Which of the following isotope is commonly used in teletherapy: September 2010
**Question:** Which of the following isotopes is commonly used in teletherapy: September 2010
**Core Concept:** Teletherapy, also known as remote radiation therapy, is a method of delivering ionizing radiation to cancer cells from a distance, using isotopes and devices like telecobalt machines. This helps in minimizing damage to surrounding healthy tissues.
**Why the Correct Answer is Right:** The correct answer to this question is **C. Cobalt-60 (60Co)**. Cobalt-60 is a gamma-emitting radioactive isotope that has a half-life of around 5.27 years. Its half-life allows for a stable source of radiation for a significant duration, ensuring adequate treatment for cancer patients. Gamma radiation from Cobalt-60 can penetrate deeper into tissues, making it useful for treating deep-seated tumors.
**Why Each Wrong Option is Incorrect:**
A. **Iodine-131 (131I)**: Iodine-131 is a beta-emitting isotope with a half-life of 8 days. While it has some clinical uses, it is not as effective for teletherapy due to its short half-life and limited tissue penetration.
B. **Iodine-125 (125I)**: Iodine-125 is a beta-emitting isotope with a half-life of approximately 59.4 days. Its use in teletherapy is limited due to similar reasons as option A.
D. **Iodine-125 (125I)**: As mentioned earlier, Iodine-125 is a beta-emitting isotope with a half-life of approximately 59.4 days. Its use in teletherapy is limited due to similar reasons as options A and B.
**Clinical Pearl / High-Yield Fact:**
Teletherapy, particularly teletherapy involving gamma radiation, is a form of internal radiation therapy (IRT) used for treating deep-seated tumors. Cobalt-60 (option C) is a gamma-emitting radioactive isotope with a relatively long half-life (5.27 years) and the ability to penetrate deeper tissues, making it suitable for teletherapy applications.