1. Department of Radiation Oncology, Cancer Center Amsterdam, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
2. Department of Radiation Oncology, Erasmus MC, Rotterdam, The Netherlands
3. Department of Medical Physics, Regional University Hospital of Málaga, Malaga, Spain
4. Kantonsspital Aarau, Centre for Radiation Oncology KSA-KSB, Aarau, Switzerland
5. Department of Medicine III, University Hospital LMU Munich, Munich, Germany
6. Department of Radiation Oncology, University Hospital Erlangen, Erlangen, Germany
7. Department of Radiation Oncology, Charité Universitätsmedizin Berlin, Berlin, Germany