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Biomedical subjects

V A Zolotov

Publications and source records attributed to V A Zolotov.

6 recordsLinked to original sources
PubMed1995

Relative biological effectiveness of proton medical beam at Moscow synchrotron determined by the Chinese hamster cells assay.

PURPOSE: Assessment of relative biological effectiveness (RBE) of the proton medical beam at Moscow synchrotron. METHODS AND MATERIALS: The study was performed at Moscow proton medical facility (Institute for Theoretical and Experimental Physics). Relative biological effectiveness of the synchrotron proton beam was assessed at the entry of the unmodulated 179 MeV beam and in the center of spread out Bragg peak (SOBP), from measurements of the survival of Chinese hamster cells (clone 431). Gamma-radiation of 60Co was used as a reference source. RESULTS: According to the linear regression model, mean RBE values at 37% survival level were found to be 1.10 +/- 0.04 at the beam entry and 1.14 +/- 0.05 in the center of SOBP. Values of RBE obtained using the linear-quadratic model for 10% and 37% survival levels were 1.09 and 1.07, respectively, at the beam entry and 1.07 and 1.08, respectively, in the center of SOBP. CONCLUSIONS: The data obtained indicate that (a) the RBE values at the entry of the unmodulated beam and at the center of the SOBP are in close agreement, with an average of about 1.10; (b) protons are radiobiologically somewhat more effective than 60Co gamma rays; and, (c) high pulse dose rate of the medical beam does not significantly affect biological effects of the beam.

Animals↗
PubMed1990

[Hyperglycemia as a means of increasing the efficacy of hyperthermia in radiotherapy of tumors].

In experiments on mice with Ehrlich carcinoma transplanted into the thigh the authors determined a gain in tumor heating from the use of induced hyperglycemia (IH) during thermoradiotherapy. Tumors were irradiated at a dose of 20 Gy followed in 3 h by local hyperthermia (HT) by emerging a tumor into water at 40-45 degrees C for 30 min. IH followed irradiation (i.e. 3 h before HT) in the form of 5-time ip administration of glucose at a total dose of 10.4 g/kg for 2 h. Isoeffective tumor damage was achieved in irradiation combined with HT (45 degrees C) only and in irradiation with subsequent IH and HT (40 degrees C), i.e. a gain in the temperature of heated water as a result of glucose use was 5 degrees C. In the independent use (without irradiation) of HT this value was equal approximately 2.5 degrees C. Thermometric investigations have shown that these effects are partially accounted for by better heating (by 0.2-0.4 degrees C) of tumor tissue in IH. However glucose action was mainly connected with resultant physiological changes in tumors like a noticeable decrease in pH and stable disorder of the blood flow.

Animals↗
PubMed1990

[Ultrasonic hyperthermia during radiotherapy of experimental tumors].

The paper is devoted to the development of an experimental device and methods for controlled ultrasound hyperthermia of animal tumors and to the estimation of a radiomodifying effect of ultrasound hyperthermia in radiation therapy of neoplasms as compared to the effect achieved in a water bath. Experiments were staged on mice with transplantable Ehrlich's carcinoma. Marked and approximately equal in value enhancement of radiation action on malignant tumors with the DMF of ionizing radiation of 1.3-1.4 was obtained with both methods of tumor heating (ultrasound and in a water bath). The results obtained indicate the advisability of a practical use of ultrasound heating in radiation therapy of tumors.

Animals↗
PubMed1987

[Spiral comb filter].

The paper is concerned with some considerations on ridge filters used for proton beam therapy. Such filters are able to transform the beam energy spectrum and the corresponding Bragg curve defining proton beam depth dose distribution. Some difficulties in the manufacture of ridge filters are discussed. The authors describe a ridge filter design which is simple and fit for continuous production. An account of a calculation method and production process is given.

Filtration↗
PubMed1984

[Hypoxic proton radiotherapy of solid Ehrlich tumors with different dose magnitudes].

The paper is devoted to an experimental evaluation of the efficiency of hypoxiradiotherapy with irradiation of tumors by protons at different dose rates. In experiments performed at ITEP synchrotron it has been shown that the use of the hypoxic gas mixture containing 6% O2 for breathing appreciably diminishes the degree of skin reactions with only weak tumor protection. It is concluded that the use of hypoxic hypoxia during proton irradiation afford the same advantages as during gamma- or x-ray therapy. The skin protection can be also achieved by use of ultra-high dose rate and in this case it is associated with radiochemical depletion of oxygen. This effect may be used for the improvement of radiotherapy of malignant tumors.

Animals↗