Calculation of Equivalent Square Fields in Radiation Therapy by an Improved Vadash Correction Factor for Collimator Exchange Effects

摘要

Background and objectives: To determine the head scatter factor, a formalism presented by Vadash and Bj?rngardhas been employed to assess collimator exchange effects. The aim of this study was to determine the best Vadashcorrection factor (A) by introducing a new method based on the output factor measured in air for different square andrectangular fields. Materials and Methods: A new simple mathematical method based on selection of the best dosimetricdata was proposed to obtain the A value for Vadash to predict the equivalent square field size.