Abstract 4528: A novel transducer array design optimizing TTFields delivery to the thorax
Authors: Hershkovich Hadas S. , Strauss Sholi , Weinberg Uri , Kirson Eilon D. , Bomzon Ze'ev 
Published: July 2017

Abstract
Objective: The purpose of this study was to design transducer arrays for the delivery of Tumor Treating Fields (TTFields) to the thorax, generating high intensity in the upper torso while potentially improving patient comfort.
Background: TTFields are low intensity, intermediate frequency, alternating electrical fields that disrupt cell division. The ongoing Phase II STELLAR trial [NCT02397928] is investigating the efficacy and safety of TTFields in combination with chemotherapy for the treatment of mesothelioma. A pivotal study to evaluate the efficacy of TTFields in treating NSCLC is planned for 2017. TTFields are delivered via capacitive transducer arrays, comprising ceramic disks covered with a thin layer of conductive medical-grade gel, which are arranged in an almost rectangular order. Two orthogonal pairs of arrays are placed on the skin in the vicinity of the treated region. One pair is placed on the anterior and posterior sides of the thorax. The other pair is placed on the lateral and contralateral sides of the thorax. This configuration has limitations: (a) Sub-optimal electric contact may be caused by poor attachment of the arrays on the chest due to body curvature; (b) TTFields intensity generated by anterior-posterior arrays may be attenuated in the thorax of females and obese individuals, due to high resistivity of the thick adipose layers in the breast; (c) the current lateral-contralateral arrays generate lower field intensities in the lung’s apex. This study presents novel array designs to overcome these limitations.
Methods: Various concepts for array designs that avoid placement over regions of thick sub-cutaneous fat were designed. To evaluate the field distribution generated by these arrays and optimize their design, numerical simulations using realistic computational phantoms were used.
Results: Novel array designs were developed for the delivery of TTFields to the lungs. These arrays consist of sets of interconnected small patches that adhere to the natural contours of the human body. Simulations showed that the proposed arrays deliver uniformly distributed, high electrical field to the lungs. One notable design is a pair of arrays shaped as circular rings, in which one array is placed around the neck and shoulders, whereas the second array is placed on the lower torso. This design yielded a highly uniform field directed longitudinally throughout the torso.
Conclusion: The array designs presented in this study are expected to maintain patient comfort and will ensure high field intensity delivered to the thorax. Compliance and TTFields treatment delivery could both be improved by using these designs.
Citation Format: Hadas S. Hershkovich, Sholi Strauss, Uri Weinberg, Eilon D. Kirson, Ze'ev Bomzon. A novel transducer array design optimizing TTFields delivery to the thorax [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4528. doi:10.1158/1538-7445.AM2017-4528