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IORT apparatus design improvement through the evaluation of electron spectral distributions using Monte Carlo methods
Author(s) -
Price Robert A.,
Ayyangar Komanduri M.
Publication year - 2000
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.598886
Subject(s) - monte carlo method , electron , cathode ray , beam (structure) , dosimetry , materials science , computational physics , optics , physics , atomic physics , nuclear medicine , nuclear physics , medicine , mathematics , statistics
Clinically used IORT electron beam characteristics may vary with respect to typical external beams due to the decrease of lateral scatter equilibrium and the addition of the IORT apparatus itself. Additionally, chamber size effects may lead to inaccurate measurements of the changes in electron beam characteristics. The causal components of these beam characteristics are often difficult or impossible to measure using experimental techniques. For this reason, and for potential design improvement, the electron beams were modeled using the OMEGA/BEAM Monte Carlo software for radiation transport. The IORT electron beam characteristics of the Varian Clinac 1800 were studied for 6, 12, and 20 MeV electrons and 1–4 in. diameter flat‐end applicators. The characteristics studied include electron energy spectra, percentage depth dose, and cross‐plane profiles. It was found that by increasing the thickness of the aluminum base plate of the main attachment, the dose at d maxoutside the primary field could be reduced from approximately 9% to 1% of maximum.