2022 Thayer Investiture

All Thayer Events

MS Thesis Defense: Shannon Kossman



1:00pm - 2:30pm EST

Williamson 522 / Online

For optional Zoom link, please email shannon.e.kossmann.TH@dartmouth.edu.

"An electrical impedance tomography-based probe for intraoperative surgical margin assessment"


Prostate cancer has the highest incidence rate of cancer in men. Those with localized tumors may undergo a radical prostatectomy. Positive surgical margins (cancer at the edges of resected tissue) are associated with an increased risk of biochemical recurrence and disease progression. This project aims to help create an efficient surgical margin assessment probe compatible with robot-assisted laparoscopic surgery that utilizes bioimpedance to identify positive surgical margins while the patient is still in surgery.

Electrical impedance tomography creates an image based on the passive electrical properties of the tissue. Previous research has indicated that benign and cancerous prostatic tissue have sufficiently different electrical properties to be distinguished. A probe compatible with surgical robots was developed, but concerns of the potential for infection, noise from long cables, and a relatively lengthy data acquisition time have led to a redesign.

The electrode array for a new probe design is presented here. The new probe has dedicated voltage measurement and current source/sink electrodes and fewer current drive patterns than the previous probe design. Simulations using ex vivo data were examined to modify the electrode array design (4 current drive electrodes was determined to be insufficient to localize inclusions, so the design was modified to include 8). Simulations were also used to provide expected data for clinically relevant scenarios to aid in hardware design and understand the expected utility of the device in a surgical setting. These simulations indicate an ability to localize a 1 mm diameter cancerous inclusion against benign prostatic tissue (the most difficult clinically relevant tissue contrast). Initial bench top experiments with the electrode array are also encouraging, demonstrating an ability to localize a 2.38 mm diameter aluminum rod in saline close to the electrode array surface.

Thesis Committee

  • Ryan Halter (chair)
  • Ethan Murphy
  • Kofi Odame


For more information, contact Theresa Fuller at theresa.d.fuller@dartmouth.edu.