Patent ID: 6130929
Filing Date: 2000-10-10
Classification: G06T,Y10S

Abstract:
A computer-implemented method for correcting cone beam error in an image reconstructed from projection data acquired from a system, the method comprising the following steps:(a) using said data to infer line integrals of projection attenuation coefficients .mu.(r) within a fixed n-dimensional plane normal to a longitudinal axis of said system, where r is a position vector in n+1 dimensional space;(b) for an object presently under examination with said system, employing a priori data of variation in .mu.(r) in space over said longitudinal axis to predict whether said variation is substantially linear;if said variation is predicted to be substantially linear, using said system to acquire at least a first scan and a second scan spaced-apart from each other along said longitudinal axis a distance at least equal to a cone distance for said system;if said variation is predicted to be substantially non-linear, using said system to acquire at least a first scan, a second scan, and a third scan, each of these scans being spaced equidistant from each other such that together said scans encompass at least a distance equal to a cone distance for said system;(c) emphasizing a desired representation of .mu.(r) by defining actually acquired .mu.(r) as a series sum of terms in which a first term is a desired value on said plane, and further including an additional second term if at step (b) said variation was predicted to be substantially linear, and further including at least an additional third term if at step (b) said variation was substantially non-linear;(d) using at least some data acquired from said scans at step (b) to estimate variations in .mu.(r) resulting from terms other than said first term in said series of expansion; and(e) using estimated variations made at step (d) to subtract value from said actually acquired .mu.(r) to approximate a desired value of .mu.(r) on said plane;wherein cone beam error in said image is reduced.