Hyperthermia induced by the heating of magnetic particles (MPs) in alternating magnetic field receives a considerable attention in cancer therapy. An interesting development in the studies dedicated to magnetically based hyperthermia is the possibility to control the temperature using MPs with selective magnetic absorption properties. This paper analyzes the temperature field determined by the heating of MPs having low Curie temperature (a FeCrNbB particulate system) injected within a malignant tissue, subjected to an ac magnetic field. The temperature evolution within healthy and tumor tissues was analyzed by finite element method simulations in a thermo-fluid model. The cooling effect produced by blood flowing in blood vessels was considered. This effect is intensified at the increase of blood velocity. The FeCrNbB particles, having the Curie temperature close to the therapeutic range, transfer the heat more homogeneous in the tumor keeping the temperature within the therapeutic range in whole tumor volume. Having the possibility to automatically control the temperature within a tumor, these particle type opens new research horizons in the magnetic hyperthermia.

In magnetic hyperthermia, the spatial distribution of the magnetic nanoparticles (MNPs) inside a malignant tissue, after ferrofluid injection influences significantly the therapeutic temperature field. The inclusion of any intra-tumoral pressure as a result of ferrofluid injection modifies considerably the MNP distribution within the tumor volume. We show that this effect has crucial importance in the magnetic hyperthermia analysis. The temperature field can be controlled by the infusion parameters such as: (i) the ferrofluid infusion rate and (ii) the needle gauge size of the syringe. This paper describes the temperature field within a malignant tissue as a function of the infusion parameters. The local displacements of the tissue during the ferrofluid infusion process were considered. The therapeutic temperature field developed by the magnetite particles when an external magnetic field was applied depends strongly on the elastic parameters of the malignant tissue. The analytical model developed in this paper provides the optimum dosage of the magnetite which has to be injected within a soft malignant tissue with a large size, to achieve the hyperthermic temperature. An analysis of the spatial MNP distributions and their heating in the linear relaxation theory was done for different ferrofluid infusion parameters.

Magnetic nanoparticles (MNPs) with various shapes and special (magnetic and thermal) properties are promising for magnetic hyperthermia. The efficiency of this therapy depends mainly on the MNPs’ physical characteristics: types, sizes and shapes. This paper presents the hyperthermic temperature values induced by cubic/sphere-shaped MNPs injected within a concentric tissue configuration (malignant and healthy tissues) when an external time-dependent magnetic field was applied. The space-time distribution of the nanoparticles as a result of their injection within a tumoral (benign/malign) tissue was simulated with the bioheat transport equation (Pennes equation). A complex thermo-fluid model that considers the space-time MNP transport and its heating was developed in Comsol Multiphysics. The cubic-shaped MNPs give a larger spatial distribution of the therapeutic temperature in the tumoral volume compared to the spherical-shaped ones. MNP doses that induce the therapeutic (hyperthermic) values of the temperature (40 ÷ 45 °C) in smaller volumes from the tumoral region were analyzed. The size of these regions (covered by the hyperthermic temperature values) was computed for different magnetite cubic/sphere-shaped MNP doses. Lower doses of the cubic-shaped MNPs give the hyperthermic values of the temperature in a larger volume from the tumoral region compared with the spheric-shaped MNPs. The MNP doses were expressed as a ratio between mass concentration and the maximum clinical accepted doses. This thermo-fluid analysis is an important computational instrument that allows the computations of the MNP doses that give therapeutic temperature values within tissues.