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: Surgery
[{'content': 'In treatment of papillary carcinoma thyroid, radioiodine destroys the neoplastic cells predominantly by \nSelect and explain. \nA. X-rays, B. Beta rays, C. Gamma rays, D. Alpha particles', 'role': 'user'}, {'content': 'Answer: B \nExplanation: RADIOACTIVE IODINE (I131) THERAPY:\n\nI131 is an effective agent for delivering high radiation doses to the thyroid tissue\nIt emits mainly beta radiation (90%), which penetrates only 0.5 mm of the tissue and thus allow therapeutic effects on the thyroid without any damage to the surrounding structures, particularly the parathyroids.\n\nMechanism of Action:\n\nI131 emits beta particles and X-rays.\nBeta rays are utilized for their destructive effects on thyroid cells.\nX-rays are useful for tracer studies.', 'role': 'assistant'}]