Patent ID: 8249213
Filing Date: 2012-08-21
Classification: A61B

Abstract:
1. A calibration method for eliminating substantially circular ring artifacts (RA, RA 1 , RA 2 , RA 3 , RA 4 , RA 5 ) in a set of radiographic 2D projection images which are acquired from a number of distinct projection directions by a not perfectly isocentric 3D rotational X-ray scanner system equipped with at least one X-ray tube (S) and at least one associated X-ray detector (D) diametrically arranged with respect to said X-ray tube (S), wherein not perfectly isocentric corresponds to the 3D rotational X-ray scanner system having an imperfect aligning of (i) a focus of the at least one X-ray tube (S) and (ii) the at least one associated X-ray detector (D) exposed to and irradiated by X-ray beams emitted from the at least one X-ray tube (S), which causes a center of rotation to vary over a rotation angle for the distinct projection directions, said calibration method comprising the steps of scanning (S for each projection direction, calculating (S determining (S