1. Department of Radiation Oncology, University Hospital Essen, University Duisburg‐Essen, Essen, Germany
2. Statistics Department, European Organisation for Research and Treatment of Cancer (EORTC), Brussels, Belgium
3. Nuclear Research and consultancy Group (NRG), Petten, The Netherlands
4. Pharmacy of the University Hospital Essen, University Duisburg‐Essen, Essen, Germany
5. Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Essen, University Duisburg‐Essen, Essen, Germany
6. Institute for Medical Informatics, Biometry and Epidemiology, University Hospital Essen, University Duisburg‐Essen, Essen, Germany
7. Institute of Pathology and Neuropathology, University Hospital Essen, University Duisburg‐Essen, Essen, Germany
8. HFR Unit, Institute for Energy, Joint Research Centre, European Commission, Petten, The Netherlands