| Hyperthermia by microwave or RF has been broadly used in clinical tumor therapy in recent years. Since the 1990s, a lot of countries have developed experimental researches about chemotherapy/radiotherapy plus hyperthermia and medication. Researches have shown that hyperthermia can induce cells damage, and genes or anticancer genes have a close relationship with thermosensitity. The therapy has been used to treat malignant tumors at early and middle stage, and achieved well prognosis.However, the curative effect is not satisfactory enough, because the fundamental research is insufficient and some problems such as heating time and heating pattern in the therapy have not been well solved. In order to exactly predict the degree and scope of the heat damage area in tissues and provide theoretical foundation by the distribution of electromagnetic field and thermal field, the heat mechanism, the physical change and field change in the heating, designs for appropriate applicators as well as heating pattern should be took into consideration, and the further modeling researches need to be carried out.Together with the transverse development of engineering thermophysics, the research on body's heat transfer should be converted from qualitative analysis into quantitative analysis along with the development of bioenvironment, especially of the clinical medicine and convalescence medicine such as hypothermia surgical, freezing storage of transplanted organ, tumor thermotherapy, hypothermia encephalon revitalization and rehabilitation, disease thermodiagnosis, empyrosis, chimatlon and scalding. Thus the researches on heat transfer characteristics and mechanisms become imperative.Organism's heat transfer is an intricate process, and it deals with several interactive realms including electromagnetics, bioenergetics, thermobiology, biomechanics, biothermodynamics and biocybernetics, which have mutual influence on each other. This research must be based on the ideal heating model, and the mutual action among the main fields is under discussion. For example, we pay close attention to the mutual action between the electromagnetic and thermal fields in the microwave hyperthermia, whereas other realms are not discussed. There is a causal relationship between the two fields, because the electromagnetic energy absorbed by biologic tissues has been translated into resistive heating and increases the tissue's temperature, then it forms thermal field distribution. Since microwave heating is a time-dependent process, however, we can either solve the problems in electromagnetic field and then solve the thermal field, or deal with the two at the same time.Provided biologic tissue is homogeneous, thermal field distributions of several antennas made by coaxial cable have been discussed in order toprobe into their distribution pattern and practicability. FEM is used in theoretical calculation, and FEMLAB software is used to define the boundary and domain conditions of electromagnetic field and thermal field. Thermal field distributions of several antennas used in clinic at present are discussed firstly, including bare antenna, half-bare antenna, sleeve antenna and dipole antenna. Then we make coaxial-slot antenna, Y-shape antenna, furcate antenna and clawlike antenna on the basis of above, and calculate the distribution of electromagnetic field, temperature field as well as SAR in 2D r-z plane. At the same time, we experiment with excised pig liver by HDZ-1 flexo microwave tumor treatment apparatus with a frequency of 2450MHz, and compare the experimental results with theoretical calculation, which shows that they are coincident with each other.Blood vessel heat transfer in biologic tissues has become one of the focuses of biothermomedical engineering in recent years. But because of its complexity, the research is limited to the research of the special configuration of blood vessels. We analyze Pennes equation with blood perfusion theoretically and calculate the distributions of temperature field, SAR and electromagnetic field in 2D r-z plane. Nevertheless, when the applicator is spatial, 2D r-z plane could not show spatial distributions of thermal field, so 3D thermal model must be set up and the thermal field be analyzed in 3D space. But the calculation of 3D spatial thermal field has its own particularities, because the calculation of 3D electromagnetic field of spatial applicator is very complex, and the mesh number of 3D is much larger than that of 2D, which brings about difficulties to 3D calculation ofthermal field. We simplify the model by providing DC for applicator, and then develop elementary discussions of 3D thermal field distribution about body tissues with ideal blood perfusion. Three aspects have been discussed in order to make comparison, namely, no blood vessel, one blood vessel parallels to the applicator and two crossed blood vessels. We calculate their 3D temperature distribution, SAR distribution and heat flux distribution.Several conclusions have been deduced through the above study about 2D and 3D distributions of thermal field and electromagnetic field: 1 -. The radiation of bare antenna is too strong to use in clinic, becausethe exorbitant local temperature may burn up the antenna. 2> The thermal field distribution of half-bare antenna is the same as that of sleeve antenna, but the radiation of sleeve antenna is stronger. When the peeled part of the two antennas is longer, the figure of the thermal field takes on a strip, so they are applicable to heating strip-like tumors, but not applicable to small tumors. When the peeled part is short, local energy radiation is so strong as to burn up the antennas.3n The thermal field distribution of dipole antenna and coaxial-slot antenna is even, and of the two the dipole antenna has higher local temperature, so the coaxial-slot antenna is much applicable to the actual heating.4% Y-shape antenna, furcate antenna and clawlike antenna are made on the basis of coaxial-slot antenna. They all have even thermal field distributions, whose figures are similar to rotundity, so they are...
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