• Manfred Sassowsky, Philipp Gut, Tobias Hölscher, Guido Hildebrandt, Arndt-Christian Müller, Yousef Najafi, Götz Kohler, Helmut Kranzbühler, Matthias Guckenberger, Daniel R Zwahlen, Ngwa C Azinwi, Ludwig Plasswilm, Istvan Takacs, Christiane Reuter, Marcin Sumila, Peter Manser, Piet Ost, Dirk Böhmer, Christiane Pilop, Daniel M Aebersold, and Pirus Ghadjar.
• Department of Radiation Oncology and Division of Medical Radiation Physics, Bern University Hospital, Switzerland.
• Int. J. Radiat. Oncol. Biol. Phys. 2013 Nov 1; 87 (3): 534-41.

PurposeDifferent international target volume delineation guidelines exist and different treatment techniques are available for salvage radiation therapy (RT) for recurrent prostate cancer, but less is known regarding their respective applicability in clinical practice.Methods And MaterialsA randomized phase III trial testing 64 Gy vs 70 Gy salvage RT was accompanied by an intense quality assurance program including a site-specific and study-specific questionnaire and a dummy run (DR). Target volume delineation was performed according to the European Organisation for the Research and Treatment of Cancer guidelines, and a DR-based treatment plan was established for 70 Gy. Major and minor protocol deviations were noted, interobserver agreement of delineated target contours was assessed, and dose-volume histogram (DVH) parameters of different treatment techniques were compared.ResultsThirty European centers participated, 43% of which were using 3-dimensional conformal RT (3D-CRT), with the remaining centers using intensity modulated RT (IMRT) or volumetric modulated arc technique (VMAT). The first submitted version of the DR contained major deviations in 21 of 30 (70%) centers, mostly caused by inappropriately defined or lack of prostate bed (PB). All but 5 centers completed the DR successfully with their second submitted version. The interobserver agreement of the PB was moderate and was improved by the DR review, as indicated by an increased κ value (0.59 vs 0.55), mean sensitivity (0.64 vs 0.58), volume of total agreement (3.9 vs 3.3 cm(3)), and decrease in the union volume (79.3 vs 84.2 cm(3)). Rectal and bladder wall DVH parameters of IMRT and VMAT vs 3D-CRT plans were not significantly different.ConclusionsThe interobserver agreement of PB delineation was moderate but was improved by the DR. Major deviations could be identified for the majority of centers. The DR has improved the acquaintance of the participating centers with the trial protocol.Copyright © 2013 Elsevier Inc. All rights reserved.

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