Due to the very high complexity of IMRT treatment plans, it is imperative to perform dose verification, preferably before patient delivery. The aim of this project is to develop a Monte-Carlo-based model to verify the final dose distributions of plans developed using the Peacock system (CORVUS Treatment Planning System and MIMiC collimator). The system delivers radiation through arc therapy and uses sinogram files to determine the state of each of the multileaf collimator leaves. In-house software was developed using Matlab to decode the sinograms and create blocklets that are used as input in an MCSIM model of the MIMiC collimator attached to a Varian Clinac 600C. After validating the model, a prostate and head and neck case were simulated. The CORVUS-predicted dose distributions were compared with the Monte Carlo dose distributions. As expected, the results agreed very closely for the homogeneous case of the prostate but there were large discrepancies observed for the more heterogeneous head and neck case.

Key words: IMRT; Dose verification; Monte Carlo; Serial tomotherapy.