This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
[{'content': 'Which of the following is used in the treatment of well differentiated thyroid cancer? \nSelect and explain. \nA. 32 P, B. 131 I, C. 99mTc, D. 131I-MIBG', 'role': 'user'}, {'content': 'Answer: B \nExplanation: I 131 is used in the treatment of well differentiated thyroid cancer and hypehyroidism. I 131 has a half life of 8 days and emits beta paicles as well as gamma rays. Radiation dose to thyroid is mainly due to the emitted beta paicles (90%) rather than gamma radiation. Ref: Oncology for Health-Care Professionals By V. Pervan, Page 262; Radiation in Medicine: A Need for Regulatory Reform By U.S. Nuclear Regulatory Commission, Page 74', 'role': 'assistant'}]