Estimation of SLP/ILP parameters inside a female breast tumor during hyperthermia with mobilized and immobilized magnetic nanoparticles

Purpose: Magnetic hyperthermia is a medical procedure for treating cancerous tumors that are medically unsuitable for resection or other treatments. It involves injecting magnetic nanoparticles (MNPs) into the cancerous tissue and applying an external alternating magnetic field (AMF) to induce heat in the target tissue. Under the influence of an AMF at radiofrequency range, eddy currents are generated, and MNPs are heated in the tumor’s volume, resulting in apoptosis or necrosis. The purpose of this study is to numerically analyze the power losses generated by MNPs, such as specific loss power (SLP) and intrinsic loss power (ILP), as well as the temperature distribution during magnetic hyperthermia concerning a tumor placed in an anatomical model of the female breast.

Methods: The AMF source was a helical induction coil with an excitation current surrounding the female breast phantom. Numerical analysis was based on the solving the Helmholtz equation for the magnetic vector potential coupled with the modified Pennes equation, using the finite element method (FEM). The numerical model under consideration included the power dissipation generated by MNPs based on the linear response theory, proposed by Rosensweig, and the Joule heating generated by eddy currents.

Results: Comparison of the effects of MNPs concentrations on the outcome thermal profiles of irregularly shaped breast tumors is presented. Additionally, tumor temperature profiles and SLP/ILP parameters are determined in the case of mobilized and immobilized MNPs.

Conclusions: MNPs immobilization within the tumor microenvironment significantly diminishes magnetic losses, with a corresponding reduction of approximately 30% in specific SLP/ILP parameter values.