Reproducibility of multi-slice spiral computed tomography scans: an experimental study

In multi-slice spiral computed tomography (CT) images interpolation artifacts are present. The relationship between the x-ray tube rotation angle and these artifacts is demonstrated. A head phantom was repeatedly scanned with a four-slice CT scanner at different pitch values. Two scans, made with identical scan parameters, nearly always have different x-ray tube starting angles. Consequently, artifacts appeared differently and residual artifacts appeared when subtractions were made. We conclude that only if the x-ray tube starting angle is equal for both scans or if a very low pitch is used, images are highly reproducible.