Evaluation of a commercial three-dimensional electron beam treatment planning system

We evaluated a commercial three-dimensional (3D) electron beam treatment pl anning system (CADPLAN V.2.7.9) using both experimentally measured and Mont e Carlo calculated dose distributions to compare with those predicted by CA DPLAN calculations. Tests were carried out at various field sizes and elect ron beam energies from 6 to 20 MeV. For a homogeneous water phantom the agr eement between measured and CADPLAN calculated dose distributions is very g ood except at the phantom surface. CADPLAN is able to predict hot and cold spots caused by a simple 3D inhomogeneity but unable to predict dose distri butions for a more complex geometry where CADPLAN underestimates dose chang es caused by inhomogeneity. We discussed possible causes for the inaccuracy in the CADPLAN dose calculations. In addition, we have tested CADPLAN trea tment monitor unit and electron cut-out factor calculations and found that CADPLAN predictions generally agree with manual calculations. (C) 1999 Amer ican Association of Physicists in Medicine. [S0094-2405(99)00412-5].