1 Medical Physics, San Raffaele Scientific Institute, Milano, Italy. Electronic address: fiorino.claudio@hsr.it.
2 Department of Medical Physics, Aarhus University/Aarhus University Hospital, Denmark.
3 Medical Physics, Royal Surrey County Hospital, Guildford, UK; National Physical Laboratory, Teddington, UK.
4 Department of Radiation Oncology (MAASTRO), GROW - School for Oncology and Developmental Biology, Maastricht University Medical Centre, The Netherlands.
5 Servei de Radiofísica i Radioprotecció, Hospital Sant Pau, Barcelona, Spain.