Bartosz Sawicki

Simulation of magnetic stimulation of the brain

The paper presents a computer simulation of the transcranial magnetic stimulation of the brain with a low-frequency magnetic field, a technique which is proposed to replace the electroconvulsive treatment in psychiatry. The field model is based on the T-/spl Omega/ formulation, that, by the low electric conductivity and constant magnetic permeability of the human tissue, allows us to build a finite-element model of the head only.

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.

Efficient visualization of 3D models by web browser

The article presents software module designed for efficient and convenient visualization of 3D models inside the web browser environment. It is written purely in JavaScript and takes advantages of the new HTML 5 standard. The authors focus on mobile devices, so special attention is given on efficiency and low network usage. Proposed solution based on progressive mesh streaming is compared with server side rendering approach. The results of usability tests performed on real-life random users group will be discussed.

A comparison of two models of electrodes for ECT simulations

This paper discusses some numerical aspects of the simulation of electroconvulsive therapy (ECT). A realistic finite-element model of the human head is used to discuss two approaches to modeling the electrodes applied to human head skin. The first approach models the electrode by a mixed-boundary condition, while the second one uses additional subdomain imitating electrode-to-skin contact for that purpose [three-dimensional (3-D) model]. An algorithm of grid modification used to add an external subdomain modeling the electrode contact resistance is presented. The authors examine the influence of the electrode model on the convergence speed of the iterative solver. The authors state that the 3-D model is better conditioned, and, thus, it converges faster

Numerical model of magnetic stimulation with metal implants

The paper presents numerical model of the magnetic stimulation of the human body. The proposed model allows one to calculate eddy current distribution inside the body with a metal implant, which can be ferromagnetic or diamagnetic. A hybrid Toarr-Omega, Aoarr finite-element method formulation is used, where Omega is calculated by semi-analytical integration over a boundary of the conducting region. The three-step algorithm is presented, with discussion about implementation and computational problems

Internet application concept to trivialize EMF biomedical computing

Purpose – The purpose of this paper is to describe a new concept of a computer system devoted to simulations of electromagnetic fields inside the human body. The main idea is based on application of the cloud computing approach to the electromagnetic simulator for inexperienced operators.Design/methodology/approach – Modular design of the system is based on web technologies. The logic of simulation processes is stored in the form of scenarios consisting of several simple steps.Findings – The authors found that a system based on a predefined, precise scenario will help an inexperienced user to solve realistic EMF simulations using state‐of‐the‐art technology. Highly modular application could be easily extended to the new functionality provided by independent programs (Processors) utilizing any type of a dedicated hardware platform.Practical implications – The remote computing is known by computer science for its early beginning, but extraordinary growth of the internet network is renewing this term for the...

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.

Multiscale Finite Element Model of the Electrically Active Neural Tissue

The paper presents a mathematical approach to modeling of continuous, spatial and active neural tissue. It combines a nonlinear discrete cell membrane model with spatial bidomain model into one multiscale problem. The bidomain allows us to simulate the action potential (AP) propagation in the selected human brain neural tissues. The evoked potentials are stimulated by applying artificial stimulation current in the nonlinear cell model which is equivalent to direct injection of current by the internal electrode. Such approach can be used to model electrical stimulation of the neural tissue during the surgical operations or stimulation by surgically implanted devices. The model can be extended to deal with external electric or magnetic stimulus. The main focus of the paper is put on numerical adaptation of the bidomain commonly used for modeling human heart activity to new area of interest: human neural system. The authors present two formulations of the bidomain model. The first uses a pair of intra and extracellular potentials, and the second uses a pair of extracellular potential and membrane voltage. Both formulations are compared with respect to results and numerical efficiency.

Bidomain formulation for modeling brain activity propagation

The paper presents a mathematical approach to the modeling of continuous active neural tissue together with a nonlinear discrete cell model. The main focus is put on the numerical formulation adapted from the bidomain model for the human heart. The bidomain model uses two scalar electrical potentials: intra- and extracellular to simulate propagation of the action potential from the spiking neurons in the white and gray matter tissues. The evoked potentials are forced by applying artificial stimulation current through the neuron membrane. The authors introduced new values of material parameters and neuron models to adequately simulate the brain activity

Distributed evolutionary algorithm for optimization in electromagnetics

This paper presents a distributed universal evolutionary optimization environment designed for optimal design in electromagnetics. The optimizer can be tuned to act as a genetic algorithm or as an evolutionary strategy. Basic principles of optimizer design are discussed. The system is coded in Java and uses a remote method invocation technique to distribute computational tasks between local and/or remote servers. T.E.A.M Workshop problem 25 was used to estimate parallel performance of the system. An example of application is the optimal location of electrodes for electroconvulsive stimulation is presented