# US 10,478,142 B2 · Method and apparatus of spectral differential phase-contrast cone-beam CT and hybrid cone-beam CT > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,478,142 B2 - Document ID: US10478142B2 - Status: Granted - Kind: B2 - Application number: 15/134,581 - Filed: 2016-04-21 - Published: 2016-12-29 - Granted: 2019-11-19 - Earliest claimed: 2013-02-11 - Assignees: University of Rochester - Applicants: Ruola Ning; Weixing Cai - Inventors: Ruola Ning; Weixing Cai - Web page: https://patentgrep.com/patent/US10478142B2 ## CPC - A61B 6/5235: {combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT} - A61B 6/032: {Transmission computed tomography [CT]} - A61B 6/4035: {the source being combined with a filter or grating} - A61B 6/4085: {Cone-beams} - A61B 6/4241: {using energy resolving detectors, e.g. photon counting} - A61B 6/4291: {the detector being combined with a grid or grating} - A61B 6/482: {involving multiple energy imaging} - A61B 6/484: {involving phase contrast X-ray imaging} - A61B 6/502: {for diagnosis of breast, i.e. mammography} - G01N 23/087: using polyenergetic X-rays - G01N 23/20091: Measuring the energy-dispersion spectrum [EDS] of diffracted radiation - G06T 12/10: Image preprocessing, e.g. calibration, positioning of sources or scatter correction - G06T 2207/10081: Computed x-ray tomography [CT] - G06T 2207/20212: Image combination - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract DPC (differential phase contrast) images are acquired for each photon energy channel, which are called spectral DPC images. The final DPC image can be computed by summing up these spectral DPC images or just computed using certain ‘color’ representation algorithms to enhance desired features. In addition, with quasi-monochromatic x-ray source, the required radiation dose is substantially reduced, while the image quality of DPC images remains acceptable. ## Claims ### Claim 1 A method of cone beam CT imaging of a human breast without penetrating the chest cavity of a patient, comprising: acquiring projection images of the breast taken at different view angles by using a polychromatic x-ray source irradiating the breast but not the chest cavity with primary radiation, an energy-resolving detector having a plurality of energy channels, and a grating system; said acquiring comprising acquiring, for each of the plurality of energy channels of the detector, a respective plurality of the projection images of the breast taken at different view angles; performing three-dimensional (3D) computed tomography reconstructions of the breast for each of the plurality of energy channels to produce a respective plurality of differential phase contrast 3D reconstruction images; and combining the plurality of differential phase 3D reconstruction images to thereby produce one or more output images of the breast; wherein said combining of the plurality of differential phase 3D reconstruction images comprises assigning different weights to the images being combined. ### Claim 2 (depends on 1) The method of claim 1, wherein said combining of the plurality of differential phase 3D reconstruction images comprises assigning different colors to the images being combined. ### Claim 3 (depends on 2) The method of claim 2, wherein the assigning of different colors comprises applying a two-dimensional matrix of color weighting coefficients to the images being combined. ### Claim 4 (depends on 1) The method of claim 1, wherein the combining produces the output image comprising three-dimensional (3D) matrix of attenuation coefficients of breast tissue voxels. ### Claim 5 (depends on 1) The method of claim 1, wherein the combining produces an output image comprising a three-dimensional (3D) matrix of phase coefficients of breast tissue voxels. ### Claim 6 (depends on 1) The method of claim 1, including stepping a source grating, which is between the x-ray source and the breast, to vary the spacing of the source grating from the x-ray source for different portions of said acquisition. ### Claim 7 (depends on 6) The method of claim 6, wherein the stepping comprises moving the source grating linearly along an imaging x-ray beam from the source irradiating the breast. ### Claim 8 (depends on 6) The method of claim 6, wherein the stepping comprises moving, to a different position between the x-ray source and the breast for different portions of said acquisition, a source grating mounted on a respective branch of a multi-branch source grating mechanism. ### Claim 9 (depends on 8) The method of claim 8, wherein the stepping comprises rotating the multi-branch source grating mechanism about an axis along a propagation direction of the imaging x-ray beam. ### Claim 10 (depends on 1) The method of claim 1 in which the grating system comprises a phase grating and an analyzer grating that are between the breast and the detector, and said acquiring comprises acquiring the projection images while the phase and analyzer grating are misaligned to thereby produce a Moire pattern at the detector. ### Claim 11 (depends on 1) The method of claim 1, further comprising the following steps carried out before said acquiring of the projection images with the polychromatic source: imaging the breast using a different imaging modality to determine a region of interest in the breast; and selecting a relative position between an imaging beam from the polychromatic x-ray source and the breast determined by said region of interest and then carrying out the steps recited in claim 1. ### Claim 12 (depends on 11) The method of claim 11 in which the different imaging modality is CT imaging other than differential phase imaging. ### Claim 13 (depends on 1) The method of claim 1, wherein the combining of the 3D reconstruction images comprises producing a combined image resolving sub-micron structures in the breast. ### Claim 14 A breast CT system imaging a human breast with an x-ray imaging beam without penetrating the chest cavity of a patient with primary radiation, comprising: a projection image acquisition gantry a polychromatic x-ray source configured to irradiate the breast but not the chest cavity of a patient with an imaging beam of x-rays rotating around the breast, an energy-resolving detector configured to receive the imaging beam after passage thereof through the breast, and a grating system; said detector being configured to acquire, for each of the plurality of energy channels, a respective plurality of the projection images of the breast taken at different view angles; a computer processor configured to apply computer algorithms to the projection images and produce a respective differential phase 3D reconstruction image of the breast for each of the plurality of energy channels; and said computer processor being further configured to combine the plurality of differential phase 3D reconstruction images to thereby produce one or more output images of the breast; and a computer display configured to display the one or more of the output images of the breast; wherein said computer processor is configured to combine the plurality of differential phase 3D reconstruction images in a process that includes assigning different weights to the images being combined. ### Claim 15 (depends on 14) The system of claim 14, wherein said computer processor is configured to combine the plurality of differential phase 3D reconstruction images in a process that includes assigning different colors to the images being combined. ### Claim 16 (depends on 15) The system of claim 15, wherein the computer processor is configured to assign the different colors by applying a two-dimensional matrix of color weighting coefficients to the images being combined. ### Claim 17 (depends on 14) The system of claim 14, wherein the computer processor is configured to produce an output image that is a three-dimensional (3D) matrix of attenuation coefficients of breast tissue voxels. ### Claim 18 (depends on 14) The system of claim 14, wherein the computer processor is configured to produce an output image that is a three-dimensional (3D) matrix of phase coefficients of breast tissue voxels. ### Claim 19 (depends on 14) The system of claim 14, wherein the grating system comprises a stepping source grating that is between the x-ray source and the breast and is configured to vary the spacing between the source grating and the x-ray source for different portions of the rotation of the imaging beam of x-rays. ### Claim 20 (depends on 19) The system of claim 19, wherein the grating system comprises a motorized drive configured to move the source grating linearly along the imaging x-ray beam to vary said spacing. ### Claim 21 (depends on 19) The system of claim 19, wherein the source grating comprises a multi-branch arrangement of individual source grating configured to rotate around an axis of the imaging beam to thereby place a respective source grating at a respective different distance from the source for different portions of the rotation of the imaging beam around the breast. ### Claim 22 (depends on 14) The system of claim 14, wherein the grating system comprises a phase grating and an analyzer grating that are between the breast and the detector and are misaligned to thereby produce a Moire pattern at the detector. ### Claim 23 (depends on 14) The system of claim 14, further comprising an imaging system that is in addition to said gantry and is configured to image the breast using a different imaging modality to determine a region of interest in the breast, and wherein said gantry is configured to select a relative position between the imaging beam and the breast determined by said region of interest. ### Claim 24 (depends on 23) The system of claim 23 in which the different imaging modality is CT imaging other than differential phase imaging. ### Claim 25 (depends on 14) The system of claim 14, wherein the computer processor configured to combine the plurality of differential phase 3D reconstruction images to thereby produce one or more output images of the breast is further configured to produce an output image resolving sub-micron structures in the breast. ### Claim 26 A method of cone beam CT imaging of an object, comprising: acquiring projection images of the object taken at different view angles by using a polychromatic x-ray source irradiating the object with an imaging beam, an energy-resolving detector having a plurality of energy channels receiving the imaging beam after passage thereof through the object, and a grating system; said acquiring comprising acquiring, for each of the plurality of energy channels of the detector, a respective plurality of the projection images of the object taken at different view angles; performing three-dimensional (3D) computed tomography reconstructions of the object for each of the plurality of energy channels to produce a respective plurality of differential phase contrast 3D reconstruction images of the object; and combining the plurality of differential phase 3D reconstruction images to thereby produce one or more output images of the object; wherein said combining of the plurality of differential phase 3D reconstruction images comprises assigning different weights to the images being combined. ### Claim 27 (depends on 26) The method of claim 26, wherein said combining of the plurality of differential phase 3D reconstruction images comprises assigning different colors to the images being combined. ### Claim 28 (depends on 27) The method of claim 27, wherein the assigning of different colors comprises applying a two-dimensional matrix of color weighting coefficients to the images being combined. ### Claim 29 (depends on 26) The method of claim 26, wherein the combining produces the output image comprising three-dimensional (3D) matrix of attenuation coefficients of object voxels. ### Claim 30 (depends on 26) The method of claim 26, wherein the combining produces an output image comprising a three-dimensional (3D) matrix of phase coefficients of object voxels. ### Claim 31 (depends on 26) The method of claim 26, including stepping a source grating, which is between the x-ray source and the object, to thereby vary the spacing of the source grating from the x-ray source for different portions of said acquisition. ### Claim 32 (depends on 31) The method of claim 31, wherein the stepping comprises moving the source grating linearly along the imaging x-ray beam. ### Claim 33 (depends on 31) The method of claim 31, wherein the stepping comprises moving, to a different position between the x-ray source and the object for different portions of said acquisition, a source grating mounted on a respective branch of a multi-branch source grating mechanism. ### Claim 34 (depends on 33) The method of claim 33, wherein the stepping comprises rotating the multi-branch source grating mechanism about an axis of the imaging x-ray beam. ### Claim 35 (depends on 26) The method of claim 26 in which the grating system comprises a phase grating and an analyzer grating that are between the object and the detector, and said acquiring comprises acquiring the projection images while the phase and analyzer grating are misaligned to thereby produce a Moire pattern at the detector. ### Claim 36 (depends on 26) The method of claim 26, further comprising the following steps carried out before said acquiring of the projection images with the polychromatic source: imaging the object using a different imaging modality to determine a region of interest in the object; and selecting a relative position between the imaging beam from the polychromatic x-ray source and the object determined by said region of interest and then carrying out the steps recited in claim 26. ### Claim 37 (depends on 36) The method of claim 36 in which the different imaging modality is CT imaging other than differential phase imaging. ### Claim 38 (depends on 26) The method of claim 26, wherein the combining of the 3D reconstruction images comprises producing a combined image resolving sub-micron structures in the object.