[Radionuclide diagnosis of upper urinary tract patency in patients with cancer of the cervix uteri ].

The experience with dynamic renal scintigraphy has shown its high informative value and safety in evaluating the degree of intrarenal urine outflow disorders. However, failure to make an objective assessment of ureteral patency considerably limits its study. The set of studies, which is given in this paper, is devoted to precisely this, highly urgent, problem. The authors have developed an original procedure for diagnosing impaired urine outflow along the ureters during dynamic renal scintigraphy. The visual and digital characteristics of normal and impaired urine outflow in the supravesical segment are defined. The criteria characterizing severe impairments of renal urine derivation along the ureters are denoted. Risk factors for urine outflow disorders are identified in patients with cancer of the cervix uteri, who receive various treatment modalities.

[A model for the age-dependent dynamics of growth of terrestrial mammals]. / Model' vozrastnoi dinamiki rosta sukhoputnykh mlekopitaiushchikh.

Two hypothetical biological mechanisms were proposed that largely determine the dynamics of growth of overland mammals. The first mechanism is the maintenance of a spatial similarity of the anatomy of the organism during its growth, and the second is the maintenance of the stability of the internal environment of the organism. On the basis of the advanced hypothesis, a model of age-dependent dynamics of growth was constructed, and a differential equation describing the changes in the body mass with time was derived. According to this model, the dynamics of growth and the mass of an adult individual are determined by two energy constants that characterize the mechanism of food assimilation and the energy expenditures for the movement of the individual in space. The deviation between the solution obtained and the experimental data on age-dependent changes in the mass of the human body was on the average 6%. These insignificant deviations were explained in the framework of the proposed hypothesis, which indicates its validity.

131I content in the human thyroid estimated from direct measurements of the inhabitants of Russian areas contaminated due to the Chernobyl accident.

The method of processing and the results of measurements of 131I content in the thyroids of Russian people performed in May-June 1986 are presented. The contribution of radiation from Cs radionuclides in the human body was taken into account in the processing of measurement data with an SRP-68-01 device. The greatest individual 131I content was found in the thyroids of inhabitants of the Bryansk region, up to 250-350 kBq, and in the Tula and Orel regions, up to 100 kBq. The average 131I thyroid activity in the middle of May 1986 reached 80 kBq for inhabitants of some settlements in the Bryansk region, 5-8 kBq in the Tula region and 5 kBq in the Orel region.

[Energetic model for formation of cellular mass]. / Energeticheskaia model' formirovaniia massy kletki.

Based on the law of conservation of energy, a differential equation describing changes with time in the mass of a dividing cell was obtained. A mathematical expression for the greatest possible value of the mass of an infinitely long growing cell that does not enter the process of division was derived. This value depends on the correlation between the energy constants characterizing the rate of the entrance of substances into the cell and the expenditures for the transport of substances inside the cell. A relationship between the time of the cell division cycle and these constants was established. For a population of dividing cells, the density of their distribution by mass was determined. The efficiency of a dividing and a specialized cell was studied. Within the framework of the energy approach, possible reasons predetermining the real value of the cell mass were considered. A hypothesis was advanced that cell realizes the strategy of maximum productivity. It was found that, for this strategy be realized, the optimum mass of a parent cell at the end of mitotic division should be 39% of its greatest possible value, and that of a specialized cell should be 29.6% of its respective greatest possible value. Thus, only a third of the energy equivalent of the biological mass consumed by both a dividing and a specialized cell fall on useful work. Methodical aspects of the experimental verification of these results are considered.

[The limited value of non-linear inner space of gamma-chamber]. / Predelnoe znachenie vnutrennei prostranstvennoi nelineinosti gamma-kamery.

The main sources of an error resulting from the derivation of a matrix for correcting the space nonlinearity of a gamma--chamber. The maximum probability method was used to make a mathematical evaluation of the low bound of absolute space nonlinearity (ASNL). Recommendations are given how to choose the modes of measurements of and the methods of calculation of the matrix correction elements ensuring the required ASNL value.

[The dynamics of the content of incorporated cesium radionuclides in the population of regions with an elevated background radiation]. / Dinamika soderzhaniia inkorporirovannykh radionuklidov tseziia u naseleniia raionov s povyshennym radiatsionnym fonom.

The authors represent summarized data on the time course of incorporated Cs in the population of the Krasnogorsk District of Bryansk Province over the period of June 1986-July 1989. A RIKh-5M device used as a counter of human radiations, its technical data and calibration methods were described. A retrospective analysis has shown that the main accumulation of radionuclides occurred before May 15 1986. The highest rates of Cs clearance from the body were noted in the period of August 1986 till February 1987, the average resultant periods of semiclearance for different populated areas and groups of population were 55-85 days. The ratio of accumulated Cs in children and adults was 0.3, in men and women--1.4. The effectiveness of measures aimed at reducing collective doses of internal irradiation was analyzed.

[The use of radiodiagnostic apparatus as human radiation counters in large-scale radiation accidents]. / Ispol'zovanie radiodiagnosticheskoi apparatury v kachestve schetchikov izlucheniia cheloveka pri krupno-masshtabnykh radiatsionnykh avariiakh.

The problem of dosimetry of internal irradiation necessitates the use of human radiation counters (HRC). A state system of radiation safety should be based on a HRC stock in case of large-scale radiation accidents. Radiodiagnostic units can run in the HRC mode therefore they must be considered as an active reserve widely spread throughout the country. Radiodiagnostic devices can be used for control of the thyroid level of 131I and the whole-body content of a mixture of 134Cs and 137Cs.

[The use of a hybrid scanner as a human radiation counter]. / Primenenie gibridnogo skanera v kachestve schetnika izlucheniia cheloveka.

The most promising devices of those for radionuclide diagnosis that can be used for control of nuclides incorporated in the human body during a radiation incident are hybrid scanners. The authors made the calibration of devices of this type to register a mixture of 137Cs and 134Cs. The minimum detected activity was 40 nCi. A methodological error of measurements was +/- 3%. A mathematical criterion for optimization of the geometry of measurements was drawn for devices, including the methodological and statistical components of a total error. This criterion was used for finding optimum sizes of a slot collimator of the device.

[Economic criteria of comparing radionuclide diagnostic instruments]. / Ekonomicheskii kriterii sopostavleniia radionuklidnykh diagnosti- cheskikh priborov.

Based on a number of general postulates a mathematical equation was derived for computing the economically justified unbalance of the prices of two different instruments for the same uses depending on concrete values of their main technical parameters. The approach thus elaborated can be used for an analysis of instruments for any uses including medical ones. The criterion suggested makes it possible as well to assess, from the economic standpoint, the efficacy of the technical servicing of the equipment.

[Methods for monitoring the integral nonuniformity of the response of a gamma-camera detector]. / Metody kontrolia integral'noi neodnorodnosti otklika detektora gamma-kamery.

The paper is concerned with methods of monitoring of integral inhomogeneity (II) used in standards of international organizations and in recommendations of the IAAE. Quantitative analysis of errors at different stages of measurement and processing was performed. Statistical effects were investigated on a mathematical model of an absolutely homogeneous detector. The precision of theoretical calculations was confirmed by experimental testing. Nomograms and their description by simplified formulas with account of such errors in II determination were presented by the authors. They proposed methods for calculation of a 95% confidence interval for an II value of a response of a gamma-camera detector, and issued recommendations for testing computerized gamma-cameras without corresponding special programs of processing.