RESUMEN

B. L. Cohen showed that lung cancer lethality in U.S. sharply contradicts linear no-threshold (LNT) dependence on lung dose. This conclusion undermines established theory and practice for estimation of the irradiation remote risk; therefore, an unusual discussion has risen. Cohen's opponents (LNT adherents) said that he substituted the mean risk in a county for the individual risk that resulted in inadmissible bias of results. However, his critics' conclusions contradict many results found by Cohen and investigations by other authors.

Asunto(s)

RESUMEN

The present paper describes results of the first independent evaluation of the accuracy of the dose-reconstruction technique by electron paramagnetic resonance using tooth enamel. Each of twenty-four teeth donated by Mayak nuclear workers with known occupational radiation exposure histories was cut into two parts so that each tooth could be shared for blind electron paramagnetic resonance examination by at least two of the four laboratories participating in the study. The mean difference (+/- SD) between electron paramagnetic resonance estimates of the paired samples of each tooth shared by the two laboratories in best agreement was 0.02 +/- 0.15 Gy. Mayak workers can be classified into two groups: modern workers (after 1961) having reliable official dose information and earlier nuclear workers whose dose information is less reliable because they were exposed mainly before 1961. Film badges did not contain filters until 1954. Doses in this earlier group are much higher (up to 5 Gy). Comparison of the electron paramagnetic resonance results with tooth doses calculated from official film-badge doses showed a close agreement for the first group, whereas in the second group, official doses appeared to be slightly higher than the electron paramagnetic resonance doses. The results suggested a possibility that the official doses were somewhat overestimated among the high-dose-exposed workers. Consequently, cancer risks derived from this high-dose group might tend to be slightly underestimated.

Asunto(s)

RESUMEN

An epidemiological study has been carried out among 1,479 male workers who started working at the "Mayak" Production Association in 1948-1958 and were exposed to external gamma radiation and plutonium aerosols. Lung cancer mortality for the follow-up period 1948-1993 has been analyzed. No statistically significant association of lung cancer mortality and external gamma-ray dose has been revealed in the range of accumulated doses of 0.2-5.5 Gy. Association of lung cancer mortality and the dose of alpha-particle radiation to the lung is statistically significant. In the dose range below 30 Sv, this association can be described in terms of a linear nonthreshold function. Lifetime lung cancer risk in the dose range below 30 Sv is 1.21 x 10(-2)Sv(-1).

Asunto(s)

RESUMEN

The accepted linear no-threshold (LNT) dose response for stochastic effects is not valid even for the cellular level. Published data on the human radiation carcinogenesis demonstrate now the radiation hormesis or the absence of effects or its reduction in the whole low dose interval when a dose rate is decreased. This is demonstrated for leukemia and for lung, breast, thyroid, bone, skin and liver solid cancers, for such organs, which are responsible in the more, than 1/2 of cancer detriment postulated by the ICRP. It is possible valid for the whole of solid cancers and for nontumorogenic death.

Asunto(s)

Asunto(s)

RESUMEN

Radiation receivers used in medicine for image visualization and measuring the radiation characteristics are considered. The main attention is focussed on modern image converters for x-ray diagnosis and thermoluminescent detectors for dosimetry.

Asunto(s)

RESUMEN

On the basis of the results of radiobiological studies on acute nonuniform irradiation of the animal's abdomen a dose dependence has been found for the duration of the injury to barrier properties of the small intestine epithelium, T(D). With relative coordinates x = D/LD50 and y = T (D)/T(LD50), this dependence may be represented by a single function for various animal species.

Asunto(s)

RESUMEN

Using different quality coefficients as functions of LET, generalized equivalent doses were calculated, and the survival of dogs after gamma/neutron irradiation was determined using the concept of an equivalent dose. LET functions of the generalized quality coefficients providing a good agreement between theoretical and experimental results were chosen. Various functions of the generalized quality coefficients for different ingredients of bone-marrow haemopoiesis activity should be used to estimate the severity of radiation injury to red bone marrow.

Asunto(s)

RESUMEN

The notion of "a generalized equivalent dose" was introduced in order to use an equivalent dose as a dosimetric criterion for the estimation of acute exposure to densely ionizing radiation. The generalized quality coefficients that were used to quantify a generalized equivalent dose depended on LET, and with gamma/neutron radiation, on neutron energy. Several possible LET functions of the generalized quality coefficients were chosen and mean quality coefficients were transformed, depending on neutron energy, and estimated for actual neutron energy distributions, used in radiobiological experiments, with due regard for the alteration in the neutron spectrum with the body depth.

Asunto(s)

Asunto(s)

RESUMEN

A set of differential equations is proposed reflecting the time-dependent postirradiation changes that occur in the quantitative composition of various cell pools within the cell regeneration system of the small intestine epithelium. The solution of the equations permits to find a dose dependence of the time of reduction in the number of the epithelium functional cells below a threshold level and to obtain in equal dose.

Asunto(s)

RESUMEN

Dynamics of cell regeneration in the small intestine epithelium of man has been investigated in normal conditions and after acute exposure to ionizing radiation. It is suggested that the severity and outcome of the intestinal form of acute radiation sickness are determined by the time interval within which the number of functional cells of the epithelium villi remains below some threshold level that provides the retention of barrier properties of the small intestine.

Asunto(s)

Asunto(s)

RESUMEN

It was shown that shielding of a relatively small area of the bone marrow during acute total--body irradiation of dogs permitted to obtain a prognosticated constant increase in the survival rate within a wide range of doses exceeding the minimal absolutely lethal ones.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)