TY - CHAP M1 - Book, Section TI - Toxic Effects of Radiation and Radioactive Materials A1 - Hoel, David G. A2 - Klaassen, Curtis D. A2 - Watkins, John B. PY - 2021 T2 - Casarett & Doull’s Essentials of Toxicology, 4e AB - KEY POINTSThe four main types of radiation are due to alpha particles, electrons (negatively charged beta particles or positively charged positrons), gamma rays, and x-rays.Alpha particles are helium nuclei (consisting of two protons and two neutrons), with a charge of +2, that are ejected from the nucleus of an atom.Beta particle decay occurs when a neutron in the nucleus of an element is effectively transformed into a proton and an electron, which is ejected.Gamma-ray emission occurs in combination with alpha, beta, or positron emission or electron capture. Whenever the ejected particle does not utilize all the available energy for decay, the excess energy is released by the nucleus as photon or gamma-ray emission coincident with the ejection of the particle.The Compton Effect occurs when a photon scatters at a small angle from its original path with reduced energy because part of the photon energy is transferred to an electron.Ionizing radiation loses energy when passing through matter by producing ion pairs (an electron and a positively charged atom residue).Radiation may deposit energy directly in DNA (direct effect) or may ionize other molecules closely associated with DNA, hydrogen, or oxygen, to form free radicals that can damage DNA (indirect effect). SN - PB - McGraw Hill CY - New York, NY Y2 - 2024/03/29 UR - accessbiomedicalscience.mhmedical.com/content.aspx?aid=1178016738 ER -