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Calculational methods for estimating skin dose from electrons in Co‐60 gamma‐ray beams
Author(s) -
Higgins P. D.,
Sibata C. H.,
Attix F. H.,
Paliwal B. R.
Publication year - 1983
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 - 10.1118/1.595332
Subject(s) - electron , physics , photon , scattering , gamma ray , pencil (optics) , dosimetry , x ray , gaussian , detector , monte carlo method , computational physics , atomic physics , optics , nuclear physics , nuclear medicine , mathematics , quantum mechanics , medicine , statistics
Several methods have been employed to calculate the relative contribution to skin dose due to scattered electrons in Co‐60 γ‐ray beams. Either the Klein–Nishina differential scattering probability is employed to determine the number and initial energy of electrons scattered into the direction of a detector, or a Gaussian approximation is used to specify the surface distribution of initial pencil electron beams created by parallel or diverging photon fields. Results of these calculations are compared with experimental data. In addition, that fraction of relative surface dose resulting from photon interactions in air alone is estimated and compared with data extrapolated from measurements at large source–surface distance (SSD). The contribution to surface dose from electrons generated in air is 50% or more of the total skin dose for SSDs greater than 80 cm.