Local Diagnostic Reference Levels for Common Computed Tomography Procedures at a Tertiary Hospital in South Africa

An operational computed tomography (CT) scanner is a major source of human exposure to ionizing radiation. Exposure increases the risk of cancer and aplastic anaemia. All radiation exposures should be justified and optimized to meet the clinical objective. In order to avoid the administration of excessive radiation dose to patients, diagnostic reference levels (DRLs) were proposed. The DRLs identify unusually high radiation doses during CT procedures, which are not commensurate with the clinical objective. They have been successfully implemented in Europe, United States, some developed countries, and a few developing countries. In this regard, the present study aimed at establishing DRLs for the head, chest, and abdomen/pelvis CT procedures at a tertiary hospital in South Africa.
A retrospective analysis of volume CT dose index (CTDIvol) and dose length product (DLP) was performed on 100 randomly selected adult patients for each of the head, chest, and abdomen/pelvis CT procedures. The mean values of the DLP and CTDIvol dose parameters were calculated using SPSS, version 24.  
The established DRLs for CTDIvol were 32; 7, and 32 mGy for the head, abdomen/pelvis, and chest, respectively, while the DLPs for the respective protocols were 767, 386, and 593 mGy.cm.
The implementation of DRLs facilitates identifying CT doses that are not commensurate with the clinical objective, thereby lowering patients’ doses significantly.