ABSTRACT
Sources of ionizing radiation are inside and surrounding all the time and everywhere. This radiation comes from radionuclides which occur naturally as trace elements in rocks and soils of the earth as a consequence of radioactive decay. Radionuclides also exist in the atmosphere, lithosphere, hydrosphere, and biosphere. The chapter deals with three main themes: interactions of radiation with matter, radiation detectors, and radioactivity analysis of environmental and food samples. A radiation detection system is composed of a detector, signal processor electronics, and a data output display device such as a counter or multichannel analyzer. The backbone of any radiation detection system is the radiation detector. Radioactivity analysis of food and environmental samples is a very significant task in any radioecological study and the accuracy of the measured natural and artificial radionuclide concentrations affects the study conclusions and the consequent recommendations for environmental and human protection.
