1. Department of Radiation Oncology University of North Carolina School of Medicine Chapel Hill North Carolina USA
2. Lineberger Comprehensive Cancer Center University of North Carolina Hospitals Chapel Hill North Carolina USA
3. Royal Marsden NHS Foundation Trust London UK
4. Institute of Cancer Research London UK
5. Department of Radiation Oncology University of Florida Jacksonville Florida USA
6. Department of Radiology University Medical Center Utrecht, Princess Máxima Center for Pediatric Oncology Utrecht The Netherlands
7. Department of Surgery Division of Otolaryngology University of Tennessee Health Science Center Memphis Tennessee USA
8. Department of Particle Therapy University Hospital Essen, West German Proton Therapy Centre Essen (WPE), West German Cancer Center (WTZ), German Cancer Consortium (DKTK) Essen Germany
9. Department of Radiation Oncology Memorial Sloan Kettering Cancer Center New York New York USA