This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Radiology
[{'content': 'Isotope used in myocardial perfusion scan is - \nSelect and explain. \nA. Technetium, B. Thallium, C. Stannous pyrophosphate, D. Gallium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Technitium is used in myocardial perfusion scans', 'role': 'assistant'}]