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
All of the following radioisotopes are used as systemic radionucleide, except: 
Select and explain. 
A. Phosphorus -- 32, B. Strontium -- 89, C. Iridium -- 192, D. Samarium -- 153
C: Iridium -- 192
Answer: C: Iridium -- 192 
Explanation: Ans. Iridium -- 192