ABSTRACT OF THESIS

Positron Emission Tomography (PET)/Computed Tomography (CT) Guided Diffuse Optical Tomography (DOT) Study for Breast Cancer Imaging

by

Kavita Kumar

Master of Science in Biological Engineering and Small – scale Technologies

University of California, Merced, 2018

Professor Changqing Li, Chair

Diffuse optical tomography (DOT) is known to be a promising imaging technique for breast cancer detection. It involves the detection of transmitted light photons in the near infrared range through soft biological tissues. It can provide functional images of oxyhemoglobin, deoxyhemoglobin, water and lipid content in breast tissue. DOT itself is low – cost and uses non – ionizing light. However, it is ill – posed and has low spatial resolution. Structural prior information from other imaging modalities can be used to counter these issues. Computed tomography (CT) utilizes high - energy x-ray photons to obtain high spatial resolution images and can provide good structural information for DOT. Positron emission tomography (PET) is a nuclear medicine imaging technique that can be used to observe the metabolic processes in the body. A PET/CT guided DOT imaging system can be used for therapeutic monitoring during neoadjuvant chemotherapy in breast cancer patients.

In this study, Clinical PET and CT breast images containing a breast tumor is used to create 3D meshes using the finite element mesh method. The process involves applying an edge detection algorithm to the CT images. The breast tumor location is extracted from the PET images via a thresholding method. After the breast mesh is made, the breast tumor location is interpolated to the breast mesh nodes. Two different breast meshes are compared in this study. Three different detector based setups for the two breast mesh cases are compared. The soft prior method of reconstruction is used which requires the use of structural prior information from the CT images and segmentation. The results presented are for the two different breast mesh cases and compare different noise levels. The reconstruction results validate the feasibility of the design and optimization of the optical detectors and laser sources for a future physical PET/CT guided DOT imaging system.