An IIR Ramp Filter for Filtered Backprojection Reconstruction of X-ray CT

摘要

In filtered backprojection algorithm that is one of the CT reconstruction methods, the authors recently have developed the new method decomposes a ramp filter into a series of differentiator and discrete Hilbert transformer (DHT), and directly applies them. In this paper, we propose a method to compromise ultra-low frequency artifacts (dishing artifact) and ripple artifacts, using 1st order covariance model. Moreover, we expand the point spread function (PSF) from projection to backprojection with respect to the transition bandwidth. Since the lowest second order PSF implies the contribution to DC-shift, this paper proposes a compensation of DC-shift. Computer simulations showed the proposed method with DC-shift compensation is comparable to the existing method.