Analysis of 4-D CT Images Degraded by Motion Artifacts

4-D computed tomography (CT) scanner provides a dynamic volumetric imaging and good contrast detectablity with a high speed for collecting projections. In spite of these merits, some motion effects such as respiration, cardiac motion, and patient restlessness produce artifacts that appear as blurring, doubling, and distortion in the reconstructed images, and may lead to inaccurate diagnosis. To reduce these negative effects on reconstructed CT images, we have developed an approximative thorax phantom to analyze the motion effect in 4-D CT for testing the performance of the algorithm. The semi-anthropomorphic raw projections are obtained by based on this phantom with less computer resources. We simply simulate the motion artifacts and apply a knowledge-based method to improve the reconstructed images.