1. Department of Radiation Physics; The University of Texas MD Anderson Cancer Center; Houston TX 77030 USA
2. The University of Texas Graduate School of Biomedical Sciences at Houston; Houston TX 77030 USA
3. Department of Radiation Oncology; The University of Texas Medical Branch of Galveston; Galveston TX 77555 USA
4. Department of Radiation Oncology; The University of Alabama at Birmingham; Birmingham AL 35294 USA
5. Department of Epidemiology; The University of Texas MD Anderson Cancer Center; Houston TX 77030 USA
6. Consortium of Rheumatology Researchers of North America (CORRONA), Inc.; Southborough MA 01772 USA