates an integrated phase distribution image 14 by integrating the plurality of phase distribution images 13.
  • the image processing unit 5 generates the integrated average value image 12 and the integrated visibility image 16 by integrating the plurality of average value images 11 and the visibility images 15 respectively.
  • the phase distribution image 13 and the accumulated phase distribution image 14 are images showing the distribution of the phase values of the moire fringes mf.
  • the possible range of the phase value of the phase distribution image 13 and the integrated phase distribution image 14 is ⁇ to ⁇ , and the phase value is a periodic value that repeats the range. Therefore, in the phase distribution image 13 (integrated phase distribution image 14), a wrapping region in which discontinuity occurs due to the phase value being shifted by one period is generated. In the example shown in FIG. 3, since the range of the phase value is ⁇ to ⁇ , the sign of the phase value is inverted in the wrapping region.
  • the image processing unit 5 determines the phase value of the pixel region Ra based on the change in the phase value between the images of the pixel regions Ra (see FIG. 4) of the acquired plurality of phase distribution images 13. And a single integrated phase distribution image 14 is generated based on the plurality of phase distribution images 13 obtained by correcting the phase value of the pixel region Ra.
  • the image processing unit 5 acquires a plurality of phase distribution images 13 and, based on the change in the phase value between the images of each pixel of the plurality of phase distribution images 13, the plurality of phase distribution images 13.
  • An unwrapping process of phase values between images is performed, and a plurality of phase distribution images 13 subjected to the unwrapping process are integrated to generate one integrated phase distribution image 14.
  • the phase distribution image 13 and the integrated phase distribution image 14 are examples of the “phase distribution image” in the claims. A detailed description of phase value correction processing and unwrapping processing between images will be given later.
  • the image processing unit 5 is configured to generate one integrated phase distribution image 14 based on the plurality of phase distribution images 13 captured while moving the second grating 3. ing. That is, the image processing unit 5 generates a plurality of phase distribution images 13 by a so-called fringe scanning method.
  • phase distribution image 13 when acquiring the phase distribution image 13 by the fringe scanning method, if a lattice thermal fluctuation occurs due to heat generation from the X-ray source 1 or the like, between the images of a plurality of images 10 (images 10a to 10d).
  • the phase of the moire fringe mf is shifted.
  • artifacts are generated in the phase distribution image 13, and the image quality of the phase distribution image 13 is deteriorated.
  • the image quality of the phase distribution image 13 deteriorates
  • the image quality of the integrated phase distribution image 14 also deteriorates. Since lattice thermal fluctuations accumulate with time, increasing the imaging time to obtain an image with high contrast increases the effect of artifacts due to thermal fluctuations.
  • the imaging time of each image 10 (X-ray exposure time) is shortened and imaged. Yes. Since the imaging time of each image 10 is short, the contrast of each image 10 decreases. Therefore, each phase distribution image 13 generated based on the image 10 is also an image with low contrast.
  • the first embodiment by integrating a plurality of phase distribution images 13 with low contrast, one integrated phase distribution image 14 with high contrast is acquired. Since deterioration of the image quality of each phase distribution image 13 can be suppressed, deterioration of the image quality of the integrated phase distribution image 14 can be suppressed. However, when thermal fluctuation occurs in the lattice, the distribution of phase values between the images of the phase distribution images 13 changes.
  • FIG. 4 is a schematic diagram of a plurality of phase distribution images 13 and a schematic diagram of an image 17 (a part of the phase distribution image 13) in which the pixel region Ra of each phase distribution image 13 is enlarged.
  • the example shown in FIG. 4 is an example in which the phase value distribution in each phase distribution image 13 changes due to the change in the phase of the moire fringes mf due to the thermal fluctuation of the second grating 3.
  • the example illustrated in FIG. 4 is an example in which a change in phase value distribution is illustrated by focusing on the pixel G among the pixels included in the pixel region Ra of each phase distribution image 13. Note that the example shown in FIG. 4 represents the difference in phase value depending on the presence or absence of hatching.
  • the hatched area is an area having a lower phase value than the area not hatched.
  • subject hatching is an area
  • the sign of the phase value is inverted and becomes discontinuous. Such an area is called a wrapping area.
  • the position of the wrapping region is on the left side of the position of the pixel G, and the pixel G is positioned in a region having a high phase value (region not hatched).
  • the position of the wrapping region and the position of the pixel G are substantially the same.
  • the position of the wrapping region is on the right side of the position of the pixel G, and the pixel G is positioned in the region having a low phase value. That is, in the example shown in FIG. 4, the phase of the moire fringe mf changes between the first X-ray image set and the NX-ray image set due to thermal fluctuations of the second grating 3 over time. This is an example in which the wrapping region in the phase distribution image 13 gradually moves to the right side of the image.
  • the phase value in the pixel region Ra is smoothed, and the change in the phase value in the wrapping region becomes gentle.
  • an artifact occurs in the integrated phase distribution image 14.
  • the phase value since the phase value also changes abruptly at the boundary portion between the subject Q and the background, the boundary portion of the internal structure of the subject Q, etc., if the phase value between the images changes, the phase value changes at the boundary portion.
  • the image quality of the integrated phase distribution image 14 deteriorates, for example, the edge of the subject Q becomes unclear. Therefore, the first embodiment is configured to correct the phase value of each pixel region Ra.
  • the image processing unit 5 is configured to correct the phase value of the pixel in the pixel region Ra based on the change in the phase value of the pixel G of each phase distribution image 13. Specifically, the image processing unit 5 performs a wrapping region where the phase value between the images of each of the plurality of phase distribution images 13 is discontinuous by one period as a correction process of the phase value of the pixel region Ra. The unwrapping process is performed to correct the phase value so that the phase value continuously changes. In the example shown in FIG.
  • the image processing unit 5 performs phase value correction processing also in regions other than the pixel region Ra. That is, the image processing unit 5 determines whether or not phase value wrapping occurs between the images in each pixel of the phase distribution image 13, and performs unwrapping processing on the pixels where wrapping occurs between the images. .
  • FIG. 5 is a schematic diagram of the graph 18 before performing the unwrapping process in the image processing unit 5 and the graph 20 after performing the unwrapping process.
  • the horizontal axis is the image No (N)
  • the vertical axis is the phase value (rad).
  • the unit (N) of pixel No. on the horizontal axis is the order in which the phase distribution image 13 is captured, and is an integer value including 0 (zero).
  • the imaging order of the first captured image is 0th.
  • the plot pv shown in the graph 18 and the graph 20 indicates the phase value of the pixel G of each phase distribution image 13.
  • the image processing unit 5 plots the phase values of the pixels G of the plurality of phase distribution images 13 in the order in which the phase distribution images 13 are captured. Since the phase of the moire fringes mf due to thermal fluctuation is changed, the wrapping region is generated in the portion surrounded by the ellipse Rb in the phase value of each pixel G shown in the graph 18.
  • phase value of each pixel region Ra is indicated by a line segment 19. It becomes a phase value (average value of phase values of each pixel G), and the value of the phase value of each pixel region Ra varies greatly. Such a large variation in the phase value boundary pb causes deterioration of the image quality of the integrated phase distribution image 14.
  • the image processing unit 5 changes the phase value between the images of the pixels of the plurality of phase distribution images 13 arranged in the imaging order of the plurality of phase distribution images 13.
  • An unwrapping process is performed based on this.
  • the unwrapping process is a process of correcting the phase value of each pixel G after the wrapping region so that the phase value of each pixel G is continuous before and after the wrapping region.
  • the phase value of the pixel G of the phase distribution image 13 is continuous in the portion surrounded by the ellipse Rc, and the wrapping region is eliminated.
  • the phase value of each pixel region Ra becomes the phase value indicated by the line segment 21 (the average value of the phase values of each pixel G).
  • the value of the phase value of the pixel region Ra does not vary so much. Therefore, deterioration of the image quality of the integrated phase distribution image 14 can be suppressed.
  • the image processing unit 5 is configured to perform unwrapping processing on the pixels in the vicinity of the boundary pb where the phase values are discontinuous in the plurality of phase distribution images 13. Specifically, the image processing unit 5 performs, for the pixels included in the range mr in which the phase value boundary pb moves in the first phase distribution image 13a to the Nth phase distribution image 13c in the pixel region Ra. An unwrapping process is performed.
  • the example illustrated in FIG. 5 is an example in which unwrapping processing is performed on the pixels G of each phase distribution image 13 as pixels in the vicinity of the boundary pb where the phase values are discontinuous. That is, the image processing unit 5 performs an unwrapping process on the same pixel G of each image from the first phase distribution image 13a to the Nth phase distribution image 13c.
  • step S1 the image processing unit 5 acquires a plurality of phase distribution images 13 based on the images 10 captured at different timings.
  • step S1 the image processing unit 5 acquires a plurality of phase distribution images 13 by a fringe scanning method. Thereafter, the process proceeds to step S2.
  • step S2 the image processing unit 5 performs a process of correcting the phase value of the pixel region Ra based on the change of the phase value between the images of the pixel region Ra of the plurality of phase distribution images 13. Thereafter, the process proceeds to step S3.
  • step S3 the image processing unit 5 generates one integrated phase distribution image 14 based on the plurality of phase distribution images 13 obtained by correcting the phase value of the pixel region Ra, and ends the process.
  • FIG. 7 is a schematic diagram of a plurality of phase distribution images 13, a schematic diagram of an integrated phase distribution image 22 obtained by integrating the plurality of phase distribution images 13, and a schematic diagram of an enlarged image 17 in which the pixel region Ra of each image is enlarged.
  • the integrated phase distribution image 22 is an image obtained by integrating a plurality of phase distribution images 13. Since the position of the wrapping region in each phase distribution image 13 is slightly shifted, the change of the phase value in the wrapping region becomes gentle. Therefore, as shown in FIG. 7, in the wrapping region of the integrated phase distribution image 22, the phase value of the first phase distribution image 13 changes in a gradation.
  • FIG. 8 is a schematic diagram of a graph 23 showing a change in the phase value of the wrapping region in the integrated phase distribution image 14, and a graph showing a change in the phase value in the region Rd in the pixel region Ra of the second phase distribution image 13b.
  • FIG. 24 is a schematic diagram of 24 and a schematic diagram of a graph 25 showing a change in the phase value in the region Re in the pixel region Ra of the integrated phase distribution image 22.
  • phase value is inverted in the wrapping region of the second phase distribution image 13b.
  • the phase value changes stepwise, and the change in the phase value is gentle compared to the wrapping region of the graph 24.
  • a vertical stripe artifact 26 occurs at the position of the wrapping region.
  • phase distribution images 13 are integrated after the unwrapping process is performed on the phase values of the pixel regions Ra, the phase value in the wrapping region of the integrated phase distribution image 14 after the integration is represented by the graph 23. Invert as shown. Therefore, as shown in FIG. 10, the artifact 26 can be suppressed from occurring in the integrated phase distribution image 14.
  • the influence of pixel deficiency in each image occurs only in the same pixel. It is possible to suppress the influence on the pixel. That is, since the influence of the defective pixel can be limited to only that pixel, it is possible to suppress the occurrence of the striped artifact 28 in the phase distribution image 13.
  • the optical imaging apparatus 100 includes the X-ray source 1 that irradiates the subject Q with light, the detector 4 that detects the light emitted from the X-ray source 1, and the detector 4.
  • An image processing unit 5 that generates a phase distribution image 13 based on the signal detected by the image processing unit 5.
  • the image processing unit 5 includes a plurality of phase distribution images acquired based on images 10 captured at different timings. Based on a plurality of phase distribution images 13 in which the phase value of the pixel region Ra is corrected and the phase value of the pixel region Ra is corrected based on the change in the phase value between the images of the thirteen pixel regions Ra.
  • the integrated phase distribution image 14 is generated.
  • phase value change occurs between the pixel regions Ra of each phase distribution image 13
  • the generated accumulated phase distribution image 14 it is possible to suppress the occurrence of an artifact 26 based on the change of the phase value in the pixel region Ra between the phase distribution images 13, and the generated accumulated phase. It can suppress that the image quality of the distribution image 14 deteriorates.
  • the image processing unit 5 performs the phase value correction processing for the pixel region Ra by shifting the phase value between the images of the pixels of the plurality of phase distribution images 13 by one period.
  • an unwrapping process is performed to correct the phase value of the wrapping region that becomes discontinuous so as to be continuously changed.
  • the position of the wrapping region between the images can be aligned by unwrapping the phase value between the images of each pixel.
  • the phase values in the vicinity of the wrapping region are smoothed by synthesizing the phase distribution images 13 in which the wrapping region varies. It can be suppressed.
  • the image processing unit 5 is based on the change in the phase value between the images of the pixels of the plurality of phase distribution images 13 arranged in the imaging order of the plurality of phase distribution images 13.
  • An unwrapping process is performed.
  • the thermal fluctuation of the second lattice 3 occurs in a specific direction with the passage of time. Therefore, by configuring as described above, it is possible to acquire a change in phase value between images of each pixel in time series. As a result, it is possible to acquire a time-series phase value change, so that the phase value change due to the thermal fluctuation of the second grating 3 occurring in a specific direction with time in each image can be accurately determined. It becomes possible to grasp and an accurate unwrapping process can be performed.
  • the image processing unit 5 performs the unwrapping process on the pixels near the boundary pb where the phase values are discontinuous in the plurality of phase distribution images 13. It is configured. Thereby, it can suppress performing unwrapping processing with respect to the area
  • the X-ray source 1 is configured to irradiate X-rays
  • the detector 4 is configured to detect X-rays.
  • a plurality of first gratings 2 disposed between the source 1 and the detector 4 and irradiated with X-rays from the X-ray source 1 and second gratings 3 irradiated with X-rays from the first grating 2
  • the image processing unit 5 obtains a plurality of phase distribution images 13 and, based on the change of the phase value between the images of each pixel of the plurality of phase distribution images 13, the plurality of phase distribution images 13.
  • the phase value unwrapping process is performed between the images, and a plurality of phase distribution images 13 subjected to the unwrapping process are integrated to generate one integrated phase distribution image 14.
  • the unwrapping process is performed on the plurality of phase distribution images 13 in which the positions of the wrapping regions vary, thereby making it possible to align the positions of the wrapping regions in each phase distribution image 13.
  • integrating the images 13 it is possible to prevent the phase values from being smoothed between the pixels in the vicinity of the wrapping region of the plurality of phase distribution images 13.
  • the grid moving mechanism 8 that moves the second grating 3 is further provided, and the image processing unit 5 captures a plurality of phase distribution images that are captured while moving the second grating 3. 13 is configured to generate one integrated phase distribution image 14.
  • the image processing unit 5 captures a plurality of phase distribution images that are captured while moving the second grating 3. 13 is configured to generate one integrated phase distribution image 14.
  • step S1 for acquiring a plurality of phase distribution images 13 acquired based on the images 10 captured at different timings, and pixel regions of the plurality of phase distribution images 13 Based on step S2 for correcting the phase value of the pixel region Ra based on the change in the phase value between the images of Ra, and a plurality of phase distribution images 13 on which the phase value of the pixel region Ra has been corrected, Step S3 for generating one integrated phase distribution image 14.
  • the generated accumulated phase distribution image 14 it is possible to suppress the occurrence of artifacts due to the change in the phase value in the pixel region Ra between the phase distribution images 13, and the generated accumulated phase It is possible to provide an image processing method capable of suppressing deterioration of the image quality of the distribution image 14.
  • an optical imaging apparatus 200 (see FIG. 1) according to the second embodiment will be described with reference to FIG. 1 and FIG.
  • the image processing unit 5 displays the moire fringes mf.
  • a plurality of phase distribution images 13 are generated based on an image 30 obtained by capturing the subject Q in the generated state.
  • symbol is attached
  • the image processing unit 5 slightly shifts the position of the second grating 3 by the grating moving mechanism 8 and based on the image 30 captured in a state where the moire fringes mf are generated in advance, a plurality of phase distributions.
  • An image 13 is acquired.
  • the image processing unit 5 is configured to generate a plurality of phase distribution images 13 by performing Fourier transform processing and inverse Fourier transform processing on images 30 captured at different timings.
  • step S4 the image processing unit 5 acquires a plurality of phase distribution images 13 based on the images 10 captured at different timings.
  • the image processing unit 5 does not use the fringe scanning method for imaging while moving the second lattice 3 in translation, but performs Fourier transform processing and image processing on the image 30 that has been captured in a state where the moire fringes mf are generated in advance.
  • a plurality of phase distribution images 13 are acquired by a Fourier transform method that performs an inverse Fourier transform process. Thereafter, the process proceeds to steps S2 and S3, where one integrated phase distribution image 14 is generated based on the plurality of phase distribution images 13 in which the phase value of the pixel region Ra is corrected, and the process ends.
  • the image processing unit 5 performs a Fourier transform process and an inverse Fourier transform process on the images 30 captured at different timings to generate a plurality of phase distribution images 13. It is configured.
  • the image processing unit 5 performs a Fourier transform process and an inverse Fourier transform process on the images 30 captured at different timings to generate a plurality of phase distribution images 13. It is configured.
  • the Fourier transform method for generating the phase distribution image 13 by the Fourier transform process and the inverse Fourier transform process in the generated accumulated phase distribution image 14, the change in the phase value at each pixel between the phase distribution images 13 It is possible to suppress the occurrence of artifacts caused by it, and it is possible to suppress deterioration of the image quality of the generated integrated phase distribution image 14.
  • an optical imaging apparatus 300 uses the light reflected by the reference surface 37 and the subject Q.
  • the phase distribution image is generated based on the phase difference between the two.
  • symbol is attached
  • the optical imaging apparatus 300 includes a light source 31, a filter 32, a first beam splitter 33, an objective lens 34, a second beam splitter 35, a subject mounting table 36, and a reference surface 37. And a detector 38 and an image processing unit 39.
  • the light source 31 is configured to emit white light toward the first beam splitter 33.
  • the light source 31 includes, for example, a white laser or a white LED.
  • the filter 32 is provided between the light source 31 and the first beam splitter 33.
  • the filter 32 is configured to transmit light having a predetermined wavelength among light emitted from the light source 31.
  • the filter 32 includes, for example, a band pass filter.
  • the first beam splitter 33 is configured to reflect the light transmitted through the filter 32 among the white light emitted from the light source 31 toward the objective lens 34.
  • the first beam splitter 33 is configured to transmit light reflected by the subject Q and the reference surface 37.
  • the objective lens 34 is provided between the first beam splitter 33 and the second beam splitter 35.
  • the second beam splitter 35 transmits the light transmitted through the objective lens 34 toward the subject mounting table 36.
  • the second beam splitter 35 reflects the light transmitted through the objective lens 34 toward the reference surface 37.
  • the subject mounting table 36 mounts the subject Q.
  • the reference surface 37 is configured to reflect the irradiated light.
  • the reference surface 37 includes, for example, a reflection mirror.
  • the detector 38 is configured to detect light reflected by the subject Q placed on the subject placing table 36 and light reflected by the reference surface 37.
  • the detector 38 is configured to convert the detected light into an electrical signal and read the converted electrical signal as an image signal.
  • the detector 38 includes, for example, an image sensor such as a CCD (Charged Coupled Devices) or a CMOS (Complementary Metal Oxide Semiconductor).
  • the image processing unit 39 is configured to generate a phase distribution image based on the signal detected by the detector 38.
  • the image processing unit 39 includes, for example, a processor such as a GPU or an FPGA configured for image processing.
  • the optical imaging apparatus 300 in the third embodiment is a so-called scanning white interferometer.
  • the image processing unit 39 is configured to generate a phase distribution image based on the phase difference between the light reflected by the subject Q and the light reflected by the reference surface 37.
  • the pixel value of the phase distribution image is a phase value based on the phase difference between the light reflected by the subject Q and the light reflected by the reference surface 37.
  • the image processing unit 39 is configured to generate one phase distribution image by combining a plurality of phase distribution images picked up at different imaging times.
  • the image processing unit 39 integrates the phase values of the wrapping regions in the pixel regions Ra of the plurality of phase distribution images after the unwrapping processing. By doing so, one phase distribution image is generated.
  • the remaining configuration of the third embodiment is the same as that of the first and second embodiments.
  • the image processing unit 39 that generates the phase distribution image based on the phase difference between the light reflected by the subject Q and the light reflected by the reference surface 37 is included.
  • the optical system such as the first beam splitter 33, the objective lens 34, and the second beam splitter 35 is subject to thermal fluctuation.
  • the generated phase distribution image it is possible to suppress the occurrence of artifacts based on the change of the phase value in the pixel region between the phase distribution images, and the image quality of the generated phase distribution image is deteriorated. This can be suppressed.
  • the present invention is not limited to this.
  • the lattice moved by the lattice moving mechanism 8 may be any lattice.
  • the present invention is not limited to this.
  • the third grating 40 has a plurality of slits 40a and an X-ray absorber 40b arranged in the Y direction at a predetermined period (pitch) p3.
  • Each slit 40a and the X-ray absorption part 40b are formed so as to extend linearly.
  • each slit 40a and X-ray absorption part 40b are each formed so that it may extend in parallel.
  • the third grating 40 is disposed between the X-ray source 1 and the first grating 2 and is irradiated with X-rays from the X-ray source 1.
  • lattice 40 is comprised so that the X-ray which passed each slit 40a may be used as the line light source corresponding to the position of each slit 40a.
  • the coherence of the X-rays irradiated from the X-ray source 1 by the third grating 40 can be enhanced.
  • a self-image of the first grating 2 can be formed without depending on the focal diameter of the X-ray source 1, so that the degree of freedom in selecting the X-ray source 1 can be improved.
  • the image processing unit 5 may be configured to generate the integrated phase distribution image 14 by averaging a plurality of phase distribution images 13.
  • the image processing part 5 showed the example of a structure which performs an unwrapping process based on the change of the phase value between the images of each pixel of the some phase distribution image 13 arranged in the imaging order.
  • the present invention is not limited to this.
  • the image processing unit 5 may be configured to perform an unwrapping process based on a change in phase value between images of each pixel of the plurality of phase distribution images 13 arranged in the order opposite to the imaging.
  • the example in which the image processing unit 5 corrects the phase value of the pixel G included in the pixel region Ra of each phase distribution image 13 has been described. Not limited to.
  • the image processing unit 5 calculates the phase value of the pixel G included in the pixel region Ra of each phase distribution image 13 and the phase value of pixels other than the pixel G among the pixels included in the range mr of the pixel region Ra.
  • An unwrapping process may be performed on the basis of the change.
  • the image processing unit 5 performs a process of increasing the phase value of a pixel having a low phase value as the unwrapping process has been described.
  • the image processing unit 5 may be configured to perform the unwrapping process by lowering the phase value of a pixel having a high phase value.
  • the X-ray source 1 (light source 31) emits X-rays (white light)
  • the image processing unit 5 image processing unit 39) outputs the phase of X-rays (white light).
  • the optical imaging apparatus 100 (200, 300, 400) is configured to irradiate the subject Q with light outside the visible region, such as infrared rays or ultraviolet rays, in addition to X-rays and white light (visible light). May be. If the image processing unit 5 (image processing unit 39) can form an image using the phase distribution, what kind of light the optical imaging apparatus 100 (200, 300, 400) irradiates the subject Q is? It may be light.

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Abstract

L'invention concerne un dispositif optique d'imagerie (100) comprenant une source (1) de rayons X, un détecteur (4) et une unité (5) de traitement d'images. L'unité (5) de traitement d'images est configurée de sorte à corriger une valeur de phase d'une région de pixels (Ra) sur la base d'une variation de la valeur de phase entre images de la région de pixels d'une pluralité d'images de distribution de phase (13), et à générer une image de distribution de phase intégrée unique (14) sur la base de la pluralité d'images de distribution de phase dans lesquelles la valeur de phase de la région de pixels a été corrigée.
PCT/JP2019/001921 2018-04-24 2019-01-22 Dispositif optique d'imagerie et procédé de traitement d'images WO2019207860A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012061300A (ja) * 2010-08-19 2012-03-29 Fujifilm Corp 放射線撮影システム及びその画像処理方法
US20120099702A1 (en) * 2009-06-16 2012-04-26 Koninklijke Philips Electronics N.V. Correction method for differential phase contrast imaging
WO2013187150A1 (fr) * 2012-06-11 2013-12-19 コニカミノルタ株式会社 Système d'imagerie médicale et dispositif de traitement d'images
JP2017006468A (ja) * 2015-06-24 2017-01-12 キヤノン株式会社 放射線撮像装置および微分方向推定方法
JP2018029777A (ja) * 2016-08-24 2018-03-01 株式会社島津製作所 Ｘ線位相差撮像装置
JP2018099269A (ja) * 2016-12-20 2018-06-28 株式会社島津製作所 Ｘ線位相撮影装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120099702A1 (en) * 2009-06-16 2012-04-26 Koninklijke Philips Electronics N.V. Correction method for differential phase contrast imaging
JP2012061300A (ja) * 2010-08-19 2012-03-29 Fujifilm Corp 放射線撮影システム及びその画像処理方法
WO2013187150A1 (fr) * 2012-06-11 2013-12-19 コニカミノルタ株式会社 Système d'imagerie médicale et dispositif de traitement d'images
JP2017006468A (ja) * 2015-06-24 2017-01-12 キヤノン株式会社 放射線撮像装置および微分方向推定方法
JP2018029777A (ja) * 2016-08-24 2018-03-01 株式会社島津製作所 Ｘ線位相差撮像装置
JP2018099269A (ja) * 2016-12-20 2018-06-28 株式会社島津製作所 Ｘ線位相撮影装置

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