title: Choosing a therapy electron accelerator target.
abstract: Angular distributions of photon depth dose produced by 25-MeV electrons incident on several fully stopping single-element targets (C, Al, Cu, Mo, Ta, Pb) and two composite layered targets (Ni-Al, W-Al) were studied. Depth-dose curves measured using TLD-700 (thermoluminescent dosimeter) chips embedded in lucite phantoms. Several useful therapy electron accelerator design curves were determined, including relative flattener thickness as a function of target atomic number, "effective" bremsstrahlung endpoint energy or beam "hardness" as a function of target atomic number and photon emission angle, and estimates of shielding thickness as a function of angle required to reduce the radiation outside the treatment cone to required levels.
mesh_terms: D004583:Electrons; D010315:Particle Accelerators / Q000295:instrumentation; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000295:instrumentation*