1. Department of Radiation Oncology, Miami Cancer Institute at Baptist Health South Florida, Miami, FL, USA;
2. Northwestern Medicine Chicago Proton Center, Warrenville, IL, USA;
3. ProCure Proton Therapy Center Oklahoma City, Oklahoma City, OK, USA;
4. ProCure Proton Therapy Center New Jersey, Somerset, NJ, USA;
5. Department of Radiation Oncology, University of Washington, Seattle, WA, USA;
6. Scripps Proton Center, San Diego, CA, USA;
7. Department of Radiation Oncology, University of Maryland, Baltimore, MD, USA;
8. Department of Radiation Oncology, Willis-Knighton Cancer Center, Shreveport, LA, USA;
9. Department of Radiation Oncology, Mayo Clinic, Scottsdale, AZ, USA