The one used for treatment of thyroid cancer is

Options

A. Ra-224
B. I-131
C. U-238
D. C-14

Answer

To solve the question regarding the treatment of thyroid cancer, we need to identify the correct radioisotope used for this purpose from the given options: RA-224, I-131, U-238, or C-14.

### Step-by-Step Solution:

1. **Understanding the Options**:
- RA-224: This is a radioisotope of radium, primarily used in certain types of cancer treatment but not specifically for thyroid cancer.
- I-131: This is a radioisotope of iodine, which is known for its role in thyroid treatment.
- U-238: This is a uranium isotope, mainly used in nuclear reactors and not for thyroid cancer treatment.
- C-14: This is a carbon isotope, primarily used in dating organic materials and not in cancer treatment.

2. **Identifying the Relevant Isotope**:
- Among the options, I-131 stands out as it is specifically used in the treatment of thyroid conditions, including thyroid cancer. It is a radioactive form of iodine that is absorbed by the thyroid gland.

3. **Understanding the Use of I-131**:
- I-131 is utilized in higher doses for the surgical removal of any remaining thyroid tissue after a complete thyroidectomy (removal of the thyroid gland). This is crucial in treating thyroid cancer effectively.

4. **Conclusion**:
- Based on the analysis, the correct answer to the question is I-131 (option B). This isotope is specifically used in the treatment of thyroid cancer.

### Final Answer:
The one used for treatment of thyroid cancer is **I-131** (option B).

---