1. Department of Radiation Oncology; University Medical Center Utrecht and Princess Máxima Center for Pediatric Oncology; Utrecht The Netherlands
2. Radiation Oncology Department; Leuven Cancer Center; Leuven Belgium
3. Department of Radio-Oncology; University Hospital of Saarland; Homburg Germany
4. Department of Statistics; The Netherlands Cancer Institute; Amsterdam The Netherlands
5. Cancer Section; University College London Institute of Child Health; London UK
6. Department of Paediatric Oncology; Centre Leon Berard; Lyon France
7. Department of Paediatric Oncology; University Hospital of Saarland; Homburg Germany
8. Princess Máxima Center for Paediatric Oncology; Utrecht The Netherlands
9. Department of Radiation Oncology. The Christie NHS Foundation Trust; The Christie NHS Foundation Trust; Manchester UK
10. Department of Radiation Oncology; Academic Medical Center; Amsterdam The Netherlands