المستخلص: |
Computed tomography examination (CT) is a diagnostic imaging modality giving higher patient dose in comparison with other radiological procedures. The aims of this study are, first, to determine the magnitude of radiation doses received by selected organs of patients undergoing CT examinations, secondly to assess how CT scanning protocols in practice affect patient organ doses. In order to achieve these objectives, patient organ doses from four common CT examinations were obtained from sixteen hospitals in Libya with different CT models. The Impact survey data were used to determine the parameters related to patient dose. This was done by correlating the measurements from the National Radiological Protection Board (NRPB-R250) scanners with the effective dose calculated, using the CT-EXPO software. Patient dose index in air (CTDIair) was measured as function of tube exposure ranged from 80 to 250 mAs at constant kVp and slice thickness, using a special pencil-shaped ionisation chamber and phantoms. RESULTS: The mean organ doses in this study for head, chest, and abdomen and for pelvis were 61.5 mGy, 28.5 mGy, 38.4 mGy, and 24.0 mGy, respectively. These values were slightly higher than the values of organ doses reported from the literature. It was concluded that patient organ doses could be substantially minimized through careful selection of scanning parameters based on clinical indications of study, patient size, and body region being examined. Additional dose reduction to superficial organs would require the use of shielding materials.
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