Radiation Safety Units

Dose Equivalent (DE)—A quantity used in radiation safety practice to account for the relative biological effectiveness of the several types of radiation. It expresses all radiations on a common scale for calculating the effective absorbed dose. It is defined as the product of the absorbed dose in rad and certain modifying factors. (The unit of dose equivalent is the rem. In SI units, the dose equivalent is the sievert, which equals 100 rem.)... 

Rem—A unit of dose equivalent that is used in the regulatory, administrative, and engineering design aspects of radiation safety practice. The dose equivalent in rem is numerically equal to the absorbed dose in rad multiplied by the quality factor (1 rem is equal to 0.01 sievert). 

This Report is one of the series developed under the auspices of Scientific Committee 46, a scientific program area committee of the National Council on Radiation Protection and Measurements (NCRP) concerned with operational radiation safety. The Report provides practical recommendations on the use of personal monitors to estimate effective dose equivalent (Hg) and effective dose (E) for occupationally-exposed individuals. The Report is limited to external exposures to low-LET radiation. Recent additions to the radiation protection literature have made the recommendations possible. In order to avoid delay in utilizing the recommendations in the United States, the quantity as well as E, has been included until such time as the federal radiation protection guidance and associated implementing regulations are revised to express dose limits in E as recommended by the NCRP. 

In this chapter, we will follow this convention of using units of Gy and rad when we are concerned about the short-term risk of skin burns, radiation sickness, or fatal radiation injury that results from acute radiation exposure and using units of Sv and rem when we discuss the risk of developing cancer many years or decades after the radiation exposure, or when we are discussing compliance with radiation safety regulations. 

The information contained in this section deals with radiation safety for users of analytical x-ray systems. It was developed by the Environmental, Safety, Health and Assurance Office of the United States Department of Energy Ames Laboratory. In the content of this book it is intended to raise awareness about the potential dangers associated with the continuous or acute exposure to x-ray radiation and has no legal force. Each workplace where analytical x-rays are used should have a set of established policies and... 

In this special case, additional approval is needed from the national authorities overseeing radiation safety. For example, in the United Kingdom this is the Administration of Radioactive Substances Advisory Committee (ARSAC). Application to ARSAC only requires a summary of the study protocol, but a careful scientific justification of the amount of radiation employed and the number of subjects exposed. The EU Directive 97/43/EurATOM sets dose limits for healthy subjects and patients. 

Accidents. Any incidents involving radioactive sources should be reported to the unit s radiation safety officer (RSO). They should inform the license manager the incidents. 

Anyone working with any t)rpe of radiation must take precautions. Radiation safety is required, monitored, and enforced in the United States imder provisions of the Occupational Safety and Health Act (OSHA). 

The performance of a diagnostic X-ray machine should be checked at least annually with appropriate instruments by a qualified person. If the capability to do this is not available in-house, a qualified consultant should be hired to do the task. If any maintenance is done or if the machine is relocated, a survey should be undertaken for leakage radiation fromthe source. If the unit is moved to another facility, the exposure levels in the adjacent areas should be tested to ensure that the exposure levels are within the permissible limits forcontrolled and uncontrolled areas. Records of all maintenance, surveys, leakage checks, calibration, personnel monitoring, etc. should be maintained at the facility and at the radiation safety office. Because of the long latency period for cancer developing from radiation exposures, it would not be unreasonable to maintain personnel exposure records for up to 40 years. 

I. Radiation — Safety measures. I. International Atomic Energy Agency. II. Food and Agriculture Organization of the United Nations. III. Series. 

FEDERAL NUCLEAR AND RADIATION SAFETY AUTHORITY OF THE RUSSIAN FEDERATION, Recommendations on In-depth Safety Assessment of Operating Nuclear Power Units with WWER and RBMK Reactors (OUOB AS), Rep. RB-001-97 (RB G-12-42-97), Moscow (1997) (in Russian). 

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