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': 'Computed Tomography (CT scan) is least accurate for diagnosi of – \nSelect and explain. \nA. Aneurysm in the Hepatic Artery, B. Lymph node in the para- aortic region, C. Mass in the tail of pancreas, D. Gall stones', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Computed Tomography (CT) scan has limited value in the diagnosis of gallstones since gallstones may exhibit the same radiographic density as bile and hence may not be seen on CT.', 'role': 'assistant'}]