Fluence to dose equivalent conversion factors calculated with EGS3 for electrons from 100 keV to 20 GeV and photons from 11 keV to 20 GeV.

The EGS3 Monte-Carlo electron-photon transport simulation package has been used to calculate dose equivalent per unit fluence vs depth curves for broad parallel beams of mono-energetic electrons, positrons and photons incident on a 30-cm-thick slab of ICRU four-element tissue. The electron kinetic energy range covered is 100 keV to 20 GeV and that for photons is 11 keV to 20 GeV. It was found that by making minor modifications, EGS3 is in reasonable agreement with other codes for electron energies down to 100 keV. Complete dose equivalent vs depth curves as a function of electron and photon energy are presented to allow proper calculations of the maximum dose equivalent for a mixed photon and electron spectrum since there are substantial variations in the locations of the peak dose equivalent. Explicit calculations demonstrate that l/r2 corrections give an accurate means to convert results for broad parallel beams to those for point source geometries. The relative contributions of various physical processes to the peak dose equivalent are presented.