According to the domestic and international guidelines for the treatment of thyroid diseases, patients with differentiated thyroid cancer (papillary and follicular carcinoma) should routinely be treated with iodine-131 and follow up with eugenol after total or subtotal thyroidectomy, i.e. “surgery + iodine 131 + eugenol”. The advantage is that it can destroy the existing and potential tumor cells, and the patient can survive for a long time, and it is also convenient to track and review the condition. 131 iodine treatment for nail cancer requires strict inpatient isolation and can be discharged in 3 days. Patients are kept in special wards with special bathrooms, and their clothes and bedding are placed in decay treatment and washed separately. These can reduce the effects of irradiation. Patients can be discharged if the amount of 131 iodine retained in their bodies is equal to or less than 1.11 GBq (30 mCi), usually after 3 days, but they still should not go to dense public places, especially not to close contact with pregnant women and children. That is, still try to do a good job of radiation protection and reduce the exposure of unnecessary people! Only a few hospitals in China have set up inpatient wards in nuclear medicine departments, and patients are usually asked to go home for observation and disposal. A radioactive isotope of iodine-131 has a physical half-life of 8.04 days, and after 8 days, the radioactivity is reduced by half on its own. Together with the biological excretion of the body, the radioactivity in the human body is very, very low after 8 days. We have found in our clinical tests that after iodine 131, SPECT whole body scan, as long as the patient has no metastases or lesions, more than 95% of the radioactivity in the body has been eliminated after 5 days, and only about 1 to 5% remains. 131 Iodine treatment generally requires the patient to be isolated for 2 weeks, and after 2 weeks it is safe and has no effect on other people. Patients are advised to drink more water and urinate repeatedly for 3 days after taking iodine 131 to eliminate the retained iodine 131 and to reduce gonadal exposure, and to flush the toilet with water. Studies have shown no evidence of effects on fertility or congenital abnormalities in newborns, but patients who need to have children or become pregnant should do so one year after taking iodine 131. Radiation protection protective measures: time protection, distance protection, shielding protection . For patients, it is mainly time and distance. Extend the distance of contact with other people, as well as shorten the time of contact. Special attention is needed for pregnant women and infants. The radiation safety of iodine 131 treatment, according to the U.S. Nuclear Regulatory Commission (NRC), can be released from isolation by meeting the following three criteria: 1. residual activity in the body does not exceed 33 mCi; 2. the radiation dose rate at a distance of 1 meter is less than 7 mR/h (0.07 mSv/h); 3. the maximum radiation dose to adults does not exceed 5 mSv. The American Journal of Medicine reported that patients with outpatient oral iodine- 131 dose between 70-150 mCi, and the patient went home after taking the drug. The maximum radiation dose was measured (mean 0.58 mSv), and radiation doses to family members ranged from 0.001-1.09 mSv. The radiation dose is well below the dose limit (5 mSv) set by contemporary NRC norms. Therefore, you have no need to worry at all, and family members are separated by 3-5 meters, the radiation to family members is extremely small, family members are in the safe range.