Date of Graduation

5-2019

Document Type

Thesis

Degree Name

Bachelor of Science in Biomedical Engineering

Degree Level

Undergraduate

Department

Biomedical Engineering

Advisor/Mentor

Rajaram, Narasimhan

Committee Member/Reader

Quinn, Kyle

Committee Member/Second Reader

Mudloon, Timothy

Committee Member/Third Reader

Jensen, Morten

Committee Member/Fourth Reader

Kim, Michelle

Abstract

Around 50-60% of all cancer patients undergo radiation therapy. Although some patients show complete response with no recurrence, a significant proportion of the population still develop radiation resistance. It is important to identify tumor resistance at early stages of therapy in order to adjust treatment protocol and avoid extra exposure to radiation. Current methods to assess treatment response are only limited to anatomical measurements of tumor volume after therapy. Novel approaches that shed the light on any functional information during the course of radiotherapy could significantly improve our ability to identify patients who do not respond to radiation therapy. Diffuse reflectance spectroscopy (DRS) is an optical fiber-based technique that is capable of quantitative, nondestructive, and repeated measurements of tumor biology. Our aim was to determine the sensitivity of DRS to escalating doses of radiation. An additional goal was to determine DNA damage and changes in hypoxic fraction post-radiation, and to determine if these immunohistochemical assessments were concordant with changes in optical properties, such as tissue scattering, hemoglobin concentration, and vascular oxygenation. Lookup table (LUT)-based model was used to fit the acquired DRS spectra and extract wavelength-dependent absorption and scattering properties from tissue. Our results have shown that the measurements of tumor optical properties such as oxygen saturation and total hemoglobin can provide reliable estimates of the hypoxic state of tissue. Additionally, we present significant increase in hypoxic fraction between control and irradiated groups.

Keywords

Radiation Therapy, Hypoxia, Diffuse Reflectance Spectroscopy, tumor oxygenation, breast cancer

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