Search

To systematically investigate the performance of the analytical anisotropic algorithm (AAA) within the extremes of small tumor volumes and near-minimum lung and tumor tissue densities in order to identify combinations of these parameters where the use of AAA could result in a therapeutically unacceptable loss of tumor coverage on an energy and fractionation-specific basis.Clinically appropriate volumetric modulated arc therapy (VMAT) treatment plans were generated with AAA for 180 unique combinations of lung density (0.05-0.30 g/cmThe strongest predictors of a statistically significant reduction in tumor coverage were lung density ≤0.15 g/cmThe accuracy of AAA rapidly diminishes near the minima of clinical lung density, particularly in combination with small tumors and when using a photon energy of 10 MV. The magnitude of the effect can be more dramatic than previously reported data suggests and could potentially compromise the ablative qualities of treatments performed within these environments, particularly with less aggressive fractionation approaches.