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Monte Carlo based phase‐space evolution for electron dose calculation
Author(s) -
Scora Daryl,
Faddegon Bruce A.
Publication year - 1997
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 - 10.1118/1.597925
Subject(s) - monte carlo method , computational physics , electron , physics , monte carlo method for photon transport , cathode ray , phase space , dynamic monte carlo method , nuclear physics , mathematics , direct simulation monte carlo , statistics , thermodynamics
A system of computer codes based on phase‐space evolution is developed and applied to low energy therapeutic electron beams. Monte Carlo (EGS4) is used to pre‐calculate the electron transport and dose deposition in a 0.5 cm width cubic voxel. Dose calculations at larger scales are computed from the pre‐calculated data using phase‐space evolution. This approach has the theoretical accuracy of Monte Carlo with potentially significant speed gains resulting from the pre‐calculation. This study demonstrates the accuracy of this technique while providing a preliminary assessment of the calculation time. For a 4.3 MeV electron beam in water with a 0.5 cm thick slab of either water (homogeneous), air, or aluminum at 1 cm depth, we observe differences relative to Monte Carlo of less than 3 % along the central axis for a pencil‐beam. For a 3.5 cm × 3.5 cm field we observe a maximum difference on the central axis of 4% in the build‐up region and less than 0.1 cm in the fall‐off region for all three phantoms. Calculation times are disappointing; however, there is high potential for their reduction to values comparable to or better than condensed history Monte Carlo while retaining clinically acceptable accuracy.