Radiation is part of our everyday lives. In addition, we create and use sources of radiation for medical uses in the diagnosis and treatment of injury and disease. The word radiation is general and includes light, radio waves, and electric fields. These are examples of non-ionizing radiations, whose energies are lower than ionizing radiation. They do not affect matter in the same way.
All matter is made up of atoms.
The basic parts of atoms are neutrons, protons, and electrons. An atom of a particular element has a unique number of protons in its nucleus. Alpha particles are completely absorbed by the outer dead layer of skin and is therefore not a hazard outside the body. If alpha particles are taken into the body by inhalation or with food or water, they can directly expose internal tissues and can be a hazard. Beta particles are more penetrating than alpha particles and can sometimes penetrate the skin, but like alpha particles, they are generally more hazardous when inhaled or ingested.