1. Department of Medical Physics, Oncology, Aalborg University Hospital, Aalborg, Denmark
2. Department of Oncology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
3. Department of Oncology, Radiotherapy Research Unit, Herlev and Gentofte Hospital, University of Copenhagen, Herlev, Denmark
4. Laboratory of Radiation Physics, Odense University Hospital, Odense, Denmark
5. Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark