As mentioned earlier, the thyroid gland is the largest endocrine gland in the body, producing and secreting thyroid hormones to maintain growth, development and material metabolism. The thyroid gland uses iodine as the main raw material to produce thyroid hormones, therefore, the thyroid gland has a high iodine uptake function, i.e. once iodine from food, water and medicine enters the body through the digestive tract, it is quickly absorbed by the thyroid gland, therefore, 80% of the total iodine in the body is concentrated in the thyroid gland. When it is taken orally, it can be concentrated in the thyroid gland as quickly as ordinary iodine, and the beta rays it releases can gradually destroy the hyperplastic thyroid tissue, causing the thyroid gland to shrink and the production of thyroid hormones to decrease, thus reducing or curing hyperthyroidism. As a result, hyperthyroidism is reduced or cured. This is a biological missile type of treatment. Surgery involves removing a portion of the thyroid gland with a scalpel to achieve treatment. 131 iodine, on the other hand, uses beta radiation to destroy a portion of the thyroid gland to achieve treatment. These two treatments are similar, but 131 iodine treatment is bloodless, safe and painless, hence the name “bloodless and painless internal surgery”.