For a high-dose-rate intracavitary brachytherapy insertion in carcinoma of the cervix, the most commonly used radionuclide source is:
- A Iridium-192, half-life 74 days ✓
- B Iodine-125, half-life 60 days
- C Cobalt-60, half-life 5.26 years
- D Strontium-90, a pure beta emitter
Correct answer: A. Iridium-192, half-life 74 days
Explanation
Ir-192 is the standard source for temporary high-dose-rate remote afterloading brachytherapy because its moderate average photon energy (about 0.38 MeV) allows practical shielding and its 74-day half-life permits economical source replacement every few months. I-125 is used for permanent interstitial prostate seed implants, not temporary HDR gynaecological work. Co-60 is bulky and highly penetrating, suited to teletherapy machines rather than compact afterloaders.
Reference: Khan, The Physics of Radiation Therapy, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.