Diagnostic reference levels for head and abdominal computed tomography of adult patients in selected states in South-South Nigeria

Abstract

Context: Diagnostic reference level (DRL) is the first step in the optimization process to manage patient dose corresponding with the medical purpose. Aim: The objective of this study was to develop local DRL for computed tomography (CT) of the head and abdomen in adult patients in four CT centers in South-South Nigeria. Materials and Methods: A prospective, cross-sectional study of 546 adult patients that underwent CT examination of the head and abdomen from 2018 to 2020 using four different CT scanners. Volume CT dose index (CTDIvol) and dose length product (DLP) of contrast and non-contrast CT examinations of the head and abdomen were collated and the 50th percentile DRL was determined and compared to other published DRLs. Results: The 50th percentile CTDIvol/DLP for non-contrast head CT examination for centers A, B, C, and D was 75.3 mGy/1776.6 mGy.cm, 21.8 mGy/457 mGy.cm, 17.4 mGy/373.6 mGy.cm, and 29.6 mGy/628.5 mGy.cm, respectively. The 50th percentile CTDIvol/DLP for contrast head CT examination for centers A, B, C, and D was 150.6 mGy/3326.2 mGy.cm, 41.4 mGy/832.4 mGy.cm, 35.6 mGy/653.6 mGy.cm, and 77.9 mGy/1458.4 mGy.cm, respectively. The 50th percentile CTDIvol/DLP for non-contrast abdomen CT examination for centers A and B was 22.8 mGy/1488.5 mGy.cm and 7.9 mGy/302.3 mGy.cm, respectively. The 50th percentile CTDIvol/DLP for contrast abdomen CT examination for centers B and C was 19.6 mGy/825.7 mGy.cm and 31.5 mGy/1555.5 mGy.cm, respectively. There was correlation between contrast and non-contrast CTDI (P = 0.003) and DLP (P = 0.025) for the head. Conclusion: Wide variations CTDIvol and DLP values were observed among the centers for similar body part CT examinations.