Patients administered with a therapeutic dose of I for thyroid cancer treatment are potential sources of unacceptably high radiation exposure to other individuals, particularly the patient's immediate family members. Generally, patients are hospitalized until such time that the retained radioactivity in the body or the measured dose rate at 1 m from the patient's body surface fall to within acceptable levels. Patient release criteria are set to ensure that no individual shall be liable to receive exposures above the regulatory dose limit for the public or dose constraints for the patient's relatives or caregivers.