Radiotherapy technologist dose from high-energy electron medical accelerators.

Whole-body doses incurred by radiation therapy technologists working with 18- and 24-MV medical linear accelerators have been measured at two clinics under normal working conditions with a sensitive solid-state personal dosimeter. The results based on 84 treatments indicate that average monthly doses in the range 12-19 mrem can be expected for 30 daily treatments similar to those monitored. It was also found that 76% of the in-room dose was due to activated components in the treatment head, the balance of the in-room dose being due to activated concrete. Other statistics were obtained on patient in-room times and technologist times and doses outside the treatment room. Although the monthly film dosimetry records show no detectable doses for technologists working with these particular machines, in the spirit of ALARA, steps have been taken to reduce residual activities even further by choice of material less susceptible to activation.