Harmonic phases of the nanoparticle magnetization: An intrinsic temperature probe

Abstract

International audienceMagnetic fluid hyperthermia is a promising cancer therapy in which magnetic nanoparticles act as heat sources activated by an external AC magnetic field. The nanoparticles, located near or inside the tumor, absorb energy from the magnetic field and then heat up the cancerous tissues. During the hyperthermia treatment, it is crucial to control the temperature of different tissues: too high temperature can cause undesired damage in healthy tissues through an uncontrolled necrosis. However, the current thermometry in magnetic hyperthermia presents some important technical problems. The widely used optical fiber thermometers only provide the temperature in a discrete set of spatial points. Moreover, surgery is required to locate these probes in the correct place. In this scope, we propose here a method to measure the temperature of a magnetic sample. The approach relies on the intrinsic properties of the magnetic nanoparticles because it is based on monitoring the thermal dependence of the high order harmonic phases of the nanoparticle dynamic magnetization. The method is non-invasive and it does not need any additional probe or sensor attached to the magnetic nanoparticles. Moreover, this method has the potential to be used together with the magnetic particle imaging technique to map the spatial distribution of the temperature. (C) 2015 AIP Publishing LLC

Magnetic Hyperthermia and Radiation Therapy: Radiobiological Principles and Current Practice †

“… MNPs can act as contrast agents in MRI (theranostic action) [ 151 , 202 ]. The MNPs can be used as temperature probes, thus providing non-invasive, real-time, 3D temperature distribution [ 203 , 204 ]. This is in contrast to standard methods of thermometry, such as optical fibers, that are both invasive and can measure the temperature only at a few points.…”

Fundamentals and advances in magnetic hyperthermia

“…the thermal variation of the high-order harmonics of AC magnetization was recently proposed to monitor temperature [222]. The calibration process is very important for the development of better temperature measurement techniques, as different tissues/organs will show different calibration curves for the same patient.…”

Principles of Magnetic Hyperthermia: A Focus on Using Multifunctional Hybrid Magnetic Nanoparticles

“…Thus, MRI thermometry might not be the optimum choice of thermometry in hyperthermia treatment. Several other noninvasive methods which depend on the magnetic response of MNPs to the applied magnetic field were proposed [113][114][115][116][117][118][119][120][121][122]. In these methods, the temperature-dependent of coercively [117,123], the temperature-dependent of magnetization, and the higher-order harmonics of the magnetization of MNPs were used as temperature sensors.…”