[1] Univ Texas Southwestern Med Ctr Dallas, Dept Radiat Oncol, Dallas, TX 75390 USA
[2] Mem Sloan Kettering Canc Ctr, 1275 York Ave, New York, NY 10021 USA
[3] UT Southwestern Med Ctr, Dallas, TX USA
[4] Univ Texas Southwestern Med Ctr Dallas, Simmons Comprehens Canc Ctr, Dallas, TX 75390 USA