Magnetic Nanoparticle-Guided Blind Focusing in Microwave Hyperthermia of Neck Tumors

This paper aims to assess a recently proposed approach for microwave hyperthermia, exploiting magnetic nanoparticles as modulable contrast agents in order to blindly focus on the tumor the electric field radiated by an antenna array. The approach has been improved and numerically assessed in the realistic and clinically relevant case of the treatment of neck tumors. To this end, a realistic system, whose layout is inspired to an existing one, currently under clinical testing, has been considered. The Zubal phantom has been exploited to carry out the simulations. The numerical results show that the proposed blind focusing approach works properly even in realistic and complex situations like the one considered in this paper. Moreover, the results compare very well with those obtained through not-blind focusing approaches, based on the knowledge of geometry, positioning, and electric properties of the irradiated tissues. The robustness of approach against the measurement noise has been also analyzed, in order to identify the requirements that the measurement apparatuses must satisfy and the minimum amount of magnetic nanoparticles to be administered to the patient in order to make the approach feasible. The performed thermal analysis confirmed the ability of the approach to selectively heat the tumor. The proposed approach could be a valid alternative to achieve an effective field focusing without any a priori information on the electric and geometrical properties of the anatomical region to be treated. Moreover, it could be employed in combination with magnetic hyperthermia to improve the effectiveness of the therapy.