Room: ePoster Forums
Purpose: The aim of this study was to implement and evaluate the validation testing of IMRT/VMAT commissioning at 7 institutions in the mainland of China and establish a quantitative confidence limit (CL) as a baseline expectation values for IMRT/VMAT commissioning and quality assurance(QA) on the basis of AAPM TG 119 and 244.
Methods: AAPM TG 119 and 244 proposed planning, dose delivery and dose measurements of a set of test cases. Head and neck, prostate, abdomen and C-shape test cases were selected to generate intensity modulated radiation therapy IMRT and VMAT plans in this study. Dose prescriptions and planning objectives were used as recommended by AAPM TG 119 and 244 reports. For each plan the point dose measurements were performed in the high dose region. The planar dose distribution was analyzed with the gamma analysis in 3%/3 mm and 2%/2 mm evaluation criteria for the composite plan.
Results: This multicenter validation testing included 4 different brands of treatment planning system, 5 different models of linear accelerators and 3 different types of QA devices for planar dose measurement in seven institutions. For point dose measurement, the average dose variations were 1.32 %. For planar dose measurement, the average percentage is 97.2 % and 93.6% for gamma passing rate in 3 %/3 mm and 2 %/2 mm evaluation criteria. Based on the results of validation testing, the CL was 2.96% in point dose measurement, 1.42% in gamma analysis with 3 %/3 mm evaluation criteria, and 4.96% with 2 %/2 mm evaluation criteria.
Conclusion: AAPM TG119 and 244 test cases could be applied successfully for IMRT and VMAT commissioning. Moreover, based on multiple institutions planning and dosimetry comparisons, this study establishes a quantitative CL as a baseline expectation values for IMRT/VMAT commissioning and QA.
Funding Support, Disclosures, and Conflict of Interest: This study was supported by National natural Science Foundation of China (No.81071237)