[1] Gustave Roussy Univ Hosp, Dept Radiat Oncol, F-94800 Villejuif, France
[2] Princess Margaret Canc Ctr, Dept Radiat Oncol, Toronto, ON, Canada
[3] Vrije Univ Amsterdam, Med Ctr, Dept Radiat Oncol, Amsterdam, Netherlands
[4] Maastricht Univ, Dept Radiat Oncol, Maastro Clin, GROW Sch Oncol & Dev Biol,Med Ctr, NL-6200 MD Maastricht, Netherlands
[5] Katholieke Univ Leuven, Dept Oncol Expt Radiat Oncol, Leuven, Belgium
[6] Netherlands Canc Inst, Dept Radiat Oncol, Amsterdam, Netherlands
[7] Med Coll Wisconsin, Dept Radiat Oncol, Milwaukee, WI 53226 USA