Computed Tomography Technologist Practice Exam 2025 - Free CT Technologist Practice Questions and Study Guide

The formula for calculating the distance covered in a single slice SDCT (Single Detector Computed Tomography) helical scan sequence is indeed based on the relationship between pitch, total acquisition time, and rotation time.

In helical CT scanning, pitch refers to the ratio of the table movement to the x-ray beam width per rotation. The total acquisition time represents how long the scan takes, and rotation time indicates the time it takes for the x-ray tube to make a complete rotation.

The correct formulation comes from understanding that the total distance covered during the scan is the product of the pitch and the total acquisition time, normalized by the rotation time to factor in the speed of rotation. This way, the scan distance can be calculated as:

Distance = (pitch * total acquisition time * 1) / rotation time

This reflects that over the duration of the scan (total acquisition time), the table moves a distance proportional to the pitch, and this needs to be adjusted based on how quickly the x-ray tube rotates (rotation time). Understanding how these components interact allows for an accurate calculation of the total distance covered during a helical scan, aiding in planning and assessment in CT imaging.