I, Hiroshi Doi, am a board certified Radiation Oncologist with ≥10years experiences. I have worked on radiobiology during and after graduate school. I have studied abroad and belonged to radiation biology lab (PI, Knox SJ, MD, PhD) at Stanford University School of Medicine, USA. My clinical interests are GI cancers and liver cancers and precision radiation oncology (eg SBRT/SABR, IMRT). I have a total of 49 scientific articles with wide range of themes; liver SBRT, re-irradiation, trimodal treatment for rectal cancer, and basic research on radiation induced-normal tissue damages.