Field shaping for electron-beam radiation therapy.

A system for designing electron-beam treatment fields of any shape and size using the low-melting alloy Lipowitz's metal is described. An individualized shield is produced for each patient. The shields are designed to be mounted on any of the six cone sizes provided with the Varian Clinac 18 linear accelerator but should be adaptable to most accelerators which use cones for electron-beam collimation. Materials are reusable upon completion of treatment.