[1] Brigham & Womens Hosp, Dana Farber Canc Inst, Dept Radiat Oncol, 75 Francis St, Boston, MA 02115 USA
[2] Harvard Med Sch, Boston, MA 02115 USA
[3] Dana Farber Canc Inst, Dept Radiol, Lurie Family Imaging Ctr, Boston, MA 02115 USA
[4] Hokkaido Univ, Sapporo, Hokkaido, Japan