Open AccessAnalytical correction of an extension of the "MU Fraction Approximation" for Varian enhanced dynamic wedges
Author(s) -
Michael S. Gossman,
Subhash C. Sharma
Publication year - 2010
Publication title -
journal of medical physics/journal of medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.292
H-Index - 24
eISSN - 1998-3913
pISSN - 0971-6203
DOI - 10.4103/0971-6203.62195
Subject(s) - wedge (geometry) , extension (predicate logic) , mathematics , matrix (chemical analysis) , fraction (chemistry) , photon , mathematical analysis , function (biology) , physics , optics , geometry , computer science , materials science , chemistry , organic chemistry , evolutionary biology , composite material , biology , programming language
The most common method to determine enhanced dynamic wedge factors begins with the use of segmented treatment tables. These segmental dose delivery values set as a function of upper jaw position are the backbone of a calculation process coined the "MU Fraction Approximation." Analytical and theoretical attempts have been made to extend and alter the mathematics for this approximation for greater accuracy. A set of linear equations in the form of a matrix are introduced here which correct one published extension of the MU Fraction Approximation as it applies to both symmetric and asymmetric photon fields. The matrix results are compared to data collected from a commissioned Varian Eclipse Treatment Planning System and previously published research for Varian linear accelerators. A total enhanced dynamic wedge factor with excellent accuracy was achieved in comparison to the most accurate previous research found. The deviation seen here is only 0.4% and 1.0% for symmetric and asymmetric fields respectively, for both 6MV and 18MV photon beams.