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': 'Which is of the following is used in investigating a parathyroid pathology? \nSelect and explain. \nA. CT scan, B. Gallium scan, C. Thallium scan, D. T.C thallium subtraction scan', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Gallium scan is used for tumors. Thallium scan is used to study myocardial perfusion.', 'role': 'assistant'}]