1. Department of Radiation Oncology, Virginia Commonwealth University Health System, Richmond, Virginia, USA
2. Department of Radiation Oncology, Penn State Cancer Institute, Hershey, Pennsylvania, USA
3. Department of Public Health Sciences, Penn State College of Medicine, Hershey, Pennsylvania, USA
4. Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, Canada
5. Department of Radiation Oncology, Odette Cancer Centre—Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
6. Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
7. Department of Radiation Oncology, The James Cancer Hospital at the Ohio State University Wexner Medical Center, Columbus, Ohio, USA
8. Department of Radiation Oncology, Mayo Clinic, Jacksonville, Florida, USA
9. Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota, USA