Determination of water-equivalent diameter (Dw) and size-specific dose estimates (SSDE) for adult patients in abdominal CT examinations

Abstract

This work aims to calculate size-specific dose estimates (SSDE) and establish the relationship between water equivalent diameter (Dw) values and SSDE in images of abdominal CT examinations undergone by 30 adult patients. These patients had a mean age of 51 years, a mean height of 164 cm, and a mean weight of 62.71 kg. The water equivalent diameters (Dw) measured 25.30 cm on average, with mean volumetric computed tomography dose index (CTDIvol) doses of 7.95 mGy and a mean SSDE of 11.31 mGy. Images were retrospectively collected using a Hitachi Supria 16-slice CT scanner, and Dw and SSDE values were calculated based on lateral and anteroposterior (LAT + AP) measurements of cross-sectional images from each CT examination. Dw was calculated from ED, and their close correspondence allowed for interchangeable use, following AAPM guidelines. The calculated doses (SSDE) were significantly higher than the doses displayed by the scanner (CTDI). Furthermore, a strong correlation (R2 = 0.63) was observed between SSDE and Dw. Consequently, assessing patient dose based on size becomes essential to optimize radiation exposure in CT imaging.