1. Rigshospitalet, Copenhagen, Denmark;
2. Norwegian Radium Hospital, Oslo, Norway;
3. Uppsala University Hospital, Uppsala, Sweden;
4. Lund University Hospital, Lund, Sweden;
5. Karolinska Institute, Stockholm, Sweden;
6. Aarhus University Hospital, Aarhus, Denmark;
7. Oulu University Hospital, Oulu, Finland;
8. Sahlgrenska Hospital, Gothenburg, Sweden; and
9. Helsinki University Central Hospital, Helsinki, Finland