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': 'Radiation exposure is the least in the following procedure – \nSelect and explain. \nA. Micturating cystourethrogram, B. IVP, C. Bilateral nephrostomogram, D. Spiral CT for stones', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Amongst the given options micturating cystourethrogram has least radiation exposure with number of chest x-ray equivalent of 60.\nIVP has chest x-ray equivalent 120, nephrostomogram has x-ray eqiuvalent 170, and CT Plevis has x-ray equivalent 500.', 'role': 'assistant'}]