1. Division of Radiation Oncology, Department of Oncology, London Health Sciences Centre, London, ON N6A 5W9, Canada
2. Division of Radiation Oncology, Department of Oncology, Kingston General Hospital, Queen’s University, Kingston, ON K7L 3N6, Canada
3. Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
4. Radiation Oncology Department, Hospital Sirio Libanês, Sao Paulo 01308-050, Brazil
5. Department of Medical Imagings, Ribeirão Preto Medical School, Hematology and Oncology of University of São Paulo (FMRP-USP), Ribeirão Preto 14049-900, Brazil
6. Latin America Cooperative Oncology Group (LACOG), Porto Alegre 90619-900, Brazil
7. Division of Radiation Oncology, Department of Oncology, Juravinski Cancer Centre, McMaster University, Hamilton, ON L8V 5C2, Canada