It is also the source of around 90% of the discharge of technetium-99, a long-lived radionuclide that lingers in shellfish.This particular waste, discharges of which have risen in recent years, worries the Irish and Danish governments, which detect it washing up on their beaches.
Diagnosis is confirmed by radionuclide bone scans.
The radionuclide used in virtually all phases of radionuclide imaging is technetium-99.
Radionuclides emit various ionizing radiations (e.g., electrons, positrons, alpha particles, gamma rays, or even characteristic X rays), the precise types of which depend on the radionuclide in question.
A given amount of plutonium-239, for example, still retains about one-half of its radioactivity after 25,000 years, so that reactor wastes containing this long-lived radionuclide must be safely isolated for centuries.
As the radionuclide decays, positrons are annihilated by electrons, giving rise to gamma rays that are detected simultaneously by the photomultiplier-scintillator combinations positioned on opposite sides of the patient.
Radionuclide imaging (radioactive nuclides) provides a safe, quantitative evaluation of cardiac function and a direct measurement of myocardial blood flow and myocardial metabolism.
The second requirement is that the physical properties of the radionuclide be satisfactory with respect to the instrumentation being used.
Exposure to a radionuclide and its emissions may be external, in which case the penetrating power of the radiation is an important factor in determining the probability of injury.
The primary requirement of radionuclide imaging is that the bolus of radionuclide should remain within the blood vessels during its first passage through the right and left sides of the heart.
These techniques are used to assess myocardial damage, left ventricular function, valve regurgitation, and, with the use of radionuclide potassium analogues, myocardial perfusion.
