X-RAY SYSTEM FOR THE ITERATIVE DETERMINATION OF AN OPTIMAL COORDINATE TRANSFORMATION BETWEEN OVERLAPPING VOLUMES THAT HAVE BEEN RECONSTRUCTED FROM VOLUME DATA SETS OF DISCRETELY SCANNED OBJECT AREAS
This disclosure relates to an X-ray system for obtaining referencing information in the form of a coordinate transformation between a first volume and a second volume, with the volumes partially overlapping. In this case two partially overlapping subareas of an extended object having a continuous distribution of a physical size are discretely sampled with a measuring apparatus； the volumes are reconstructed and the overlapping volumes are iteratively changed, wherein a bandpass filter is applied to the overlapping volumes, where said bandpass filter changes the Fourier domain representation of the overlapping volumes. The filtered overlapping volumes, in which the artifacts, induced by the discrete sampling, are matched, are compared by means of a measure of similarity, which is iteratively maximized by means of mathematical optimization. The coordinate transformation with the maximum result for the measure of similarity is used as the optimal coordinate transformation for combining the two volumes in the correct position. One application is the combination of 3D X-ray volumes that have been reconstructed by means of a cone beam computed tomography scanner, preferably a 3D C-arm.
