Experimental and analytical evaluation of body's reaction to small doses of radiation

Full text: The aim of this work is to develop the method of evaluating the body's reaction to small doses of radiation. The task evolved from the fact that presently the evaluation of the possible radio-biological consequences at small doses is based on the linear extrapolation model of the effects of cancerous and genetic damage. The model, valid for a certain range of large doses, may be significantly overestimating the risk at small doses since the question of the existence of a threshold of such effects is still open. On the other hand, at small radiation doses (or of other toxic agents), changes in the characteristics of the general body systems are not impossible, pointing at the possibility of the formation and development of pathological effects at later times. An evaluation of such changes allows us to follow the body's reaction during preventive and inpatient X-ray treatments, and can be used for dynamic control and adjustment of the treatment. The analytical method employs an image recognition technique, which is based on non-static evaluation and cluster analysis. The object of the study is the blood-generating system of the body as the most sensitive, highly informative and having a large number of quantitative parameters that are convenient for a mathematical description. The full Automatic Classification System (ACS) consists of a testing apparatus (10-18 parameters) and a computer processing unit with a multi-functional program. The ACS method has been used for the evaluation of the consequences of irradiation of 125 liquidators in the aftermath of the Chernobyl accident, using a two-state classification system 'healthy-sick'. In accordance with the changes in their blood parameters, 113 workers have been classified as sick. A wider study of 1300 people living in contaminated areas of the Bryansk region with known dosages of prolonged irradiation, using a four-state classification system, allowed us not only to evaluate the body's reaction, but also to work out the dose-effect dependency in the effective dose range of 5-100 mSv, which is described by an non-linear function with two plateaus. A similar study has been carried out in the conditions of a single X-ray irradiation of patients in the range of 5-20 mSv. It should be noted that the ACS method does not diagnose an illness, but helps to determine the degree of deviation of the body from the normal and its predisposition to develop an illness, allowing the doctors to do preventive treatments. Thus, the ACS method allows us to determine the reaction of the body to small doses of radiation (up to 200 mSv) that leads to an increase in the probability of general somatic illnesses. (author)