Abstract
INTRODUCTION: Computed Tomography (CT) involves larger radiation dose than the more common conventional x-ray imaging procedures. Existing DRLs have been established based on anatomical locations. However, some limitations of this approach have been identified. CT examinations, for the same anatomical location, could have several clinical indications with consequently different protocols corresponding to different radiation exposure levels. The objective of the study was to establish adult CT Clinical Indication Diagnostic Reference Level (DRLCI) and determine its Relationship with age, weight and Gender in Enugu State, Nigeria. METHODS: Dose values and technical parameters were obtained using International Commission on Radiological Protection (ICRP) Publication 135. Quality control checks were carried out on the machines. 2490 adult patients with weight 50±10 kg, the distribution was 1200 brain scans (48.2%), 420 chest scans (16.9%) and 870 abdominal scans (34.9%) were studied from the 5 participating centers. Head - CVA (300), Trauma (300), Metastasis/abscess (300), Infection (180), Seizure (120). Chest - Lung disease (240), Lung cancer/mass (180). Abdomen/Pelvis - Abdominal cancer/metastasis (120), Abdominal mass (300), Liver disease (240), Urography (210). RESULTS: DRLci for trauma, CVA, metastasis, infection and seizure are 43, 43, 43, 34 and 28 mGy respectively. Their corresponding DLP includes; 907, 879, 1689, 969, 995 mGy.cm. In the chest, the CTDI for lung disease and mass are 13 and 13 mGy. Their corresponding DLP includes; 763 and 1531 mGy.cm. In the abdomen, the CTDI for liver disease, malignancy, mass and urography are 16, 12, 16, and 15 mGy. CONCLUSION: DRLci for 10 common CT examination were established. Radiographers should focus on clinical DRLs rather than anatomical DRLs.
