Evaluation of the Differences Between Measurements in Multiple Institutions and Calculation Modeled by Representative Beam Data in Prostate VMAT Plan.

BACKGROUND/AIM: This study aimed to investigate the potential differences between multi-institutional measurements and treatment planning system (TPS) calculation modeled by representative beam data for patient-specific quality assurance (QA), including multi-leaf collimator (MLC) parameters. MATERIALS AND METHODS: Eleven TrueBeam from nine institutions were used in this study. Volumetric arc therapy (VMAT) plan for verification was created using Eclipse. The point dose of the CC13 ionization chamber and the dose distribution of the GAFCHROMIC EBT3 film were measured and analyzed. RESULTS: Point dose differences in patient-specific QA provided a mean±standard deviation of 1.0%±0.6%. Mean gamma pass rates of dose distribution were in excess of 99% and 96% for 3%/2 mm and 2%/2 mm gamma criteria, respectively. CONCLUSION: There was good agreement between measurements and calculations, indicating the small influence of complex VMAT in the underlying processes. Therefore, implementation of the same MLC parameters on TPS among different institutions with the same planning policy should be considered to ensure consistency and efficiency in radiation treatment processes.