[1] Univ Halle Wittenberg, Clin Radiotherapy, D-06097 Halle, Germany
[2] Staedt Krankenhaus Dessau, Clin Radiotherapy, Dessau, Germany
[3] Univ Halle Wittenberg, Clin Head & Neck Surg, Halle, Germany
[4] Univ Halle Wittenberg, Clin Oral Maxillo & Plast Facial Surg, Halle, Germany
[5] Univ Rostock, Clin Radiotherapy, Rostock, Germany
[6] Univ Lubeck, Clin Radiotherapy, Lubeck, Germany