Potential Radiation Exposure in Military Operations Protecting the Soldier Before, During, and After (1999) / Chapter Skim
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2 Fundamentals of Radiation Safety and Protection
2 Fundamentals of Radiation Safety and Protection
Pages 23-41
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From page 23... ...
Consequently, alpha particles emitted by radioactive materials are not likely to be harmful when striking the outside of a human body Throughout this report, the term radiation refers to ionizing radiation and does not include radiation from nonionizing sources, such as lasers and radiofrequency generators.
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From page 24... ...
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, whereas x rays are most commonly encountered in the use of radiation-producing equipment used in medical applications (including those in combat medical facilities)
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From page 25... ...
Equivalent Dose The dosimetric quantity that accounts for the differences in biological effectiveness of various types of radiation and that allows doses from different radiations to be combined, through expressing their health effects on a common basis, 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 26... ...
The effective dose (that is, the dose to the whole body that represents an equivalent risk) is estimated by multiplying the equivalent dose in each tissue type by its corresponding tissue weighting factor and summing these weighted equivalent tissue doses.
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The first type measures the radiation exposure or dose to which personnel may be subjected. This category of instrument includes devices such as microroentgen meters and ion chambers.
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From page 28... ...
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 29... ...
Apart from routine occupational exposures, the only exposure of large numbers of U.S. military personnel to radiation has been to the approximately 400,000 service members who either were in the occupation forces near Nagasaki and Hiroshima, Japan, at the close of World War II or participated in the aboveground nuclear test program conducted between 1945 and 1962.
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From page 30... ...
The primary means of protection from internal radiation exposure is to prevent radioactive materials from entering the body in the first place. Appropriate respiratory protection can prevent the inhalation of airborne radioactive materials.
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From page 31... ...
However, some tissues, such as lymph nodes, which can accumulate radionuclides to high concentrations and which can receive high radiation doses, are much less susceptible to radiation-caused cancers than other tissues, such as red bone marrow. For a tissue to be affected by radiation it must be directly irradiated.
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From page 32... ...
TABLE 2-3. Estimated Threshold Doses for Deterministic Effects of Acute Radiation Exposure Health Effect Organ Dose (mSv)
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From page 33... ...
Other factors that influence the expression of the deterministic effects of radiation include the region of the body irradiated and variation between individuals in their physiologic responses to radiation. A small group of deterministic effects tends to appear beyond the characteristic early (2-month)
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From page 34... ...
Examples of populations in which these associations have been found include the Japanese atomic bomb survivors, some groups of individuals who have lied medical diagnostic or treatment exposures, and some occupationally exposed individuals. Although many people were exposed to significant radiation doses after the accident at the Chernobyl nuclear power plant in the former Soviet Union, the follow-up for these individuals is not yet sufficiently long to allow these data to be used to predict the incidence of various cancers induced by radiation exposure.
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From page 35... ...
. Dose Range Covered by the Guidelines in This Report Risks estimated by a commander are based upon estimated doses for that mission; however, the commander should be aware than an individual's radiogenic cancer risk is a function of his or her cumulative radiation doses including those incurred prior to an anticipated mission.
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From page 36... ...
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From page 37... ...
For a given absorbed dose, high LET types of radiation, such as neutrons and alpha particles, are more effective than low LET types, such as gamma and x rays, in inducing malignancies. Dose Rate and Magnitude Dose rate and dose magnitude have significant effects on malignancy induction, particularly for low LET radiation.
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From page 38... ...
Groups of people exposed to radiation in this way have a higher risk of developing thyroid cancer than unexposed groups. Heritable and In Utero Effects On the basis of a review of data for the children and grandchildren of Japanese atomic bomb survivors, there is no significant evidence of an increased incidence of heritable abnormalities following radiation doses.
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From page 39... ...
of Different Tissues to Radiation-Induced Cancer 39 High Bone marrow (leukemia other than chronic lymphocytic leukemia) Breast (female)
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From page 40... ...
For radiation protection purposes, it is assumed, in the absence of data for humans exposed to very low radiation doses, that there is no dose of radiation below which there is no increased cancer risk. Thus, the risk for 100 mSv (10 rem)
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From page 41... ...
In his conclusions in the Annals of the ICRP, Upton states, "On the basis of the latest evidence summarized in the reports from UNSCEAR and BEIR V, the task group concludes that the life time excess risk of fatal cancer for a member of the general population exposed to low dose rate whole-body irradiation can be assumed to average approximately 5 per cent per sievert" (Upton, 1991, pp.
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