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Browsing by Author "White, Natalie B."

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    Dynamic Electrical Responses of Biological Cells and Tissue to Low- and High-Frequency Irreversible Electroporation Waveforms
    White, Natalie B. (Virginia Tech, 2021-04-23)
    Irreversible electroporation (IRE) is a local ablation technique that has been shown to be both safe and effective in the treatment of solid tumors. The treatment typically consists of inserting needle electrodes directly into the treatment zone and applying high-voltage pulses with widths on the order of hundreds of microseconds. These pulses permeabilize tissue leading to loss of homeostasis among the cells in the treatment zone. Predicting these treatments is challenging as the electric field (EF) induced through the electrode configuration is heterogeneous and is affected by several adjustable parameters. Computational treatment planning models aim to provide a visualization of the treatment zone, and they rely on two critical pieces of information: the electric field distribution (EFD) within the tissue, and the lethal EF threshold for the target tissue type. This work primarily aims to quantify tissue properties necessary for computing the EFD for any electrode configuration, for both traditional IRE as well as next-generation high-frequency IRE treatments. Also included is the determination of pancreatic tumor lethal EF threshold using collagen tissue mimics. Additionally, this work builds on previous reports of an optimal resistance reached during IRE by examining the changes in patients' immune cell populations following treatment, and proposing a method of optimizing these populations by monitoring real-time current achieved during IRE.
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    A Patient-specific Irreversible Electroporation Treatment Planning Model Based on Human Tissue Properties
    White, Natalie B. (Virginia Tech, 2018)
    Irreversible electroporation (IRE) is a focal ablation technique that has been shown in recent clinical trials to be effective in treating pancreatic cancer. The technique uses short, high voltage pulses to induce nanoscale pores in the target cell membranes, leading to cell death. Due to its non-thermal mechanism, IRE is particularly well suited for treating a tumor that is unresectable due to its close location to crucial structures such as blood vessels and nerves. Predicting the region of treatment is critical for optimal treatment of the tumor. The only predictive tools clinicians currently rely on for IRE treatment planning are computer tomography (CT), ultrasound (US) imaging, and real-time resistance measurement is used to monitor treatment progress. However, there is currently no method to plan optimal pulse parameters such as voltage, pulse duration, pulse number, and electrode spacing prior to treatment. Computational treatment planning models aim to perform this prediction in 3D, however, the electric field region relies on the electrical response of human tissue during IRE. This work quantifies this response for the first time and implements human tissue properties in a patient-specific, 3D treatment planning model.