Abstract:
Abstract
Background In medical imaging, a computed tomography (CT) scanner is a major source of ionizing radiation. All
medical radiation exposures should be justifed and optimized to meet the clinical diagnosis. Thus, to avoid unnecessary radiation doses for patients, diagnostic reference levels (DRLs) have been used. The DRLs are used to identify
unusually high radiation doses during CT procedures, which are not appropriate for the clinical diagnosis. It has been
successfully implemented in Europe, Canada, Australia, the United States, several industrialized countries, and a few
underdeveloped countries. The present study aimed to establish DRLs for the head, chest, and abdominopelvic (AP)
CT procedures in Addis Ababa, Ethiopia.
Methods A pilot study identifed the most frequent CT examinations in the city. At the time of the pilot, eighteen
CT scan facilities were identifed as having functioning CT scanners. Then, on nine CT facilities (50% of functional CT
scanners), a prospective analysis of volume CT dose index (CTDIvol) and dose length product (DLP) was performed. We
collected data for 838 adult patients’ head, chest, and AP CT examinations. SPSS version 25 was used to compute the
median values of the DLP and CTDIvol dose indicators. The rounded 75th percentile of CTDIvol and DLP median values
were used to defne the DRLs. The results are compared to DRL data from the local, regional, and international levels.
Result The proposed DRLs using CTDIvol (mGy) are 53, 13, and 16 for the head, chest, and AP examinations respectively, while the DLP (mGy.cm) for the respective examinations were 1210, 635, and 822 mGy.cm.
Conclusion Baseline CT DRLs fgures for the most frequently performed in Addis Ababa were provided. The discrepancies in dose between CT facilities and as well as between identical scanners suggests a large potential for dose
optimization of examinations. This can be actually achieved through appropriate training of CT technologists and
continuous dose audits
