Imrt and Vmat Commissioning for Versa Hd Linear Accelerator Using Aapm Tg-119.

Abstract

Aim:Purpose of study is to evaluate the end to end commissioning accuracy of intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) for Versa HD linear accelerator using AAPM TG-119 protocol. Materials & methods: IMRT and VMAT plans were created for TG119 test cases. All the plans were generated using Monaco 5.1 treatment planning system (TPS) for Elekta Versa HD linear accelerator. Prescription and planning goals were as kept as per TG119. For point dose measurement CC01 (0.01cc) ion chamber was used and measurements were carried out as per TG119 specified points in high and low dose gradient regions. Planar dose measurement I'matriXX along with multicube-lite phantom was used. Planned and measured dose planes were compared using gamma index criteria. Results: All planning goals have been achieved as per TG119 report. At high dose point measurement mean dose differences averaged over different techniques planned with different energies for all test cases was 0.002±0.020, and corresponding confidence limit was 0.041. At low dose point measurement mean dose averaged over different techniques planned with different energies for all test cases was -0.004±0.021, and corresponding confidence limit was 0.045. For planar dose measurement gamma passing rate averaged over all test cases was 99.40%±0.40 for 3%/3mm criteria and 97.82%±0.13 for 2%/2mm criteria respectively. Present work overall confidence limit for composite planar dose measurement was 1.38(i.e., 98.62% passing) for 3%/3mm and 2.45(i.e., 97.55% passing) for 2%/2mm criteria. Conclusion: Planning and delivery of IMRT/VMAT has been validated using published TG119 report results.