Clinical evaluation of fast electron Monte Carlo dose calculation algorithms for treatment planning systems
(2012)
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- Abstract
- (en) The present study is focused on the clinical validation of two electron Monte Carlo (eMC) based treatment planning systems (TPS), Oncentra MasterPlan TPS (OMTPS) and XiO eMC. We present a new approach on the commissioning process based on, (a) homogeneous water phantom validation, (b) heterogeneous phantom validation with film measurements and, (c) Full MC validation. As a first step, MC models of electron beams (4, 8, 12 and 18 MeV) from an Elekta SL25 medical linear accelerator were build using the popular EGSnrc/BEAMnrc user MC code. The calculated dose distributions were benchmarked by a comparison with the measurements made in the water phantom for a wide range of open field sizes and insert combinations, at a single source to surface distance (SSD) of 100 cm. These BEAMnrc models were used to evaluate the accuracy of OMTPS (respectively XiO eMC) for two energies 4 and 12 MeV (respectively for 4, 8, 12 and 18 MeV) in a homogeneous water phantom. As a second step, the accuracy of both TPSs has been evaluated by comparing dose distributions in a heterogeneous phantom containing ribs structures. Dose distributions in the lung and non-lung tissue predicted from BEAMnrc simulation were compared with those computed with OMTPS and XiO eMC. In the case of OMTPS calculations, differences between BEAMnrc simulation and measurements range from 0.5%-2.0% between two ribs and 0.6%-1.0% below the ribs, whereas the range difference between OMTPS and measurements was the same (0.5-4.0%) in both areas. BEAMnrc models have been set as reference in the case of XiO eMC computation and the overall agreement between the two schemes lies under 2.5% for the most tested dose distributions at 8, 12 and 18 MeV and is better than the 4 MeV one. The present work demonstrates the added value of MC TPS compared to pencil beam algorithms. Results show that OMTPS and XiO eMC can predict dose perturbation induced by high-density heterogeneities for the electron beam energies investigated, except at 4 MeV electron beam energy in which significant deviations have been found with both algorithms. This demonstrates that caution is necessary in using both TPSs at low energies.
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Edimo, P. (2012). Clinical evaluation of fast electron Monte Carlo dose calculation algorithms for treatment planning systems. https://hdl.handle.net/2078.5/160423