FIGURE 90.10 Types of radiation Alpha particles have a 2+ electrical charge and a large mass (two protons and two neutrons) Beta particles have a single negative charge and a small mass (one electron) Charged particles not penetrate the body very well Because of their larger mass and charge, alpha rays cannot penetrate even the dead layers of skin 239Pu (plutonium), an alpha emitter, is a biologic hazard only when it is inhaled, ingested, or otherwise introduced into the body Beta particles (“beta rays”) are more penetrating and in high doses can severely damage the skin Beta rays cannot damage the deep radiation-sensitive organs in the body unless the radioactive source is incorporated into the body At the Chernobyl nuclear plant accident in Ukraine, some of the firefighters had severe skin damage due to intense beta particle exposure, which contributed to their deaths The words “radiation” and “radioactive” are often confused An atom that is unstable spontaneously gives off energy as radiation and is therefore radioactive In contrast, an x-ray machine cannot spontaneously give off radiation: an external power source is needed Therefore, an x-ray machine is not radioactive A patient