1. Department of Radiation Oncology, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland
2. Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen, Switzerland
3. Department of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, University of Bern, 3010 Bern, Switzerland