Welcome, Dr. Aleksander Riyadi, M.D., and Dr. Alvita Dewi Siswoyo, MD, the radiologists from Indonesia, to undertaking the short training program, ‘1-Week International Observership Program in Neurology-Oncology PET/CT and Theranostics’ at the Division of Nuclear Medicine, Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, under the supervision of the Assoc. Prof. Tanyaluck Thientunyakit, M.D., FANMB., from December 4th – 8th, 2023.