Xenon-133 (sold as a drug under the brand name Xeneisol, ATC code ) is an isotope of xenon. It is a radionuclide that is inhaled to assess pulmonary function, and to image the lungs. It is also used to image blood flow, particularly in the brain. 133Xe is also an important fission product. It is discharged to the atmosphere in small quantities by some nuclear power plants.
