The commercial release of volumetric modulated arc therapy techniques using a conventional linear accelerator and the growing number of helical tomotherapy users has triggered renewed interest in both MC dose verification methods and tools for doing treatment planning studies and exploring the impact of machine tolerance and patient motion on dose distributions. We report here the development of a method for performing complete position‐probability‐sampled Monte Carlo dose calculation using the BEAMnrc / DOSXYZnrc code. The method includes full accelerator head simulation and a realistic representation of continuous motion, with no resort to discretization approximations or analytical procedure. Accelerator head models were defined and validated against measurements for a conventional accelerator (Elekta Synergy ™) and a helical tomotherapy accelerator (TomoTherapy Hi‐Art®). The method functionality was tested by comparing simulated and treatment planning dose distributions for four types of treatment techniques: 3D‐conformal, step‐shoot intensity modulated radiation therapy, helical tomotherapy and volumetric modulated arc therapy. Absolute dose agreement for static fields between MC and measurements is within 2% / 2mm. Absolute dose agreement between MC and TPS was determined to be 3% / 3mm. The method simplifies the simulation process, improves the dose calculation accuracy and involves a minimal change in computation time.

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Journal Medical Physics
Belec, J., Ploquin, N., la Russa, D., & Clark, B. (2010). Sci—Fri PM: Delivery — 02: Position‐Probability‐Sampled Monte Carlo Calculation of VMAT, 3DCRT, Step‐Shoot IMRT and Helical Tomotherapy Dose Distributions Using BEAMnrc / DOSXYZnrc. In Medical Physics (Vol. 37). doi:10.1118/1.3476190