An Evaluation of Radiation Exposure Guidance for Military Operations Interim Report (1997) / Chapter Skim
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2 Principles of Radiation Protection
2 Principles of Radiation Protection
Pages 13-24
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From page 13... ...
Consequently, alpha particles are not likely to be s Throughout this report, the term radiation refers to ionizing radiation and does not include nonionizing radiation sources, such as lasers and radiofrequency generators.
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From page 14... ...
Gamma rays are characteristic of a wide variety of radioactive contaminants associated with nuclear weapons and nuclear waste and also with radioactive sources used in medicine and industry, while x rays are most commonly encountered in medical applications (including those in combat medical facilities)
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From page 15... ...
Equivalent Dose The dosimetric quantity that accounts for the differences in biologic effectiveness of various types of radiation and allows doses from different radiations to be combined is called the equivalent dose. It is calculated by multiplying the absorbed dose by the appropriate radiation weighting factor, "WR" (ICRP, 1991a)
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From page 16... ...
that describe the sensitivity of different tissues. Tissue weighting factors facilitate combining doses to allow quantitative comparison of long-term risk from partial body exposure to that from total body exposure.
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From page 17... ...
However, these instruments are not usually calibrated for alpha and beta particles, so the instrument reading may not be accurate for them. A Geiger-Mueller detector is primarily designed to measure the number of alpha, beta, or gamma rays emanating from a source and striking the detector in a given time.
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From page 18... ...
Natural sources of radiation constitute the major source of radiation exposure to the populations of most, if not all, countries, with the next largest source being applications of medical technology. In the United States the average annual effective dose of naturally occurring background radiation is about 3 mSv (0.30 rem)
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From page 19... ...
Since the volume of the DNA is very small compared with the total volume of the cell, the probability of this occurring is low. Indirect damage occurs when radiation interacts in close proximity to the genetic material the interaction can create a free radical in water that can subsequently damage DNA.
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From page 20... ...
. The type and severity of deterministic effects depend upon the type of ionizing radiation involved, the magnitude of the dose, and the rate at which the dose is accumulated (dose rate)
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From page 21... ...
The likelihood of alpha and beta emitters deposited inside the body causing generalized symptoms of radiation exposure early in the postexposure period is minimized by their limited penetrating power, which restricts their biological effectiveness to nearby cells.
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From page 22... ...
nodules in thyroid gland and female breast tissue, several types of cancer (e.g., lung, thyroid gland, and female breast) , and all forms of leukemia except chronic lymphocytic leukemia have been strongly associated with external exposure to ionizing radiations, primarily at high dose rates.
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From page 23... ...
Studies of cancer mortality among radiation workers whose exposures were controlled by stringent radiation protection standards (i.e., at low doses and low dose rates) yield risk estimates consistent with those derived for low doses and low dose rates from studies of cancer mortality among atomic bomb survivors (Cardis et al., 1995~.
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From page 24... ...
However, the duration of internal exposure may be reduced by increasing the rate of excretion of the radioactive material through elimination of body fluids or solids. The primary means of protection from internal radiation exposure is to prevent radioactive materials from entering the body in the first place.
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