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

The calculation for the number of images produced in a helical scan system involves understanding how the pitch, total acquisition time, and rotation time work together. In a helical CT scan, the pitch is defined as the distance the table moves during one complete rotation of the X-ray tube divided by the width of the beam.

To determine the number of images created, the formula (pitch * total acquisition time * 1) / rotation time effectively accounts for how many slices are acquired during the entire scan process. Here’s how it works:

- The total acquisition time defines how long the scanning occurs.

- The rotation time represents the duration it takes for the X-ray tube to complete one full rotation.

- During each rotation, the pitch indicates how far the table moves, which influences how many slices or images are generated within that time frame.

Thus, multiplying the pitch by the total acquisition time gives you the total distance covered during the scan. Dividing that by the rotation time provides the number of rotations that fit within that scan duration, leading to the calculation of the total number of images created.

This results in a clear understanding of how pitch and time interrelate in determining the imaging output in a helical scanning system.