Development of an Automatic Localization System of Magnetic Particles for Hyperthermia Therapy

Magnetic hyperthermia is a promising cancer therapy gaining great interest in recent years. In this therapy, in addition to magnetic particles, important elements include techniques for detecting the position and temperature of magnetic particles in a tumor region in determining the effectiveness of therapeutic heating. In previous studies, we developed a low invasive heating and wireless temperature measurement system for magnetic hyperthermia using a ferromagnetic implant with low Curie temperature (FILCT). To make this approach feasible in clinical settings, a challenge remains when the FILCT injected into the tumor region deviates from the central axis of drive coil. As a result, the heating efficiency of FILCT and the temperature measurement accuracy of FILCT decrease. In this study, we develop an automatic localization system for magnetic particles. Using the constructed system, it was possible to automatically locate the position of magnetic particles with an accuracy below 1 mm in vitro by operating magnetic field supply and detection (MFSD) unit in two modes of coarse scanning (rotary scanning) and fine-tuned scanning (linear scanning) based on three pickup voltages induced in three pickup coils symmetrically installed inside drive coil.

I. Introduction

Cancer a major public health challenge worldwide and the largest cause of death in Japan since 1981 accounting for 27.4% (373.547 deaths) of all deaths in 2018 [1]. There are different types of cancer treatment such as surgery, chemotherapy, and radiation therapy. Recently, magnetic hyperthermia has been gaining great interest as a promising cancer therapy with less invasive than surgical therapy and fewer side effects compared with chemotherapy [2]–[4]. Cancer cells are more sensitive to heat than healthy cells, and the antitumor effect occurs when the tumor is heated within the therapeutic temperature range of 40–45 °C. Magnetic hyperthermia utilizes heat generation ascribed to magnetic particles subjected to a high-frequency magnetic field [5], [6]. In addition to magnetic particles [7]–[10], important elements include techniques for detecting the position [11]–[14] and temperature [15]–[18] of magnetic particles in a tumor region in determining the effectiveness of therapeutic heating.