Feasibility of a method for optimizing the electrode array structure in tumor-treating fields therapy

The present study investigated electrode array structures that maximize the therapeutic electric field intensity to tumors with different shapes and locations, while minimizing electric field intensity to the surrounding organs at risk (OARs). A human body phantom model was created from magnetic resonance images of a patient and divided into regions including a tumor and OARs. The shapes and sizes of the electrode arrays were altered for tumors differing in shape and location, and these electrode array structures were tested in the phantom. Use of a conformal electrode array based on the shape of the tumor maintained therapeutic electric field intensity to the tumor while reducing electric field intensity to the surrounding OARs by approximately 18%. Although the electric field intensity delivered to the tumor was proportional to the size of the electrode array, it was saturated at a critical area. Simulation results showed that optimal sizes of electrode arrays for specific tumors located at depths of 2 cm, 4 cm and 6 cm were 91, 273 and 830 cm², respectively, indicating that the optimal size of the electrode array is proportional to the depth of tumor in the phantom. These results suggest that a tumor location-dependent optimal ratio between the size of the electrode array and the size of the individual electrodes could be calculated. In summary, this study indicated that customizing the electrode array structure to individual tumors can markedly increase the electric field intensity delivered to the tumor while minimizing the intensity delivered to OARs.