USING NANOPARTICLES FOR ENHANCING THE FOCUSING HEATING EFFECT OF AN EXTERNAL WAVEGUIDE APPLICATOR FOR ONCOLOGY HYPERTHERMIA: EVALUATION IN MUSCLE AND TUMOR PHANTOMS

A technical challenge in hyperthermia therapy is to locally heat the tumor region up to an appropriate temperature to destroy cancerous cells, without damaging the surrounding healthy tissue. Magnetic fluid hyperthermia (MFH) is a novel, minimally invasive therapy aiming at concentrating heat inside cancerous tissues. This therapy is based on the injection of different superparamagnetic nanoparticles inside the tumor. In our study, superparamagnetic nanoparticles, which we developed and characterized, consisted of iron oxide nanoparticles stabilized with polyethylene glycol. Moreover, a new technique for MFH using a specially designed external electromagnetic waveguide as applicator is presented. Three magnetite concentrations were used for making the tumor phantoms, which were embedded in muscle phantoms. The phantoms were radiated and located at three different distances from the applicator. Furthermore, two volumes of tumor (2.5 mL and 5.0 mL) were assayed. Heating curves, as a function of time, allowed the establishment of a more appropriate nanoparticle concentration for obtaining the temperature increase suitable for hyperthermia therapy. The results shown in this paper confirm the feasibility of using nanoparticles as agents to focus the energy over the tumor, without creating hot spots in healthy tissue. In addition, the experiments validated that by using this applicator in combination with nanoparticles, it is also possible to locally control the increments of temperature in tissues.