Large-field Superficial Electron Therapy with Linear Accelerators

An electron therapy technique is described for treating large field superficial lesions, particularly mycosis fungoides, which has been in use for several years at Stanford Medical Center (Karzmark et al., 1960). An X-ray linear accelerator has been modified to permit convenient, rapid and routine conversion to this treatment modality with minimum interference to a large supervoltage therapy programme. Information is presented on treatment geometry, electron/X-ray conversion features, dosimetry and treatment planning.The system can be adapted to different accelerators, although it lends itself particularly well to the isocentric geometry found on many linacs, and results similar to those described would probably be obtained with existing 4 MeV equipments. The use of carbon decelerator-scatterers (Szur et al., 1962), could extend the technique to somewhat higher energy accelerators as well as permitting a wider choice of depth dose characteristics.