Toward quantitative short-scan cone beam CT using shift-invariant filtered-backprojection with equal weighting and image domain shading correction.

Quantitative short-scan cone beam CT (CBCT) is impeded by streaking and shading artifacts. Streaking artifacts can be caused by approximate handling of data redundancy in short-scan FDK with Parker's weighting, while shading artifacts are caused by scatter and beam hardening effects. In this work, we improve the image quality of short-scan CBCT by removing the streaking artifacts using a previously proposed algorithm in a framework of filtered backprojection with shift-invariant filtering and equal weighting. An efficient image domain shading correction using sparse samples is subsequently applied to further improve the image uniformity. The improved image quality is shown for this approach, both in visual appearance and quantitative measurements of three clinical head scans.