1 Faculty of Medicine, Dalhousie University, Saint John, New Brunswick, Canada.
2 Department of Radiation Oncology, Dalhousie University, Saint John, New Brunswick, Canada.
3 Department of Radiation Oncology, University of Toronto, Radiation Medicine Program, Stronach Regional Cancer Centre, Newmarket, Ontario, Canada.
4 Department of Radiation Oncology, University of British Columbia, Vancouver, British Columbia, Canada.
5 Department of Radiation Oncology, McGill University, Montreal, Quebec, Canada.
6 Department of Radiation Oncology, University of Alberta, Edmonton, Alberta, Canada.
7 Department of Radiation Oncology, University of Toronto, Ontario, Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, Ontario, Canada.