SU‐FF‐T‐106: Clinical Implementation of Varian Enhanced Dynamic Wedges Into the Pinnacle Treatment Planning System: Monte Carlo Dosimetry and Patient‐Specific Quality Assurance Techniques

Abstract

Purpose: To present a commissioning study of enhanced dynamic wedges (EDWs) into the Pinnacle3 treatment planning system (TPS) and to evaluate various QA techniques for validating the treatment plans using EDWs. Method and Materials: Dose distribution modeling for EDW fields in the Pinnacle3 TPS is based on a combination of open‐field beam data and the Varian “Golden Segmented Treatment Table” (GSTT) unique to each photon beam. To validate the EDW models, dose profiles of 6− and 10−MV photon beams from a Clinac 2100C/D were measured in water for depths from near‐surface to 31.5 cm for a wide range of field sizes and wedge angles using a linear detector array of 25 energy‐compensated diodes (LDA‐25) to integrate the dose at multiple points in the EDW field for each exposure. The EDW output factors for square fields from 4 to 20 cm wide were measured in solid water using a cylindrical ionization chamber at a depth of 10 cm on central axis. The 6− and 10−MV photon beams emerging from the treatment head of the Clinac 2100C/D were fully simulated using the BEAMnrc and DOSXYZnrc was used to calculate the central‐axis percentage depth doses and dose profiles for the open and dynamically‐wedged fields in a water phantom. Film and MapCHECK data were compared with Pinnacle3 and MC predictions. Results: (1) Pinnacle collapsed‐cone convolution algorithm and MC simulations agreed with the measured EDW dose distributions to an accuracy of better than 3%. (2) Measured EDW output factors used for monitor‐unit calculation in Pinnacle3 TPS agreed with the MC predictions within 1–2%. (3) EDW‐based treatment plans were satisfactorily validated using MapCHECK and chamber measurements. Conclusions: We have successfully modeled EDWs into the Pinnacle3 TPS and demonstrated that MapCHECK and films dosimetry constitute valuable QA tools for validating planned dose distributions resulting from dynamically‐wedged beams.