1. University of Florida Health Proton Therapy Institute, Jacksonville, FL, USA;
2. Northwestern Chicago Proton Center, Warrenville, IL, USA;
3. Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA;
4. New Jersey Procure Proton Therapy Center, Oklahoma City, OK, USA;
5. Mayo Clinic, Scottsdale, AZ, USA;
6. Department of Radiation Oncology, University of Washington, Seattle, WA, USA;
7. Oklahoma City Procure Proton Therapy Center, Oklahoma City, OK, USA