Patent ID: 6442288
Filing Date: 2002-08-27
Classification: G01N,G06T

Abstract:
A tomosynthesis method for reconstructing a three-dimensional image of an object, comprising the steps of:providing an x-ray source having an x-ray focus; providing a radiation detector; disposing a three-dimensional object in a three-dimensional object space between said x-ray focus and said radiation detector; scanning said object by moving at least said x-ray focus relative to said object to irradiate said object with x-rays from a plurality of different projection angles &phgr;; detecting said x-rays attenuated by said object with said radiation detector at each of said projection angles &phgr; as respective projection images in a 2D recording geometry, each of said projection images comprising a set of projection image data of said object in a 2D projection image space; applying a 2D filtering function H2Dfilter,&phgr;(&ohgr;u,&ohgr;v) to said sets of projection image data to obtain filtered sets of projection image data; in a computer, individually back-projecting said filtered sets of projection image data into a 3D reconstruction image volume for producing a reconstruction image of said object; and determining said 2D filtering function by the steps of: calculating a 3D transmission function Hproj(&ohgr;x,&ohgr;y,&ohgr;z) from the recording geometry for the individual sets of projection image data and back-projecting the individual sets of projection image data into the 3D reconstruction image volume; inverting by approximation, the 3D transmission function Hproj(&ohgr;x,&ohgr;y,&ohgr;z) and thereby determining an inversion function Hinv(&ohgr;x,&ohgr;y,&ohgr;z); producing a 3D filtering function Hopt(&ohgr;x,&ohgr;y,&ohgr;z) dependent on at least one selected image characteristic of the reconstruction image; determining a resulting 3D filtering function Hfilter(&ohgr;x,&ohgr;y,&ohgr;z) by multiplying the 3D filtering function Hopt(&ohgr;x,&ohgr;y,&ohgr;z) and the inversion function Hinv(&ohgr;x,&ohgr;y,&ohgr;z); and determining said 2D filtering function H2Dfilter,&phgr;(&ohgr;u,&ohgr;v) from the resulting 3D filtering function Hfilter(&ohgr;x,&ohgr;y,&ohgr;z) by coordinate transformation of the 3D object space into the 2D projection image space of the respective individual sets of projection image data at the projection angles &phgr;.