Bremsstrahlung dose to patients in rotational electron therapy.

Dose and integral dose from bremsstrahlung in a 10-MeV electron beam were measured for irradiation of large areas with 120 degrees-arc rotational fields. The maximum bremsstrahlung dose ranged from 2% to 7% of the maximum electron dose for the different beam arrangements, while the integral dose showed the same range of variation. The concomitant bremsstrahlung beam should be collimated by the x-ray photon collimators and the use of narrow field rotations avoided.