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24 May 2012

Answer to Question #412 Submitted to "Ask the Experts"

Category: Radiation Basics — Radiation Quantities and Units

The following question was answered by an expert in the appropriate field:

When and by whom were Standard International (SI) radiation dose units created? In what areas of the world are SI units used? Please name a few major countries. What use of SI units is being made in the United States today? What is the origin of the names "gray" and "sievert"? Thanks for your help.

The answers for the gray and sievert can be found in answers to other questions on this site; look at Q4745 for the gray. See Q583 for the sievert.

Question: "In what areas of the world are SI units used?" Most of the world, outside of the United States, uses the SI quantities and units for radiological protection. A few major countries include France and Great Britain.

Question: "What use of SI units is being made in the United States today?" In the Nuclear Regulatory Commission and Department of Energy regulations, the SI units are given in parentheses after the old units, e.g., 5 rem (0.05 Sv). The SI units (and quantities) are employed in most papers published in the scientific literature (U.S.), e.g., Health Physics. Many government publications also employ the SI system of units, e.g., the Environmental Protection Agency Federal Guidance Reports. The two key documents on SI units are ICRU Report 60 Fundamental Quantities and Units for Ionizing Radiation, Bethesda, Maryland (1998), and ICRU Report 51 Quantities and Units in Radiation Protection Dosimetry, Bethesda, Maryland (1993).

Paul Frame, CHP, PhD

Editor's Note: ICRU Reports can be ordered from the ICRU website.

Answer posted on 31 October 2000. The information and material posted on this website is intended as general reference information only. Specific facts and circumstances may alter the concepts and applications of materials and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice specific to whatever facts and circumstances are presented in any given situation. Answers are correct at the time they are posted on the Website. Be advised that over time, some requirements could change, new data could be made available, or Internet links could change. For answers that have been posted for several months or longer, please check the current status of the posted information prior to using the responses for specific applications.