Comparison of IMRT dose calculations with a PBC and AAA algorithms in the lung cancer

Abstract

the pencil beam convolution (PBC) algorithms in radiation treatment planning system are widely used to calcu- late the radiation dose. A new photon dose calculation algo- rithm as known as anisotropic analytical algorithm (AAA) released in the Varian medical system. The aim of this paper is to investigate the difference of dose calculation between AAA and PBC algorithm at the intensity modulated radiotherapy (IMRT) plan on the lung cancer case with a inhomogeneity for the low density. We analyzed quantitatively dose difference using the eclipse planning system and I'mRT matirxx equipment to compare the gamma evaluation. The 11 patients with lung cancer in the various sites were selected. Almost of the normal tissue did not changed significantly for the maximum, mean, minimum dose. But the volume of the PTV covered by the 95% isodose curve was decreased by 6% with inhomogeneity due to the difference of the algorithms. From this result, acceptable criteria of the treatment plan calculated by AAA algorithm should be re-evaluated. © 2013 Springer-Verlag.