Abstract
In 1896, Becquerel discovered the natural radioactivity in potassium uranyl
sulphate. Since then, Pierre and Marie Curie, E. Rutherford and F. Soddy all
made tremendous contributions to the discovery of many other radioactive
elements. The work of all these scientists has shown that all elements found in
nature with an atomic number greater than 83 (bismuth) are radioactive.
Artificial radioactivity was first reported by I. Curie and F. Joliot in 1934. These
scientists irradiated boron and aluminium targets with a particles from polonium
and observed positrons emitted from the target even after removal of the a
particle source. This discovery of induced or artificial radioactivity opened up a
brand new field of tremendous importance. Around the same time, the
discovery of the cyclotron, deuteron and neutron by various scientists facilitated
the discovery of many more artificial radioactivities. At present time more than
2700 radionuclides have been produced artificially in the cyclotron, the nuclear
reactor, the neutron generator and linear accelerator. Radiopharmaceuticals are drugs that contain a radionuclide and are used for
imaging if the radionuclide is a photon emitter (gamma-g or positron-b+) or for
therapy if the radionuclide is a particle emitter (alpha-a or beta-b- or
Auger/conversion e-).
Prof. A. Roodt