Exposure, radiation external

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

Using the miner data for this purpose may be overestimating the risk due to indoor exposure, since it includes risks from simultaneous exposure to external gamma radiation, long lived alpha emitters. This effect, however, may be outweighed by the fact... 

CLAYCAMP, H.G. (1996). Optimisation of monitor weighting factors for the estimation of effective dose equivalent from external photon exposures, Radiat. Prot. Dosim. (in press). 

Therapeutic Procedures Therapeutic procedures—those in which radiation is used to kill diseased tissue—can involve either external or internal sources of radiation. External radiation therapy for the treatment of cancer is often carried out with y rays from a cobalt-60 source. The highly radioactive source is shielded by a thick lead container and has a small opening directed toward the site of the tumor. By focusing the radiation beam on the tumor and rotating the patient s body, the tumor receives the full exposure while the exposure of surrounding parts of the body is minimized. Nevertheless, sufficient exposure occurs so that most patients suffer some effects of radiation sickness. 

Radiation Safety Guide. 1999. Occupational radiation exposure monitoring External monitoring. http //www.nih.gov/od/ors/ds/rsb/rsguide/orem.htm. 

Notice that the atomic number in the equation decreases by two while the mass number decreases by four. Alpha particles have very low penetrating ability because they are large and soon collide with other matter. Exposure to external sources of alpha radiation is usually harmless. However, if substances that undergo alpha decay are ingested or inhaled, the radiation can be quite damaging to the body s internal organs. 

Inhalation slope factors are central estimates in a linear model of the age-average, lifetime attributable radiation cancer incidence (fatal and nonfatal cancer) risk per unit of activity inhaled, expressed as risk per picocurie (pCi). qExternal slope factors are central estimates of the lifetime attributable radiation cancer incidence risk for each year of exposure to external radiation from photon-emitting radionuclides distributed uniformly in a thick layer of soil, expressed as risk/year per pCu per gram of soil. 

Air sampling is required around nuclear facilities and in populated areas that may be exposed to elevated radionuclide levels to evaluate radiation exposure from external or inhaled radionuclides. Airborne radionuclides may be in the form of a gas, vapor, or particles. Different sampling techniques are employed depending on the radionuclide of interest, its form, and the sample volume required to reach the detection limit. Samples may be collected at fixed stations or from vehicles moving on the ground or in the air. 

Management must promptly report to the worker and the regulatory agency any unusually elevated radiation exposures—both external and internal—or concentrations of hazardous chemicals, and institute changes in the work environment to prevent continuing exposures that reach exposure limits. The IH/CHO or RSO/RCM staff must be instrumental in achieving such changes. The exposure must be recorded with a description of the causes and instituted remedies. 

Because it decays by gamma radiation, external exposure to large sources of Co-60 can cause skin burns, acute radiation sickness, or death. Most Co-60 that is ingested is excreted in tlie feces however, a small amount is absorbed by the liver, kidneys, and bones. Co-60 absorbed by the liver, kidneys, or bone tissue can cause cancer because of exposure to the gamma radiation. 

British) Medical Research Council papers from its Committee on Protection Against Ionizing Radiations, as follows Maximum permissible dietary contamination after the accidental release of radioactive material from a nuclear reactor. Brit. Med. J. 1,967-969 (1959) Maximum permissible contamination of respirable air after an accidental release of radioiodine, radiostrontium and caesium 137. Brit. Med. J. ii, 576-579 (1961) Report on emergency exposure to external radiation, in Hazards to Man of Nuclear and Allied Radiations, Appendix K, Cmnd 1225, HM Stationery Office, London, I960. 

Under the Q system a series of exposure routes are considered, each of which might lead to radiation exposure, either external or internal, to persons in the vicinity of a Type A package involved in a severe transport accident. The dosimetric routes are illustrated schematically in Eig. I.l and lead to five contents limit values Q, Qg, Q, Qp and Qg, for external photon dose, external beta dose, inhalation dose, skin and ingestion dose due to contamination transfer, and submersion dose, respectively. Contents limits for special form alpha and neutron emitters and tritium are considered separately. 

The influence of the earth s electromagnetic radiation on water by electrochemical method is analyzed in Chapter 15. The aim and scope of this analysis are to search for a new concept of mechanism of mild exposure of external factors on physical-chemical properties of water. 

Recognize that radiation can be hazardous (and that it is different from chemical hazards) and recognize the potential for exposures to external and internal radiation sources. 

As part of the investigation of integrated human exposure to natural radiation, external penetrating radiation absorbed dose rates in air were determined both indoors and outdoors in communities where previous geological and geochemical studies indicated the elevated uranium and thorium content of the local rocks (Table 8) [73]. In the comparison to world averages, the estimated total (gamma + cosmic)... 

One important purpose of monitoring is to provide data that permit the analysis and evaluation of human radiation exposure. For this purpose, programmes for monitoring radionuclides in the environment should focus on pathways of human exposure. An exposure pathway defines routes from a source of radionuclides and/or radiation to a target individual or a population through media in the environment. There are two main categories of exposure pathway external exposure pathways (the source of exposure remains outside the body) and internal exposure pathways (the source of exposure is incorporated into the body). 

The hazard proposed by radiation exposures depends to a large extent on the combination of radiation quality (alpha, beta, gamma) and the exposure pathway. External exposure to radionuclides is of concern only if it results from gamma emitters because they can penetrate tissue and deliver a deep dose of radiation. Alpha- and beta-emitting radionuclides only pose a significant hazard when inhaled or ingested because their energy is deposited locally in tissues and cells. 

Protection against exposure from external radiation is achieved through the application of three principles shielding, distance or time. In practice... 

Assess worker exposure to external gamma radiation, the inhaled and ingested radioactive dust, and alpha radiation from radon and estimate the total dose of ionizing radiation to which workers may be exposed. 

Even if the resirlting dose is below that associated with the recording level, the measirrement resirlts shoitld always be maintained in the radiation monitoring records for the workplace and for the individrral [17] (see also Section 8). In cases of worker exposure to external radiation or to mrrltiple radionuclides, management may decide to reduce the derived levels for individrral radionuclides appropriately. 

Ainsbury, E.A., Bakhanova, E., Barquinero, J.F., et al., 2011. Review of retrospective dosimetry techniques for external ionising radiation exposures. Radiat. Prot. Dosim. 147 (4), 573-592. 

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