Neutron Dosimetry By Blood Activation Of Radiated Human Body In Nuclear Terror Attack

Objective The chief task of medical rescue against nuclear accidents is to determine the exposure radiation dose so as to collect dosimetry data efficiently for the following classification, diagnosis and medical treatment. During the common process of determining the radiation dose, it is difficult to measure the neutron dose, which becomes the hotspot and difficult point of nuclear and radiation medical emergency rescue research. This paper aims to build a set of technical methods which can measure the exposure neutron dose of human body precisely and quickly, as well as to develop a set of measuring device.Method The isotope of 23Na contained in the human blood will becomes the radioactive isotope 24Na through capturing thermo neutrons. The quantity of gamma photons emitted by the decay of 24Na is measured,then is converted to the activity. A rough estimation of the exposure radiation dose can be estimated by using the specific activity-neutron dose coefficient. A multiple of factors that affect the dose estimation are analysed , and are used to correct the neutron dose.Results In simulating experiments, by measuring the blood samples with the NaI detector, both the characteristic peak with and without background of 24Na are found. After reducing the interference of theγpeak of 1.461MeV 40K from the background, it is found that the absolute activity of the collected 3mL blood samples is 14.8Bq. After using the effective activity, the dose transfer coefficient, provided by ORNL in the calculation, it founds that the dose is 1.94~2.82Gy.Conclusion This paper focuses on the method of estimating the neutron dose of human body after exposing to neutron radiation by measuring the activatory blood. The following are the details:1. It analyzes the technical process of human neutron radiation dose estimation after exposure, summarizing a whole method for human dose estimation.2. It concludes a standard neutron dose measuring flow for nuclear medical emergency rescue.3. By analyzing the effective activity-neutron dose transfer coefficient and the influencing factors, the chief effecting factors are found, and the regulating technical method and theory are suggested. Five factors are provided with correcting value or data.4. Simulating experiments on developing the portable blood neutron radiation dose inspection device is made. And the feasibility of its design principle and measuring technology are verified.5. A set of portable blood neutron radiation dose measuring device is developed. Two improving advices for the development of blood-contained Na measuring device are pointed out. One is that the shielding room has great influence on the portability of the device, and the other is that the available dose transfer coefficient data is not enough, and more experiments should be done on the development of devices and more related dose transfer data in different situations should be cumulated.This paper aims to regulate the neutron dose measuring flow, with which a quick standard measurement can be achieved in the site scene of an accident; meanwhile, a set of portable neutron dose measuring devices are developed and related adjustment experiments are made.