A method for describing the doses delivered by transmission x-ray computed tomography

TLDR

The study proposes a method to describe the absorbed dose delivered by x‑ray transmission CT, enabling characterization of doses from series of adjacent scans. The method defines the average dose at multiple locations in the central scan of a series and estimates it by integrating the dose profile perpendicular to the scan plane from a single scan, evaluated across scan counts and phantom locations using data from five CT systems. The approach demonstrates that the average dose can be derived from a single‑scan dose profile, and for high‑dose phantom regions the multiple‑scan descriptor overestimates the true average by no more than 10% when at least eight scans are performed.

Abstract

A method for describing the absorbed dose delivered by x-ray transmission computed tomography (CT) is proposed which provides a means to characterize the doses resulting from CT procedures consisting of a series of adjacent scans. The dose descriptor chosen is the average dose at several locations in the imaged volume of the central scan of the series. It is shown that this average dose, as defined, for locations in the central scan of the series can be obtained from the integral of the dose profile perpendicular to the scan plane at these same locations for a single scan. This method for estimating the average dose from a CT procedure has been evaluated as a function of the number of scans in the multiple scan procedure and location in the dosimetry phantom using single scan dose profiles obtained from five different types of CT systems. For the higher dose regions in the phantoms, the multiple scan dose descriptor derived from the single scan dose profiles overestimates the multiple scan average dose by no more than 10%, provided the procedure consists of at least eight scans.