Abstract
Tumor-treating fields (TTFields) are low-intensity alternating electric fields known to disrupt cancer cell division. TTFields are approved by the Food and Drug Administration for the treatment of glioblastoma multiforme (GBM). Simulation-based studies have shown that the distribution of TTFields within the brain is heterogeneous and depends on patient anatomy. These observations suggest that optimizing treatment requires a deep understanding about how TTFields distribute within the brain. Since measuring field distributions within patient’s brain is extremely difficult, studies addressing this topic rely on numerical simulations utilizing realistic computational head models. These models are typically derived by segmenting MRI datasets into several tissue types and assigning appropriate dielectric properties to each tissue. However, the visibility of skull defects, bone flaps, and titanium plates on MRI images is low, and these features are often ignored or segmented inaccurately within current models. However, these features are easily identified and outlined in CT image datasets. Here we present two patient-specific computational head models created using datasets that combine both MRI and CT 3D images. In order to create the head models, the MRI images were first co-registered with the CT images using 3D Slicer (www.slicer.com). Next, the patient tumor was segmented manually from the T1 post-contrast image using ITK-SNAP (www.itk-snap.com). ITK-SNAP was also used to manually segment skull defects and metal plates and screws on the skull from the CT images. Automatic segmentation of the healthy tissues in the head was performed using the Multi-Atlas Robust Segmentation (MARS) segmentation tool. Finally, virtual transducer arrays were placed on the computational model, and delivery of TTFields simulated using the Sim4Life V3.0 low frequency solver. These models will help to elucidate to what extent the small skull defects that are commonly present following brain surgery influence TTFields distribution within the head.