Reduction of scattering artifact in multislice CT

Abstract

The new multi slice CT scanners are characterized by a wide coverage (collimation) in the longitudinal (z) direction. This large collimation provides large and rapid coverage, it may however introduce artifacts caused by scatter, which are enlarged with collimation. The scattering in the z direction induces artifacts that appear as dark shadows between bones.We present a software correction that reduces the scattering artifacts.The correction is based on a subtraction of a low frequency offset, as foreseen in simulations of scatter effect, from the raw data. The study includes tests of the scattering correction of both phantoms and clinical scans.The corrected images are compared to un-corrected images scanned with the same z-coverage (collimation) and to images scanned with narrower z-coverage with the same scan parameters. The results demonstrate that the correction of the images, scanned with the wide collimation, reduces the scattering artifact significantly. The obtained image quality levels to that of the images scanned with narrower collimation.