**1. Introduction**

114 Gamma Radiation

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The sources of radiation are so varies, some of them are natural and others are man-made. Also the types of radiation can be categorized according to their wave length or energy or even to the ability of ionizing the media.

Non-ionizing radiation is electromagnetic radiation that does not have sufficient energy to remove the electrons from the outer shell of the atom. Types of non-ionizing radiation are: ultra violet (U/V), Visible light, infrared (IR), microwave (radio and television), and extremely low frequency (ELF, or as they called EMF or ELF-EMF). Non-ionizing radiations produced by a wide variety of sources at homes and in the workplaces, form lasers to power lines, tanning beds to household appliances, cellular phones to home radios (Smith F. A. 2000).

Ionizing Radiation: refer to the types of radiation that has capability to ionize the media directly or indirectly such as X-ray, γ-ray and neutron.
