[1] Princess Margaret Canc Ctr, Radiat Med Program, Toronto, ON, Canada
[2] Aarhus Univ Hosp, Dept Oncol, Aarhus, Denmark
[3] Univ Med Ctr Utrecht, Dept Radiat Oncol, Utrecht, Netherlands
[4] Univ Montreal, Maisonneuve Rosemont Hosp, Dept Radiat Oncol, Montreal, PQ, Canada
[5] Med Univ Vienna, Dept Radiat Oncol, Ctr Comprehens Canc, Vienna, Austria
[6] Tata Mem Hosp, Dept Radiat Oncol, Mumbai, Maharashtra, India
[7] Mt Vernon Hosp, Ctr Canc, London, England
[8] Univ Ljubljana, Inst Oncol Ljubljana, Fac Med, Dept Radiotherapy, Ljubljana, Slovenia
[9] Univ Ljubljana, Inst Oncol Ljubljana, Fac Med, Dept Radiotherapy, Ljubljana, Slovenia
[10] Oslo Univ Hosp, Norwegian Radium Hosp, Dept Oncol, Oslo, Norway
[11] Univ Amsterdam, Amsterdam Univ, Dept Radiat Oncol, Med Ctr, Amsterdam, Netherlands
[12] Univ Med Ctr Rotterdam, Erasmus MC Canc Inst, Dept Radiotherapy, Rotterdam, Netherlands