Estimation of overall heat transfer coefficient of cooling system in RF capacitive hyperthermia
The 
study presented in this article involves the estimation of the overall heat 
transfer coefficient of cooling system in RF capacitive hyperthermia 
treatment using inverse problem based on the conjugate gradient method to 
provide improved distribution of temperature. The temperature data computed 
numerically from the direct problem using the finite difference time domain 
method are used to simulate the temperature measurements. The effects of the 
errors and sensor positions upon the precision of the estimated results are 
also considered. The results show that a reasonable estimation of the unknown 
can be obtained. Finally, measurements in a tissue-equivalent phantom are 
employed to appraise the reliability of the presented method. The comparison of 
computed data with measurements shows a good agreement between numerical 
and experimental results.
ELECTROQUASISTATIC MODEL OF CAPACITIVE HYPERTHERMIA AFFECTED BY HEAT CONVECTION
An electroquasistatic (EQS) model of capacitive hyperthermia for treating lung tumors is proposed, based on which the finite element method is applied to compute the electrical potential in a human thorax model. The temperature distribution in the thorax model, which is surrounded by a bolus maintained at a constant temperature, is computed by numerically solving a bio-heat equation, which includes metabolic heat generated in the tissues, heat convection mechanism in tissues and bolus, as well as the heat delivered by the microwave field computed with the EQS model and finite element method. Temperature-dependent blood perfusion rates of blood and muscle, respectively, are adopted to account for the physiological reaction of tissues to temperature variation. By simulations, it is observed that adjusting the dielectric properties of adipose tissue via injection, the time evolution of temperature distribution can be controlled to some extent, providing more flexibility to customize a hyperthermia treatment plan for specific patient.
Optimization of SAR distributions in liver and lung regions irradiated by the H-horn annular phased array hyperthermia system
The author discusses a type of annular phased array (APA) system-the H-horn APA. The phase and amplitude control of power deposition patterns for this system have been theoretically analyzed at a frequency of 200 MHz. The formulas for calculating the electric field (E-field) and specific absorption rate (SAR) for this APA system have been derived and can be applied to other types of APA systems. Models on computerized tomography (CT) scans from liver and lung regions have been used for predicting optimization of the E-field and SAR patterns in the case of the relative phase and amplitude changes. It is shown that the phase and amplitude control of SAR patterns results in a more selective and effective heating of tumors situated eccentrically and deeply within the body. The numerical results indicate that it is possible to shift the absorbed power patterns by electrically varying the phase and/or the amplitude of the sources and manually moving the positions of the horns. >