Radiation doses to patients during selected CT procedures at four hospitals in Tanzania

The dose characteristics of CT scanners from local scanning protocols were investigated on the basis of questionnaire information provided by four hospitals conducting CT procedures in Tanzania. The information included scanner model, scanner manufacturer, number of most frequent CT examinations and the employed scanning parameters to previously diagnosed patients. For each scan technique, patient doses were estimated in terms of computerized tomography dose index, dose length product and effective dose using the software developed by the ImPACT scan group in conjunction with the NRPB conversion coefficients data. The results show that the mean CTDI_w,100, DLP and effective dose ranged from 8.5 +/- 2.8 to 79.3 +/- 23.7mGy, 145 +/- 5 to 1400 +/- 812.5 mGy cm and 3 +/- 2.3 to 15.7 +/- 10.4 mSv, respectively. On average, the observed CT doses are however roughly higher than the reported literature data such as 30 to 60 mGy, 570 to 1050 mGy cm and 2.4 to 11.7 mSv recommended by European Commission for similar CT examinations. The higher dose levels, which are possibly associated with significant risks, justify extensive similar studies at the national level in order to unify different approaches towards optimisation of CT examinations. In pursue of this noble objective, the need to train the radiology personnel, establish and using protocols and continuously monitor the performance of CT equipment to control patient CT doses is of utmost importance.