Real-world examples of sensitivity failures of the 3%/3mm pass rate metric and published action levels when used in IMRT/VMAT system commissioning

B. Nelms, G. Jarry, M. Chan, C. Hampton, Y. Watanabe, V. Feygelman

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

In IMRT/VMAT system commissioning (as with any system), quality is improved by striving for tight tolerances of stringent metrics of accuracy. For 5 cases, passing rates for 3%/3mm gamma analysis were generated following the TG119 instructions. Subsequently, more stringent/sensitive criteria combined with advanced volumetric dose analysis were applied, and in each case significant systematic errors were clearly identified despite the high 3%/3mm passing rates. In 4 of 5 cases, the error was easily remedied. These real-world examples of observed "false negatives" (insensitivities) point towards the inappropriateness of the 3%/3mm gamma passing rate metric as the basis for acceptance testing/commissioning of the IMRT/VMAT delivery chain.

Original languageEnglish (US)
Article number012086
Pages (from-to)012086
JournalJournal of Physics: Conference Series
Volume444
Issue number1
DOIs
StatePublished - 2013
Event7th International Conference on 3D Radiation Dosimetry, IC3DDose 2012 - Sydney, NSW, Australia
Duration: Dec 4 2012Dec 8 2012

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