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