1. Department of Radiation Oncology, University of Texas Southwestern, Dallas
2. Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas
3. Harold Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas
4. Department of Radiation Oncology, Brigham and Women’s Hospital, Boston, Massachusetts
5. Dana-Farber Cancer Institute McGraw/Patterson Center for Population Sciences, Boston, Massachusetts