Examination of ideal physical parameter choices for efficacious hyperthermic treatment of cancer

Abstract

This dissertation presents results on the computational modeling of electromagnetic and thermal effects during the hyperthermic treatment of cancer using magnetic nanoparticles. Magnetic nanoparticle hyperthermia can be used for direct targeting and destruction of tumors through heat treatment or as a complement to chemotherapy. This method of treatment would be much less invasive than many current treatment options. Additionally, since these are nanoscale devices, the hyperthermic treatment of the cancer cells would be extremely localized. This would cause very minimal damage to surrounding tissue, making these systems superior to traditional hyperthermic treatment.

The use of ferrofluids for cancer treatment requires that appreciable volumetric heating power be generated, while maintaining safe values of frequency and magnetic field strength and reducing the risk of spot heating healthy tissue. In order to implement this treatment in the clinical setting, it is therefore necessary to determine an ideal range of input parameters. These include the complex magnetic susceptibility of the ferrofluid, the magnitude of the driving magnetic field, and and frequencies of oscillation.

It is also necessary to study the impact of variation in biological parameters within the patient population on treatment effectiveness. These parameters include the rates of blood perfusion and the electrical and thermal properties of each of the tissue layers. The determination of the ideal set of parameters for magnetic nanoparticle hyperthermia is accomplished by the coupling of the solution of Maxwell’s equations in a model of the tumor and surrounding tissue as input to the Pennes Bioheat Equation (PBE). Both sets of equations are solved via the Finite Difference Time Domain (FDTD) Method.

It is found, based on the models used in this research, that for tumor tissue perfusion rates and/or brain tissue perfusion rates which are low, that magnetic nanoparticle hyperthermic therapy is able to safely and thoroughly heat a tumor region of diameter 3 cm to steady-state temperatures which lead to apoptotic cell death. Additionally, it is also found that for these parameter values, the tumor border is also heated to apoptotic temperatures. However, for larger values of tumor/healthy tissue perfusion rates, even for field strengths and frequencies above the regime deemed safe, apoptotic heating is not achieved for nanoparticle volume fractions deemed to be safe. However, temperatures for these parameter values are large enough to possibly amplify the effects of chemotherapy drugs or radiotherapy.