The purposes of the present study are to measure the total radiation doses for the radiation workers and for the accompanying person to the patients in positron emission tomography (PET)/computed tomography (CT) imaging. Urines samples from the patients were collected at 43, 62, 87, 117, 238, 362 min after the 555-MBq (18)flour-fluorodeoxyglucose (F-18-FDG) injection and activities were measured. Dose rates were recorded using a Geiger-Muller counter and the total radiation doses were measured with using an electronic personnel dosemeter. According to the results here, 18.4 % of F-18-FDG was excreted in the urine in 117 min after injection. At 117th min after injection, dose rates were determined as 345, 220, 140, 50 and 15 mu Sv h(-1), at proposed distances. The radiation doses after 117 min were measured as 3.92 mSv at 0.1 m, 2.11 mSv at 0.25 m and 1.08 mSv at 0.5 m. In conclusion, radiation protection will be sufficient within 2 h after 18F-FDG injection for PET/CT imaging in daily practice.