Arkadiusz Miaskowski

Magnetic Fluid Hyperthermia Modeling Based on Phantom Measurements and Realistic Breast Model

Magnetic fluid hyperthermia (MFH) is a minimally invasive procedure that destroys cancer cells. It is based on a superparamagnetic heat phenomenon and consists in feeding a ferrofluid into a tumor, and then applying an external electromagnetic field, which leads to apoptosis. The strength of the magnetic field, optimal dose of the ferrofluid, the volume of the tumor and the safety standards have to be taken into consideration when MFH treatment is planned. In this study, we have presented the novel complementary investigation based both on the experiments and numerical methodology connected with female breast cancer. We have conducted experiments on simplified female breast phantoms with numerical analysis and then we transferred the results on an anatomically-like breast model.

Specifying the ferrofluid parameters important from the viewpoint of magnetic fluid hyperthermia

The article presents the experimental study of magnetic fluid hyperthermia (MFH) utilizing magnetite nanoparticles with diameter of 15.2 nm. Temperature measurements of the ferrofluid samples were carried out in real measurement system using parallel resonance phenomenon. Based on the obtained temperature curves the basic heating parameters of ferrofluid, namely the Specific Absorption Rate (SAR) and power losses in tested nanoparticles have been specified. The authors systematize the current knowledge of these quantities and additionally propose two models that simplify their determination with given errors, omitting the mass and volume concentrations of the individual components of magnetic fluid.

A coil system for real-time magnetic fluid hyperthermia microscopy studies

Abstract Purpose: We describe the design and application of a new apparatus for applying Radiofrequency (RF) electromagnetic fields to cells in culture on a microscope stage. This new design enables real-time studies of the actuation of magnetic nanoparticles bound to membrane receptors or internalised within cells together with the study of magnetic fluid hyperthermia (MFH)-associated effects. Materials and methods: RF coils were fabricated and electromagnetic simulations were performed along with compatibility evaluations and calorimetric experiments using this apparatus at discreet frequencies between 100 kHz and 1 MHz. Cell killing via MFH was investigated in a neuroblastoma tumour cell line. Results: Simulations and evaluations showed that the field intensity and homogeneity experienced by the cells within the chamber is best with a planar coil configuration. The incubation chamber was suitable for cell culture and the design was compatible with mountings on different makes of microscopes as it mimics a standard 96/24/6 tissue-culture well plate. Successful calorimetric and MFH cytotoxicity proof-of-principle experiments were performed and are presented. Conclusions: We conclude from these experiments that alternating magnetic field (AMF)-mediated activation and magnetic fluid hyperthermia (MFH) research will benefit from this RF coil that fits inside an incubation chamber, mounted onto a microscope. This new design could be used to assist real-time MFH studies in vitro.

A numerical evaluation of eddy currents distribution in the human knee with metallic implant

Purpose – The purpose of this paper is to use numerical methods and modelling to estimate the effect of a passive, metallic (conducting) implant on eddy currents distribution in a human knee model. There exists a concern among wearers of such implants that they alter electromagnetic field (eddy currents) significantly and there is a need for standardization of that problem.Design/methodology/approach – The numerical model of a human knee has been built on the base of Visual Human Project and electromagnetic field calculations were carried out using Meep FDTD engine. In total, two scenarios have been considered: the knee model with and without a metallic implant. The knee implant model has been prepared as the knee model with overestimated electrical parameters of bone tissues by titanium metal. Alternating eddy current distribution has then been evaluated for both models using FDTD low frequency algorithm.Findings – The highest values of eddy currents occurred on the interface between skin and muscle tiss...

Nonlinear higher-order transient solver for magnetic fluid hyperthermia

The article is devoted to numerical methods for transient solution of Pennes’ bioheat equation as required for Magnetic Fluid Hyperthermia (MFH) modeling. Special attention has been paid to the role of non-linearity of blood perfusion and its influence on temperature distribution. The authors show that the higher-order time integration algorithms are highly advised for this type of problem, which should be classified as a stiff one. Popular low-order solvers give very different solutions. Furthermore, the application of adaptive time stepping scheme reduces calculation time and raises the efficiency of the simulation software.

Computer modelling of magnetotherapy in orthopedic treatments

Purpose – The paper aims to clarify the method/methodology of establishing a computer model of the electromagnetic therapy connected with some knee joint problems. Two cases are considered: the arthritis of the knee and the fracture of bone. In both cases the analysis of eddy current distribution in the knee is made. It gives results which can be helpful in the planning of treatment. The paper presents the exemplary results of eddy current distribution inside a bone. A short discussion on the safety aspect of magnetotherapy has been carried out.Design/methodology/approach – In order to calculate the eddy current distribution in human knee joint the low frequency finite‐difference time‐domain algorithm has been applied. The numerical model of the leg was based on US Air Force Research Laboratory data and the electrical properties of tissues were modeled using 4‐Cole‐Cole approximation with parameters taken from Gabriels.Findings – The paper presents the general methodology which can be used in magnetothera...

SAR calculations for titanium bar-implant subjected to microwave radiation

The paper describes the assessment of exposure of a six-year-old male patient with a titanium bar implanted after Nuss procedure to microwave radiation with frequency of 2.45 GHz. The local SAR concentrations inside the boys trunk for two variants of plane wave polarizations with regard to the titanium implant have been considered. It was demonstrated that an analyzed concave bar-implant poses no danger during occupational and environmental exposures according to current safety standards.

The investigation of electromagnetic field influence generated by mobile phones on cardiac pacemakers with the anatomically based human model

Purpose – The aim of this paper is to investigate the coupling model which describes the relationship between the electromagnetic (EM) field emitted by a field source, in this case the mobile phone, and the interfering voltage at a cardiac pacemaker which is digitally implanted into the human body model.Design/methodology/approach – The research was carried out using two kinds of numerical phantoms with various configurations, i.e. the mobile placed in front of a trunk and the mobile placed near the human ear (totally 12 configurations). Moreover, the simplified homogeneous human model with numerically implanted cardiac pacemaker is considered (two configurations). The simulations are carried out using the finite difference time domain method according to international standards.Findings – From the investigation it was found that the interfering voltage at the cardiac pacemaker (for each of the considered models) was much smaller than the one proposed by IEC standard. A practical conclusion that can be dr...

Remote manipulation of magnetic nanoparticles using magnetic field gradient to promote cancer cell death

The manipulation of magnetic nanoparticles (MNPs) using an external magnetic field, has been demonstrated to be useful in various biomedical applications. Some techniques have evolved utilizing this non-invasive external stimulus but the scientific community widely adopts few, and there is an excellent potential for more novel methods. The primary focus of this study is on understanding the manipulation of MNPs by a time-varying static magnetic field and how this can be used, at different frequencies and displacement, to manipulate cellular function. Here we explore, using numerical modeling, the physical mechanism which underlies this kind of manipulation, and we discuss potential improvements which would enhance such manipulation with its use in biomedical applications, i.e., increasing the MNP response by improving the field parameters. From our observations and other related studies, we infer that such manipulation depends mostly on the magnetic field gradient, the magnetic susceptibility and size of the MNPs, the magnet array oscillating frequency, the viscosity of the medium surrounding MNPs, and the distance between the magnetic field source and the MNPs. Additionally, we demonstrate cytotoxicity in neuroblastoma (SH-SY5Y) and hepatocellular carcinoma (HepG2) cells in vitro. This was induced by incubation with MNPs, followed by exposure to a magnetic field gradient, physically oscillating at various frequencies and displacement amplitudes. Even though this technique reliably produces MNP endocytosis and/or cytotoxicity, a better biophysical understanding is required to develop the mechanism used for this precision manipulation of MNPs, in vitro.

Practical bioinstrumentation developments for AC magnetic field-mediated magnetic nanoparticle heating applications.

Heat dissipation during magnetization reversal processes in magnetic nanoparticles (MNP), upon exposure to alternating magnetic fields (AMF), has been extensively studied in relation to applications in magnetic fluid hyperthermia (MFH). This current paper demonstrates the design, fabrication, and evaluation of an efficient instrument, operating on this principle, for use as (i) a non-contact, in vitro, real-time temperature monitor; (ii) a drug release analysis system (DRAS); (iii) a high flux density module for AMF-mediated MNP studies; and (iv) an in vivo coil setup for real-time, whole body thermal imaging. The proposed DRAS is demonstrated by an AMF-mediated drug release proof-of-principle experiment. Also, the technique described facilitates non-contact temperature measurements of specific absorption rate (SAR) as accurately as temperature measurements using a probe in contact with the sample. Numerical calculations estimating the absolute and root mean squared flux densities, and other MNP – AMF studies suggest that the proposed stacked planar coil module could be employed for calorimetry. Even though the proposed in vivo coil setup could be used for real-time, whole body thermal imaging (within the limitations due to issues of penetration depth), further design effort is required in order to enhance the energy transfer efficiency.