(1)EORTC Headquarters, Medical Department, Brussels, Belgium;(2)Ospedale Niguarda Ca Granda, Department of Medical Physics, Milan, Italy;(3)Institut Curie, Department of Radiation Therapy, Paris, France;(4)Gloucestershire Hospital NHS Foundation Trust - Cheltenham General Hospital, Oncology Department, Cheltenham, United Kingdom;(5)EORTC Headquarters, Data Management, Brussels, Belgium;(6)Institut Jules Bordet, Medical Physics Department, Brussels, Belgium;(7)Catharina Ziekenhuis, Department of Radiotherapy, Eindhoven, The Netherlands;(8)UniversitätsSpital Zürich, Department of Radiation Oncology, Zurich, Switzerland;

(1)Greater Poland Cancer Centre, Radiation Oncology Department, Poznan, Poland;(2)Greater Poland Cancer Center, Physics Department, Poznań, Poland;