Richard A Popple1, Peter A Balter2, Colin G Orton. 1. Hazelrig-Salter Radiation Oncology Center, University of Alabama Birmingham, Birmingham, Alabama 35249-6832 (Tel: 205-934-1762; E-mail: rpopple@uabmc.edu). 2. Division of Radiation Oncology, UT MD Anderson Cancer Center, Houston, Texas 77030-0547 (Tel: 713-563-2560; E-mail: pbalter@mdanderson.org).