This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Introduction to Radiology, Subject name: Radiology
[{'content': 'Radio frequency waves are used in which of the following imaging modality? \nSelect and explain. \nA. PET scan, B. MRI, C. CT, D. Ultrasound', 'role': 'user'}, {'content': 'Answer: B \nExplanation: *MRI is based on Gyromagnetic propey of protons. *MRI uses Non-ionizing radiation i.e. Radiofrequency waves. *USG is also Non-ionizing but uses UltraSound waves. *PET scan uses Gamma rays. *CT scan uses X rays.', 'role': 'assistant'}]