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Radiation sickness

Radiation sickness is a disease caused by ionizing radiation (see Ionizing Radiation). The clinic of radiation sickness depends on the exposure conditions: exposure (see) can be external - the whole body or most of it - and internal, when radioactive substances (see Isotopes) through the respiratory tract or the digestive tract get inside the body, accumulate in it and such way create foci of permanent exposure of the body. Thus, radioactive strontium accumulates in the bones, radioactive cesium in muscles and other tissues, radioactive yttrium in the liver, radioactive iodine in the thyroid gland , radioactive phosphorus in the bone marrow.

The basis of the pathogenesis of radiation sickness are dysfunctions of all organs and systems, but the most important, determining the development of various clinical syndromes, is damage to the central nervous system and hemodynamics, damage to the gastrointestinal tract; suppression of physiological tissue regeneration and toxemia.

There is an acute form of radiation sickness (acute radiation syndrome) that occurs with a single intensive (several hundred happy) exposure, a lightning-like form resulting from exposure in doses of the order of several thousand rad, and a chronic one that develops with prolonged exposure to the organism in small doses.

Radiation sickness is a complex clinical syndrome that develops under the influence of ionizing radiation.

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The first descriptions of radiation sickness relate to occupational radiation injuries in radiologists and radiologists, as well as in people exposed for therapeutic purposes. In the future, health problems have become known for workers with radiation sources. After the use of nuclear weapons and their tests (1945), massive radiation injuries arose. In addition, there were observed lesions of individuals as a result of accidents, mainly when operating in atomic reactors.

Pathogenesis
The development of radiation sickness is the final stage in a chain of processes that begin with the interaction of radiation with tissues, cells and liquid media in a complex system of the whole organism (see Radiobiology).

The specific features of the action of individual types of radiation are mainly determined by the difference in penetrating power, the number of ionization acts per unit volume of tissue, and the length of the particle’s path. The development of changes at the molecular level and the formation of chemically active compounds leads to intensive exchange transformations. The appearance in the blood of products of pathological metabolism under the action of high doses of radiation is the basis of radiation toxemia. Of great importance are disorders of the processes of physiological regeneration of a number of tissues, as well as changes in the functions of the nervous and endocrine systems, which forms the clinical syndrome of radiation sickness.

Proved a great sensitivity to the effects of radiation of hematopoietic tissue, spermatogenic epithelium, epithelium of the skin, intestines. Especially large is the damaging effect of radiation on systems that are in a state of active organogenesis and differentiation (the nervous system of the embryo, fetal bone, etc.). The effect of radiation on organs and systems depends on the level of radiation doses and the dose distribution over time. In the whole organism, especially when it is irradiated in small doses, individual reactivity, the initial functional state of the nervous and endocrine systems, as well as congenital or acquired inferiority of other organs, are of great importance.

The course of radiation sickness is divided into three periods: formation, recovery, and long-term consequences or outcomes (GD Baysogolov and AK Gus'kova). Depending on the nature of the exposure (single massive or prolonged repeated in relatively small doses, local or total exposure), acute and chronic radiation sickness of varying severity is distinguished with a predominance of local or general changes. The formation of the disease occurs, as a rule, in the period of contact with radiation sources and as soon as possible after its termination. The recovery period is from 2 to 5 years after cessation of exposure (or has eaten a significant reduction in its intensity).