What is a key difference between axial and helical CT scanning?

The key difference between axial and helical CT scanning lies in the way images are captured and the technology used during the scanning process. In axial scanning, the CT scanner captures images one slice at a time, meaning that the tube rotates around the patient, takes a slice, then moves the table to the next position for the next slice. This process is more time-consuming and can lead to longer examination times.

On the other hand, helical scanning – also referred to as spiral CT – allows for continuous rotation of the X-ray tube and simultaneous movement of the table. This means that as the tube rotates around the patient, the table moves continuously through the scanning area, creating a helical (spiral) path. This results in much faster image acquisition, improved spatial resolution, and the ability to reconstruct images in multiple planes without needing to rescan.

This continuous nature of helical scanning can also lead to reduced motion artifacts, allowing for clearer images, especially beneficial in cases where patients may have difficulty remaining still. The advantages of helical scanning are significant in clinical practice, particularly in emergency situations or when imaging larger areas of the body.