Improving Prediction of the Potential Distribution Induced by Cylindrical Electrodes within a Homogeneous Rectangular Grid during Irreversible Electroporation

Featured Application The Electric-Potential Estimation (EPE) method provides the possibility to considerably shorten the simulation time of treatment planning within a uniformly distributed rectangular grid by using large voxel-sized models without largely affecting the accuracy of the electric-field distribution. Thus, real-time clinical IRE treatment planning in realistic heterogeneous target volumes becomes feasible. Background: Irreversible electroporation (IRE) is an ablation technique based on the application of short, high-voltage pulses between needle electrodes (diameter: ~1.0 x 10(-3) m). A Finite Difference-based software simulating IRE treatment generally uses rectangular grids, yielding discretization issues when modeling cylindrical electrodes and potentially affecting the validity of treatment planning simulations. Aim: Develop an Electric-Potential Estimation (EPE) method for accurate prediction of the electric-potential distribution in the vicinity of cylindrical electrodes. Methods: The electric-potential values in the voxels neighboring the cylindrical electrode voxels were corrected based on analytical solutions derived for coaxial/cylindrical electrodes. Simulations at varying grid resolutions were validated using analytical models. Low-resolution heterogeneous simulations at 2.0 x 10(-3) m excluding/including EPE were compared with high-resolution results at 0.25 x 10(-3) m. Results: EPE significantly reduced maximal errors compared to analytical results for the electric-potential distributions (26.6-71.8%-> 0.4%) and for the electrical resistance (30%-> 1-6%) at 3.0 x 10(-3) m voxel-size. EPE significantly improved the mean-deviation (43.1-52.8%-> 13.0-24.3%) and the calculation-time gain (>15,000x) of low-resolution compared to high-resolution heterogeneous simulations. Conclusions: EPE can accurately predict the potential distribution of neighboring cylindrical electrodes, regardless of size, position, and orientation in a rectangular grid. The simulation time of treatment planning can therefore be shortened by using large voxel-sized models without affecting accuracy of the electric-field distribution, enabling real-time clinical IRE treatment planning.