1. Department of Otorhinolaryngology and Laryngological Oncology, Medical University of Silesia, Zabrze, Poland
2. Department of Radiotherapy, Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland
3. Department of Otolaryngology and Maxillofacial Surgery, University of Zielona Góra, Zielona Góra, Poland