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': 'Ghost like shadow is seen in \nSelect and explain. \nA. MRI, B. OPG, C. CT, D. Cephalogram', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Structures located between the X-ray source and moving center of rotation (orange zone) cast ghost images.\nOn\xa0the panoramic image, ghost images appear on the image on the\xa0opposite side of its true anatomic location and at a higher level, because of the upward inclination of the X-ray beam. Because the object is located outside of the focal plane and close to the X-ray source, the ghost image is blurred and significantly magnified. Several anatomic structures cast ghost images.', 'role': 'assistant'}]