Sterilisation by irradiation

Abstract

Sterilisation refers to any process that eliminates/inactivates transmissible infectious agents. There are two main types of sterilisation physical and chemical one. Radiation sterilisation is a physical process based on the action of radiation energy with the matter. The term ionising radiation covers all types of radiations carrying the energies capable to produce cascades of ionisations in the matter. Sterilisation efficacy of ionising radiation lies in its good penetrability in the matter followed by killing effect on pathogens. For that reason irradiation became a very frequently used sterilisation method in tissue banks that decided to use terminal sterilisation of non-viable tissue grafts. Authors describe in the chapter types of irradiation used for sterilisation of human tissue grafts: electromagnetic rays e.g. gamma and X-rays and corpuscular radiation e.g. fast moving mono-energetic electrons. Following subchapters are focused on the specificity of radiation sterilisation with gamma rays and electron beams, then dosimetry methods applied for radiation sterilisation are described. Detailed mechanisms of action involved in the inactivation of micro-organisms is the next raised very important issue. As an important topic in tissue banking practice radiation resistance of micro-organisms is also described. Finally, factors affecting the effectiveness of radiation sterilisation and the sensitivity of micro-organisms to irradiation are discussed.