Closed Sinusoid Trajectory for C-Arm CT Imaging

In this paper, we investigate cone-beam reconstruction for C-arm CT imaging using a closed sinusoid trajectory, which was firstly studied in [17] and can be considered a generalization of a saddle trajectory [7]. Inspired by the work in [10] and [13], we propose an exact shift-invariant filtered backprojection (FBP) reconstruction algorithm when the scanning trajectory is a closed sinusoid, or a perturbed closed sinusoid. We determine the filtering lines on the detector plane and give the steps to implement the algorithm for the planar detector geometry in a C-arm system. We also give two view independent reconstruction formulae for this geometry, both of which do not involve the view differencing operation and improve the reconstructed images by reducing discretization and sampling errors. The proposed algorithm is tested by simulation studies.