| During the nuclear and radiological emergency, internal exposure due to radionuclides inhaled through respiratory tract is the main mechanism by which health harms are caused to human body. Rapid screening of large groups of internally contaminated people near the site according to detection limits deduced from the extent of inflicted hurt is one of the most important tasks facing the implementation of medical emergency response to radioactive materials. Based on that ,the research set up a pilot method for rapidly measuring radionuclides in the body near the site using in vivo counting techniques.In the research work, various possible nuclear and radiological events were analyzed and possibly inhaled radionuclides were determined. The activity measuring standard of radionuclides in the lung were further set up according to the probability of stochastic effects. For the convenience of measurement, three activity detection limits and corresponding action levels—1mSv,10mSv,50mSv were established, which set basis for in vivo counting and medical diagnosis.For the purpose of measurement, the portable gamma spectroscopy system were used to set up lung counting method in the research work. Experiments and Monte Carlo simulation were combined to evaluate the counting efficiency of NaI(T1) and HPGe detectors for point soureces , volume sources and anthropomorphic phantoms. Related efficiency curves and functions have been fitted and optimal counting geometry determined. The most rational counting time have been found by comparing detection limits and MDA.The ICRP66 human respiratory tract biokinetic model was applied in the last part of the research. The method for calculating IRF(t) of three types of aerosols:F,M,S using Mathematica software have been established. Through IRF(t), the measurement results at any moment have been linked with the initial intake. Then the extent of nuclear and radiological harm can be determined and corresponding disposition action be initiated. |
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