Sequential CT image acquisition

Sequential CT scanning, also referred to as "scan-move-scan" or "step and shoot", was the conventional method of image acquisition in computed tomography before the advent of helical CT.

In sequential scanning, the patient is moved forward along the longitudinal axis of the CT scanner, pausing at intervals to allow a trans-axial image to be captured at each position along the axis.

The tube gantry is restricted from rotating continuously by the use of high-tension cabling instead of slip ring technology seen in modern CT scanners.

Helical scanners are now fast replacing sequential scanners in modern practice.

The disadvantages of sequential scanners include:

• uniplanar imaging (axial slices only)
• longer scan acquisition times
• increased radiation dose (secondary to longer scan times)
• increased motion artefact (secondary to longer scan times)