Publication Date

2021

Document Type

Dissertation/Thesis

First Advisor

Coutrakon, George

Degree Name

Ph.D. (Doctor of Philosophy)

Legacy Department

Department of Physics

Abstract

Proton therapy is a form of radiation treatment for cancer that utilizes the Bragg peak to create conformal high dose regions around the tumor volume. However, the use of x-ray computed tomography (CT) and x-ray radiography for treatment planning and pre-treatment quality assurance procedures improves the achievable effectiveness of proton treatment plans (using proton CT) and the pretreatment verification (using proton radiography). Errors in the conversion from x-ray Hounsfield units (HU) to proton relative stopping powers (RSP) leads to errors in the predicted proton range. To account for the errors, 3.5% margins are included in the treatment plan. This means that there are healthy tissues surrounding the tumor volume that receive high levels of dose and could potentially incur serious toxicities. Furthermore, after the patient initially receives a CT, there is no method of detecting anatomical changes that could lead to proton range errors. Proton CT and proton radiography are low dose alternatives for x-ray imaging that will lead to safer and more effective treatments. Proton CT removes the need for an error-prone conversion, allowing the treatment plan margins to be reduced to as low as 1%. Additionally, proton radiography can be used to detect anatomical changes that could lead to errors in the proton range prior to the daily treatment. In this dissertation, we discuss two pre-clinical proton imaging systems and quantify the image quality using three metrics: spatial resolution, noise, and accuracy. We discuss the feasibility of clinical implementation by looking at the percent of patients that can be imaged with clinical proton beam energies. We also measure the ability to detect anatomical changes with proton radiography and compare the range accuracy of proton treatment plans created on x-ray CT and proton CT images.

Extent

182 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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