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Fast Volume Rendering Methods for Voxel-based 2D/3D Registration – A Comparative Study

Voxel-based 2D/3D registration enables the use of preoperative 3D CT scans during X-ray fluoroscopy guided interventions for navigation purposes. Both a high accuracy and a short computation time are crucial. The method used in this project is described. Most time consuming is the computation of a perspective projection from the 3D data. Several volume visualisation methods to compute such a projection quickly and accurately are compared. The advantages and disadvantages of the methods in regard to our problem are discussed. Direct volume rendering methods proved to be particularly suitable and two specific methods were evaluated using a clinical dataset. Several optimisations of these methods in regard to 2D/3D registration are discussed and the results of two appropriate optimisations on the test dataset are shown. A recently proposed method based on a shear-warp factorisation of the viewing transformation combined with runlength encoded data showed the best results.