The risk of radiation from the diagnostic use of radionuclides is very small because of the low dosage and short half-life of the materials used. Most radionuclides leave the body in 6 to 24 hours; others can take as long as 8 days. The radiation dose is actually less than that received in x-ray studies. The use of radionuclides for diagnostic studies does not require that personnel and others be protected from the presence of radiation in the client. Specific precautions, however, are required to protect others from the radiation in the client if therapeutic doses are administered, because these doses are much higher and the radiation that results is about 1000 times more than that from a diagnostic dose. Agencies that are approved to use radioactive materials for diagnosis, therapy, or research are provided with standards and guidelines from the government regulating commissions. These guidelines include directions to be followed in the handling, storage, and disposal of radiopharmaceuticals with short and long half-lives. Also provided are guidelines and requirements for the care and handling of specimens collected for testing, procedures to follow to protect the client and others from radiation, and procedures for the disposal of body excretions.
Because of the potential effect of radiation on cell growth if a fetus is exposed to radionuclide material, pregnant women are not considered Candidates for nuclear scanning procedures. Mothers who are breast-feeding their babies are generally excluded as well, but they can be considered for this method of diagnostic testing with dosages calculated to provide the maximum results while using a minimum amount of the radionuclide.14 Children also are not generally considered Candidates for nuclear testing unless dosage is carefully calculated, although there are instances when frequent scanning is performed, such as in bone cancer. The decision to perform nuclear studies on these groups varies with diagnosis and physicians as they compare the benefits and risks of using the very low doses for scanning against more invasive diagnostic procedures.