This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nuclear medicine, Subject name: Radiology
[{'content': 'Dye used in SPECT- \nSelect and explain. \nA. O-14, B. Tc-99, C. Nitrogen-16, D. Iodine 124', 'role': 'user'}, {'content': 'Answer: B \nExplanation: SPECT imaging: It has a 360deg revolving gamma camera giving 3D images Tc99m radioisotope is used (t1/2 = 6 hrs) Tc99m - HMPAO: Lipophilic/Lipid soluble Crosses blood brain barrier Cerebral perfusion is evaluation', 'role': 'assistant'}]