1. Dept. of Hygiene and Epidemiology, Athens University Medical School, Athens, Greece
2. Dept. of Nuclear Medicine, Athens University Medical School, Athens, Greece
3. Dept. of Epidemiology, Harvard School of Public Health, Boston, USA
4. Dept. of Pediatric Hematology-Oncology, Ahepa Hospital, Thessaloniki, Greece
5. Dept. of Pediatric Hematology-Oncology, Agia Sophia Children's Hospital, Athens, Greece
6. Dept. of Pediatric Hematology-Oncology, University Hospital, Heraklion, Greece
7. Dept. of Pediatric Hematology-Oncology, Hippokrateion Hospital, Thessaloniki, Greece
8. Dept. of Pediatric Hematology-Oncology, Aglaia Kyriakou Children's Hospital, Athens, Greece
9. Dept. of Mechanical Engineering, Nuclear Engineering Section, Technical University of Athens, Athens, Greece