(1)University Hospital Tübingen, University Department of Radiation Oncology, Tübingen, Germany;(2)University Medical Center Freiburg, Department of Radiation Oncology, Freiburg, Germany;(3)University Hospital Tübingen, Department of Radiology, Tübingen, Germany;(4)Ruprecht Karls University Heidelberg, University Department of RadioOncology and Radiotherapy, Heidelberg, Germany;(5)University Hospital Tübingen, Medical Physics- University Department of Radiation Oncology, Tübingen, Germany;(6)University Hospital Tübingen, Section for Biomedical Physics- University Department of Radiation Oncology, Tübingen, Germany;

¹Ramon y Cajal University Hospital, Radiation Oncology, Madrid, Spain; ²Ramon y Cajal University Hospital , Radiation Oncology, Madrid, Spain

(1)University Medical Center Utrecht, Radiation Oncology, Utrecht, The Netherlands;(2)University Medical Center Utrecht, Oral and Maxillofacial Surgery and Special Dental Care, Utrecht, The Netherlands;(3)VU University Medical Center, Otolaryngology-Head and Neck Surgery, Amsterdam, The Netherlands;(4)University Medical Center Utrecht, Oral and Maxillofacial Surgery and Special Dental Care & Julius Center for Health Sciences and Primary Care & Head and Neck Surgical Oncology, Utrecht, The Netherlands;