TY - JOUR A1 - Toussaint, André A1 - Richter, Anne A1 - Mantel, Frederick A1 - Flickinger, John C. A1 - Grills, Inga Siiner A1 - Tyagi, Neelam A1 - Sahgal, Arjun A1 - Letourneau, Daniel A1 - Sheehan, Jason P. A1 - Schlesinger, David J. A1 - Gerszten, Peter Carlos A1 - Guckenberger, Matthias T1 - Variability in spine radiosurgery treatment planning – results of an international multi-institutional study JF - Radiation Oncology N2 - Background The aim of this study was to quantify the variability in spinal radiosurgery (SRS) planning practices between five international institutions, all member of the Elekta Spine Radiosurgery Research Consortium. Methods Four institutions provided one representative patient case each consisting of the medical history, CT and MR imaging. A step-wise planning approach was used where, after each planning step a consensus was generated that formed the basis for the next planning step. This allowed independent analysis of all planning steps of CT-MR image registration, GTV definition, CTV definition, PTV definition and SRS treatment planning. In addition, each institution generated one additional SRS plan for each case based on intra-institutional image registration and contouring, independent of consensus results. Results Averaged over the four cases, image registration variability ranged between translational 1.1 mm and 2.4 mm and rotational 1.1° and 2.0° in all three directions. GTV delineation variability was 1.5 mm in axial and 1.6 mm in longitudinal direction averaged for the four cases. CTV delineation variability was 0.8 mm in axial and 1.2 mm in longitudinal direction. CTV-to-PTV margins ranged between 0 mm and 2 mm according to institutional protocol. Delineation variability was 1 mm in axial directions for the spinal cord. Average PTV coverage for a single fraction18 Gy prescription was 87 ± 5 %; Dmin to the PTV was 7.5 ± 1.8 Gy averaged over all cases and institutions. Average Dmax to the PRV_SC (spinal cord + 1 mm) was 10.5 ± 1.6 Gy and the average Paddick conformity index was 0.69 ± 0.06. Conclusions Results of this study reflect the variability in current practice of spine radiosurgery in large and highly experienced academic centers. Despite close methodical agreement in the daily workflow, clinically significant variability in all steps of the treatment planning process was demonstrated. This may translate into differences in patient clinical outcome and highlights the need for consensus and established delineation and planning criteria. KW - planning variability KW - spine radiosurgery KW - vertebral metastases KW - delineation Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-146687 VL - 11 IS - 57 ER - TY - JOUR A1 - Colvill, Emma A1 - Booth, Jeremy A1 - Nill, Simeon A1 - Fast, Martin A1 - Bedford, James A1 - Oelfke, Uwe A1 - Nakamura, Mitsuhiro A1 - Poulsen, Per A1 - Worm, Esben A1 - Hansen, Rune A1 - Ravkilde, Thomas A1 - Rydhög, Jonas Scherman A1 - Pommer, Tobias A1 - af Rosenschold, Per Munck A1 - Lang, Stephanie A1 - Guckenberger, Matthias A1 - Groh, Christian A1 - Herrmann, Christian A1 - Verellen, Dirk A1 - Poels, Kenneth A1 - Wang, Lei A1 - Hadsell, Michael A1 - Sothmann, Thilo A1 - Blanck, Oliver A1 - Keall, Paul T1 - A dosimetric comparison of real-time adaptive and non-adaptive radiotherapy: a multi-institutional study encompassing robotic, gimbaled, multileaf collimator and couch tracking JF - Radiotherapy and Oncology N2 - 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. Methods and materials: 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 gamma-tests recorded. Results: For all lung traces all measurement sets show improved dose accuracy with a mean 2%/2 mm gamma-fail rate of 1.6% with adaptation and 15.2% without adaptation (p < 0.001). For all prostate the mean 2%/2 mm gamma-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%/2 mm gamma-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. KW - Robotic tracking KW - Gimbaled tracking KW - MLC tracking KW - Couch tracking KW - Organ motion Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-189605 VL - 119 IS - 1 ER -