Influence of data completion on scatter artifact correction for truncated cone-beam CT data

Abstract

X-ray scatter leads to one of the major artifacts limiting the image quality in cone-beam CT (CBCT). Hence the interest to perform an accurate scatter correction is very high. A particularly large amount of scatter is created in CBCT, due to the large cone-angle and the small distance between the rotation axis and the detector. Even if an anti-scatter grid is used, a scatter correction is necessary. The performance of an accurate scatter correction is difficult, especially when the data are additionally truncated due to a small field of measurement (FOM) (e.g. dental CT systems or C-Arm CT systems). In addition to the image degradation due to scatter artifacts, numerous CBCT artifacts like beam-hardening artifacts and cone-beam artifacts contribute to a further reduction in image quality. In this paper different detruncation methods are compared with respect to scatter to find a quantitative scatter correction approach for truncated CBCT data. The evaluation shows that a precise detruncation is crucial for an appropriate scatter correction. Additionally, the general image quality limit is enhanced by performing further artifact correction methods to reconstruct a nearly artifact-free CBCT volume.