Difference between sequential and helical CT acquisition?
Sequential (or axial) CT acquisition is a step-and-shoot mode in which the patient table does not move during image acquisition of one or several slices at a time through the patient. Subsequently, the table advances and the process is repeated until the entire body region has been scanned. Helical (or spiral) CT acquisition is faster and involves continuous image acquisition while the patient table moves through the CT gantry. In this mode, the x-ray tube traces a helical trajectory around the patient. All modern CT scanners are helical scanners but can acquire images in sequential mode if desired.