Which of the following is used in Brachytherapy:
**Core Concept**
Brachytherapy involves the placement of a radioactive source close to or within a tumor to deliver high doses of radiation while minimizing exposure to surrounding healthy tissues. This treatment modality relies on the principles of radiation oncology and nuclear medicine.
**Why the Correct Answer is Right**
Iridium-192 (Ir-192) is a commonly used radioactive isotope in brachytherapy for treating various types of cancer, including cervical, prostate, and breast cancer. Ir-192 emits beta particles and gamma rays, which are effective in destroying cancer cells. The use of Ir-192 in brachytherapy allows for precise targeting of tumors and minimizes damage to surrounding healthy tissues.
**Why Each Wrong Option is Incorrect**
**Option A:** Radium-226 (Ra-226) was historically used in brachytherapy but has largely been replaced by more modern radioactive isotopes due to its relatively short half-life and potential toxicity.
**Option B:** Cesium-137 (Cs-137) is used in some brachytherapy applications but is not as widely used as Ir-192 due to its higher gamma radiation output and potential for increased toxicity.
**Option C:** Gold seeds containing I-125 are used in low-dose rate brachytherapy for prostate cancer treatment, but they are not the most commonly used radioactive isotope in brachytherapy.
**Clinical Pearl / High-Yield Fact**
When considering brachytherapy, it's essential to remember that the choice of radioactive isotope depends on the specific tumor type, size, and location, as well as the patient's overall health and treatment goals.
**Correct Answer:** C.