1. Memorial Sloan Kettering Cancer Center, New York, NY
2. Statistical Center, Radiation Therapy Oncology Group, Philadelphia, PA
3. University of Maryland Greenebaum Cancer Center, Baltimore, MD
4. Department of Radiation Oncology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA
5. Boston University Medical Center, Boston, MA
6. Karmanos Cancer Institute, Wayne State University, Detroit, MI
7. Vanderbilt-Ingram Cancer Center, Nashville, TN
8. University of Utah, Salt Lake City, UT
9. John H. Stroger Jr. Hospital of Cook County, Chicago, IL
10. University of Maryland, Baltimore, MD
11. USOR-Texas Oncology, Sugarland, TX
12. University of Pittsburg Medical Center, Pittsburgh, PA
13. Helen F. Graham Cancer Center, Wilmington, DE
14. Southeast Radiation Oncology, Charlotte, NC
15. Cleveland Clinic, Cleveland, OH
16. Schiffler Cancer Center, Wheeling, WV
17. Brown University Oncology Research Group, Providence, RI
18. The University of Texas MD Anderson Cancer Center, Houston, TX