# US 10,441,237 B2 · Motion correction method in dual energy radiography > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,441,237 B2 - Document ID: US10441237B2 - Status: Granted - Kind: B2 - Application number: 15/536,346 - Filed: 2015-12-15 - Published: 2017-11-30 - Granted: 2019-10-15 - Earliest claimed: 2014-12-16 - Assignees: Agfa NV - Applicants: Agfa NV - Inventors: Tom Bertens - Web page: https://patentgrep.com/patent/US10441237B2 ## CPC - A61B 6/5264: {due to motion} - A61B 6/482: {involving multiple energy imaging} - A61B 6/5235: {combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT} - G06T 7/0012: {Biomedical image inspection} - G06T 7/33: using feature-based methods - G06T 7/337: {involving reference images or patches} - A61B 6/505: {for diagnosis of bone} - G06T 2207/10116: X-ray image - G06T 2207/30008: Bone - G06T 2207/30061: Lung - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL ## Abstract A motion correction method includes two steps. The first step includes a global motion correction using the bilinear warping technique and a rough delineation of the lung fields. One of the native images (low energy image, high energy image) is deformed to match the other image. In a second step, local motion corrections are applied to the globally motion corrected image by computing a proximity value in small overlapping tiles. Only tiles with a sufficient high proximity value are taken into account. The maximum shift applied in this second step is limited to a few pixels to avoid strong deformations of the native images. ## Claims ### Claim 1 A method for correcting motion artifacts in a dual energy radiography image, the method comprising the steps of: correcting a global position to globally correct positions of pixels in at least one of a high energy radiographic native image and a low energy radiographic native image of a same subject to obtain a globally corrected image; and after the step of correcting the global position, correcting a local position to locally correct pixel positions in the globally corrected image; wherein the step of correcting the global position includes: determining, for pre-defined control points in one of the high energy radiographic native image and the low energy radiographic native image, a local proximity value for multiple translation offsets using local image patches centered at the pre-defined control points; deriving a displacement vector for each of the pre-defined control points from the determined local proximity values; deducing warping coefficients for a warping transformation from the displacement vectors; and applying the warping transformation to one of the high energy radiographic native image and the low energy radiographic native image to obtain the globally corrected image; and the step of correcting the local position of the globally corrected image includes: defining overlapping tiles in the globally corrected image and a non-globally corrected high energy radiographic native image or a non-globally corrected low energy radiographic native image; computing local displacement vectors for each of the overlapping tiles; using the local displacement vectors to build a displacement map; and applying the displacement map to the globally corrected image. ### Claim 2 (depends on 1) The method according to claim 1, wherein the warping transformation is a bilinear warping transformation. ### Claim 3 (depends on 1) The method according to claim 1, wherein the dual energy radiography image is a chest image and the control points are corner points of a quadrangle substantially delineating a lung field in the chest image. ### Claim 4 (depends on 1) The method according to claim 1, further comprising defining and using additional control points to derive the displacement vector. ### Claim 5 (depends on 1) The method according to claim 1, wherein the displacement vector is a translation offset for which the local proximity value obtained for the multiple translation offsets reaches a maximum and exceeds a predefined threshold. ### Claim 6 (depends on 5) The method according to claim 5, wherein the local proximity value is a cross correlation coefficient of an image patch centered at a corner point in one of the high energy radiographic native image and the low energy radiographic native image and a template of the other of the high energy radiographic native image and the low energy radiographic native image. ### Claim 7 (depends on 6) The method according to claim 6, wherein at least one of the high energy radiographic native image and the low energy radiographic native image is multiplicatively demodulated. ### Claim 8 (depends on 5) The method according to claim 5, wherein the local proximity value is defined as a cross correlation coefficient of an image patch in the globally corrected image and a template of the non-globally corrected high energy radiographic native image or the non-globally corrected low energy radiographic native image. ### Claim 9 (depends on 8) The method according to claim 8, wherein at least one of the globally corrected image and the non-globally corrected high energy radiographic native image or non-globally corrected low energy radiographic native image is multiplicatively demodulated. ### Claim 10 (depends on 1) The method according to claim 1, wherein the local displacement vector for each pixel is computed by applying interpolation to values of the displacement map. ### Claim 11 (depends on 1) The method according to claim 1, wherein the displacement map is applied to the globally corrected image using bilinear interpolation. ### Claim 12 A non-transitory computer readable medium comprising computer executable program code adapted to carry out, when the computer executable program code is executed on a computer, the steps of: correcting a global position to globally correct positions of pixels in at least one of a high energy radiographic native image and a low energy radiographic native image of a same subject to obtain a globally corrected image; and after the step of correcting the global position, correcting a local position to locally correct pixel positions in the globally corrected image; wherein the step of correcting the global position includes: determining, for pre-defined control points in one of the high energy radiographic native image and the low energy radiographic native image, a local proximity value for multiple translation offsets using local image patches centered at the pre-defined control points; deriving a displacement vector for each of the pre-defined control points from the determined local proximity values; deducing warping coefficients for a warping transformation from the displacement vectors; and applying the warping transformation to one of the high energy radiographic native image and the low energy radiographic native image to obtain the globally corrected image; and the step of correcting the local position of the globally corrected image includes: defining overlapping tiles in the globally corrected image and a non-globally corrected high energy radiographic native image or a non-globally corrected low energy radiographic native image; computing local displacement vectors for each of the overlapping tiles; using the local displacement vectors to build a displacement map; and applying the displacement map to the globally corrected image.