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Semianalytical expressions for ( L ̄ / p ) air med and P repl for electron 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 - 10.1118/1.596745
Subject(s) - stopping power , fluence , imaging phantom , electron , physics , atomic physics , energy (signal processing) , computational physics , optics , nuclear physics , irradiation , detector , quantum mechanics
The tables of the mean restricted collision mass stopping power ratios for water, polystyrene and acrylic relative to air given in the AAPM TG‐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 calculated values agree with the tabulated values within +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 repl has been fitted to an expression with four coefficients using the mean electron energy at depth z as an independent variable.