Which of the following radioactive isotopes is used in the detection of thyroid cancer?

Options

A. Iodine -131
B. Carbon-14
C. Uranium -238
D. Phosphorus -32

Explanation

To determine which radioactive isotope is used in the detection of thyroid cancer, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of the Thyroid Gland**:
- The thyroid gland is located in the front of the neck and is responsible for producing hormones such as thyroxine (T4) and triiodothyronine (T3). These hormones are crucial for regulating metabolism.

2. **Identify the Importance of Iodine**:
- Iodine is an essential mineral required for the synthesis of thyroid hormones. The thyroid gland absorbs iodine from the bloodstream to produce T3 and T4.

3. **Recognize the Use of Radioactive Isotopes**:
- Radioactive isotopes can be used in medical diagnostics to detect various conditions, including cancers. In the case of the thyroid gland, specific isotopes can help visualize and assess thyroid function.

4. **Determine the Relevant Radioactive Isotope**:
- Among the radioactive isotopes, Iodine-131 (I-131) is commonly used in the diagnosis and treatment of thyroid conditions, including thyroid cancer. It emits radiation that can be detected by imaging techniques.

5. **Select the Correct Answer**:
- Based on the information gathered, the radioactive isotope used in the detection of thyroid cancer is Iodine-131.

### Final Answer:
The radioactive isotope used in the detection of thyroid cancer is **Iodine-131**.

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