Monte Carlo benchmarking of a CCC-based treatment planning system in case of irregularly shaped fields

Abstract

Advanced radiation techniques, like intensity modulated radiotherapy (IMRT) and intensity modulated arc therapy (IMAT), are based on small, elongated and highly irregular field shapes. In our study we use in-house developed Monte Carlo software to investigate the accuracy of a commercial available treatment planning system (Pinnacle, Philips Medical Systems, Best, The Netherlands) in calculating the dose distribution for irregular fields. Pinnacle calculates the dose distribution using the collapsed cone convolution (CCC) algorithm. The analysis of the considered beams showed that the differences in flattening filter, leaf tip and tongue-andgroove modeling introduce important discrepancies between Pinnacle and MC results for single irregular fields. Therefore, great attention should be given to the degree of irregularity and to the number of this type of beams included in the treatment plans. A benchmark tool, like MC simulations or measurements, should be used to verify treatment plans with high irregular beams. © 2009 Springer-Verlag.