Personalized X-ray Reconstruction of the Proximal Femur via a New Control Point-based 2D-3D Registration and Residual Complexity Minimization

Abstract

In this paper we present a new control point-based 2D-3D registration approach for a deformable registration of a 3D volumetric template to a limited number of 2D calibrated C-arm images and show its application to a personalized X-ray reconstruction of the proximal femur. In our approach, the 2D-3D registration is done with a hierarchical two-stage strategy: the scaled rigid 2D-3D registration stage followed by a regularized deformable b-spline 2D-3D registration stage. In both stages, a set of control points with uniform spacing are placed over the domain of the 3D volumetric template first. The registrations are then driven by computing updated positions of these control points with intensity-based 2D-2D image registrations of C-arm images with the associated digitally reconstructed radiographs (DRRs), which then allows computing the associated registration transformation at each stage. In order to account for intensity nonstationarities and complex spatially-varying intensity distortion in the deformable b-spline 2D-3D registration stage, the intensity-based 2D-2D image registrations at this stage are done based on minimizing the complexity of the residual images between the C-arm images and the associated DRRs. Comprehensive experiments on simulated images, on images of cadaveric femurs and on clinical datasets are designed and conducted to evaluate the performance of the proposed approach. Quantitative and qualitative evaluation results are given, which demonstrate the efficacy of the present approach.