2 Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, Department of Medical Physics, 33081 Aviano, PN, Italy.
3 School of Physics, National University of Ireland Galway, Galway, Ireland.
4 Department Oncology, Laboratory of Experimental Radiotherapy, KU Leuven and Department of Radiation Oncology, UZ Leuven, Belgium.
5 Medical Physics, Az. Ospedaliero-Universitaria di Modena, Modena, Italy.
6 Leiden University Medical Center (LUMC), Radiology Department, Division of Image Processing, Albinusdreef 2, 2333ZA Leiden, The Netherlands.
7 3DMI Research Group, Department of Medical Physics, School of Medicine, University of Patras, GR 265 04, Greece.
8 Faculty of Mathematics and Computer Science, University of Barcelona, Barcelona, Spain.
9 Geneva University Hospital, Division of Nuclear Medicine and Molecular Imaging, CH-1211 Geneva, Switzerland.
10 Università di Napoli Federico II, Dipartimento di Fisica "Ettore Pancini", I-80126 Naples, Italy.
11 Department of Physics, Medical Radiation Physics, Stockholm University, Stockholm, Sweden; Department of Oncology and Pathology, Medical Radiation Physics, Karolinska Institutet, Stockholm, Sweden.
12 HUS Medical Imaging Center, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.