Fifty-seventh annual meeting of the American association of physicists in medicine
TH-AB-303-01: Benchmarking Real-Time Adaptive Radiotherapy Systems: A Multi- Platform Multi-Institutional Study
The era of real-time adaptive radiotherapy is here: patients are being treated by CyberKnife (since 2004), Vero (2011) and MLC tracking (2013) technology, with couch tracking planned to be clinical in 2015. We have developed a common set of tools for benchmarking real-time adaptive radiotherapy systems and to test the hypothesis that, across delivery systems and institutions, real-time adaptive radiotherapy improves the dosimetric accuracy over non-adaptive radiotherapy in the presence of realistic tumor motion.
Ten institutions with CyberKnife, Vero, MLC or couch tracking technology were involved in the study. Common materials were anonymized lung and prostate CT and structure sets, patient-measured motion traces (four lung, four prostate) and SBRT planning protocols (lung: RTOG1021, prostate: RTOG0938). The institutions delivered lung and prostate plans to a moving dosimeter programmed with tumor motion. For each trace the plan was delivered twice; with and without motion adaptation, each measurement was compared to the static dosimeter dose and the percentage of failed points for γ-tests recorded.
Eleven measurement sets were obtained for this study; two CyberKnife, two Vero, five MLC and two couch tracking sets. For all lung traces all sets show improved dose accuracy from a mean 2%/2mm γ-failrate of 1.6% with adaptation and 14.7% with no motion correction(p<0.001). For all prostate traces the mean 2%/2mm γ-failrate was 1.6% with adaptation and 17.4% with no motion correction (p<0.001). The difference between the four adaptive systems was small with an average 2%/2mm γ-failrate of <3% for all systems with adaptation for lung and prostate.
A common set of tools has been developed for benchmarking real-time adaptive radiotherapy systems and a multi-platform multi-institutional study performed. The results show the systems all account for realistic tumor motion accurately and performed to a similar high standard, with real-time adaptation significantly outperforming non-adaptive methods.