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Titolo: Electron spectra derived from depth dose distributions
Autore: Faddegon, BA; Blevis, I;
 Indirizzi:
 Sunnybrook Reg Canc Ctr, Toronto, ON M4N 3M5, Canada Sunnybrook Reg Canc Ctr Toronto ON Canada M4N 3M5 nto, ON M4N 3M5, Canada Elgems, IL30200 Tirat Hacarmel, Israel Elgems Tirat Hacarmel Israel IL30200 s, IL30200 Tirat Hacarmel, Israel
 Titolo Testata:
 MEDICAL PHYSICS
fascicolo: 3,
volume: 27,
anno: 2000,
pagine: 514  526
 SICI:
 00942405(200003)27:3<514:ESDFDD>2.0.ZU;24
 Fonte:
 ISI
 Lingua:
 ENG
 Soggetto:
 MONTECARLO CODE; BEAM; RADIOTHERAPY; ENERGY; ALGORITHM;
 Keywords:
 beam modeling; dose calculation; electrons; Monte Carlo; unfolding;
 Tipo documento:
 Article
 Natura:
 Periodico
 Settore Disciplinare:
 Clinical Medicine
 Life Sciences
 Citazioni:
 31
 Recensione:
 Indirizzi per estratti:
 Indirizzo: Faddegon, BA Sunnybrook Reg Canc Ctr, 2075 Bayview Ave, Toronto, ON M4N 3M5, Canada Sunnybrook Reg Canc Ctr 2075 Bayview Ave Toronto ON Canada M4N 3M5



 Citazione:
 B.A. Faddegon e I. Blevis, "Electron spectra derived from depth dose distributions", MED PHYS, 27(3), 2000, pp. 514526
Abstract
The technique of extracting electron energy spectra from measured distributions of dose along the central axis of clinical electron beams is exploredin detail. Clinical spectra measured with this simple spectroscopy tool are shown to be sufficient in accuracy and resolution for use in Monte Carlo treatment planning. A set of monoenergetic depth dose curves of appropriateenergy spacing, precalculated with Monte Carlo for a simple beam model, are unfolded from the measured depth dose curve. The beam model is comprised of a point electron and photon source placed in vacuum with a sourcetosurface distance of 100 cm. Systematic error introduced by this model affects the calculated depth dose curve by no more than 2%/2 mm. The component of the dose due to treatment head bremsstrahlung, subtracted prior to unfolding, is estimated from the thintarget Schiff spectrum within 0.3% of the maximum total dose (from electrons and photons) on the beam axis. Optimal unfolding parameters are chosen, based on physical principles. Unfolding is donewith the publicdomain code FERDO. Comparisons were made to previously published spectra measured with magnetic spectroscopy and to spectra we calculated with Monte Carlo treatment head simulation. The approach gives smooth spectra with an average resolution for the 27 beams studied of 16 +/ 3% ofthe mean peak energy. The mean peak energy of the magnetic spectrometer spectra was calculated within 2% for the AECL T20 scanning beam accelerators,3% for the Philips SL25 scattering foil based machine. The number of low energy electrons in Monte Carlo spectra is estimated by unfolding with an accuracy of 2%, relative to the total number of electrons in the beam. Central axis depth dose curves calculated from unfolded spectra are within 0.5%/0.5 mm of measured and simulated depth dose curves, except near the practical range, where 1%/1 mm errors are evident. (C) 2000 American Association ofPhysicists in Medicine. [S00942405(00)011032].
ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/12/20 alle ore 14:12:51