Date of Award

1-1-2022

Language

English

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College/School/Department

Department of Physics

Content Description

1 online resource (vi, 47 pages) : illustrations (some color)

Dissertation/Thesis Chair

Carolyn MacDonald

Committee Members

Carolyn MacDonald, Jonathan Petruccelli, Alexander Khmaladze, Matthew Szydagis

Keywords

Radiography, Medical, Breast, X-ray optics

Subject Categories

Physics

Abstract

Traditional x-ray images are good for distinguishing between materials with very different absorption coefficients. However, detecting breast cancer using conventional x-ray imaging is hard because cancer tissue has similar absorption coefficients as normal tissue. Annually 43,600 women will die from breast cancer. The odds of survival are better if the cancer is diagnosed at an early stage, but mammography tends to have high rates of missed cancers. Mammography also tends to have a high false-positive rate, which leads to unnecessary biopsies. Two techniques with potential to add additional information to breast imaging have been investigated. X-ray phase imaging has been shown to improve the image contrast by factors of 100 or more but generally requires complex precision equipment. In addition to differing phase signatures, carcinoma also shows a different coherent scatter signature than normal tissue. A goal of this work was to demonstrate a system that could simultaneously collect phase and coherent scattering images and that would be compatible with slot-scan mammography for the detection of breast cancer. A simple, inexpensive mesh-based phase imaging system was characterized and shown to show a significant improvement of the contrast and signal-to-noise ratios compared to a conventional imaging. The system applied meshes of stainless steel wire with a period of 100-200 μm which could be imaged directly. The distortion of the mesh pattern with a sample present was analyzed with a code that used Fourier transform techniques to produce a phase contrast image. The analysis included deblurring applied as deconvolution which sharpened the absorption and differential phase contrast images. In addition, the use of a focusing polycapillary optic to improve phase images relative to a conventional large source was investigated. The coherent scatter imaging technique employed simple slots. It was designed to detect carcinoma and fat separately with a scanning camera. Small aperture diffraction ring measurements with a developed radial integration code confirmed the diffraction angle of graphite was approximately the same as that of cancer, so graphite was employed as a cancer surrogate. Multiple images of the checkerboard sample were taken with the developed stitching code at graphite and fat diffraction angles separately, and the resulting images have been shown to accurately detect the locations of fat and graphite. Finally, a sample of combination of fat and graphite with glass beads and small nylon rod with tape was used in this system and the resulting images have shown there is potential to overlay coherent scatter information on the phase images.

Download

Included in

Physics Commons

Share

COinS