1. Department of Radiation Oncology, University Medical Center Utrecht and Princess Maxima Centre for Pediatric Oncology, Utrecht, The Netherlands;
2. Department of Oncology and Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark;
3. Department of Radiation Oncology, Academic Medical Center, Amsterdam, The Netherlands;
4. Department of Radiation Oncology, Hygeia Hospital, Athens, Greece;
5. Department of Oncology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK;
6. Clinic for Particle Therapy, West German Protontherapy Center Essen, University Hospital Essen, Essen, Germany;
7. The University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, UK and The Children's Brain Tumour Research Network, University of Manchester, Royal Mancheste Children's Hospital, Manchester, UK;
8. The Christie NHS Foundation Trust, Manchester, UK;
9. Department of Radiotherapy, Centre Hospitalier Universitaire de La Timone, Marseille, France;
10. Pediatric Radiotherapy Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, Milano, Italy;
11. Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands;
12. Department of Radiation Oncology, Institut Curie and Centre de protontherapie, Paris and Orsay, France;
13. Department of Oncology, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway;
14. The Royal Marsden NHS Foundation Trust, Sutton, UK;
15. Joint Department of Physics at The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, UK;
16. Protontherapy Center, Azienda Provinciale per i Servizi Sanitari APSS, Trento, Italy;
17. Department of Radiation Therapy, University Hospital Leipzig, Leipzig, Germany