Enhancement of prompt gamma response for treatment planning verification

Thumbnail Image

Date

2022

Authors

Hart, Shanyn-Dee

Journal Title

Journal ISSN

Volume Title

Publisher

Abstract

In this project I present the results of a feasibility study on a novel strategy for real-time dose verification using secondary prompt γ-ray emissions produced by way of proton–nuclear interactions within selected materials during proton irradiation. To provide a proof-of principle of this methodology, Monte Carlo simulations were performed using an approximately mono-energetic 70 MeV proton beam, irradiating different materials in salt and solution form. The choice of the target element is the key to obtaining a prompt γ-ray spectrum significantly different from the background produced by the human body, as well as for physiological considerations (such as uptake and toxicity effects). The promising candidates were: 63Cu, 89Y and 31P. I investigated the emission spectra of γ-rays exiting the target and assessed the enhancement of the γ-ray yield with respect to the background, comparing simulation and experimental results as conducted by the research group of the Trento University, Italy. I demonstrated how proton reactions with a solution containing the target elements can produce signature prompt γ-rays related to the material irradiated despite the significant background. The minimum material concentration required to obtain a significant enhancement was also studied. The results show that the prompt γ-ray spectra differ significantly for each type of target studied. The relative intensity of the characteristic γ-rays emitted from a given solution containing the target elements was shown to be proportional to the concentration of each element in that material. Based on these results, I discuss the potential use of prompt γ-ray emission as a method to verify the accuracy and efficacy of doses delivered with proton radiotherapy

Description

A dissertation submitted in fulfilment of the requirements for the degree of Master of Science to the Faculty of Science, School of Physics, University of the Witwatersrand, Johannesburg, 2022

Keywords

Citation

Collections

Endorsement

Review

Supplemented By

Referenced By