Cause and correction for 3D image artifact in helical CT

In recent years, helical computed tomography (HCT) has gained significant popularity in clinical applications. The advantages of HCT include the capability of scanning a complete anatomical volume in a single breath-hold and the capability of generating images at arbitrary locations. Because of the inherent inconsistency in the helical data set, however, recent studies have unveiled various HCT related image artifacts. In this paper, the authors perform a detailed analysis on one of the artifacts in the 3D shaded surface display (SSD): the “grooving” artifact. The authors develop an analytical model to show that the artifact is caused by the angular dependent edge response of the HCT reconstruction algorithm. The accuracy of the model is confirmed by both computer simulations and phantom experiments. Based on the model, the authors present several correction algorithms to combat the “grooving” artifacts. Computer simulations and phantom experiments are used to demonstrate the effectiveness and robustness of the corrections