Radiation safety survey on a flattening filter-free medical accelerator

Dose rates at several locations outside a treatment room were measured for 6 and 18 MV photon beams from a Varian Clinac 21EX accelerator operated with and without a flattening filter. Also, dose rates in the treatment room due to activation were measured at 18 MV. An analysis of the measured data is presented. The results suggest that substantial reduction in doses outside the treatment room and lower activation can be achieved with a flattening-filter free accelerator. (authors)