Determination and Verification of Parameters of Lévy Distribution Incident Energy Spectrum of High-energy Electron Beam

Abstract

The incident electron energy spectrum was determined by an estimation formula based on the Lévy distribution in order to calculate the PDD and OAR that is consistent with the measurement. EGSnrc was used to calculate PDD and OAR at nominal energies of 4, 6, 9, 12, and 15 MeV. The parameters for determining the incident electron energy spectrum were adjusted to be a reasonable value in the error between the measured and the calculated values. Location and scaling parameters were determined to be 0.5 and 0.001, respectively. The calculated PDD based on the determination formula was in agreement with the measurement within 2 mm/2% at all depths. The OAR also was in agreement with the measurement within 2 mm/2%. In this study, the incident electron energy spectrum was estimated by determining the location and scaling parameters. This method is simpler and more accurate than previously reported, and can be applied to the calculation of dose distributions in Monte Carlo simulations.