1. Department of Radiation Biology; Oslo University Hospital the Norwegian Radium Hospital; Montebello 0310 Oslo Norway
2. Department of Pediatrics; Haukeland University Hospital; 5021 Bergen Norway
3. Department of Clinical Medicine; Section of Pediatrics; University of Bergen; Bergen Norway
4. Department of Medicine; Section of Endocrinology, Nutrition and Diabetes, Vitamin D Skin and Bone Research Laboratory; Boston University Medical Center; Boston MA U.S.A
5. Institute of Clinical Medicine; Faculty of Medicine; University of Oslo; 0316 Oslo Norway
6. Department of Oncology; Oslo University Hospital the Norwegian Radium Hospital; Montebello 0310 Oslo Norway
7. Institute of Physics; University of Oslo; 0316 Oslo Norway