A dosimetric comparison of real-time adaptive and non-adaptive radiotherapy: A multi-institutional study encompassing robotic, gimbaled, multileaf collimator and couch tracking.

PURPOSE - A study of real-time adaptive radiotherapy systems was performed to test the hypothesis that, across delivery systems and institutions, the dosimetric accuracy is improved with adaptive treatments over non-adaptive radiotherapy in the presence of patient-measured tumor motion.

MATERIALS AND METHODS - Ten institutions with robotic(2), gimbaled(2), MLC(4) or couch tracking(2) used common materials including CT and structure sets, motion traces and planning protocols to create a lung and a prostate plan. For each motion trace, the plan was delivered twice to a moving dosimeter; with and without real-time adaptation. Each measurement was compared to a static measurement and the percentage of failed points for γ-tests recorded.

RESULTS - For all lung traces all measurement sets show improved dose accuracy with a mean 2%/2mm γ-fail rate of 1.6% with adaptation and 15.2% without adaptation (p<0.001). For all prostate the mean 2%/2mm γ-fail rate was 1.4% with adaptation and 17.3% without adaptation (p<0.001). The difference between the four systems was small with an average 2%/2mm γ-fail rate of <3% for all systems with adaptation for lung and prostate.

CONCLUSIONS - The investigated systems all accounted for realistic tumor motion accurately and performed to a similar high standard, with real-time adaptation significantly outperforming non-adaptive delivery methods.

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. 2016 Mar 22 [Epub ahead of print]

Emma Colvill, Jeremy Booth, Simeon Nill, Martin Fast, James Bedford, Uwe Oelfke, Mitsuhiro Nakamura, Per Poulsen, Esben Worm, Rune Hansen, Thomas Ravkilde, Jonas Scherman Rydhög, Tobias Pommer, Per Munck Af Rosenschold, Stephanie Lang, Matthias Guckenberger, Christian Groh, Christian Herrmann, Dirk Verellen, Kenneth Poels, Lei Wang, Michael Hadsell, Thilo Sothmann, Oliver Blanck, Paul Keall

Radiation Physics Laboratory, University of Sydney, Australia; Northern Sydney Cancer Centre, Royal North Shore Hospital, Australia., Northern Sydney Cancer Centre, Royal North Shore Hospital, Australia; School of Physics, University of Sydney, Australia., The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK., The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK., The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK., The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK., Department of Radiation Oncology and Image-Applied Therapy, Kyoto University, Japan., Aarhus University Hospital, Denmark., Aarhus University Hospital, Denmark., Aarhus University Hospital, Denmark., Aarhus University Hospital, Denmark., Radiation Medicine Research Center, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Denmark., Radiation Medicine Research Center, Rigshospitalet, Copenhagen, Denmark; Section of Radiotherapy Physics and Engineering, Medical Physics Department, Karolinska University Hospital, Stockholm, Sweden., Radiation Medicine Research Center, Rigshospitalet, Copenhagen, Denmark; Niels Bohr Institute, University of Copenhagen, Denmark., Department of Radiation Oncology, University Hospital Zurich, Switzerland., Department of Radiation Oncology, University Hospital Zurich, Switzerland., Department of Radiation Oncology, University Hospital of Würzburg, Germany., Computer Science Department, Würzburg University, Germany., Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Belgium., Department of Radiotherapy, Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Belgium., Radiation Oncology Department, Stanford University, Palo Alto, United States., Radiation Oncology Department, Stanford University, Palo Alto, United States., Department for Radiation Oncology, University Clinic Eppendorf, Hamburg, Germany., Department for Radiation Oncology, University Clinic Schleswig-Holstein, Kiel, Germany; Saphir Radiosurgery Center, Güstrow and Frankfurt am Main, Germany., Radiation Physics Laboratory, University of Sydney, Australia.