Electrical Impedance Tomography Based Closed-Loop Tumor Treating Fields in Dynamic Lung Tumors

Tumor treating fields (TTFields) are a noninvasive anticancer modality that utilizes alternating electric fields (EFs) to disrupt cancer cell division and growth. While generally well-tolerated with minimal side effects, traditional TTFields therapy for lung tumors faces challenges due to the influence of respiratory motion. In this study, we introduce a novel closed-loop TTFields strategy for lung tumors by incorporating electrical impedance tomography (EIT) for real-time respiratory phase monitoring and dynamic parameter adjustments. Furthermore, we conduct theoretical analysis to evaluate the performance of the proposed method using the lung motion model. Compared to conventional TTFields settings, we observed that variations in the electrical conductivity of lung during different respiratory phases led to a decrease in the average EF intensity within lung tumors, transitioning from end-expiratory (1.08 V/cm) to end-inspiratory (0.87 V/cm) phases. Utilizing our proposed closed-loop TTFields approach at the same dose setting (2400 mA, consistent with the traditional TTFields setting), we can achieve a higher and consistent average EF strength at the tumor site (1.30 V/cm) across different respiratory stages. Our proposed closed-loop TTFields method has the potential to improve lung tumor therapy by mitigating the impact of respiratory motion.

I. Introduction

Tumor treating fields (TTFields), as a noninvasive approach that uses low-intensity (1–3 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields (EFs), have emerged as a promising therapeutic modality for various malignancies [1]. This treatment strategy harnesses the power of EFs to disrupt the division of cancer cells, impeding their growth and progression [2], [3]. It is generally well-tolerated by patients and has minimal reported side effects compared to traditional cancer treatments [4]. Furthermore, research indicates that adding TTFs to maintenance temozolomide chemotherapy for patients with glioblastoma [5], [6], as well as to standard systemic therapies for patients with metastatic nonsmall-cell lung cancer who have progressed on or after platinum-based therapy [7], can significantly improve progression-free survival and overall survival.