1 Medical University of Vienna, Department of Radiation Oncology, Comprehensive Cancer Center, 1090 Vienna, Austria. Electronic address: maximilian.schmid@akhwien.at.
2 Department of Radiation Oncology, Zürich University Hospital, Zürich, Switzerland.
3 Homi Bhabha Cancer Hospital and Research Centre, Visakhapatnam, India.
4 Medical University of Vienna, Department of Radiation Oncology, Comprehensive Cancer Center, 1090 Vienna, Austria.
5 Aarhus University Hospital, Department of Oncology, Aarhus, Denmark.
6 University Medical Centre Utrecht, Department of Radiation Oncology, Utrecht, Netherlands.