Neutron contamination of X-ray beams produced by the Varian Clinac 1800

Abstract

High energy X-ray beams produced by medical accelerators are contaminated with neutrons as a result of photon interactions with the target, flattering filter and collimator. It is important to evaluate the neutron dose to patients undergoing X-ray therapy and a number of studies have been conducted to determine dose levels in the patient plane produced by neutrons transmitted through the accelerator head shielding. On the other hand, few publications exist which report neutron dose measurements in the main X-ray beam (McGinley et al 1976, Nath et al 1979. Axton and Bardell 1979, Almond 1979, Bading et al 1982).