The importance and required detection levels of radionuclide impurities--a medical physicist's view.

All radioactive impurities in radiopharmaceuticals contribute unnecessary radiation dose to the patient. gamma-Emitting impurities can adversely affect the quality of gamma-camera images and measurements of organ and sample radioactivity and can interfere with concurrent and subsequent nuclear medicine procedures. Full specification of radionuclidic content of all radiopharmaceuticals would help the user to avoid or minimise these effects. Detection levels of 1 in 10(6), and for alpha emitters 1 in 10(9), are required of suppliers and monitoring laboratories.