**1. Introduction**

Radiation can be divided into two groups, namely *ionizing radiation* and *nonionizing radiation*. While ionizing radiation of sufficient energy is able to ionize the atoms of the matter with which it interacts, nonionizing radiation has not this ability. In general, **ionizing radiation**—particles or electromagnetic waves—carries enough energy to knock electrons from atoms or molecules, thereby ionizing them. The result is a positive ion and a free electron, which may be later attached to a neutral atom, thus forming a negative ion.

An illustration of nonionizing and ionizing radiation wavelengths (from the left with increasing values to the right) is shown in **Figure 1** (based on [1]).

In principle, ionizing radiation can be directly ionizing radiation (charged particles) and indirectly ionizing radiation represented by photons (gamma, X-ray, annihilation photons) and neutrons. The interaction of this radiation can also result in

### **Figure 1.**

*Nonionizing and ionizing photon radiation.*

positive and negative ions and free electrons, which were created by secondary charged particles released by the interaction of indirectly ionizing radiation with matter. It means that indirectly ionizing radiation is ionizing the matter through the charged particles released by such interactions as photoeffect, Compton effect, and pair production. Neutrons themselves cannot directly ionize atoms. They do it through charged particles released as a result of their interaction with matter.

This chapter will deal *only with ionizing radiation* (further only as radiation). As to its interaction with matter, the following processes should be considered:


Radiation is emitted by sources, which may be in the principle of two categories: *radioactive sources* and *radiation generators*. Radioactive sources (radionuclides) produce radiation that produces, as a result of the decay of unstable nuclei, radiation continuously, and the process cannot be stopped. Radiation generators (X-ray tubes and charged particle accelerators) produce radiation only when appropriate conditions are created. This requires a power supply from outside. When the supply is disconnected or switched off, the production of radiation will be stopped.

These features of two different radiation sources have a significant implication for radiation protection. On one side, we have sources that continuously emit radiation whether we use them, transport or store them, and we have to keep them under control all the time. As to radiation generators, the care for radiation protection is much simpler since when they are not in operation practically, no protection measures should be in place.

For safety reasons, it is important to use standard warning signs in places where radioactive sources, radioactive or nuclear waste, and radiation generators are present (**Figure 2**).

The term radiation protection is used universally with the meaning of radiation safety or radiation security. Strictly speaking, one may apply these terms in a more specific manner: radiation safety is related to ensuring people and the environment *Basic Radiation Protection for the Safe Use of Radiation and Nuclear Technologies DOI: http://dx.doi.org/10.5772/intechopen.108379*

**Figure 2.** *Radiation warning signs, a) a universal sign, b) a new symbol of radiation presence (based on [2, 3]).*

against harmful effects of radiation emitted by the source, while radiation (nuclear) security is associated with providing sufficient protection of the source of radiation against a person who may not be aware of the source or who may use it to commit a malevolent or terrorist attack.
