Publication Date


Document Type


First Advisor

Coutrakon, George

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Physics


Protons are used in radiation therapy to lower doses to healthy tissues by utilizing their Bragg peak. Protons can be used both in imaging and treatment. One of the uses of protons in imaging we tested is its use to align patients using a single beam's eye proton radiograph (pRad). By using a beam's eye pRad, and comparing the water equivalent thickness (WET) to proton digitally reconstructed radiographs (pDRRs), we show that we can measure the best alignment on six axes, three translational and three rotational. This is done by defining a cost function, chi squared, which quantifies the misalignment between two images. We then find the minimum of the cost function by shifting and rotating the images with respect to each other.

In the second part of the thesis, we measure the proton range errors occurring in treatment planning software that uses X-Ray CT for 3D imaging and then compare that result with our measured range errors of a similar treatment plan that uses proton CT. These plans have known errors in the range of the protons. This means that there are healthy tissues that receive higher doses that could lead to future cancers. By using proton computed tomography (pCT) we show that we are able to reduce the errors in the predicted range of the protons in the treatment plan as compated to XCT.


89 pages




Northern Illinois University

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