Establishment and utilization of National Diagnostic Reference Level for adult computed tomography examinations in Ghana

Abstract As part of measures to enhance radiation protection and safety of patients undergoing medical exposure, it is recommended that various countries initiate a project for the establishment of diagnostic reference levels (DRLs) in Africa. The aim of the project was to establish and utilize national DRLs of computed tomography dose index (CTDI) and dose length product (DLP) for routine computed tomography (CT) examinations. Additionally, the project was also to identify the potential for clinical protocol and dose optimisation in relation to disease and patient specific CT examination in the country. The methodology involved the estimation of CTDI and DLP values from a minimum of 20 patient images data dose report of the most commonly used procedures (head, chest, abdomen-pelvis and lumbar spine) CT examinations. 22 CT centres in Ghana, took part in this study which represent 54% of CT equipment in Ghana. Data of 2,156 dose report were randomly selected from the 22 CT centres of adult patients undergoing CT examination of head, chest, abdomen and lumbar spine from these centres and analysed. The total number of CT examinations for the 22 Centres was 186300, comprising of 111800 head CT, 22592 chest CT, 38260 abdominal CT and 13648 lumber spine CT. Head CT represented 60% of the total CT examination of all the Centres. Additionally, the percentage distribution of the remaining three body regions were 12.1, 20.6 and 7.3% for chest CT, abdomen CT and lumbar spine CT examinations respectively. The measured median and its upper quartile CTDI vol for head CT were 56.5 and 61.0 mGy, chest CT 12.6 and 15.7 mGy, abdomen CT 13.5 and 20.5 mGy, and lumbers spine 19.6 and 23.8 mGy. While DLP for head CT were 574.5 and 962.9 mGy-cm, chest CT 874.5 and 1102.8 mGy-cm, abdomen CT 1110.7 and 1393.5 mGy-cm, and lumber spine 693.5 and 824.6 mGy-cm. These preliminary results were comparable with data from 16 other African countries, European Commission (EC), IAEA, United Kingdom (UK), United States of America (USA) and the International Commission on Radiological Protection (ICRP).