1. Division of Radiation Oncology Department of Radiology Faculty of Medicine, Chiang Mai University Chiang Mai Thailand
2. Northern Thai Research Group of Radiation Oncology (NTRG‐RO) Faculty of Medicine, Chiang Mai University Chiang Mai Thailand
3. Chiang Mai Cancer Registry Maharaj Nakorn Chiang Mai Hospital Faculty of Medicine, Chiang Mai University Chiang Mai Thailand