1 Department of Radiation Oncology, Haaglanden Medical Center, Leidschendam, The Netherlands.
2 Department of Medical Physics, Haaglanden Medical Center, Leidschendam, The Netherlands.
3 Department of Radiation Oncology, Iridium Netwerk, Wilrijk-Antwerp, Belgium; University of Antwerp, Faculty of Medicine and Health Sciences, Wilrijk-Antwerp, Belgium.