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Abstract: Prostate cancer is the most highly-diagnosed form of cancer in male subjects in the United States. As a result, over 100,000 radical prostatectomies are performed annually in the US. However, it is currently difficult for surgeons to confirm that all impacted tissues have been effectively removed from the patient. Positive surgical margins are an independent risk factor for the recurrence of cancer, yet currently there is no method to efficiently, intraoperatively assess the status of surgical margins during a radical prostatectomy. There is a need for a new tool that is small enough to fit into a laparoscopic port, images the tissues in real time, is ideally radiation-free, and is cost-effective. Electrical impedance tomography is a strong option for filling this void. Yet currently developed EIT probes have limitations.

This thesis focuses on combatting these limiting factors and producing a novel, more accurate, miniaturized EIT probe design. Building upon previous EIT designs, a more stable, constant current source was implemented into the system to attempt to improve accuracy, the number of electrodes used for voltage measurement was increased and their arrangement re-designed for added resolution, and the circuitry was simplified to reduce the possible introduction of parasitic impedances. High impedance buffers and low noise components were also implemented for this reason. Additionally, noise and stray capacitance were combatted by moving all analog circuitry onto the device pcb close to the electrodes to eliminate the need for long leads which can introduce distortion of signals. In the process of implementing these improvements, previous EIT probe designs were evaluated, a new electrode layout was designed, improved current sources were analyzed, extensive component evaluation was performed, pcb prototypes of a system layout with the above changes were produced, a calibration scheme for these new designs was developed, these calibrated systems were evaluated, this improved design was miniaturized, and the final, miniaturized, probe layout was analyzed. This research has been another step towards the development of a small scale, clinically implementable, low noise, high accuracy, high precision EIT probe which could provide vital, real-time information to surgeons during radical prostatectomies.

Thesis Committee: Ryan Halter (chair), Kofi Odame, Ethan Murphy