1 University of Trento, Department of Physics, Trento, Italy; Istituto Nazionale di Fisica Nucleare, Trento Institute for Fundamental Physics and Applications, Trento, Italy.
2 National Research Council Institute of Biostructures and Bioimaging, Napoli, Italy.
3 Protontherapy Department, Azienda Provinciale per i Servizi Sanitari (APSS), Trento, Italy.