1. Department of Radiation Oncology, University of Perugia, Perugia
2. ATreP, Provincial Agency for Proton Therapy, Trento
3. Medical Physics Unit, European Institute of Oncology, Milan
4. Department of Radiotherapy, Sacred Heart Catholic University, Rome
5. Department of Radiotherapy, Policlinico Hospital, Modena
6. Radiotherapy Unit, Trieste General Hospital, Trieste, Italy