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Fast 2D-3D marker-based registration of CT and x-ray fluoroscopy images for image-guided surgery

We propose a fast 2D-3D marker-based registration technique to fuse anatomical structure of 3D CT scans onto 2D X-ray fluoroscopy image. Our method is composed of three stages. First, DRRs (Digitally Reconstructed Radiography) are generated by maximum intensity projection based on hardware texture-based volume rendering. This technique is over 200 times faster than software-based one. Second, confirmation markers are automatically segmented in DRRs and X-ray fluoroscopy images, respectively. Third, in/out-plane registration is proposed for real-time performance. In out-plane registration, we search for an optimal position of X-ray source in a 3D spherical coordinate system. Then we calculate optimal translation and rotation vectors by using principal axes method in in-plane registration. Our method has been successfully six different CT and X-ray fluoroscopy pairs generated from cardiac phantom datasets. For accuracy evaluation, we calculate root-mean-squared error (RMSE) between confirmation markers of DRRs and X-ray fluoroscopy images. Experimental results show that our DRRs generation method performs very fast and the hierarchical registration effectively finds the matching of DRRs and 2D images.