Patent ID: 7782996

Claim:
A method for performing a bone hardening correction and a scattered radiation correction in X-ray computer tomography of a heterogeneous object with a CT system comprising an x-ray source and a flat detector, comprising: iteratively reconstructing a volumetric data of the object by an arithmetic-logic unit from a plurality of projection data of the object recoded by the CT system; iteratively reprojecting the volumetric data by the arithmetic-logic unit for soft tissue and bone in a vector; and iteratively performing the bone hardening correction and the scattered radiation correction during the reconstruction for at least two different material components of the object, wherein the iteration comprises steps of: starting the iteration by: determining a first standardized radiation distribution of a radiation striking the detector for a plurality of projection angles, calculating a first projection image from the first logarithmized radiation distribution for the plurality of projection angles, reconstructing a first volumetric image, and performing an iteration loop comprising steps of: segmenting a last-ascertained volumetric image into a plurality of material components of the object and determining a distribution of the material components on each measuring beam, estimating the scattered radiation correction by taking account of the distribution of the material components on all measuring beams, correcting a last-ascertained radiation distribution using the scattered radiation correction, calculating a scattered radiation-corrected projection image from the corrected last-ascertained radiation distribution, estimating the hardening correction by taking account of a fraction of material components penetrated on each measuring beam, correcting the scattered radiation-corrected projection images by a last-ascertained hardening correction, reconstructing a scatter and hardening corrected volumetric image, wherein the iteration is terminated or continued depending on a predetermined ascertained iteration condition.