Computer modelling and vegetable bench test of a bipolar electrode array intended for use in high frequency irreversible electroporation treatment of skin cancer.

Purpose: Pulsed electrical field (PEF) ablation is an energy-based technique used to treat a range of cancers by irreversible electroporation (IRE). Our objective was to use computational and plant-based models to characterize the electric field distribution and ablation zones induced with a commercial 8-needle array-based applicator intended for treatment of skin cancer when high-frequency IRE (H-FIRE) pulses are applied. Electric field characterisation of this device was not previously assessed. Methods: Vegetable experimental were conducted using parallel plate electrodes to obtain the lethal threshold for H-FIRE pulses. Then a 3D computational model of the applicator was built mimicking the experimental conditions. The computational ablation zones were validated with the experiments for different voltage levels ranging from 220 to 525 V. Results: A threshold of 453 V/cm was estimated for H-FIRE pulses, which was used to predict computationally the ablation zones. It was found that the model showed a low prediction error, ranging from 2% for the minor diameter to 4.5% for the depth compared with experiments. Voltages higher than 370 V created an ablation volume with a rectangular prism shape determined by the positions of the needles, whereas lower voltages provoked the appearance of untreated areas (gaps). Conclusions: Our computer model predicts reasonably well the ablation zone induced by H-FIRE pulses, suggesting that a sufficiently large voltage must be applied to avoid the appearance of gaps. The validated model with vegetable experiments could serve as the basis for future computer studies to predict the behaviour of this device on heterogeneous tissues.