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Deviation analysis of plan verification results of 260 volumetric modulated arc therapy plans / 中华放射肿瘤学杂志
Chinese Journal of Radiation Oncology ; (6): 252-255, 2014.
Article in Chinese | WPRIM | ID: wpr-446688
ABSTRACT
Objective To investigate the γ pass rate and contributing factors by summarizing the plan verification results of 260 volumetric modulated arc therapy (VMAT) plans.Methods From 2010 to 2012,two different detector arrays (MapCheck2,Sun,Nuclear,USA ; Delta4 ScandiDos,Swenden) were used for plan verification in 260 patients.The measured dose distributions were compared with the calculation results of treatment planning system using γ pass rate (Pγ ≤ 1 for 2%/2 mm,3%/3 mm and 5%/3 mm,threshold 10%).And the results were put under independent-samples t test.The impact of multi-leaf collimator (MLC) on the γ pass rate (3%/3 mm) was analyzed.Results The average γ pass rates of 2%/2 mm,3%/3 mm and 5%/3 mm of 260 VMAT plans were 91.7%,98.5% and 99.7%,respectively.Among 260 VMAT plans,3 VMAT plans (1.2% of the total) failed to meet the clinical acceptable pass rate and needed to be redesigned or re-optimized.The γ pass rate of 2%/2 mm was slightly different between two measurement devices (90.0% vs 93.5%,P =0.000),while the γ pass rate of 3%/3 mm showed no significant difference between two measurement devices and two accelerators (98.5% vs 98.5%,P =0.926 and 98.5% vs 98.6%,P =0.670).The γ pass rate (3%/3 mm) of the treatment plan before MLC calibration was 61.1%,compared to 94.1% after calibration.Conclusions Most dose verification results of treatment plans can meet the clinical requirement.Gantry rotation may influence the γ pass rate of VMAT dose verification under stricter pass rate standard (2%/2 mm).MLC calibration is essential for VMAT.

Full text: Available Index: WPRIM (Western Pacific) Language: Chinese Journal: Chinese Journal of Radiation Oncology Year: 2014 Type: Article

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Full text: Available Index: WPRIM (Western Pacific) Language: Chinese Journal: Chinese Journal of Radiation Oncology Year: 2014 Type: Article