1Radiation Oncology, Geneva University Hospital, CH-1211, 14 Geneva, Switzerland
2Faculty of Medicine, Geneva University, Geneva, Switzerland
3Radiation Oncology, Humanitas University, Rozzano, Milan, Italy
4Radiation Oncology, Humanitas Research Hospital and Cancer Center, Rozzano, Milan, Italy
5Radiation Oncology, Kantonsspital Graubünden, Chur, Switzerland
6Radiation Oncology, University Hospital Zürich, Zürich, Switzerland
7Radiation Oncology, Sacro Cuore Don-Calabria, Negrar, Italy
8Methodology and biostatistic unit, Centre Georges François Leclerc, Dijon, France
9Faculty of Medecine, University of Brescia, Brescia, Italy
© The Author(s). 2018
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