Radioactive iodine therapy, commonly known as "Atom Therapy," is a treatment method aimed at destroying thyroid cancer cells that may have remained in the neck region or are undetectable after thyroid surgery. This therapy is administered by orally taking a radioactive iodine-131 (I-131) molecule (in liquid medicine or capsule form). Once absorbed into the body, radioactive iodine selectively targets and is absorbed by any remaining thyroid cells, including potential cancer cells. The iodine, once inside the cell, emits beta radiation, destroying these cells from within, thereby preventing their growth and proliferation. Radioactive iodine therapy is widely used not only in the treatment of thyroid cancer but also in the management of conditions characterized by excessive thyroid hormone production, such as thyrotoxicosis and hyperthyroidism (colloquially referred to as "toxic goiter").