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 one of the following radioisotope is not used as a permanent implant : \nSelect and explain. \nA. Iodine–125, B. Palladium–103, C. Gold–198, D. Caesium–137', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Caesium - 131 →\xa0Permanent implant\nCaesium - 137 →\xa0Temporary implant', 'role': 'assistant'}]