title: Argon/propane ionization-chamber dosimetry for mixed x-ray/neutron fields.
abstract: The photoneutrons produced by high-energy x-ray machines can diffuse through the mazes usually employed at the treatment-room entrance and readily penetrate the lead-lined doors used for x-ray shielding. The measurement of these neutrons in the presence of x-rays and the determination of dose equivalent poses a problem for which there is currently no standard method of solution. In order to separate x-ray dose from neutron dose, the author employed an ionization chamber alternately filled with argon or propane. The response characteristics of this chamber to x-ray and neutrons are described. Quality factors were determined from a calculated neutron spectrum. As a result of these measurements, a 10-in. polyethylene door was added to the entranceway of a 25-MV linear accelerator.
mesh_terms: D001128:Argon; D009502:Neutrons; D010315:Particle Accelerators / Q000592:standards*; D011407:Propane; D011835:Radiation Protection / Q000379:methods; D011874:Radiometry / Q000295:instrumentation*; D011882:Radiotherapy, High-Energy / Q000592:standards*; D014965:X-Rays
chemical_list: D001128:Argon; D011407:Propane