1. Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
2. Institute of Radiation Emergency Medicine, Hirosaki University, Hirosaki 036-8564, Japan
3. Natural Radiation Survey and Analysis Research Unit, Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand
4. Thailand Institute of Nuclear Technology, Nakhon Nayok 26120, Thailand
5. Toxicology Section, Department of Forensic Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
6. Graduate School of Health Science, Hirosaki University, Hirosaki 036-8564, Japan