Abstract

Radiation therapy is one of the most common treatments of cancer that sends high energy X-rays (~5 MeV) to kill cancer cells. Gel dosimeters are used to measure the amount of radiation applied and its distribution to ensure a lethal dose is applied to the cancerous tissue while sparing surrounding healthy tissue. In this research, we are developed novel multiparametric MRI-readable gel dosimeters that can image X-ray doses in 3D biomimetic phantoms and computationally model the attenuation of radiation throughout the phantoms. Fricke gel and polymer gels were tested. In Fricke gel dosimeters, ferrous ions transform into ferric ions when irradiated. In polymer gel dosimeters, monomers polymerize when exposed to radiation. Quantitative MRI was used before and after irradiation to measure changes in spin relaxation times T1, T2, and water diffusion constant. Changes to these values mean the dosimeter is radiation sensitive and is therefore a good dosimeter. Fricke and polymer solutions have shown to be radiation sensitive. In addition to being able to correlate changes in T1, T2, and D to X-ray dose, these measurements give information on how the materials are changing in response to radiation. Polymer gels were used to measure the accuracy of LINACs and found there to be error of up to \SI{2.5}{Gy} in dose plans. A multiparametric polymer gel dosimeter was found and used throughout this study. Measuring toxicity effects of sublethal doses in surrounding tissue is now a critical issue since, as more people survive cancer, long term quality of life after treatment is a primary concern.

Advisor

Manz, Niklas

Department

Physics

Disciplines

Biological and Chemical Physics

Keywords

Gel, Dosimetry, Physics, Radiation Therapy, MRI, NMR, Radiation Dosimetry

Publication Date

2025

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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Available for download on Monday, July 22, 2030

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© Copyright 2025 Eric Johnson