C-arm 투시 사용 시 방향과 거리에 따른 입사선량

Entrance Dose according to Direction and Distance Using C-arm Fluoroscopy

Purpose : Nowadays, the use of C-arm during the operation is on the increase. As the frequency of C-arm use is increasing, the entrance skin dose of the operator is increased. Therefore, the radiation dose in operating room was measured to compare operator’s entrance skin doses according to direction and distance from C-arm. Materials and Methods : The C-arm fluoroscopy unit was used automatic control function. Entrance skin doses were measured at 8 different directions (45° interval), and the entrance skin doses with and without apron were measured at 4 different distances of 50-200cm (with 50cm interval) from the phantom pelvis center Results : The maximum entrance skin dose rate at a distance of 50cm was 0.526mGy/min without apron and 0.057mGy/min with apron in E zone, and the minimum entrance skin dose tate was 0.049mGy/min without apron and 0.005mGy/min with apron in the C zone (A zone, where was placed C-arm unit was excepted). Because radiation dose was shield by an operating table, the entrance skin dose in the direction of C zone was lower than that in the direction of E zone. The average entrance skin dose rate by the 8 directions was 0.312mGy/min without apron, and 0.033mGy/min with apron at a distance of 50cm The entrance skin dose with apron was 10.6-16.0% of that without apron. The entrance skin dose rate at the directions occupied by the operator and assistant was 0.356mGy/min at 50cm and 0.122mGy/min at 100cm without apron, and 0.038mGy/min at 50cm and 0.012mGy/ min at 100cm with apron. The expected entrance skin dose of the operator was 3.45mGy/procedure, 10.35mGy/day and 993.60mGy/ year without apron, and 0.37mGy/procedure, 1.11mGy/day and 106.56mGy/year with apron. Conclusion : Entrance skin dose according to direction and distance was different more than10 times. As the radiation protective apron was present or not, entrance skin dose was different about 6-10 times. It is essential to decide appropriate position of operator and to wear the apron. Operator should use C-arm with professional knowledge and accurate skill to minimize the radiation dose of medical staffs.