RECONSTRUCTION METHOD FOR HELICAL CONE-BEAM CT

摘要

The invention relates to a method and a system for the reconstruction of an object function (f(x)) based on projections acquired during the motion of a radiation source on a helical trajectory (17). The method is particularly suited for an n-PI+ acquisition which by definition completely comprises an n-PI and additionally some overscan data from the (n+2)-PI window. According to the method, two sets (?=m, ?>m) of filtered projections are generated from the measuring values and separately back- projected to yield two absorption functions. The first absorption function (f^lf(x)) is based on contributions of Radon-planes with at most m intersections with the source trajectory (17), while the second absorption function (f^hf(x)) is based on Radon-planes with more than m intersections with the source trajectory (17). The two absorption functions are added to yield the final absorption function (f(x)) of an object in the examination zone. In an approximative version of the method, the sets (?=m, ?>m) of filtered projections are first added and then back-projected.