Dosimetric Validation of RapidArc for Stereotactic Radiotherapy for Peripheral Lung Tumors

Abstract

Purpose/Objective(s): In hypofractionated stereotactic treatments of Stage I lung tumors, highly conformal treatment techniques are required in order to minimize normal tissue toxicity. RapidArc, a new volumetric intensity modulated arc therapy (Varian Medical Systems, Palo Alto, USA), offers this possibility within very short treatment times, the latter being important to reduce the risk of intra-fraction baseline shifts of tumor position. Due to the small field sizes, tissue inhomogeneities and possible occurrence of interplay effects between MLC motion and tumor motion, the dosimetry of RapidArc in these cases is challenging. We examined the dosimetric accuracy of RapidArc in a heterogeneous phantom, with and without motion of the target.