Biomedical subjects

L Ia Klepper

Publications and source records attributed to L Ia Klepper.

66 records · Page 4Linked to original sources

PubMedDate not supplied

[Estimated equivalent radiation conditions (EERC), more useful clinical data and estimation of potential resorption of lesion nodule with respect to its volume and total focal dose].

Assumptions on properties of tumor cells are defined. On the basis on them the survival rate of tumor cells is described by the LQ function and the dependence of resorption probability (RP) in the lesion nodule on the number survived tumor cells (tumor volume) and on the total focal dose (TFD) is described by the Poisson function. An analysis of the above approach to the determination of lesion-nodule RP resulted in designing a calculation method for EERC that can be used to estimate the lesion-nodule RP as a function of its volume and TFD. An analytical or graphical description of the RP/TFD dependence for a fixed volume of lesion nodule is needed for the implementation of EERC. There is no need to determine the cell structure of tissue or the radiobiological properties of its cells. The possibility to construct the RP section function and to extend, thus, the volume of useful clinical data belongs to the method's advantages.

Humans↗

PubMedDate not supplied

[Interactive input and correction of data about the structure of irradiated organism in the planning of radiotherapy for malignant tumor].

A method is suggested for the interactive input, conversion and presentation of data about the structure of irradiated organism preset as Data Reference Planes (DRP). The possibility to build a library of DRP and the simplicity of their adjustment to each disease case witness to that the method of input, storage, conversion and presentation of data about the irradiated organism is promising in tumor radiotherapy.

Algorithms↗

PubMedDate not supplied

[Synthesis of radiological models and radiological invariants (constants). Part 2].

The goal of this work was to synthesize a mathematical model (MM) on the basis of Klepper and Lyman MMs, which describe the probability of post-radiation complications (PRC) in tissue subjected to radiation therapy with given scheme of dose fractionating (DF), and the LQ-model, which describes equivalent DF schemes for a fixed PRC value. Construction of synthesized MMs (SMMs) becomes possible only on the basis of several assumptions requiring further clinical validation. Synthesized MMs can be used for determination of the optimal dynamic conditions of irradiation of malignant tumors. These conditions include the optimal physical plan of irradiation and the optimal time scheme of its implementation. Synthesis of MMs leads to determination of radiological invariants (constants), which can become a basis for a new branch of medical science, quantitative radiology.

Dose-Response Relationship, Radiation↗

PubMedDate not supplied

[Synthesis of radiological models and radiological invariants (constants). (Part 3: synthesis of population-phenomenological models and Klepper model)].

The goal of this work was to synthesize Klepper mathematical models (MM), which describes the probability of post-radiation complications (PRC) in tissue subjected to radiation therapy with given scheme of dose fractionating (DF), and population-phenomenological (PP) MMs PP3 and PP4, which describe equivalent DF schemes for a fixed PRC value. Construction of synthesized MMs (SMMs) becomes possible only on the basis of several assumptions requiring further clinical validation. Synthesized MMs can be used for determination of the optimal dynamic conditions of irradiation of malignant tumors. These conditions include the optimal physical plan of irradiation and the optimal time scheme of its implementation. Synthesis of MMs leads to determination of radiological invariants (constants), which can become a basis for a new branch of medical science, quantitative radiology.

Mathematics↗

PubMedDate not supplied

[Synthesis of radiological models and radiological constants. Part 4: Synthesis of population-phenomenological models and Lyman model].

The goal of this work was to synthesize Lyman mathematical models (MM), which describe the probability of post-radiation complications (PRC) in tissue subjected to radiation therapy with given scheme of dose fractionating (DF), and population-phenomenological (PP) MMs PP3 and PP4, which describe equivalent DF schemes for a fixed PRC value. Construction of synthesized MMs (SMMs) becomes possible only on the basis of several assumptions requiring further clinical validation. Synthesized MMs can be used for determination of the optimal dynamic conditions of irradiation of malignant tumors. These conditions include the optimal physical plan of irradiation and the optimal time scheme of its implementation. Synthesis of MMs leads to determination of radiological invariants (constants), which can become a basis for a new branch of medical science, quantitative radiology.

Dose-Response Relationship, Radiation↗

PubMedDate not supplied

[Planning of fractionated methods of lung irradiation using the TDF factor].

Analyzing the data available in the literature shows that lung tissue is most radiosensitive and the impact of the volume of exposure of lung tissue to radiation per tolerance dose is greater than that of connective tissue. A modified Ellis model including the volume of irradiated tissue as a variable in addition to the number of fractions and the duration of radiation therapy. It has been used to calculate tables of TDF values for planning the fractionated regimens of lung radiation.

Humans↗

PubMedDate not supplied

[Method of calculating the probability of radiation-induced complications in organs and tissues in relation to volume of radiation and dose fractionation].

Mathematical models have been first developed, which describe the probability of radiation-induced complications of particular types as a function of the dose and volume of radiation and the scheme of dose fractionation in time. New mathematical models were derived from the synthesis of the mathematical models which describe the probability of radiation-induced complications for the fixed scheme of dose fractionation and which describe the equivalent schemes of dose fractionation for the fixed likelihood of radiation-induced complications.

Humans↗

PubMedDate not supplied

[Methods for calculating tolerance levels of lung irradiation as function of radiation dose and volume (modified LQ and TDF models)].

Modified mathematical TDF and LQ models that take into account the volumes of the irradiated lung were designed. An important radiological parameter, such as a single tolerance, has been inserted into the LQ model. Mathematical model parameters versus irradiated lung volume curves have been plotted. It is shown that the tolerance calculated using two models may greatly differ particularly for the small irradiated lung. Further collection and processing of radiological information are required for making a justified conclusion on the comparative efficiency of the above models used in radiological practice.

Humans↗

PubMedDate not supplied

[The determination of the optimal irradiation dose in the tumor tissue-normal body tissues system].

To estimate the optimal cancerocidal dose, it is necessary to construct the mathematical models describing the probability of radiation sterilization of tumor tissue and that of a radiation-induced complication in the selected system of normal tissues or in the particular normal tissue if its radiosensitivity is higher than that of other tissues. The optimal cancerocidal dose may be estimated while solving a special emergency problem from the proposed criterion by taking into account the limited probabilities of radiation-induced complications in normal organs and tissues if they are damaged.

Dose-Response Relationship, Radiation↗

PubMedDate not supplied

[Assessment of tolerance doses in multifractionated irradiation of the lung using Ellis and LQ models].

Ellis and LQ models were used to examine the tolerance dose dependences in different schemes of multifractionated radiation of the lung. For characterization of multifractionated radiation, a tolerance dose increment coefficient (TDIC) was introduced, which showed how the tolerance dose increased during multifractionated radiation as compared to the conventional scheme of dose fractionation with radiation given once a day. The Ellis models were shown to yield the TDIC values which were associated with the number of daily radiations rather than with the number of active days of radiation while the LQ models provides the TDIC values which depend not only on the number of daily radiations, but also on the number of active days of radiation. As the number of active radiation days increased, TDIC reduced. The studies were made according to a package of specially elaborated programmes which calculated tolerance doses in relation to the volume of radiation and to the scheme of dose fractionation in time, by using the TDF and LQ models.

Dose Fractionation, Radiation↗

PubMedDate not supplied

[Programmed complex for planning fractionated regimens of malignant tumor irradiation by local adjustment of mathematical model parameters].

The accuracy of planning the fractionated radiation regimens may be enhanced by the proposed method of local adjustment of its parameters. For planning the fractionated radiation regimens in practical radiology, TDF was used to design a programmed complex (PC) which defines the main radiological parameters of a radiation plan as a system of interchangeable values in remote, contact, and combined radiation therapy for uniform and nonuniform dose fractionation regimens. PC allows a radiologist to actively use his clinical observation for local adjustment of mathematical model parameters and for planning the fractionated radiation regimens. The method of local adjustment of mathematical model parameters for dose fractionation is applicable to lung tissue radiation. Its advantage is that it permits one to consider the complexity of the organism exposed to radiation and, to a definite extent, to minimize the possible inadequacy of the used mathematical model of dose fractionation.

Dose Fractionation, Radiation↗

PubMedDate not supplied

[Choice of the optimum intersection point for beam radiation axis in the planning of radiotherapy].

A method has been developed to search for the optimum radiation regimen including the optimum radiation directions, the optimum duration of exposure, and the optimum point (center) of intersection of the central axes of radiation bundles. To solve the goal of determining the optimum radiation regimen for central lung cancer has indicated that variations in the intersection center of radiation bundles improves the radiation regimen. The optimum position of the intersection center of radiation bundles may greatly differ from the routine choice of the center. To standardize the optimum radiations in central lung cancer, it is necessary to solve special extreme tasks that minimize the numbers of the optimum radiation directions, which thus allows the main (structural) radiation directions to be identified.

Algorithms↗