In order to make your condition recover as soon as possible, and to let you understand the characteristics of iodine-131 treatment and protect your right to know, please read the following matters carefully before treatment. 1. You can eat 2 hours after taking iodine-131 orally on an empty stomach, and please swallow your saliva before eating to ensure the drug dose. 2.After 131I treatment, you need to observe in isolation for more than one week, and avoid contact with children and pregnant women within two weeks to minimize the contact time with others. 3, drink more water after taking 131I, empty urine in time to reduce the exposure to the gonads, bladder and the whole body, and defecate at least once a day to reduce the exposure to the intestines. The toilet should be flushed immediately after each stool and urine. 4.After taking 131I often contain plums or vitamin C or chew gum to promote saliva secretion and prevent or reduce the damage to salivary glands from radiation. 5.Please come to our department for whole-body imaging 5-7 days after taking the drug to understand the uptake of metastases and to provide a basis for further follow-up and treatment. 6.Please start to take Eugenol replacement therapy 2 days after treatment, usage: (the dosage will be explained on the day of treatment) take half an hour before breakfast, once a day, check thyroid function after 1 month of taking Eugenol, and adjust the dosage according to TSH and thyroxine level. 7.After 131I treatment, female patients should use contraception within one year and male patients within six months. 8. Treatment reactions and management: After taking 131I treatment, swelling and pain in the thyroid gland, epigastric discomfort, nausea, swelling and pain in the salivary glands, and temporary decrease in white blood cells may occur in the early stage, which can be told to the doctor and treated symptomatically. Rarely, serious conditions such as laryngeal edema may occur and require prompt treatment. Those with multiple treatments may have bone marrow suppression, but most of them are mild and reversible; repeated high-dose 131I treatment for diffuse lung metastases may cause radiation pneumonia and pulmonary fibrosis. 9.Iodine-free diet is still required within one week of 131I treatment, and normal diet is allowed after one week.