RESUMO
The radiation effective dose received by the radiologists during procedures such as fluoroscopy or different angiographies are usually evaluated using TL dosimeter. This method is a time-consuming procedure; therefore, radiologists are usually worried and unaware of their exact radiation dose received during each fluoroscopy or angiography. In this study, a new trend for quick estimation of effective dose based on measuring air-absorbed dose of the scattered radiations at body surface of the radiologists has been introduced. Scattered radiations of abdominal viscera were simulated by a fluoroscopy unit [Shimatsu, model SF5010MD], and a water phantom [spherical plastic bag 27 cm in diameter filled with water up to 22.5 cm height]. Radiation field was 20 × 20 cm on the bed and X-ray tube had 1.5 and 2 mm of Aluminum as an internal and external filtration respectively. A calibrated survey meter model RDS-110 was used to measure the scattered radiation horizontally and vertically around the phantom at different angles and distances, in front and behind of an apron. The scattered dose rate at 1 m from the phantom, during fluoroscopy at 83 kVp and 1.7 mA, was 451 microGy/h. This value reduced to 4.45 microGy/h by passing through lead ribbons of serigraph and to 1.2 microSv/h behind an apron. The scattered dose rate at different angles above the bed was constant and varied by distance from the center of the radiation field. The effective dose received by the radiologist is estimated to be about 174microGy/h, while wearing an apron and staying 50 cm away from the patient during fluoroscopy or angiography of abdominal viscera. The radiologist can estimate his/her effective dose following a fluoroscopy or different angiographies of abdominal viscera, by determining scatter radiation dose at their body surface and applying factor 0.87 for shielding effect of the body. Equivalent organ dose can also be calculated from dose rate in air after applying factor 0.87 for deep organs or 1.1 [the mass energy absorption coefficient ratio of water/tissue to air] for organs near the surface