Patient-specific QA using 4D Monte Carlo phase space predictions and EPID dosimetry

The goal of this review is to outline a solution for patient-specific QA of VMAT, IMRT, and other complex treatment delivery techniques. This solution has been developed in direct response to clinical needs, in order to allow our institution to offer VMAT to all patients who could potentially benefit from this advanced technique. To date, over 2500 VMAT patient plans and approximately 1000 IMRT patient plans have been verified by this method in Vancouver, while 40 other institutions worldwide have expressed interest in, or are already at various stages of implementing, this process. The addition of EPID in vivo dosimetry (i.e. data acquired during the patient treatment) and associated Monte Carlo predictions amounts to introducing a 'measurement component' in this QA process, which is currently mandated by the regulatory framework in some European countries, or for billing purposes in the USA. The fully automated, patient-specific, Monte Carlo based QA process described here is fast, maximally efficient in terms of departmental resources, and capable of simulating any plan in a single run, regardless of its complexity.