1. Department of Radiation Oncology; UT Southwestern Medical Center at Dallas; Dallas TX USA
2. Department of Radiation Oncology; University of Pittsburgh Medical Center at Shadyside; Pittsburgh PA USA
3. London School of Hygiene and Tropical Medicine; London United Kingdom
4. Department of Radiation Oncology; University of Nebraska Medical Center; Omaha NE USA
5. Department of Radiation Oncology; M. D. Anderson Cancer Center Orlando; Orlando FL USA