Speaker
Description
While pre-treatment VMAT QA is currently a clinical mainstay, there is growing interest in the use of QA methods that are more relevant to the actual patient treatment and are, in fact, capable of providing in vivo dosimetry. To this end, I will present a newly developed methodology for Monte Carlo based VMAT QA, which simultaneously provides the dose deposited in both the patient CT data set and any type of planar detector, such as EPID. By enabling DOSXYZnrc to optionally output a 4D IAEA phase space, it is now possible to collect the particles exiting the patient during a VMAT simulation. This phase space can be used for further synchronized simulations of EPID and/or cone-beam CT dose or images, either globally, incrementally, or per control point, allowing comparisons of the 4D phase space EPID prediction with the actual EPID data acquired with the patient on treatment. In conjunction with the use of daily cone-beam CT data and linac log files, this process provides the capability of monitoring the patient dose delivered during the entire course of treatment.
