Which isotope is commonly used to determine thyroid activity and treat diseases of the thyroid?

• A. Cobalt-60
• B. Carbon-14
• C. Iodine-131
• D. Uranium-238

Answer: (C)

Verified step by step guidance

1. Understand that isotopes are variants of elements with different numbers of neutrons, and some isotopes are radioactive, making them useful in medical applications.
2. Recognize that the thyroid gland actively absorbs iodine from the bloodstream to produce thyroid hormones, so radioactive iodine isotopes can target the thyroid specifically.
3. Identify that Iodine-131 is a radioactive isotope commonly used in both diagnostic imaging and treatment of thyroid diseases because it emits radiation that affects thyroid tissue.
4. Note that other isotopes listed, such as Cobalt-60, Carbon-14, and Uranium-238, have different applications: Cobalt-60 is used in cancer radiotherapy, Carbon-14 in radiocarbon dating, and Uranium-238 in nuclear reactors and dating.
5. Conclude that Iodine-131 is the isotope commonly used to determine thyroid activity and treat thyroid diseases due to its chemical similarity to stable iodine and its radioactive properties.