1. Department of Otorhinolaryngology; Head and Neck Surgery, Campus Ruppiner Kliniken; Neuruppin
2. Department of Otorhinolaryngology and Head and Neck Surgery; Borromaeus-Hospital; Leer
3. Department of Radiooncology; Brandenburg Medical University-Theodor Fontane, Campus Ruppiner Kliniken; Neuruppin
4. Department of Otorhinolaryngology; Head and Neck Surgery, Charite'-Universitätsmedizin Berlin, Campus Benjamin Franklin; Berlin Germany