Anatomical image-based rigid registration between fluoroscopic X-ray and CT: Methods comparison and experimental results

This paper describes a practical, whole system approach to rigid registration between preoperative CT and intraoperative X-rays obtained with a tracked C-arm and demonstrates its efficacy experimentally. Our approach is generic, targeted to orthopaedic surgery, and includes fluoroscopic X-ray calibration, image distortion correction, optical tracking, and 2D/3D image registration. For 2D/3D image registration, we use two new gradient-based and intensity-based algorithms which are fast, robust, and accurate in realistic setups. Our experiments on simulated, in vitro, and cadaver show that an overall mean target registration error of 1–1.5 mm (2 mm worst case), which succeeds on the first try 95% or more of the time in less than 2 min, is practically feasible.