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 (NRPBR250) 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, 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.