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': 'Osteoradionecrosis occurs at a dose of: \nSelect and explain. \nA. > 10 Gy, B. > 70 Gy, C. > 30 Gy, D. None of the above.', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Life-Long threat:\nHyposalivation\n\nRadiation caries\n\nOccurs 3 months after expose (PG1)\n\nTrismus\nOsteoradionecrosis > 70 Gy', 'role': 'assistant'}]