An infusion is the introduction of a medication, or fluid, directly into a vein by means of gravity flow.

Ion particles accelerated in a cyclotron are diverted by a magnetic field to a circular course until a desired energy is reached. The ion beam resulting from this procedure is e.g. used for the production of radionuclides.

See also Ion, Cyclotron.

The excretion of body wastes and toxic substances are the primary function of the kidneys. The functional excretion unit is the nephron. Each kidney contains about one million nephrons. The nephron has three primary regions that function in the renal excretion process, the glomerulus, proximal tubule, and the distal tubule.
The kidney clearance is a measurement of the renal excretion ability. The excretion of the radiopharmaceutical used for kidney clearance begins approx. four minutes after application.

The x-ray absorption is the uptake of energy or the decrease of the number of photons by the tissue or matter through which the radiation travels.
Absorption in nuclear reactions and particulate radiation is a process of taking up kinetic energy of particles or the combination of particles with an atom, a nucleus, or another particle.
Absorption characteristics of imaged tissues are represented by their linear attenuation coefficients.

See also Absorber.

Activation is the production of radionuclides (instable atoms) by bombarding atomic nuclei (stable atoms) with radiation (e.g., photons, neutrons, alpha particles).
With the activation of an atom its decay starts.

See Neutron Activation, Neutron Activation Analysis.