Electrical impedance tomography for internal radiation therapy

Abstract

Internal radiation therapy is a radiation-based treatment for various forms of localized cancer. In this treatment, several needles or catheters are inserted percutaneously into the tissue, and radiation is delivered through them directly to the site of the tumour growth. Imaging methods to delineate the dominant tumour are imperative to ensure the maximum success of the radiation procedure. This thesis investigates a new imaging approach for internal radiation therapy based on the principle of electrical impedance tomography (EIT). A novel procedure utilizing brachytherapy needles as electrodes is proposed to map the internal electrical conductivity of the tissue. Since cancerous tissue exhibits different levels of conductivity than healthy tissue, it is hypothesized that the electrical conductivity map of the tissue can be used to delineate cancerous nodules via EIT. In addition, this thesis explores the use of electrical impedance modulation via ultrasound to improve the spatial resolution of EIT images.