Premium
On the field‐size dependence of relative output from a linear accelerator
Author(s) -
Dunscombe P. B.,
Nieminen J. M.
Publication year - 1992
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 - 10.1118/1.596799
Subject(s) - linear particle accelerator , collimator , physics , optics , dosimetry , point source , field (mathematics) , beam (structure) , flattening , photon , computational physics , field size , radiation , particle accelerator , point (geometry) , mathematics , geometry , nuclear medicine , medicine , astronomy , pure mathematics
The radiation output in air on the central axis of a linac photon beam has been modeled as the sum of two components. These are a point source representing radiation direct from the target and a distributed source representing scatter in the flattening filter and primary collimator. By fitting only two parameters, the ratio of the two components for a 20×20 field and a width parameter for the distributed source this semi‐empirical model describes the relative outputs of square, symmetric rectangular, and asymmetric rectangular fields with an average error of 0.25% for the field sizes studied.