Assessment and evaluation of patient doses in adult common CT examinations towards establishing national diagnostic reference levels

Patient radiation doses from computed tomography (CT) are increasing due to the number of CT examinations performed every day. The aim of this study was assess and evaluate patient radiation doses for adult’s common CT examinations to derive local diagnostic guidance levels for common CT examinations. Volume and weighted computed tomography dose index (CTDIvol,w) and dose length product (DLP) of four common CT examinations including head, head sinus, chest, abdomen and pelvis were measured for 8 different CT scanners using standard head and body phantoms. The image quality of acquired scan images were assessed according to European Commission (EC) image quality criteria guidelines. The mean measured CTDIw for head base; head cerebrum, head sinus, chest and abdomen-pelvis were 71.8, 29.7, 35.8, 9.8 and 12.9 mGy, respectively. The DLP for head, head sinus, chest and abdomen-pelvis were 500, 371, 225 and 482 mGy.cm. The results of our study were shown more patient doses in terms of DLP for head sinus in compare with other studies while CTDIw values for head base and sinus were higher than EC measurements. The great variations of CTDIw and DLP observed among hospitals and relatively high values of DLP in some centers are evidence that radiation doses of patients from CT examinations is not fully optimized. It was concluded that future studies of continues optimization to minimize the dose without affecting image quality are needed.