The Scanning Phase

This chapter describes the first phase (scanning) of the computed tomography (CT) imaging process. This first phase is when the X-ray beam is scanned around and along the patient’s body – this chapter describes in detail how this scanning produces the data used to create images of individual slices. It explains ‘step-by-step scanning’, the first scanning method developed, which continues to be used for many procedures, especially when an image of just one slice is required. It also discusses spiral or helical scanning, a more advanced technology that increases the data acquired with respect to the number, thickness, and position of slices that can be imaged in one scanning procedure. In summary, protocol factors and variables associated with scanning are explained.