This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nuclear medicine, Subject name: Radiology
[{'content': 'CHA is used in Rx of? \nSelect and explain. \nA. Ca Lung, B. Ca Stomach, C. Head and neck cancer, D. NHL', 'role': 'user'}, {'content': 'Answer: A \nExplanation: CHA is Continous Hyper fractionated accelerated Radiotherapy used for management of non-small cell lung cancer.', 'role': 'assistant'}]