Tumor Treatment by Direct Electric Current: Computation of Electric Current and Power Density Distribution

Abstract

Electrotherapy by direct electric current was shown to have an antitumor effect in different animal tumor models and in clinic. Information on the current density distributions in the tumor, surrounding tissues, and its differences in the different electrode configurations used in our previous studies could be useful in future studies of electrotherapy mechanisms. Therefore, a three-dimensional, anatomically based, finite element model of the mouse with a subcutaneous tumor was built. Different types of electrotherapy, i.e., different electrode configurations, were modeled by applying appropriate boundaq conditions in the grid points. The magnitude of current density in anodic/cathodic electrotherapy is 50 times higher in the middle and 10 times higher on the edge of the tumor when compared to the "field" electrotherapy. The results of the computation show that the effects of the electrotherapy on tumor growth, which were similar in terms of tumor growth delay in all three configurations, are not directly related to the magnitude of the electric current or power density in the tumor.Address for correseondence: Damijan Miklavcic,

Numeric Investigation of Brain Tumor Influence on the Current Distributions During Transcranial Direct Current Stimulation

“…Besides, the induced peaking current density in the high grade RFL brain tumor fitted into the effective current density strength window for intro tumor suppression (calculated as 0.35~0.7 A/m 2 ) and reached up to 26% of the effective current density (1.8 A/m 2 ) generated by the noninvasive electrotherapy for vivo tumor suppression [70,71]. This finding provides an encouraging support to the clinical explorations on the RFL brain tumor inhibition using tDCS.…”

The Importance of Electric Field Distribution for Effective in Vivo Electroporation of Tissues

“…The model has been described in extenso in our previous publications (Miklavcic et al, 1997;S emrov and Miklavcic, 1997). Briefly, a threedimensional anatomically based finite element (FE) model of the mouse with injected subcutaneous solid tumor was built using MSC/EMAS (Electro-Magnetic Analysis System) software package (trademark of The Mac-Neal-Schwendler Corporation, Los Angeles, CA).…”

“…Anisotropic characteristics were considered for skeletal and heart muscles, whereas all other tissues (organs) were modeled as isotropic. The values of the electric conductivity of tissues (organs) used in the model were collected from literature and used in one of the previous studies in which a similar model was verified with the measurements of electric potential in the five points in the tumor and surrounding tissue (Miklavcic et al, 1997). The resulting three-dimensional model was made of 7089 three-dimensional finite elements that were defined by 7578 grid points.…”

Analytical and Numerical Solutions of the Potential and Electric Field Generated by Different Electrode Arrays in a Tumor Tissue under Electrotherapy

“…Also, these distributions depend explicitly on the difference of conductivities of both tissues [13,15,16]. The influence of some of these parameters has experimentally been verified [3,4,6,[17][18][19] and used to compute the power density distribution [20] and to increase the anti-tumor synergism of this therapy by means of the combination of this therapy with the intra-tumor injected saline solution, in agreement with previous results [3,4,21]. The good correspondence between the electric field spatial patterns obtained by experimental and theoretically ways has been demonstrated by Šersa et al by means of the electric current density imaging technique [18].…”