Dose equivalent, rem

The current federal guidelines for occupational exposure to ionizing radiation in the United States are in the Code of Federal Regulations, Part 1910.96. They stipulate that personnel working in the area where ionizing radiation is produced should not receive in any period of a calendar quarter more than the following dose equivalents (rem) ... 

Dose equivalent (rem) is a measure of biological damage that is calculated by multiplying absorbed dose by quality factor for the type of radiation involved. The unit of dose is the rem. The TEDE (total dose equivalent) is a term that combines the effects of both the internal and external exposures. 

In the old system of units, exposure was described as radiation absorbed dose rad), dose equivalent (rem), roentgen (R), or Curie (Ci). The official system of measurement, the International System of Units (SI), uses the Gray (Gy) and Sievert (Sv), where 1 Gy = 100 rad and 1 Sv = 100 rem. 1 Gy corresponds to 1 J of energy deposition in 1 kg of material. It should be noted that the Gray (and rad) are purely physical quantities reflecting the amount of absorbed radiation, while the Sievert (and rem) reflects the biological effect of the absorbed radiation and depends on the radiation type and energy. 

Ra.dia.tlon Units. Units in use for activity of a radionucHde, ie, the curie, the roentgen (exposure to x and gamma rays), the rad (absorbed dose), and the rem (dose equivalent), should eventually be replaced by the becquerel (Bq), coulomb per kilogram (C/kg), gray (Gy), and the sievert (Sv), respectively. 

The former (non-SI) unit of dose equivalent was the roentgen equivalent man (rem), which was defined in the same way as the sievert but with the absorbed dose in rad thus, 1 rem = 10 2 Sv. 

A 2.0-kg sample absorbs an energy of 1.5 J as a result of its exposure to (1 radiation. Calculate the dose in rads and the dose equivalent in rems and in sieverts. 

Someone is exposed to a source of p radiation that results in a dose rate of 1.0 rad-d. Given that nausea begins after a dose equivalent of about 100 rem, after what period will that symptom of radiation sickness be apparent ... 

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). 

Sievert (Sv)—The SI unit of any of the quantities expressed as dose equivalent. The dose equivalent in sieverts is equal to the absorbed dose, in gray, multiplied by the quality factor (1 sievert equals 100 rem). 

Dose equivalent or rem is a special radiation protection quantity that is used, for administrative and radiation safety purposes only, to express the absorbed dose in a manner which considers the difference in biological effectiveness of various kinds of ionizing radiation. The ICRU has defined the dose equivalent, H, as the product of the absorbed dose, D, and the quality factor, Q, at the point of interest in biological tissue. This relationship is expressed as H = D x Q. The dose equivalent concept is applicable only to doses that are not great enough to produce biomedical effects. 

MeV. WL-R = 100% x WL/radon concentrations (pCi/1). The dose conversion factor of 0.7 rad/working level month (WLM) (Harley and Pasternack, 1982) was used to calculate the mean absorbed dose to the epithelial cells and a quality factor (OF) of 20 was applied to convert the absorbed dose to dose equivalent rate. For example, from the average value of (WL) obtained from the arithmetic mean radon concentrations measured in the living area during winter and summer in South Carolina (Table I), the calculated dose equivalent rate is 4.1 rem/yr, e.g.,... 

Rem Radiation Equivalent Man the unit of dose equivalence commonly used in the United States. 

High radiation area Accessible area where radiation levels could allow an individual to receive a dose equivalent in excess of 0.1 rem (1 mSv) in 1 hour at 30 centimeters from the radiation source or from any surface the radiation penetrates. 

Rem (Roentgen equivalent in man) Special unit of any quantity expressed as a dose equivalent the dose equivalent in rems is equal to the absorbed dose in rads multiplied by the quality factor (1 rem = 0.01 Sv). 

A patient with a large amount of radioactive material imbedded in a wound warrants special attention because the material could cause a significant exposure hazard to treatment personnel. Dose equivalent rates from fragments resulting from the explosion of a nuclear reactor may be as high as 100 rem per hour.1 The symptoms that may be displayed by individuals exposed to weapons of mass destruction are presented in Tables 3.2 and 3.3. 

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