[1] Kyung Hee Univ Hosp Gangdong, Radiat Oncol, Seoul, South Korea
[2] Soonchunhyang Univ Hosp Cheonan, Radiat Oncol, Seoul, South Korea
[3] Korea Inst Radiol & Med Sci, Radiat Oncol, Seoul, South Korea
[4] Kyung Hee Univ Hosp, Radiat Oncol, Seoul, South Korea