1. University of Pennsylvania, Philadelphia, PA, USA
2. Oklahoma Proton Center, Oklahoma City, OK, USA
3. University of California-San Diego, San Diego, CA, USA
4. Department of Radiation Oncology (MAASTRO), GROW – School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, The Netherlands
5. University of Washington, Seattle, WA, USA
6. Mayo Clinic, Scottsdale, AZ, USA
7. Radiation Oncology Department, François Baclesse Center/ARCHADE, Normandy University, Caen, France
8. The Christie NHS Foundation Trust, University of Manchester, Manchester Academic Health Sciences Centre, Manchester, United Kingdom
9. Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
10. The University of Texas MD Anderson Cancer Center, Houston, TX, USA