# US 7,613,275 B2 · Method and apparatus for reducing cone beam artifacts using spatially varying weighting functions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,613,275 B2 - Document ID: US7613275B2 - Status: Granted - Kind: B2 - Application number: 11/305,929 - Filed: 2005-12-19 - Published: 2007-06-21 - Granted: 2009-11-03 - Earliest claimed: 2005-12-19 - Assignees: General Electric Company - Inventors: Jianying Li; Jiang Hsieh; Melissa L. Vass; Xiangyang Tang; John Howard Londt; Darin Robert Okerlund - Web page: https://patentgrep.com/patent/US7613275B2 ## CPC - A61B 6/032: {Transmission computed tomography [CT]} - A61B 6/027: {characterised by the use of a particular data acquisition trajectory, e.g. helical or spiral} - A61B 6/463: {characterised by displaying multiple images or images and diagnostic data on one display} - A61B 6/503: {for diagnosis of the heart} - A61B 6/583: {using calibration phantoms} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) ## Abstract A method for combining images acquired using helical half-scan imaging comprises identifying an image plane within an overlap region comprising data from first and second view streams representative of first and second cycles of acquired image data. The image plane comprises the same anatomical structure. First and second weighting functions are calculated for first and second images based on first and second tube positions of an x-ray tube. The first and second images correspond to the image plane and are from the first and second view streams, respectively. The first and second tube positions also correspond to the image plane. A weighted image is then formed based on the first and second weighting functions and the first and second images. ## Claims ### Claim 1 A method for combining images acquired using helical half-scan imaging, comprising: identifying an image plane within an overlap region comprising data from first and second view streams representative of first and second cycles of acquired image data, the image plane comprising the same anatomical structure; calculating first and second weighting functions for first and second images based on first and second tube positions of an x-ray tube, the first and second images corresponding to the image plane and being from the first and second view streams, respectively, the first and second tube positions corresponding to the image plane; and forming a weighted image based on the first and second weighting functions and the first and second images. ### Claim 2 (depends on 1) The method of claim 1, the first and second weighting functions further comprising a pixel radial distance-dependent weighting function for minimizing the first and second weighting functions within a portion of the first and second images. ### Claim 3 (depends on 1) The method of claim 1, further comprising: calculating lower weights for tube side areas within the first and second images closer to the x-ray tube; and calculating higher weights for better image areas within the first and second images further from the x-ray tube, the first and second weighting functions being based on the lower and higher weights. ### Claim 4 (depends on 1) The method of claim 1, further comprising: defining a center area based on the first and second images; and calculating a pixel radial distance-dependent weighting function for the center area, the pixel radial distance-dependent weighting function minimizing change to the center area by the first and second weighting functions. ### Claim 5 (depends on 1) The method of claim 1, further comprising calculating a center view tube position based on at least one of an initial position of the x-ray tube at the beginning of a scan, first and second center views of the first and second cycles, and a total number of views per rotation, the first and second tube positions being further calculated based on the center view tube position. ### Claim 6 (depends on 1) The method of claim 1, wherein the first and second cycles comprising consecutive heart cycles. ### Claim 7 (depends on 1) The method of claim 1, further comprising identifying third and fourth images within the first and second view streams, respectively, the third and fourth images comprising the same anatomical structure with respect to each other, the third and fourth images forming a non-overlapped region. ### Claim 8 A method for combining computed tomography (CT) images acquired using cone beam geometry, comprising: identifying first and second datasets comprising at least a portion of like anatomical data, the first and second datasets being acquired within first and second cycles, respectively; applying lower weighting functions to first areas of the first and second datasets and higher weighting functions to second areas of the first and second datasets, the first areas being closer to x-ray tube locations corresponding to the first and second datasets and the second areas being further from the x-ray tube locations; and forming a combined image by combining the first and second datasets with the lower and higher weighting functions. ### Claim 9 (depends on 8) The method of claim 8, further comprising: identifying an area of pixels within a center region of the first and second datasets; and calculating a pixel radial distance-dependent weighting function for minimizing the lower and higher weighting functions within the center region. ### Claim 10 (depends on 8) The method of claim 8, further comprising: calculating a center view tube position based on at least one of an initial position of an x-ray tube at the beginning of a scan, first and second center views of the first and second cycles, respectively, and a total number of views per rotation; and calculating first and second tube positions of the x-ray tube corresponding to the first and second datasets and being based on the center view tube position, the first and second areas being further defined by the first and second tube positions. ### Claim 11 (depends on 8) The method of claim 8, further comprising identifying third and fourth datasets within the first and second cycles, respectively, the third and fourth datasets comprising the same anatomical data, the third and fourth datasets forming a non-overlapped region. ### Claim 12 (depends on 8) The method of claim 8, further comprising normalizing the lower and higher weighting functions. ### Claim 13 (depends on 8) The method of claim 8, further comprising: identifying first and second detector center views and first and second x-ray tube initial positions based on the first and second cycles, respectively; and calculating first and second center view tube positions based on the first and second detector center views and the first and second x-ray tube initial positions, the first and second areas being further based on the first and second center view tube positions. ### Claim 14 (depends on 8) The method of claim 8, further comprising: identifying first and second detector center views based on the first and second cycles; and calculating a first off-center distance between the first dataset and the first detector center view and a second off-center distance between the second dataset and the second detector center view, the lower and higher weighting functions being further based on the first and second off-center distances. ### Claim 15 A system for combining images comprising like anatomical structure acquired using helical half-scan imaging, the system comprising: a computer for receiving image data comprising at least two cycles of data, the computer configured to: identify an image plane within an overlap region comprising data from first and second view streams representative of first and second cycles of image data, the image plane comprising substantially the same anatomical structure; calculate first and second weighting functions for first and second images based on first and second tube positions of an x-ray tube, the first and second images corresponding to the image plane and being from the first and second view streams, respectively, the first and second tube positions corresponding to the image plane; and form a weighted image based on the first and second weighting functions and the first and second images. ### Claim 16 (depends on 15) The system of claim 15, the computer further configured to: calculate lower weights for tube side areas within the first and second images closer to the x-ray tube; and calculate higher weights for better image areas within the first and second images further from the x-ray tube, the first and second weighting functions being based on the lower and higher weights. ### Claim 17 (depends on 15) The system of claim 15, the computer further configured to: define a center area based on the first and second images; and calculate a pixel radial distance-dependent weighting function for the center area, the pixel radial distance-dependent weighting function minimizing change to the center area by the first and second weighting functions. ### Claim 18 (depends on 15) The system of claim 15, the computer further configured to normalize the first and second weighting functions. ### Claim 19 (depends on 15) The system of claim 15, the computer further configured to: identify first and second detector center views and first and second x-ray tube initial positions based on the first and second cycles, respectively; and calculate first and second center view tube positions based on the first and second detector center views and the first and second x-ray tube initial positions, the first and second tube positions being based on the first and second center view tube positions. ### Claim 20 (depends on 15) The system of claim 15, the computer further configured to: identify first and second detector center views based on the first and second cycles; and calculate a first off-center distance between the first image and the first detector center view and a second off-center distance between the second image and the second detector center view, the first and second weighting functions being further based on the first and second off-center distances, respectively.