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Semianalytical expressions for ( L ̄ / ρ ) air med and P repl for electrom beams
Author(s) -
Wielopolski Lucian,
Pai Sujatha,
Mlyn Marc
Publication year - 1991
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 - 10.1118/1.596746
Subject(s) - stopping power , imaging phantom , fluence , mathematics , electron , energy (signal processing) , physics , expression (computer science) , collision , atomic physics , nuclear medicine , computational physics , optics , statistics , nuclear physics , irradiation , detector , computer science , medicine , computer security , programming language
The tables of the mean restricted collision masss stopping power ratios for water, polystyrene and acrylic relative to air given in the AAPMTG‐21 protocol have been fitted to an expression with 20 coefficients using the depth in the phantom and the mean incident electron energy as two independent variables. Using these expressions, the calculatd values agree with the tabulated values with + 0.5 % in 85 % of the cases and within ± 1.0 % in 95 % of the cases. For each of the four cylindrical chamber inner diameters, given in the protocol, the electron fluence correction P replhas been fitted to an expression with four coefficients using the mean electon energy at depth z as an independent variable.