1 Department of Radiation Oncology, University Muenster, Albert-Schweitzer-Campus 1, Building A1, 48149, Muenster, Germany. christos.moustakis@ukmuenster.de.
2 German CyberKnife Centre, Soest, Germany. christos.moustakis@ukmuenster.de.
3 Department of Radiation Oncology, UKSH Universitätsklinikum Schleswig Holstein, Kiel, Germany.
4 Saphir Radiosurgery Center, Güstrow and Frankfurt, Germany.
5 Department of Radiation Oncology, University Muenster, Albert-Schweitzer-Campus 1, Building A1, 48149, Muenster, Germany.
6 City Hospital Dessau, Dessau, Germany.
7 German CyberKnife Centre, Soest, Germany.
8 Department of Radiation Oncology, University Wuerzburg, Wuerzburg, Germany.
9 Department of Radiation Oncology, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany.
10 Department of Radiation Oncology, LMU Ludwig-Maximilians-University, Munich, Germany.
11 Radiationtherapy Distler, Bautzen, Germany.
12 Department of Radiation Oncology, University Medical Center Freiburg, Freiburg, Germany.
13 Department of Radiation Oncology, University Halle, Halle, Germany.
14 University Hospital Hamburg-Eppendorf, Hamburg, Germany.
15 Department of Radiation Oncology, University Mainz, Mainz, Germany.
16 University Hospital of Cologne, Cologne, Germany.
17 Gamma Knife Centre Krefeld, Krefeld, Germany.
18 University Hospital Heidelberg, Heidelberg, Germany.