Introduction to Radiation: Radiation Types ©Health Physics Society

Introduction to Radiation Objectives To provide useful information about radiation for interested individuals To introduce basic concepts of radiation and radioactivity Improve understanding of radiation – what it is and how it interacts

Types of Ionizing Radiation Alpha Particles Stopped by a sheet of paper Beta Particles Stopped by a layer of clothing or less than an inch of a substance (e.g. plastic) Gamma Rays Stopped by inches to feet of concrete or less than an inch of lead Radiation Source

An alpha particle consists of two protons and two neutrons Very large on an atomic scale Positively charged Penetration in materials Outside the body, an alpha emitter is not a hazard unless it is on the skin Inside the body, an alpha emitter is a bigger hazard if it deposits its energy in sensitive tissue Radiation Types - Alpha

Common alpha-particle emitters Radon-222 gas in the environment Uranium-234 and -238) in the environment Polonium-210 in tobacco Common alpha-particle emitter uses Smoke detectors Cigarettes/cigars Static eliminators Radiation Types - Alpha

A beta particle is a charged electron Has the size and weight of an electron Can be positively or negatively charged Penetration in materials At low energies, a beta particle is not very penetrating – stopped by the outer layer of skin or a piece of paper At higher energies, a beta particle may penetrate to the live layer of skin and may need 0.5 of plexiglass to be stopped Radiation Types - Beta

Penetration in materials, continued Inside the body, a beta particle is not as hazardous as an alpha particle because it is not as big Because it is not as big, it travels farther, interacting with more tissue (but each small piece of tissue gets less energy deposited) Radiation Types - Beta

Common beta-particle emitters Tritium (hydrogen-3) in the environment Carbon (14) in the environment Phosphorus (32) used in research and medicine Common beta-particle emitter uses Carbon dating Basic research Cancer treatment Radiation Types - Beta

A photon is an x or gamma ray Has no weight Has no charge Penetration in materials At low energies, a photon can be stopped by a very thin (almost flexible) layer of lead or several centimeters of tissue At higher energies, inches of lead might be necessary to stop a photon and they can pass right through a human Radiation Types - Photon

Common photon emitters Cesium (137) Technetium (99m) used in medicine Iodine (131) used in medicine Common photon emitter uses Determining the density of soil Diagnosing disease Cancer treatment Radiation Types - Photon

99m Tc Excited Nucleus Gamma ray 99 Tc Stable Nucleus Photon Decay

Physical Radionuclide Half-Life Activity Use Cesium yrs 1.5 x 10 6 Ci Food Irradiator Cobalt-60 5 yrs 15,000 Ci Cancer Therapy Plutonium-23924,000 yrs 600 Ci Nuclear Weapon Iridium days 100 Ci Industrial Radiography Hydrogen-3 12 yrs 12 Ci Exit Signs Strontium-9029 yrs 0.1 Ci Eye Therapy Device Iodine days Ci Therapy Technetium-99m 6 hrs Ci Imaging Americium yrs Ci Smoke Detectors Radon days 1 pCi/l Environmental Examples of Radioactive Materials