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.
Optimization of a beam shaping bolus for superficial microwave hyperthermia waveguide applicators using a finite element method.
Temperature inhomogeneity in hyperthermia treatments often limits the total thermal dose that can be delivered to the tumour region. To reduce such inhomogeneities, a prototype dynamically modifiable square array of saline-filled patches which attenuate microwave energy was developed for superficial treatments that use external microwave applicators. The array was situated inside the coupling water bolus that is often used with external applicators. The prototype has been previously tested clinically with promising results. A more complete theoretical analysis of the performance of this new bolus design and improvements to its design by modelling are presented here. The analysis was performed by performing five iterative simulations of the SAR pattern produced inside a tissue structure by a waveguide applicator with a water bolus containing the dynamic patch array attached. Between iterations the patch array configuration was modified in an attempt to improve the ability of the bolus to confine heating to an 'L'-shaped tumour region. These simulations were performed using the finite element method. The steady-state temperature profile was then computed using a finite element method based simulation of heat transfer that assumed a given applicator power level and water bolus temperature. Several iterations of these heat transfer simulations were performed with varying applicator power level and water bolus temperature to improve the confinement of heating to the target region. The analysis showed that the dynamic patch array should be capable of conforming heating to an 'L'-shaped target tumour region while limiting the heating to the surrounding normal tissue to an acceptable level.
Body conformable 915 MHz microstrip array applicators for large surface area hyperthermia
The optimal treatment with hyperthermia of superficially located tumors which involve large surface areas requires applicators which can physically conform to body contours, and locally alter their power deposition patterns to adjust for nonuniform temperature caused by tissue inhomogeneities and blood flow variations. A series of 915-MHz microstrip array applicators satisfying these criteria have been developed and clinically tested. Clinical and engineering design tradeoff's for practical devices are discussed. Measurements taken in tissue equivalent phantoms and a summary of clinical experiences with these microstrip arrays are presented.<<ETX>>