Numerical Simulation of Temperature Variations during the Application of Safety Protocols in Magnetic Particle Hyperthermia.

Gerasimos Pefanis,Nikolaos Maniotis,Antonios Makridis,Theodoros Samaras,Mavroeidis Angelakeris,Aikaterini-Rafailia Tsiapla

doi:10.3390/nano12030554

Gerasimos Pefanis, Nikolaos Maniotis + Show 4 more

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https://doi.org/10.3390/nano12030554

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Journal: Nanomaterials	Publication Date: Feb 6, 2022
Citations: 7	License type: CC BY 4.0

Affiliation: Aristotle University of Thessaloniki

Abstract

Unavoidably, magnetic particle hyperthermia is limited by the unwanted heating of the neighboring healthy tissues, due to the generation of eddy currents. Eddy currents naturally occur, due to the applied alternating magnetic field, which is used to excite the nanoparticles in the tumor and, therefore, restrict treatment efficiency in clinical application. In this work, we present two simply applicable methods for reducing the heating of healthy tissues by simultaneously keeping the heating of cancer tissue, due to magnetic nanoparticles, at an adequate level. The first method involves moving the induction coil relative to the phantom tissue during the exposure. More specifically, the coil is moving symmetrically—left and right relative to the specimen—in a bidirectional fashion. In this case, the impact of the maximum distance (2–8 cm) between the coil and the phantom is investigated. In the second method, the magnetic field is applied intermittently (in an ON/OFF pulsed mode), instead of the continuous field mode usually employed. The parameters of the intermittent field mode, such as the time intervals (ON time and OFF time) and field amplitude, are optimized based on the numerical assessment of temperature increase in healthy tissue and cancer tissue phantoms. Different ON and OFF times were tested in the range of 25–100 s and 50–200 s, respectively, and under variable field amplitudes (45–70 mT). In all the protocols studied here, the main goal is to generate inside the cancer tissue phantom the maximum temperature increase, possible (preferably within the magnetic hyperthermia window of 4–8 °C), while restricting the temperature increase in the healthy tissue phantom to below 4 °C, signifying eddy current mitigation.

Highlights

Magnetic particle hyperthermia (MPH) is a cancer treatment modality that exploits the interactions of magnetic fields with magnetic nanoparticles (MNPs) to generate heat, predominantly via magnetic hysteresis loss, in order to increase the tumor temperature in the range of 41–45 ◦ C [1,2,3,4]
Magnetic particle hyperthermia is a promising treatment, which, despite its many advantages over other forms of hyperthermia, suffers from the unwanted heating caused to healthy tissues by induced eddy currents
We managed to reduce the thermal dose from the electric field to tissue-equivalent gel phantom, and, at the same time, preserve the heating to the MNPs-bearing phantom (CTP) model by introducing two alternative protocols

Summary

Introduction

Magnetic particle hyperthermia (MPH) is a cancer treatment modality that exploits the interactions of magnetic fields with magnetic nanoparticles (MNPs) to generate heat, predominantly via magnetic hysteresis loss, in order to increase the tumor temperature in the range of 41–45 ◦ C [1,2,3,4]. Since cancer cells are more susceptible than healthy ones to 41–45 ◦ C, a rise within this temperature region leads to the suppression of cancer cells growth and tumor shrinkage [5,6]. MPH received regulatory approval by the European. The tumoral region containing the magnetic nanoparticles, which are usually made of iron oxide and dispersed in aqueous solution, is exposed to an alternating magnetic field (AMF) [10]. Low frequency (

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