Monte Carlo Study of Electron Spectra and Dose from Backscattered Radiation in the Vicinity of Media Interfaces for Monoenergetic Photons of 50-1250 keV

摘要: In the present paper electron fluence spectra and backscatter dose factors for monoenergetic photons (50, 100, 250 1250 keV) are presented. The influence of atomic number materials glass, bone, steel titanium is studied. For all radiations increases in were found immediate vicinity interface a region extending over distance determined by photon energy. thin layer several tens micrometers from interface, large increase was 50 100 keV photons. largest factor (3.5) interface. This effect to be due largely backscattered photoelectrons. K-shell fluorescent also included but have almost no on or spectra. With both fluorescence sampling photoelectron angular distribution switched off, much smaller obtained. Beyond near where increased, significant depressions these energies centimeters maximum 50more » photons, which about 35% 15% glass bone more modest enhancement close (40-50%) larger (e.g. 5 mm photons). Small differences radiation quality nearer as expressed track-averaged dose-averaged restricted linear energy transfer, {rvec L}ET{sub 1000,T} 100,D}, with this decrease 50% 100,T} 29 refs., 4 figs.« less