An ICT Reconstruction Algorithm for Rotation Off-Centered Scan

Abstract The detected samples of ICT have variable sizes. Different scanning models and corresponding reconstruction algorithms are designed to enlarge the field of view under the condition of a detector of fixed size, such as rotation off-centered、detector displaced. Generally, rebinning method is applied to rotation off-centered scanning model. Fan beam projections are rebinned to parallel beam data. Then, the data which is lost can be compensated by mirrored projections. The disadvantage of rebinning method is spatial resolution can be degraded due to interpolation in rebinning process. In addition, rebinning method is not suitable extended to cone beam data. This paper proposes a reconstruction algorithm applied to rotation off-centered scan. This method weights the redundant projection data sampled twice with a parker type function first. Then a fan beam reconstruction algorithm is applied to obtain slice images. Spatial resolution cannot be degraded without interpolation. We perform experiment with line pair to prove the validity and advantage of this method. We reconstruct images by rebinning method and our method separately. The results show a superior spatial resolution of our method. Key word: industrial CT, rotation off-centered scan, detector displaced scan, spatial resolution, field of view