title: Influence of collimator design on the shape of isodose curves in high energy electron beams.
abstract: Families of isodose curves for electron beams of 20 and 34 MeV were obtained for two different kinds of collimator designs. The lucite localizer of the original collimator of the betatron was replaced by a modified metal device. Electron isodose distributions were obtained for circular, and rectangular field sizes employing film dosimetry. The results show that an improvement was achieved in the symmetry of the beam and in the reduction of the penumbral region when the original lucite localizers were replaced by brass defining plates at the patient's skin. The new proposed electron-localizers are described in this study and their influence on depth dose distributions is discussed.
mesh_terms: D004583:Electrons; D004867:Equipment Design; D008961:Models, Structural; D011882:Radiotherapy, High-Energy / Q000295:instrumentation*