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: Unknown
[{'content': 'M/C used in Brachytheraphy of Carcinoma cervix: \nSelect and explain. \nA. Radium-226, B. Cobalt-60, C. Gold-198, D. Caesiom-137', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Brachytherapy: Type of radiation in which radioactivesources are placed in dose proximity to or directly into tumors.\nInterstial RT Needles Placed into Prostate/penis/othersoft tissue.)\nIntracavitary\neg. In urethra (m/c used csl37) M/C used source in Brachytherapy - Irl 90. C.S.I. REMEMBER, somecommonly asked half life of ISOTOPES\nRadium 226——1620 years\nCaesium- 137—30 years\nCobalt 60 ----- 5.3 years\nIridium 192—74.4years\nIodine 125 ---- 60 days\nPhosphorus32—14.3 days\nGold 198—2.7 days', 'role': 'assistant'}]