辐射剂量 The Sievert 1 Sv =1 joule/kilogram The rem is defined since 1976 as equal to 0.01 Sievert. Background Radiation Exposures in the US Yearly dose of radiation absorbed per person (world average) Radon Natural Sources 229mrem/yr Man-made Sources Cosmic 3Imrem Terrestrial from cosmic rays 19mrem/yr 0.4mSv Internal radiation 31mrem/yr absorbed internay Consumer Products yearly dose 13mrem/yr from of radiation the earth from 0.5msv natural sources 2.4mSv inhaled Nuclear Medicine Mewane (mostly radon) 74mrem/yr 1.2msv from food Medicai Procedures 223mrem/yr 0.3msv The average annual radiation dose to the general population is 620 mrem/yr from natural background and man-made sources. 材料科学与工程学院 School of Materials Science and Engineering材料科学与工程学院 School of Materials Science and Engineering 辐射剂量 The Sievert 1 Sv = 1 joule/kilogram The rem is defined since 1976 as equal to 0.01 Sievert. The average annual radiation dose to the general population is 620 mrem/yr from natural background and man-made sources. Background Radiation Exposures in the US