Doing iodine 131 lung nodules smaller may lung nodules for thyroid cancer lung metastasis caused by doing iodine 131 treatment after thyroid cancer lung metastasis is a certain therapeutic effect, iodine 131 treatment includes removing the residual thyroid tissues and treating metastatic foci of thyroid cancer after thyroid cancer surgery. Common primary malignant tumors of lung metastatic cancer include carcinoma and sarcoma of gastrointestinal tract, genitourinary system, liver, thyroid gland, breast, bone, soft tissue and skin. Iodine 131 is mainly used for the treatment of thyroid diseases in clinic, because thyroid tissues absorb iodine completely, and the use of this kind of iodine 131 radioactive nuclides can be cleared from thyroid tissues, iodine 131 mainly gathers in thyroid tissues, and the radiating area is also very small, which can be used for clearing the residual thyroid tissues and treating metastatic foci of thyroid cancers after thyroid cancer surgery. Do iodine 131 lung nodules smaller need to improve the thyroid related examination, under the guidance of the doctor for treatment.