INCLUSION OF ENERGY STRAGGLING IN A NUMERICAL-METHOD FOR ELECTRON DOSE CALCULATION

Citation
L. Papiez et al., INCLUSION OF ENERGY STRAGGLING IN A NUMERICAL-METHOD FOR ELECTRON DOSE CALCULATION, Medical physics, 21(10), 1994, pp. 1591-1598
Citations number
19
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging
Journal title
ISSN journal
00942405
Volume
21
Issue
10
Year of publication
1994
Pages
1591 - 1598
Database
ISI
SICI code
0094-2405(1994)21:10<1591:IOESIA>2.0.ZU;2-V
Abstract
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.