The Biological Effects of Proton Minibeam Therapy on High-Risk Tumors

Senior Capstone Experience by Ellie Lienert ’20

Submitted to the Department of Physics

Advised by Dr. Karl Khem

Abstract: “It is fairly typical for most cancer patients to undergo radiation therapy at some point during their cancer treatment and recovery process. Radiation therapy targets malignant tumor sites with a high energy concentration in the form of photon or ion radiation. Although conventional methods of radiation therapy are beneficial to the treatment of most tumors, they are not as sufficient for the treatment of high-risk brain tumors such as Glioblastomas and Medulloblastomas. Conventional photon radiation therapy introduces the added risk of healthy tissue exposure to radiation, which is an impediment that a complex organ, like the brain, cannot afford. This paper aims to answer the question: could there be a type of radiation treatment that provides a satisfactory treatment for these brain tumors, concentrating the most dose at the tumor site while concurrently sparing the maximum amount of surrounding healthy tissue? Several studies focusing on a novel method of radiation treatment, proton minibeam therapy (pmbRT), have attempted to answer this question, all to a successful degree. On a cellular level, 𝛾-H2Ax serves as a biomarker for signaling DNA damage done by radiation, enabling the analysis of the tissue-sparing properties of proton minibeams on a molecular level. The depth at which proton minibeams begin to merge back to a single homogenous beam was determined in another study, giving a concrete value in terms of target depth of how much healthy proximal tissue would be spared at the entrance site of the patient. Each study concluded that proton minibeams do possess even more tissue sparing properties compared to conventional open beams. “

Read Ellie’s SCE below:

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