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': 'Out of the following which is not a radiotherapy equipment? \nSelect and explain. \nA. Betatron, B. Telecurie-cobalt unit, C. Linear accelerator, D. Thimble chamber', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. Thimble chamber', 'role': 'assistant'}]