New findings on clinical experience on surface-guided radiotherapy for frameless non-coplanar stereotactic radiosurgery treatments.

Purpose: The aim of this study was to assess the accuracy of a surface-guided radiotherapy (SGRT) system for setup and intra-fraction motion control in frameless non-coplanar stereotactic radiosurgery (fSRS) using actual patient data immobilized with two different types of open-faced masks and employing a novel SGRT systems settings.

Methods And Materials: Forty-four SRS patients were immobilized with two types of open-faced masks. Sixty lesions were treated, involving the analysis of 68 cone-beam scans (CBCT), 157 megavoltage (MV) images, and 521 SGRT monitoring sessions.

A collapsed-cone based transit EPID dosimetry method.

Purpose: To develop a transit-dose portal dosimetry method based on a commercial collapsed-cone algorithm.

Methods: A Varian Clinac21EX (Varian Medical Systems, USA), equipped with an amorphous-silicon EPID aS1000, was used. Dose calculations were performed with the collapsed-cone algorithm of Pinnacle v8.