HELICAL COMPUTED-TOMOGRAPHY - WHERE IS THE CUT

The helical scanning mode in computed tomography (CT) entails continuo us table movement during image acquisition. The projections acquired i n this mode will not be consistent with those in the axial scanning mo de. A comparison of the helical and axial modes of scanning on the IGE HiSpeed Advantage CT system (software version ZA) has been made using a contrast-detail phantom. Differences seen between the two modes inc lude shadow and streaking artefacts and an increase in the partial vol ume effect in the helical scan mode.