This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Radiology
WHICH IS TRUE REGARDING STRONTIUM 89 WHEN COMPARED TO PHOSPHOROUS 32 ? 
Select and explain. 
A. STR 89 HAS SHO T1/2, B. STR 89 HAS LESS TOXICITY, C. STR 89 HAS DEEPER PENETRATION, D. NONE OF THE ABOVE
B: STR 89 HAS LESS TOXICITY
Answer: B: STR 89 HAS LESS TOXICITY 
Explanation: Strontium 89(METASTRON) * Calcium analogue * Pure beta radiation emitter * Incorporated into the bone matrix directly in areas of active bone remodelling * Biological half-life of Sr89 isotope - 50.5 days. * Administered IV as strontium chloride * Main means of isotope elimination- kidneys * Used in metastatic prostate and breast cancer ref : david sutton 9th ed