Energy straggling along electron trajectories has been incorporated in
to a numerical algorithm for electron beam dose calculations. Landau's
theory is used to predict, at any point in the absorber, the broadeni
ng of the primary electron energy spectrum due to energy loss straggli
ng. Numerical calculations have been performed for electron beams with
energies of 10-30 MeV incident upon water in order to determine the v
ariation of dose with depth and variation of energy spectra with pathl
ength. These calculations are compared with the results of Monte Carlo
simulations performed with the EGS4 code. The inclusion of energy los
s straggling in the numerical calculations leads to predictions of ene
rgy spectra and dose deposition that are in good agreement with modifi
ed Monte Carlo simulations in which bremsstrahlung is ignored and the
energy given to knock-on electrons is deposited at the site of their c
reation. Less satisfactory agreement was achieved when these calculati
ons were compared to full Monte Carlo simulations that included the br
emsstrahlung events and transported the knock-on electrons. It is conc
luded that bremsstrahlung energy loss must also be included into this
algorithm, if an acceptable dose computation accuracy is to be achieve
d for clinical applications.