1. Protontherapy Department, Azienda Provinciale per I Servizi Sanitari (APSS), Trento, Italy;
2. Perugia General Hospital, Medical Physics Unit, Perugia, Italy;
3. Institute of Biostructures and Bioimaging, National Research Council (CNR), Naples, Italy;
4. Department of Physics, University of Trento, Povo, Italy;
5. Trento Institute for Fundamental Physics and Applications (TIFPA), National Institute for Nuclear Physics (INFN), Povo, Italy;
6. Department of Advanced Biomedical Sciences, Federico II University School of Medicine, Naples, Italy;
7. Radiation Oncology Section, Perugia General Hospital, Perugia, Italy;
8. Department of Surgical and Biomedical Science, University of Perugia, Perugia, Italy;
9. National Institute for Nuclear Physics (INFN), Naples, Italy