Locations: CHI Health Bergan Mercy | CHI Health Immanuel | CHI Health Lakeside | CHI Health Mercy - Council Bluffs | CHI Health Midlands | CHI Health Schuyler A thyroid scan is a nuclear medicine examination that uses the emissions of gamma rays from radioactive iodine to help determine whether a patient has thyroid problems; including hyperthyroidism, cancer, or other growths.