Computed Tomography Technologist Practice Exam 2026 – All-in-One Guide for Exam Success!

The volumetric computed tomography dose index (CTDIvol) is a critical measure used to quantify the radiation dose delivered to a patient during a CT scan. In a helical scanner, the calculation of CTDIvol takes the average dose over the volume of tissue irradiated per rotation and factors in the pitch of the scan.

The correct formula to calculate CTDIvol incorporates the weighted CT dose index (CTDIw) divided by the pitch of the scanner. The pitch is defined as the ratio of the table movement per rotation to the total slice thickness. By using the CTDIw, which represents the dose from a single slice, and dividing it by the pitch, you effectively adjust for how the scanner is moving and the degree to which the slices overlap. This produces the CTDIvol, which gives a more accurate representation of the dose when multiple slices are acquired in a helical manner.

Other formulations proposed in the other options do not align with the established methodologies for calculating dose indices in helical scanning. For instance, multiplying CTDIw by the pitch does not accurately reflect the relationship between the slice coverage and radiation exposure. Similarly, adding or dividing CTDIvol and pitch would not yield a meaningful measure of radiation dose relevant to patient safety and