injuries poisoning
Radiation Exposure and Contamination
Types of radiation
Radiation includes High-energy electromagnetic waves (x-rays, gamma rays) Particles (alpha particles, beta particles, neutrons) Alpha particlesare energetic helium nuclei emitted by some radionuclides with high atomic numbers (eg, plutonium, radium, uranium); they cannot penetrate skin beyond a shallow depth (<0.1 mm). Beta particlesare high-energy electrons that are emitted from the nuclei of unstable atoms (eg, cesium-137, iodine-131). These particles can penetrate more deeply into the skin (1 to 2 cm) and cause both epithelial and subepithelial damage. Neutronsare electrically neutral particles emitted by a few radionuclides (eg, californium-252) and produced in nuclear fission reactions (eg, in nuclear reactors); their depth of tissue penetration varies from a few millimeters to several tens of centimeters, depending on their energy. They collide with the nuclei of stable atoms, resulting in the emission of energetic protons, alpha and beta particles, and gamma radiation. Gamma radiation and x-raysare electromagnetic radiation (ie, photons) of very short wavelength that can penetrate deeply into tissue (many centimeters). While some photons deposit all their energy in the body, other photons of the same energy may deposit only a fraction of their energy, and others may pass completely through the body without interacting. the body; only tissue in close proximity to the radionuclide is affected. Gamma rays and x-rays can cause damage distant from their source and are typically responsible for Acute radiation syndromes (ARS) . Acute radiation syndromes can be caused by a sufficient dose of some internally deposited radionuclides that are widely distributed in tissues and organs and have a high specific activity. For example, polonium-210 (Po-210) has a specific activity of 166 terabecquerels per gm (TBq/g), and 1 mcg (about the size of a grain of salt) of Po-210 delivers a whole body dose of 50 Sv (~20 times the median lethal dose). 