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 (iv, 29 pages) : illustrations (some color)

Dissertation/Thesis Chair

Jonathan Petruccelli

Committee Members

Jonathan Petruccelli, Carolyn MacDonald, Daniel Robbins

Keywords

Cancer, Detection, Imaging, Phase, Scatter, X-ray diffraction imaging, Breast, Phase-contrast microscopy

Subject Categories

Optics | Radiology

Abstract

In medical imaging, X rays are used to look inside the body to find fractures in bones, abnormal masses, cavities in teeth, and so on. What makes X rays so good at looking at these types of structures is the X ray’s penetration power. When imaging soft tissue to search for tumors, X-ray images tend to have difficulty performing well. The reason for this is that the background structures, such as fat or fibro glandular tissue have similar absorption coefficients as the tumor. Mammography tends to have a high false positive rate and can miss tumors entirely as well. There are two different imaging techniques that when used together could provide much better information about tumors and assist in diagnoses. Phase imaging has been proven to increase contrast factors by 100 times or more. Coherent scatter imaging can also help to detect tumors since carcinoma has a different scatter signature than normal soft tissue. The main purpose of this thesis was to further develop each technique and to test the feasibility of both techniques in a combined system simultaneously. The phase imaging technique used in this thesis was mesh-based phase imaging. A simple setup for this type of imaging was characterized and showed results that, with a few changes, could produce reasonable phase images. A stainless-steel mesh with a period of approximately 100-200 μm was used. When objects were placed in front of the mesh, images were taken and the distortion of the mesh image by these objects was used to produce phase images, using Fourier transform techniques The coherent scatter technique used in this experiment was also characterized. A simple slot made of lead shielding and was used to create a thin rectangular beam of X rays. This beam was then used for coherent scatter imaging. Images were taken at the different diffraction angles associated with graphite and fat. Since graphite has a similar diffraction angle to carcinoma it was used as a substitute, while bovine fat was used as a substitute for breast tissue. Raw images were taken and processed using code to clean each image and bin them to easily see the coherent scatter rings.

Download

Share

COinS