We require: absolute isolation from infants, children and pregnant women. Fetuses and infants grow and develop especially fast, and cells that grow and develop fast are sensitive to radiation, while cells that grow and develop slowly are relatively insensitive to radiation. Therefore, we require absolute isolation of infants and pregnant women from patients undergoing iodine treatment, at least 2-3 meters or a separate room isolation distance. Is there an age limit for children? There are no strict values, such as 7-8 years old or less than 14 years old, at home or abroad. However, newborns and young children develop rapidly, and children in puberty have very active gonadal cells, so it is important to keep them isolated from iodine treatment patients to avoid affecting their growth or damaging their gonads. Are there any requirements for adults? Close contact between patients receiving iodine treatment and adults is not recommended. Although adults are less sensitive to the iodine 131 gamma rays released from the patient’s body, from a protective point of view, it cannot be excluded that individuals are particularly sensitive to the rays. Therefore, patients taking iodine 131 should be specifically instructed to be isolated at home for at least 2 weeks before coming into close contact with others, since the amount of residual radiation in the patient’s body after 2 weeks of treatment is already very small and relatively safe. Patients treated with iodine 131 should sleep in separate rooms for 2-3 weeks and keep a distance between them and their colleagues. Especially now that the second child is open, it is not excluded that colleagues around you are preparing for pregnancy or are already pregnant early. There is no strict value for the age and amount of protection, but only a recommended value. We doctors should also explain this to the patient and family in person, preferably in writing.