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Dielectric Properties of Biological Media

#2071


Physical Models for Dielectric Properties of Biological Media

Tech Area / Field

  • MED-DID/Diagnostics & Devices/Medicine
  • BIO-INF/Bioinformatics/Biotechnology
  • MED-RAD/Radiomedicine/Medicine
  • PHY-RAW/Radiofrequency Waves/Physics

Status
3 Approved without Funding

Registration date
11.01.2001

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • Kurchatov Research Center / Institute of Nuclear Fusion, Russia, Moscow\nTRINITI, Russia, Moscow reg., Troitsk

Collaborators

  • Lawrence Livermore National Laboratory, USA, CA, Livermore\nRensselaer Polytechnic Institute, USA, NY, Troy\nCarolinas Medical Center, USA, NC, Charlotte

Project summary

Many modern methods of medical diagnostics and treatment are associated with the influence of radiation, differing in its physical origin, on human beings. Ultrahigh frequency radiation and ultraviolet radiation have been applied for over 50 years in physiotherapeutic practice. From the beginning of the century X-ray radiation has been used to observe bone damage and pathologies of the endogenous organs. In recent decades laser therapy and surgery have become widespread. The new perspectives of recent years are connected with the development of tomography methods, which apply microwave (MW) radiation that can be used for creation of principally new methods of tomography.
Together with the development of diagnostics and therapy a certain lagging is observed in the concepts and models of biophysical processes, which determine the interaction of MW radiation with the body’s structural components. Firstly, this touches upon the molecular structure of biological tissues. At present, a vast and valuable portion of experimental data concerning the interaction between MW radiation and substance has been already accumulated, particularly owing to scientific work of the project participants. Naturally, this data can be used to investigate the influence of MW radiation on the biological material of organisms, with account of its cellular structure. This project is exclusively focused on these urgent problems of contemporary medicine.
The project objective is the creation of reliable and realistic physical models of biological tissues; models, describing the interaction of these tissues with electromagnetic field in correlation with parameters of the human physiological state. Moreover, the development of computational methods is proposed to evaluate electromagnetic field dispersion in biological substances, as described by these models. The development of appropriate methods will allow a significant expansion of modern diagnostics, prognosis and treatment. Theoretical research is planned for mathematical models of biological substances, and experimental work will be required in order to test the proposed models on both artificial systems (phantoms) and actual biological objects.
The physical modeling of biological objects, proposed in the current project, is based upon the concept of the complex dielectric permittivity of the medium, which has been successfully applied for the macroscopic description of interactions between electromagnetic field and substance. The specificity of the biological objects appears due to anisotropy of their properties, provided by the complex 3D structure, scaled in the range from 10-3-10cm. So, at the primary stage, the description of the above specificity is to be provided using a model of the biological environment, which includes three components, each with its own dielectric properties: 1) intracellular environment; 2) biological membrane and 3) intercellular matrix. By solving the electromagnetic field equations for each of the components and by introducing the appropriate boundary conditions, one can obtain the value of average dielectric permittivity, including the case of electrically interacting cells. Starting with this and considering the real topological conformation and mutual disposition of the cells, we expect to predict those dielectric properties of the tissue, which determine its intrinsic propagation of electromagnetic field, and, in particular, the possible anisotropy of tissue properties. The description of dielectric properties of such a medium requires the development of new mathematical models, equation systems, which allow us to get closer to real events in electromagnetic field propagation and dispersion. This, in its turn, needs the development of new calculation methods to solve such equations. Thus, the logical chain of the project puts together the physical model of organism tissues, the mathematical model determining propagation of MW radiation in the medium and numerical methods facilitating the connection of experimentally observed signals with physiological parameters of an organism.
Modeling of myocardial tissues is a particularly important aspect of these investigations, because of the extraordinarily worldwide distribution of diseases, associated with heart damage. For example, every year 505,000 women die in the USA from such disorders (approximately 2/3 of the total number of fatal cases). According to statistical data of 1995, the mortality rate among men reached 455,152. Therefore, special attention shall be paid to physical modeling of the media, which are specific especially for myocardial tissue.
The approach described in the project might be shortly titled as the dielectric spectroscopy method. The method is based on the following main principles:
dielectric properties of biological tissues depend on physiological conditions. For instance the state of cordial tissue depends on fluctuations of the coronary blood circulation, ischemia damage, infarct and hypoxia;
dielectric properties are described by a physical model of environmental anisotropy with different dielectric permittivities of intercellular, intracellular and membrane compartments;
given the detailed information of the dependence of tissue dielectric properties on the different types of damage, new noninvasive diagnostic methodologies may be introduced.
As an example of realistic and effective applications, MW-tomography of myocardium should be mentioned. The method is based on analysis of MW-radiation dispersion in the different domains of myocardium and other internal organs. This method allows the reproduction of the 3D distribution of dielectric permittivity in different organs. That gives more adequate characteristics of electrical activity of heart muscle, in comparison with the distribution of nuclear spins provided by methods of nuclear magnetic resonance (NMR). The research indicates that dielectric permittivity of the tissue is directly correlated with its physiological state.
The given example demonstrates the topicality and potential of the proposed research for medicine and, in the first instance, for diagnostics of myocardial damage such as acute coronary circulation deficiency, ischemia and infarct. As it has been already mentioned, these diseases are currently the leaders in terms of mortality.
Project fulfillment is proposed in three stages:
During the first year physical models, allowing for an adequate description of the dielectric properties of biological tissues in different physiological states are to be developed, along with experimental methods for verification of the elaborated models.
During the second year the mathematical basis will be elaborated for the modeling of specific properties of biological tissues (myocardium) and the propagation of electromagnetic radiation inside them, together with experimental verification of model objects (phantoms).
The first year is devoted to the applications of model representation, developed for real biological objects. The Project team plan to demonstrate the effect of physiological factors on dielectric properties of living tissues, which, in their turn, lead to a modification of electromagnetic field scattered by the biological object and, so, make it possible to perform external registration and prognosis.
The project will conclude with the demonstration of novel methods for diagnostics of biological tissue damage, most common in endemic diseases.
It should be noted that Russian scientific research institutions, which are to participate in the project, have accumulated significant experience in the investigation of dielectric properties for a number of physical objects, including biological systems. Also, primary results, which can be successfully used to solve the considered problems, have been obtained.
New theoretical and experimental results, both of an applied and fundamental nature, needed for the development of a new diagnostics method for heart-vessel diseases, will be obtained in the course of the project.
As a result of project fulfillment, the following is supposed:
the creation of models describing radiation field formation in multicomponent non-homogeneous systems, which are common for biological media.
development of methods for numerical calculation of radiation field characteristics in such an environment, with consideration of the actual specificity of biological structures.
development of methods, which restore the structure of investigated biological media using the characteristics of dispersed radiation, registered by the equipment.
development and creation of an experimental equipment, capable of registering the radiation dispersed over biological media at HF and MW ranges.
analysis of the potential of the novel diagnostics methods, based on the detection of deviation of biological tissue dielectric properties.
tests of these methods on models (phantoms) of biological objects.
It should be noted that it is not possible to solve these main problems successfully if a number of additional ancillary tasks are ignored. These include the creation of programs to calculate certain theoretical models, analysis of data on dielectric properties for a variety of biological structures, investigation of the effectiveness of dielectric response at different frequency ranges of probe radiation and others.
In accordance with the above the following research directions may be distinguished:
Creation of physical models for biological media with consideration of dielectric permittivity of different biological structures.
Creation of a mathematical model of radiation field distribution and scattering in biological media with given dielectric properties.
Development of numerical methods to solve the mathematical model;
Development of computer programs for numerical methods;
Debugging and testing of the developed equipment specimens on model objects, which imitate the properties of biological media.
Elaborating diagnostics methodologies for the determination of pathological changes, caused by myocardial tissue damage, analysis and comparison with the results of biomedical experiments and providing conclusions on the effectiveness of developed methods.
A self-consistent complex of developed theoretical models makes it possible to elaborate, as a result of investigations, suggestions for the solution of problems of medical diagnostics of myocardium tissue diseases, to suggest new medical methods for clinical applications, and to develop new examples of corresponding diagnostic equipment. It should be noted that it is possible to wait for an essential increase in space resolution of diagnostic methods as a result of the project works, that makes it possible, in its turn, to increase the reliability of diagnostics of specific diseases.
Project authors believe the proposed project is totally compatible with the goals and purposes of the International Science and Technology Center. The implementation of this project facilitates the redirection of the efforts of over 10 scientists from armament issues to fundamental and applied problems of high frequency radiation in biophysics. Development of new models and the creation of experimental expositions will present an opportunity to utilize the great scientific and technical potential and concrete achievements of the main project participants. This will form the necessary basis for the fulfillment of the complex project program. The project will continue the integration of Russian scientists into the world scientific community by establishing contacts with a number of specialists in the USA and Western Europe, who are involved in similar research. It should be stressed that the project is oriented towards the development of peaceful medical technologies, which is absolutely in line with the work of the ISTC.
At each stage of the project intensive informational exchange will take place between ISTC project participants and collaborators, primarily with the Carolinas Medical Center at Charlotte (USA). Joint seminars are scheduled, where foreign collaborators will be able to discuss the major achievements and comment on regular ISTC reports. Also, international research is to be coordinated and contacts strengthened between different teams, involved to the project. All related scientific institutions and stand-alone scientists are welcome to participate in the project and, thus, during proposal development and project implementation further extensions may enter the collaborator list.


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