Which radioisotope is used for thyroid cancer treatment, according to the material?

• A. I-131 for prostate
• B. I-131 for thyroid
• C. I-131 for breast
• D. I-131 for brain

Answer: (B)

The key idea is that thyroid cancer treatment leverages the thyroid’s unique ability to take up iodine. Iodine-131 is used because it delivers radiation directly to thyroid tissue. The beta emissions from I-131 destroy thyroid cells and any residual or metastatic thyroid cancer cells, while its gamma emissions help doctors image and monitor the distribution and dose. This targeted approach works specifically for thyroid tissue because other organs like the prostate, breast, or brain don’t actively concentrate iodine, so I-131 isn’t effective for those sites. Therefore, the radioisotope used for thyroid cancer treatment is iodine-131.