Directional interpolation for motion weighted 4D cone-beam CT reconstruction.

Image quality of four dimensional cone-beam computed tomography (4D CBCT) is limited by streaking artifacts due to insufficient projections after respiratory sorting. In this paper, a framework is proposed to combine improved motion and stationary regions of CBCT together to enhance the final reconstructed image. Firstly, streaking artifacts are decreased in the 4D CBCT by directional interpolation for additional cone-beam projections. Secondly, motion is estimated through deformable image registration of the 4D CBCT and motion proportional weights are assigned to each voxel. Finally, the weighted combination of the 3D and an interpolated 4D image is calculated. The proposed method is validated by both phantom and clinical data. Experiments demonstrate this method decreases streaking artifacts as well as image blur, and then improves image quality.