2D/3D registration with rigid alignment of the pelvic bone for assisting in total hip arthroplasty preoperative planning

In Total Hip Arthroplasty preoperative planning requires the definition of medical parameters that help during the intraoperative process; these parameters must be allocated with accuracy to make an implant to the patient. Currently, preoperative planning carries out with different methods. It can be by using a prosthesis template (2D) projected on xray images or by using a computed tomography (CT) in order to set a 3D prosthesis. We propose an alternative developing preoperative planning through reconstructed 3D models using 2D x-ray images, which help to get the same precise information such as a CT. On this paper it has proposed to test the framework from the authors Bertelsen A and Borro D, it is an ITKBased Framework for 2D-3D Registration between x-ray images and a computed tomography. We used the approach of this paper using two fixed images (reference images) and one moving image (image to transform) to do a intensity registration. This method uses a ray casting interpolator to generate a Digitally Reconstructed Radiograph (DRR) or virtual x-ray. We also applied a normalized gradient correlation for comparing the patient x-ray image and the virtual x-ray image optimized by a nonlinear conjugate gradient, both metric and optimizer are useful to update rigid transformation parameters which have an additional scale parameter which produced better results such as 0.01855mm on the alignment of relocated reference volume and 15.5915mm on the alignment of deformed and relocated reference volume of Hausdorff distance between both models (reference volume and transformed volumetric template).