Radioactivity

Abstract

Maria Sklodowska Curie and Pierre Curie in 1898 gave the name radioactivity to describe the phenomenon of penetrating radiation emitted by uranium and thorium. This chapter provides the basic information about the radioactivity phenomenon and specifically discusses radioactivity as a natural process by which an unstable radioactive atom becomes stable by the emission of charged sub-atomic particles (β ⁻ , β ⁺ ,α) and electromagnetic radiation (γ rays). In a process known as fission, unstable atoms of some heavy elements may even break up into two lighter radionuclides. Radioactive decay is a statistical process, described mathematically using an exponential function. This chapter also provides a brief description of the units of radioactivity (Curie and Becquerel), half-life, the mathematics of parent-daughter relationships in radionuclide generator systems, and the concept of specific activity (Ci or GBq/μmol), which is a very important parameter in radioisotope based molecular imaging.