RESUMO
The basic objective of microwave hyperthermia is to raise the temperature in the tumor tissue without overheating point for a long time. It's difficult to achieve uniform temperature distribution using the continuous heating without changing the antenna shape and inserting position. In this paper, the interstitial antenna worked in the frequency of 2450 MHz inserted into an infinite muscle model is studied. The Finite Difference Time Domoin (FDTD) method was used to calculate the electromagnetic field, while the finite difference method (FDM) was used to analyze the temperature distribution in tumor tissue. The simulation results show that the long-time evenly heating can be achieved by using the alternately heating process and the treatment area can be changed by adjusting input power.
Assuntos
Humanos , Fenômenos Eletromagnéticos , Hipertermia Induzida , Micro-Ondas , Usos Terapêuticos , Neoplasias , Terapêutica , TemperaturaRESUMO
Objective To design a chock-vault antenna for injurious interventional thermotherapy and to evaluate antenna performance change when structure parameters of the antenna are adjusted. Methods Finite element method was used to simulate the distributions of the reflection coefficient and the specific absorption rate (SAR) of the chock-vault antenna of different structure parameters for microwave thermotherapy human muscle tissue model when it worked at 2 450 MHz. The chock-vault antenna for injurious interventional thermotherapy had been optimized. Results This antenna was made.And the reflection coefficient and SAR were measured with human muscle tissue model experiment. The simulation results were validated. Conclusion The SAR distribution of the improved choke-vault antenna does not depend on depth of the insertion tissue. The reflection coefficient can be reduced greatly. The top energy distribution is reasonable.
RESUMO
Objective To simulate and investigate th e electromagnetic field distribution of the insert applicator used in microwave hy perthermia for treating bone tumors. Methods Bone t umor model with layered cylindrical shape was made. The applicator was made from a coaxial cable that peeled off the out copper at the end, which were inserted into the cylindrical bone with different depths. The three dimensions finite ele ment method (FEM) was used to calculate the various parameters of the simulated electromagnetic field. Results The electromagnetic energy could be well transmitted into the tissues when the section of the out co pper cutting was embedded in the tissues. The electromagnetic energy to the tiss ue was enhanced when the tip of the applicator got close to but not penetrated t he tissue. Conclusion The intensity of irradiation t o the target tissue was determined by the dimension and depth of insertion of th e applicator. This is very important for the selection of the type and insertion depth of the applicator when using microwave hyperthermia for treating bone tum or in clinical practice.
RESUMO
This paper reviews recent research and development on microwave sterilization, including the experiments of sterilization effects, the influence of microwave radiating on the media parameters, the development of microwave sterilizers and the study of sterilization mechanism. Many results show that the method of microwave sterilization is more easy-to-perform, economical and reproducible than the conventional autoclaving method. It is necessary to study the sterilization conditions through the experiments for different media and bacteria. The research on sterilization mechanism, especially non-thermal sterilization mechanism is still a hotpoint.
