1. University of Arizona College of Medicine-Phoenix, Phoenix, AZ 85004, USA
2. Albany Medical College, Albany, NY 12208, USA
3. Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, TX 77030, USA
4. Department of Radiation Oncology, Dana–Farber Cancer Institute, Brigham & Women’s Hospital, Boston, MA 02215, USA
5. Department of Radiation Oncology, City of Hope National Medical Center, Duarte, CA 91010, USA
6. Department of Radiation Oncology, University of Iowa Hospital & Clinics, Iowa City, IA 52242, USA
7. Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, PA 15212, USA