# US 11,443,463 B2 · X-ray CT apparatus, image reconstruction device, and image reconstruction method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,443,463 B2 - Document ID: US11443463B2 - Status: Granted - Kind: B2 - Application number: 16/818,636 - Filed: 2020-03-13 - Published: 2020-09-17 - Granted: 2022-09-13 - Earliest claimed: 2019-03-15 - Assignees: Sumitomo Heavy Industries, Ltd. - Applicants: Sumitomo Heavy Industries, Ltd. - Inventors: Takashi Yamaguchi - Web page: https://patentgrep.com/patent/US11443463B2 ## CPC - A61B 6/5205: {involving processing of raw data to produce diagnostic data} - G06T 12/10: Image preprocessing, e.g. calibration, positioning of sources or scatter correction - A61B 6/032: {Transmission computed tomography [CT]} - A61B 6/5282: {due to scatter} - A61N 2005/1061: {using an x-ray imaging system having a separate imaging source} - A61N 2005/1087: {Ions; Protons} - G06T 2210/41: Medical - G06T 2211/452: involving suppression of scattered radiation or scatter correction - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - A61N: ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY (measurement of bioelectric currents A61B; surgical instruments, devices or methods for transferring non-mechanical forms of energy to or from the body A61B18/00; anaesthetic apparatus in general A61M; incandescent lamps H01K; infrared radiators for heating H05B) ## Abstract Provided is an X-ray CT apparatus including an X-ray irradiation unit that rotates around a placement portion on which an irradiation target is placed and emits X-rays; an X-ray detection unit that detects the X-rays emitted from the X-ray irradiation unit and passed through the irradiation target; and an image reconstruction unit that reconstructs a tomographic image of the irradiation target based on image data of the X-rays detected by the X-ray detection unit, in which the image reconstruction unit calculates a scattered ray component scattered in each of a plurality of three-dimensional spaces obtained by partitioning the irradiation target by a predetermined size among the X-rays detected by the X-ray detection unit in consideration of an atom number density per unit volume in each of sections included in the plurality of three-dimensional spaces and an atomic number, and reconstructs the tomographic image in consideration of the scattered ray component. ## Claims ### Claim 1 An X-ray CT apparatus comprising: an X-ray irradiation unit that rotates around a placement portion on which an irradiation target is placed and emits X-rays; an X-ray detection unit that detects the X-rays emitted from the X-ray irradiation unit and passed through the irradiation target; and an image reconstruction unit that reconstructs a tomographic image of the irradiation target based on image data of the X-rays detected by the X-ray detection unit, wherein the image reconstruction unit calculates a scattered ray component scattered in each of a plurality of three-dimensional spaces obtained by partitioning the irradiation target by a predetermined size among the X-rays detected by the X-ray detection unit in consideration of an atom number density per unit volume in each of sections included in the plurality of three-dimensional spaces and an atomic number, and reconstructs the tomographic image in consideration of the scattered ray component. ### Claim 2 (depends on 1) The X-ray CT apparatus according to claim 1, wherein the X-ray irradiation unit and the X-ray detection unit are disposed at positions opposite to each other with the placement portion, on which the irradiation target is placed, interposed therebetween. ### Claim 3 (depends on 2) The X-ray CT apparatus according to claim 2, wherein the X-ray CT apparatus includes a set or a plurality of sets of the X-ray irradiation unit and the X-ray detection unit. ### Claim 4 (depends on 1) The X-ray CT apparatus according to claim 1, wherein the image reconstruction unit includes a scattered component calculation unit and a reconstruction processing unit, the scattered component calculation unit performs processing of specifying a scattered ray component included in the detected X-ray image data, and the reconstruction processing unit estimates the scattered ray component included in the X-ray image data, and then performs processing of subtracting the scattered ray component from the X-ray image data. ### Claim 5 (depends on 4) The X-ray CT apparatus according to claim 4, wherein the scattered component calculation unit calculates the scattered ray component by using a Convex method in which an objective function is convexly transformed and a Newton method is applied. ### Claim 6 (depends on 4) The X-ray CT apparatus according to claim 4, wherein the X-ray detection unit has a plurality of detection pixels for detecting X-rays, and the scattered component calculation unit calculates the scattered ray component of X-rays detected by each detection pixel for each projection angle and for each detection pixel. ### Claim 7 (depends on 6) The X-ray CT apparatus according to claim 6, wherein the calculation of the scattered ray component is performed every time image reconstruction processing is repeated. ### Claim 8 (depends on 6) The X-ray CT apparatus according to claim 6, wherein, in the scattered component calculation unit and the reconstruction processing unit, the calculation and removal of the scattered ray component are performed for each of a plurality of detection pixels included in X-ray image data, for each of a plurality of the X-ray image data captured images at each projection angle. ### Claim 9 (depends on 1) The X-ray CT apparatus according to claim 1, wherein the X-ray CT apparatus is a cone beam CT apparatus. ### Claim 10 An image reconstruction device of an X-ray CT apparatus, for reconstructing a tomographic image of an irradiation target based on X-ray image data of X-rays passed through the irradiation target, wherein the image reconstruction device calculates a scattered ray component scattered in each of a plurality of three-dimensional spaces obtained by partitioning the irradiation target by a predetermined size among the X-rays detected by the X-ray detection unit in consideration of an atom number density per unit volume in each of sections included in the plurality of three-dimensional spaces and an atomic number, and reconstructs the tomographic image in consideration of the scattered ray component. ### Claim 11 An image reconstruction method in an X-ray CT apparatus, for reconstructing a tomographic image of an irradiation target based on X-ray image data of X-rays passed through the irradiation target, the method comprising: calculating a scattered ray component scattered in each of a plurality of three-dimensional spaces obtained by partitioning the irradiation target by a predetermined size among the X-rays detected by the X-ray detection unit in consideration of an atom number density per unit volume in each of sections included in the plurality of three-dimensional spaces and an atomic number; and reconstructing the tomographic image in consideration of the scattered ray component.