affiliation not provided to SSRN, Martin Luther University of Halle-Wittenberg - Institute of Physics, University Hospital Zurich, University Hospital Zurich, Masaryk University, Masaryk University, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Department of Radiation Oncology, University Medical Center Mainz, Department of Radiation Oncology, University Medical Center Mainz, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, Medical University of Graz, affiliation not provided to SSRN, affiliation not provided to SSRN, Charité - Universitätsmedizin Berlin, University of Hamburg - University Medical Center Hamburg-Eppendorf, University of Cologne, affiliation not provided to SSRN, Kantonsspital Graubünden, affiliation not provided to SSRN, University of Rostock - University Hospital of Rostock, Charité - Universitätsmedizin Berlin, Universitätsklinikum Leipzig, University Hospital Zurich - Department of Radiation Oncology, University of Münster, University Hospital Magdeburg, affiliation not provided to SSRN, Heidelberg University - University Medical Centre Mannheim, Universitätsklinikum Leipzig and Universitätsklinikum Leipzig