Electron fluence correction factors for various materials in clinical electron beams.

摘要: Relative to solid water, electron fluence correction factors at the depth of dose maximum in bone, lung,aluminum, and copper for nominal beam energies 9 MeV 15 Clinac 18 accelerator have been determined experimentally by Monte Carlo calculation. Thermoluminescent dosimeters were used measure doses these materials. The measured relative d max various materials versus that when irradiated with same number monitor units, has calculate ratio water. beams fully characterized using EGS4/BEAM system. EGSnrc relativistic spin option turned on was optimize primary energy exit window, five phantom optimized phase-space data. Normalizing all water stopping power corrected, calculated differ less than ±1% 4% elsewhere. ratios each material LiF convert TLD measurements into center material. Fluence perturbation a deduced from calculations amount 1% 0.15 mm thick TLDs low Zmaterials are between 3% Al Cu phantoms. Electron studied vary 0.83±0.01 1.55±0.02 varying density 0.27 g/cm3(lung) 8.96 g/cm3(Cu). difference derived ranges −1.6% +0.2% −1.9% is not significant 1σ level. Excluding data Cu, open approximately proportional only weakly dependent energy.