Fig. 4.

Deformable registration of spinal fixation rods. (a) Volumetric rendering of the post-op CT with the true component (top, magenta), and the registered component visualized in pre-op CT (bottom, yellow) for spline order $n=3$. (b) Convergence behavior of the optimizer illustrated in terms of the similarity metric (GC) and the HD measured as a function of iteration number. (c) Mean deviations from true position measured along the length of spinal rod.