An investigation of internal scatter during computed tomography using an anthropomorphic phantom

Abstract

Background: The general practice for all radiographic procedures is to use Lead Shielding to optimise radiation dose to the patient. The American Association of Physicists (AAPM) in Medicine in 2019 however, made a recommendation on the use of gonad and foetal shielding. The authors have noticed that very few papers on this topic come from developing countries, hence this study embarked on. The aim of our study was to evaluate internal scatter with Lead and without Lead Shielding in an anthropomorphic phantom during Computed Tomography of the brain, chest, abdomen, and pelvis. Methods: The methodology was based on examinations of a RANDO phantom brain, chest, abdomen and pelvis on a General Electric Optima 660 scanner; which had a 128-channel multidetector row. Examinations were performed with Lead and without Lead Shielding equivalence of 0.35 mm, and the internal scatter measured using Thermoluminescent Dosimeters. The collected data was analysed descriptively to determine the mean and standard deviation. The T-tests and two-way analysis of variance (ANOVA) were used to compare the means. Results: The findings of this study revealed that internal scatter was highest closest to the exposed area with higher internal scatter observed for thicker areas of the phantom. Although slightly higher readings were recorded without Pb shielding, a non-statistical significance was observed for all internal scatter measurements regardless of whether Lead Shielding was used or not. Conclusions: A non-statistical significance for Computed Tomography examinations with and without Lead Shielding in confirmation with the AAPM positional statement.