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A simple one‐dimensional model for understanding planar dose‐versus‐depth profiles in mixed photon/electron fields
Author(s) -
Fehl D. L.
Publication year - 1993
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 - 10.1118/1.597100
Subject(s) - electron , photon , kerma , physics , photon energy , planar , scattering , electron scattering , atomic physics , computational physics , field (mathematics) , dosimetry , optics , nuclear physics , nuclear medicine , mathematics , medicine , computer graphics (images) , computer science , pure mathematics
A one‐dimensional model is described for illustrating the perturbing effects of mixed photon/electron fields on planar dose‐versus‐depth profiles in low Z materials ( Z ≤20), and at moderate photon energies (0.3–10 MeV). An electron field may arise from photon interactions in filters upstream of a dose‐versus‐depth experiment. The effects of upstream mass, scattering of electrons out of a gap between a filter and the experiment, and differences between the incident electron energy distribution and locally produced KERMA are modeled and compared to Discrete Ordinates calculations. At transitional depths in a dose‐versus‐depth experiment, the distortions can be significant and obscure the profile of the photon component alone.