作者单位:Mayo Clin, Div Med Oncol, 200 First St SW, Rochester, MN 55905 USA[1]Mayo Clin, Dept Radiat Oncol, 200 First St SW, Rochester, MN 55905 USA[2]West Hills Radiat Therapy Ctr, West Hills, CA USA[3]Therapeut Radiologists Inc, Dept Radiat Oncol, Kansas City, MO USA[4]