METHOD AND APPARATUS FOR IMPROVED ACCURACY IN COMPUTED TOMOGRAPHY CONE-BEAM IMAGING

摘要

A system is provided for improving the operation of a computed tomography system in forming an image of an object, wherein a cone-beam source is employed to project an image of the object onto a detector plane to provide a set of cone-beam projection data, and such data is to be converted into a set of Radon data for use in constructing the desired image. In the invention, a line L' is rotated in the detector plane from a line L about a center of rotation which lies on the line L, so that L' lies at a small angle with respect to line L. Data from the cone-beam projection data set is respectively integrated along the first and second lines to generate first and second weighted line integrals respectively corresponding to the lines L and L' The two weighted line integrals are then employed to find the derivative of one of the data points in the Radon data set. The above process is repeated as required to determine each Radon derivative, from which respective data points in the Radon data set can be computed, for use in constructing an image. To avoid inaccuracies arising in determining Radon derivatives in regions proximate to the edge of the projected image, the center of rotation for each line L having a portion which intersects the projected image is positioned on said portion.