A nonlinear helical reconstruction algorithm for multislice CT

With the recent introduction of multislice computed tomography (MCT) scanners, image reconstruction techniques for multislice helical CT has become an active research topic. The majority of the previously proposed algorithms limits the plane-of-reconstruction (POR) to a flat plane (either tilted or nontilted). Additionally, linear interpolation is typically employed to estimate the projections at the POR from the measured conjugate samples. In this paper, we propose a new helical reconstruction algorithm for multislice helical CT. To avoid discontinuity in the helical weighting function, a double cone-shaped region is selected as the POR. All available projection samples that are located within a predefined distance from the POR are utilized to estimate a set of projections at the POR. In addition, a weighted interpolation-extrapolation approach is proposed to replace linear interpolation. The proposed scheme has the advantage of an improved slice sensitivity profile due to a better preservation of high-frequency contents present in the projection data set. It also exhibits better performance in terms of helical artifact suppression. Phantom experiments have been conducted to demonstrate the efficacy of our approach.