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': 'Isotope used in bone scans: \nSelect and explain. \nA. Technetium, B. Gallium, C. Selenium, D. Chromium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Technetium', 'role': 'assistant'}]