Optimizing transducer array configuration for treating tumors in the infratentorial and supratentorial brain using Tumor Treating Fields (TTFields).

Introduction:

TTFields is an antimitotic cancer treatment that utilizes low intensity (1-3 V/cm) alternating electric fields in the intermediate frequency (100-300 kHz). TTFields are delivered in two orthogonal directions using 2 pairs of transducer arrays placed on the patient’s scalp. TTFields are approved for Glioblastoma Multiforme (GBM) located in the supratentorial regions of the brain. Infratentorial location of the tumor is rare in adult patients but common in the pediatric population. Infratentorial GBM presents with limited surgical treatment options and a poorer prognosis. Computational studies have shown a strong connection between the array layout and the field distribution within the supratentorial region. Here we present a computer simulations-based study designed to identify new array layouts that could deliver high field intensities concurrently to the supratentorial and infratentorial regions of the brain.

Methods:

In order to simulate TTFields delivery to the infratentorial brain, realistic computational models of a male and female subject were used. Various array layouts involving placement of the arrays on the scalp and upper neck of the models were placed on the models, and TTFields delivery was simulated using the Sim4Life 3.0 software package (ZMT Zurich). The field intensity distributions generated by the different layouts within the supratentorial and infratentorial brains were analyzed and compared.

Results:

All tested layouts delivered field intensities with median intensities above the therapeutic threshold of 1 V/cm to both the infratentorial and supra-tentorial brain. The highest field intensities were delivered to the infratentorial region by a layout, in which each array of one pair was laterally placed superficially to the lower region of the occipital lobe, and the two arrays of the second pair were placed on the calvarium and the superior aspect of the neck.

Conclusions:

This work shows the feasibility of TTFields in treating tumors in the cerebellum, brain stem and surrounding regions which are located inferior to the tentorium. Careful selection of layouts should enable an effective treatment of multi-focal disease with tumors located in both supratentorial and infratentorial regions simultaneously.