Radiation protection estimate

NCRP115 = National Council on Radiation Protection and Measurements. 1993. Risk Estimates for Radiation Protection, Report 115. Bethesda, Maryland NRC = Nuclear Regulatory Commission. 

Some cancers are caused by exposure to the sun or to naturally occurring radioactive isotopes. The estimated cancer incidence caused by these combined exposures is approximately 0.5 to 1.0 percent during a lifetime, with two-thirds of the exposure stemming from radon alone (Kocher and Hoffman 1991,1989 National Council on Radiation Protection and Measurement 1987,15,53 International Commission on Radiological Protection 1991, 188). 

Section 1 of the Report presents the quantities Hz and E and the relationship of each quantity to its corresponding radiation protection system. Section 2 describes the use of personal monitors for workers in the United States, including their calibration and how they are worn on individuals in various occupational settings. Section 3 discusses practical ways to use one or two personal monitors to obtain estimates of Hz and E. Section 4 provides the NCRP s... 

The useful criteria introduced earlier for radiation protection purposes are that the estimate of He should (1) not be much less than the actusd He U-C., Htiest mate)/HE between 0.9 and 1.0] to avoid underestimating He by much, and (2) not be much higher than the actual He [i.e., He (estimate)///e not much greater than 2.0 to 3.0] to avoid seriously overestimating He- How the various results in Table 3.1 compare to these criteria for each irradiation geometry and algorithm is summarized in Table 3.2. 

Table 3.2—Comparison of H (estimate) /values from Table 3.1 to criteria for radiation protection purposes. 

The criteria for a desired formula for E for radiation protection purposes are (1) minimize the underestimates of E, even at the expense of larger overestimates of E for some conditions, and (2) obtain a close estimate of E at the combination most frequently encoimtered in clinical practice (i.e., 90 kVp, 0.5 mm lead equivalent apron and imdertable x-ray tube) (Rosenstein and Webster, 1994). 

SC 1-5 Uncertainty in Risk Estimates SC 1-6 Basis for the Linearity Assumption SC 1-7 Information Needed to Make Radiation Protection Recommendations for Travel Beyond Low-Earth Orbit SC 9 Structural Shielding Design and Evaluation for Medical Use of X Rays and Gamma Rays of Energies Up to 10 MeV SC 46 Operational Radiation Safety... 

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. 

Albert. R.E. (1983) The acceptability of using the cancer risk estimates associated with the radiation protection standard of 5 lems/year as the basis for setting protection standards for chemical carcinogens with special reference to vinyl chloride, Report to Ministry of Labor, Occupational Health and Safety Division, Ibronto, Ontetrio, Canada (Ministry of Labor, Occupational Health and Safety Division, Ibronto, Ontario, Canada). 

Boice, J.D., Jr., Beebe, G.M. and Land, C.E. (1985a). Absolute and relative time-response models in radiation risk estimation, page 22 in the Proceedings of the Tluentieth Annual Meeting of the NatioruU Council on Radiation Protection and Measurements, NCRP Proceedings, No. 6, (National Council on Radiation Protection and Measurements, Bethesda, Maryland). 

SC 1-2 Risk Estimates for Radiation Protection Medical X-Ray. Electron Beam and Gamma-Ray Protection for Enei gies Up to 50 MeV—Equipment Performance and Use X-Ray Protection in Dental Offices... 

The nominal probability coefficient for radionuclides normally used in radiation protection is derived mainly from maximum likelihood estimates (MLEs) of observed responses in the Japanese atomic-bomb survivors. A linear or linear-quadratic dose-response model, which is linear at low doses, is used universally to extrapolate the observed responses at high doses and dose rates to the low doses of concern in radiation protection. The probability coefficient at low doses also includes a small adjustment that takes into account an assumed decrease in the response per unit dose at low doses and dose rates compared with the observed responses at high doses and dose rates. 

First, the threshold for hazardous chemicals that cause deterministic effects is assumed for purposes of health protection to represent a lower confidence limit, taking into account uncertainties in the dose-response relationship (see Section 3.2.1.2.7). Depending, for example, on the slope of the dose-response relationship near the threshold, the chosen steps in the dosing regimen, and the magnitude of uncertainties in the data, the lower confidence limit of the assumed threshold can be substantially below MLE. In radiation protection, the estimated thresholds for deterministic effects are based on MLEs of dose-response relationships (ICRP, 1991). 

Establishing an acceptable risk or dose. There also are a number of precedents for establishing an acceptable (barely tolerable) risk or dose of substances that cause stochastic responses for the purpose of classifying waste as low-hazard or high-hazard. For radionuclides, the annual dose limit for the public of 1 mSv currently recommended by ICRP (1991) and NCRP (1993a) and contained in current radiation protection standards (DOE, 1990 NRC, 1991) could be applied to hypothetical inadvertent intruders at licensed near-surface disposal facilities for low-hazard waste. This dose corresponds to an estimated lifetime fatal cancer risk of about 4 X 10 3. Alternatively, the limits on concentrations of radionuclides in radioactive waste that is generally acceptable for near-surface disposal,... 

Sir Edward Pochin (1978) Why be Quantitative about Radiation Risk Estimates Hymer L. Friedell (1979) Radiation Protection-Concepts and Trade Offs Harold O. Wyckoff (1980) From Quantity of Radiation and Dose to Exposure and Absorbed Dose -An Historical Review James F. Crow (1981) How Well Can We Assess Genetic Risk Not Very Eugene L. Saenger (1982) Ethics, Trade-offs and Medical Radiation Merril Eisenbud (1983) The Human Environment-Past, Present and Future Harald H. Rossi (1984) Limitation and Assessment in Radiation Protection John H. Harley (1985) Truth (and Beauty) in Radiation Measurement Herman P. Schwan (1986) Biological Effects of Non-ionizing Radiations ... 

Uncertainties in Fatal Cancer Risk Estimates Used in Radiation Protection (1997)... 

As with other metals, barium is probably very poorly absorbed from the gastrointestinal tract. The International Commission for Radiation Protection (ICRP) estimates that the gastrointestinal absorption of barium is less than 5% (ICRP 1973). This percentage is supported by studies of two men whose daily input and fecal excretion were monitored for 50 weeks (Tipton et al. 1969). 

The 10-R exposure recommended by BEAR included an estimated 5 R from medical radiation, with the remainder derived from all other radiation. The National Council on Radiation Protection and Measurements (NCRP) immediately accepted this recommendation in its report, issued in January 1957. It stated that the population dose "shall not exceed 14 million man-rems per million of population over the period from conception up to age 30 and one-third that amount in each decade thereafter." The age of 30 yr is the approximate average age of reproduction. Background radiation was assumed to be about 4 million rems per million persons and medical radiation about 5 million... 

National Council on Radiation Protection and Measurements, Evaluation of Risk Estimates for Radiation Protection Purposes, Report 115, NCRP, Bethesda, MD, 1993 Protection against Radon-222 at Home and at Work, ICRP Publ. No. 65, Pergamon, Oxford, 1993 A. Kaul, W. Kraus, A. Schmitt-Hannig, Exposure of the Public from Man-made and Natural Sources of Radiation, Kemtechnik 59, 98 (1994)... 

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