In electrochemotherapy, flexible electrodes, composed by an array of needles, are applied to human tissues to treat large surface tumors. The positioning of the needles in the tissue depends on the surface curvature. The parallel needle case is preferred, as their relative inclinations strongly affect the actual distribution of electric field. Nevertheless, in some case, small inclinations are unavoidable. The purpose of this paper is to study the electric field distribution for non-parallel needles.
The effect of electrode position is evaluated systematically by means of numerical models and experiments on phantoms for two different angles (5° and 30°) and compared with the case of parallel needles. Potato model was used as phantom, as this tissue becomes dark after few hours from electroporation. The electroporation degree was gauged from the color changings on the potatoes.
The distribution of electric field in different needle configuration is found by means of finite element analysis (FEA) and experiments on potatoes. The electric field level of inclined needles was compared with parallel needle case. In particular, the electric field distribution in the case of inclined needles could be very different with respect to the one in the case of parallel needles. The degree of enhancement for different inclinations is visualized by potato color intensity. The FEA suggested that the needle parallelism has to be maintained as possible as if the tips are closer to each other, the electric field intensity could be different with respect to the one in the case of parallel needles.
This paper analyzes the effect of inclined electrodes considering also the non-linearity of tissues.
The Project was granted by CPDA138001 (Padua University). The authors thank Igea S.p.A. (Carpi, Modena Italy) for pulse generators. Research was partially made possible, thanks to COST TD1104 action (www.electroporation.net).
Campana, L.G., Di Barba, P., Dughiero, F., Forzan, M., Mognaschi, M.E., Rizzo, R. and Sieni, E. (2019), "Non-parallellism of needles in electroporation: 3D computational model and experimental analysis", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 38 No. 1, pp. 348-361. https://doi.org/10.1108/COMPEL-04-2018-0189
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