Date of Award

Spring 2005

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Computational Analysis and Modeling

First Advisor

Wei Zhong Dai

Abstract

In recent years, it has been interesting to research hyperthermia combined with radiation and cytotoxic drugs to enhance the killing of tumors. The crucial problem is that when heating the tumor tissues, one needs to keep the surrounding normal tissue below a temperature that will produce harm. Thus, it is important to obtain the temperature field of the entire treatment region. The objective of this dissertation is to develop a numerical model for obtaining an optimal temperature distribution in a 3D triple-layered cylindrical skin structure. To this end, we pre-specify the temperatures to be obtained at the center and perimeter on the surface of the cylinder. To deliver the energy to the perimeter of the skin structure during the certain exposure time, a laser irradiation pattern is configured, too. Further, the Pennes' bioheat transfer model is employed in this study.

Finite difference scheme for solving the Pennes' bioheat transfer equation in the 3D triple-layered cylindrical skin structure is then developed and is shown to be unconditionally stable with respect to the heat source. Since the laser power needs to be determined, the least squares sum between the pre-specified temperature and the calculated temperature is analyzed in order to optimize the laser power. As such, we have developed two algorithms which can be used for obtaining an optimal temperature distribution in a 3D triple-layered skin structure. To test these two algorithms, we have applied them to calculate temperature distributions in a 3D triple-layered cylindrical skin structure without any blood vessels and with a blood vessel, respectively. Numerical results show that the method is efficient and it can be used for certain types of hyperthermia cancer treatments, such as skin cancer.

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