1. Radiation Oncology Department, University of Lübeck/UKSH-CL, 23562 Lübeck, Germany
2. National Cancer Institute (NCI), Radiation Oncology Department, Cairo University, Giza 12613, Egypt
3. Department of Oto-Rhino-Laryngology and Head and Neck Surgery, University of Lübeck, 23562 Lübeck, Germany
4. Università Cattolica del Sacro Cuore, Gemelli-INTERACTS, 00168 Rome, Italy