Dosimetric verification of a 3-D electron pencil beam dose calculation algorithm.

A three-dimensional electron beam dose calculational algorithm implemented for use in a three-dimensional treatment planning system is described. The 3-D electron beam calculations have been in use clinically for more than seven years. The algorithm uses a pencil beam model based on small angle multiple Coulomb scattering theory. Our implementation allows volumetric CT-based inhomogeneity corrections and provides for irregular field shapes (fields shaped with cerrobend cutouts) and the use of bolus. As part of NCI-funded work evaluating the state of the art in electron beam treatment planning, extensive algorithm verification was undertaken and results of these tests for our implementation are presented.