Patent ID: 7596256

Claim:
A computer assisted method for identifying suspicious regions in volumetric image data of a virtual object comprised of a plurality of voxels, the method comprising the steps: determining a contour of a virtual object; selecting a voxel on a contour of the tissue boundary of the virtual object; defining a local patch on the contour about the selected voxel; defining a plurality of local landmarks on the local patch with respect to the selected voxel; computing a Euclidean distance transform vector for the plurality of local landmarks; estimating the likelihood of abnormality by evaluating the Euclidean distance transform vector; wherein the step of computation of the Euclidean distance transform vector comprises the steps of: determining a local coordinate system for the selected voxel; computing the distance between each of said landmarks with respect to the local coordinate system; and wherein the step of determining the local coordinate system comprises steps of: determination of the maximum directional derivative and computation of a direction vector denoted as Z; defining a bounding ball having an origin at the selected voxel and a predetermined radius, determining the local patch on the contour associated with the selected voxel based on the intersection of the contour by the bounding ball; defining an X vector by computing the largest direction within the bounding ball that is perpendicular to Z for the local patch; and adding at least a Y direction vector that is mutually orthogonal to the X vector and Z vector to construct the local coordinate system.