ENGS 88 Honors Thesis (AB Students)

Degree Program

A.B.

Year of Graduation

2019

Faculty Advisor

Scott C. Davis

Document Type

Thesis (Senior Honors)

Publication Date

6-2019

Abstract

Fluorescence imaging has become a standard in many clinical applications, such as tumor and vasculature imaging. One application that is becoming more prominent in cancer treatment is fluorescence-guided surgery (FGS). Currently, FGS allows surgeons the ability to visually navigate tumors and tissue structures intraoperatively. As a result, they can remove tumor more efficiently while maintaining critical structures within the patient, creating better outcomes and lower recovery times. However, background fluorescence and inability to localize depth create challenges when determining resection boundaries.

Different techniques, such as spatially modulating the illumination and imaging at longer light wavelengths, have been developed to accurately localize position and to maximize contrast of key structures at greater penetration depths in surgeries. However, combining these two techniques offers an opportunity to capitalize on their respective advantages in fluorescence imaging.

In this work, we develop instrumentation combining two cutting-edge imaging methodologies; spatial frequency domain imaging (SFDI) and short-wave infrared (SWIR) fluorescence, and evaluate the capacity of this combination to improve image quality. Using conventional flat light imaging and SFDI, images of a fluorescent tube submerged in a liquid phantom were taken in the standard “first window” of the near-infrared (NIR-I) and the SWIR. By comparing resolution and maximum signal of the resulting images, we determined whether SFDI in the SWIR can improve fluorescence imaging for surgery such as to increase sharpness and determine depth of fluorescent structures.

We found that SFDI in the SWIR localizes depth and increases contrast by removing background fluorescence. When compared to NIR-I, SWIR SFDI is not as depth sensitive but can capture deeper structures. These results show that implementing SFDI can significantly improve current biomedical applications of SWIR imaging. Next steps for SWIR SFDI include analyzing the effects from altering the optical properties of the phantom, investigating the interaction between multiple fluorescent objects, and conducting in vivo efficacy studies.

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