Radioactive iodine 131 therapy is a common treatment for thyroid malignancies and a representative technique for thyroid nuclear therapy. For radioactive iodine 131 therapy, in terms of pathology, it mainly targets differentiated thyroid adenocarcinomas, including follicular and papillary carcinomas. For postoperative adjuvant therapy or conditions that cannot be operated and the lesions have iodine absorption, radioactive iodine 131 therapy can also be implemented. For medullary carcinoma and undifferentiated carcinoma, due to their low iodine absorption rate, radionuclide iodine 131 therapy is generally not recommended in clinical treatment. In the treatment of some tumors, lymph node metastasis is found after surgery and the lesions have been completely surgically removed, radioactive iodine 131 therapy can also be implemented Iodine 131 therapy can also be implemented in some tumor treatments where lymph node metastasis is found after surgery and the lesion has been completely surgically removed. Such treatment has both diagnostic and therapeutic significance.