Preliminary study on dosimetry verification of VMAT on the basis of TG119 report / 中华放射肿瘤学杂志

ABSTRACT

Objective To preliminarily verify the feasibility of utilizing TG119 report to commission the volumetric modulated arc therapy (VMAT) plans.Methods Based on the test cases mentioned in TG119 report,7-/9-field intensity-modulated radiation therapy (IMRT) and dual-arc VMAT plans were devised by using two types of beam energy (6 MV and 10 MV) in the Eclipse TPS system according to the requirement of this report.All the plans were verified using 0.125cc semiflex thimble ionization chamber,MatriXX and Delta 4,respectively.The final results were statistically compared with the results measured by multiple institutions in the TG119 report.Results The resuhs of both IMRT and VMAT plans met the requirement of the TG119 report.The discrepancy of point dose in the high/low dose region of VMAT plans using different photon beams was ranged from-2.55％ to 2.55％,and ± 1.85％ for the IMRT plans.The percentage of γ passing points (±3％/3 mm) for the IMRT plans using 6 MV and 10 MV photon beams was 99.38％ and 99.53％,99.32％ and 99.46％ for the VMAT plans.The γ passing rate of the compound field exceeded 98％.Conclusions The VMAT plans with 6 MV and 10 MV photon beams meet the requirement of the TG119 report.TG119 report provides certain guidance for establishing a benchmark for dosimetry verification of the VMAT plans.