1. Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Borås, Sweden;
2. Department of Radiation Physics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden;
3. Department of Therapeutic Radiation Physics, Sahlgrenska University Hospital, Gothenburg, Sweden;
4. Department of Oncology, Sahlgrenska University Hospital, Gothenburg, Sweden