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Biomedical subjects

V K Ivanov

Publications and source records attributed to V K Ivanov.

At least 37 records · Page 2Linked to original sources
PubMed1997

Exposure levels for persons involved in recovery operations after the Chernobyl accident. Statistical analysis based on the data of the Russian National Medical and Dosimetric Registry (RNMDR).

We present a detailed description of dosimetric data entered in the Russian National Medical and Dosimetric Registry (RNMDR) for emergency workers (liquidators) involved in recovery operations (RO) after the Chernobyl accident. The data on the absorbed doses from external exposure are based on the documents given to liquidators by organizations that performed dosimetric monitoring in the zones of operation. Using the data on external doses currently available in the RNMDR for 119,416 liquidators (78.4% of the total number of 152,325 persons), different statistical characteristics were derived to assess the reliability of the information. The paper also discusses dose distributions according to the date of beginning work in the RO zone [up to 250 km from the Chernobyl nuclear power plant (NPP)], on the distance of the settlement where the liquidators were accommodated or worked from the NPP, and on the duration of their stay in the RO zone. To analyse the reliability of the dosimetric data, the notion of an effective exposure dose rate (EEDR), i.e. the ratio of the dose registered in RNMDR and the duration of stay in the RO zone, was introduced for each liquidator, and corresponding statistical characteristics for the distribution of EEDR depending on the date of entry into the RO zone and distance from the place of residence or work to the NPP were obtained. The analysis for different groups of liquidators shows that the dosimetric information of the RNMDR is, as a statistical aggregate, generally consistent with the data on the radiation situation in the RO zones.

Data Interpretation, Statistical↗
PubMed1997

Cancer risks in the Kaluga oblast of the Russian Federation 10 years after the Chernobyl accident.

Cancer morbidity and mortality were studied in areas of the Kaluga oblast contaminated with radionuclides. The main objective of the study was to assess the influence of radiation exposure on existing levels of cancer morbidity and mortality. Time trends and relative population risks were analysed. Based on this analysis, it was concluded that the current levels of morbidity from cancers among the populations residing in the studied areas were primarily a result of a complex of factors which predated the exposure from the Chernobyl accident. However, there seems to be an unfavourable trend concerning malignant neoplasms of the respiratory organs for women residing in the contaminated areas. To date, no statistically significant effect of radiation on cancer morbidity (except for thyroid cancer in women) has been noted. The levels of cancer morbidity and mortality in the contaminated areas generally reflect the changes in cancer incidence in the oblast as a whole. The findings are consistent with international data on latent periods for the induction of radiogenic cancers and the biological effects for similar levels of exposure to populations residing in contaminated territories. Further studies are necessary in order to monitor possible effects that are related to the accident.

Female↗
PubMed1997

Thyroid cancer among "liquidators" of the Chernobyl accident.

In 1986, immediately after the Chernobyl accident, the USSR Ministry of Health adopted a large scale programme of establishing an All-Union Distributed Registry of persons affected by radiation due to the accident. The registry was based at the Medical Radiological Research Centre of the Russian Academy of Medical Sciences (MRRC RAMS). In 1992, when the USSR was dissolved, this registry database contained information on 659,000 persons, including 284,000 Chernobyl accident emergency workers ("liquidators"). Currently, the Russian National Medical Dosimetric Registry (RNMDR) contains data on 435,276 persons, including 167,862 liquidators. This paper reviews the data for 47 verified thyroid cancers in the liquidator subgroup of the RNMDR. Analyses show that there is an excess relative risk of thyroid cancer per Gy of 5.31 (95% confidence intervals 0.04 and 10.58) and an excess absolute risk of thyroid cancer per 10(4) person-years per Gy of 1.15 (95% confidence intervals 0.08 and 2.22).

Adult↗
PubMed1997

[Oncoepidemiologic situation in the Kaluga region of the Russian Federation ten years after the Chernobyl accident].

Cancer morbidity and mortality in radionuclide-contaminated areas of Kaluga Region have been investigated. The study was mainly concerned with the extent of radiation pollution influence on the present-day cancer morbidity and mortality rates. The correlations between the latter factors, on the one hand, and relevant population risks, on the other, have been analysed. It was found that the present-day neoplasm morbidity rates recorded in Chernobyl-stricken areas are chiefly accounted for by a combination of factors which were there before the disaster. The trends of morbidity and mortality from neoplasms of the respiratory tract in females are still unfavorable. There is still no statistical verification of the radiation effect on cancer morbidity except that of thyroid cancer in women in contaminated areas. The morbidity and lethality rates in these areas basically conform to the general trends. The findings are in conformity with those reported worldwide on radiation-related cancer induction latency and biological effects observed in the inhabitants of contaminated regions.

Female↗
PubMed1996

The Chernobyl accident and radiation risks: dynamics of epidemiological rates (morbidity, disability and death rates) according to the data in the national registry.

Ten years have elapsed since the Chernobyl accident. The gravest technologically generated accident throughout human history has attracted considerable attention from the whole world community. At the same time, the problem of estimating the total damage to life and health of people exposed to radiation remains very complicated. The negative effects of Chernobyl include a spectrum of factors which may reinforce each other. In particular, to date there are no theoretical models or practical recommendations on estimating the contribution of the social, psychological or emotional factors that surround diseases due to radiation accidents. On the other hand, for maximum effective rehabilitation of the affected population, the impartial determination of the contribution by both radiation and non-radiation components is necessary. Therefore, the continuation of long-standing investigations within the framework of the National and Radiation and Epidemiological Registry along with obtaining new scientific data in the field of radiation epidemiology is of great practical importance in limiting the health consequences of the accident.

Adolescent↗
PubMed1996

[The results of medical and dosimetric research on the population and on those who worked in cleanup subjected to radiation exposure as a result of the Chernobyl catastrophe].

The Russian State Medical and Dosimetric Register (RSMDR) of subjects exposed to radiation due to the Chernobyl accident and a radiation epidemiological analysis of the data collected are described. At present, RSMDR covers 435,000 persons including 152,000 participants in the liquidation of the accident consequences (liquidators). Predictive estimates (based of the models recommended by the International Commission of Radiation Protection) and the actual data obtained 9 years after the accident are compared. It has been found that within 20 years after radiation in a cohort of liquidators an attributive risk for leukemia and for solid cancers will be 23.6 and 2.8%, respectively. The actual data after 10 years correspond with the predictive estimates. According to disability and morbidity rates, the 1986-1987 liquidators represent a high-risk group. Radiation epidemiological examinations for thyroid cancer in children (at the moment of the Chernobyl accident) were made in the Bryansk and Kaluga Regions. The relative risk for detected cancers was ascertained to be 7.15. This signifies that about 90% of the thyroid cancers detected are caused by a radiation factor.

Air Pollution, Radioactive↗
PubMed1992

[Characteristics and results of the determination of the doses of internal irradiation of the thyroid gland in the population of contaminated districts of the Byelorussian Republic].

The authors provide the results of studying the reconstruction of individual doses of thyroid radiation among the community living in polluted areas of the Byelorussian Republic according to radiation monitoring data and with regard to the nature of radioactive pollution of the land. Every individual result of estimating the degree of thyroid radiation was characterized by 3 magnitudes: the lower and upper limit of possible values and by the intermediate (basic) value. The authors hold that studies of the correlations between the values of individual doses of thyroid radiation and different parameters of the radiation situation in every region will promote further specification of individual doses of thyroid radiation.

Accidents↗
PubMed1991

[Survival of patients after combined treatment for rectal cancer].

The analysis of end results of treatment of rectal cancer showed combined therapy to assure long survival in the whole group of radically operated cases, viz. two-third of them survived 10 years. Conversely, mean survival of non-operated or surgically palliated patients was as low as 10.1 and 26.7 months, respectively. Survival of radically operated cases was found to be related to various clinico-anatomic factors, the most close relationship being observed for extent, histology and growth pattern of tumor and regional nodal status. The influence of site and surgical procedure on patient survival proved far less significant.

Adult↗
PubMed1991

[Functional status of the pituitary-thyroid system in children and adolescents exposed to radiation as a result of the accident at the Chernobyl Nuclear Power Station].

The paper is concerned with the results of a follow-up over the period of 1986-1989 of function of the hypophyseo-thyroid system in children and adolescents (approximately 6000 persons), residing in the South-West of the Kaluga Region, where radiation fallouts were observed after the Chernobyl accident. The results were based upon the analysis of medical examinations and determination of the blood levels of TSH, T4 and T3. A certain functional activation of the thyroid system was observed in a majority of the examinees. A conclusion has been made of a necessity of a long-term follow-up of the thyroid of persons who received radioactive iodine in childhood.

Accidents↗
PubMed1990

[The absorbed dosage and its fractionation in the radiation treatment of tumors in children].

Radiation therapy is widely used in pediatric oncology. Its use emphasizes the problems of the protection of growing tissues and organs. The paper is concerned with the problem of effective distribution of an ionizing radiation dose delivered to a locally advanced tumor in children. Analysis of the literature and authors' data show that the growing organs of a child are 2-2.5-fold more sensitive than the same organs of an adult. Besides some organs and tissues at various ages of a child possess a various degree of maturity. Therefore it is proposed that small single doses (0.6-1 Gy) that can be delivered 2-3 times a day, should be used in pediatric oncology. A scheme of dynamic irradiation of radiosensitive and resistant tumors of children was prepared and tested under clinical conditions.

Child↗
PubMed1987

[Dose multifractionation in radiotherapy of laryngeal cancer].

A study was made of the comparative results of radiotherapy of 332 laryngeal cancer patients of whom 237 were treated by routine methods and 95 by multifractionation (double fractionation of a daily dose by 1 Gy with a 4-5 h interval). The method of dose multifractionation was mathematically substantiated. Direct efficacy of radiotherapy was assessed in the delivery of a dose of 40 Gy. A radical dose of irradiation was 66-70 Gy. At 40 Gy complete tumor resorption in the patients of the control group was noted in 33.3% of the cases, in the study group in 58.9%. The 3-year recurrence- and metastasis-free survival rate after radical radiotherapy was 47.4% in the control group and 65.3% in the study group. A decrease in the number of late postradiation edema of the laryngeal mucosa from 28.7% in the control group to 8.7% in the study group was noted.

Humans↗
PubMed1987

[Mathematical models in clinical radiobiology and optimization of the radiotherapy of tumors].

A mathematical model was developed in the system of tumor-normal tissues. It reflected the main radiobiological factors and regularities of tumor growth kinetics: heterogeneity of cell populations with relation to radiosensitivity and a tendency to proliferation, the effects of reoxygenation. Using a package of RADON applied programs optimum irradiation regimens were obtained simultaneously for single doses and intervals of interfractional recovery. Optimum irradiation regimens were shown to be dynamic fractionation of a total dose and the entire period of treatment.

Cell Survival↗