Joint Fall 2022 Meeting of the Texas Section of the APS, Texas Section of the AAPT, and Zone 13 of the SPS
Volume 67, Number 11
Thursday–Saturday, October 13–15, 2022;
Rice University, Houston, Texas
Session K01: Plenary II
9:00 AM–10:00 AM,
Saturday, October 15, 2022
Rice University BRC
Room: Auditorium
Chair: Douglas Natelson, Rice University
Abstract: K01.00002 : Radiosensitization Enhancement by Gold Nanoparticles in 192Ir HDR Brachytherapy
9:30 AM–10:00 AM
Abstract
Presenter:
Kathryn Mayer
(University of Texas at San Antonio)
Author:
Kathryn Mayer
(University of Texas at San Antonio)
Radiation therapy has long been one of oncologists' most effective weapons against cancer, and today's state-of-the-art technology allows medical physicists to tailor advanced patient-specific treatments. However, new radiation therapy methods which can increase the local effectiveness of tumor cell killing while sparing healthy tissues are still needed. Due to gold's high atomic number, gold nanoparticles exhibit strong interactions with the X-ray photons used in radiation therapy, leading to localized radiation dose enhancement. This dose enhancement is being systematically investigated in a collaborative project between physicists at the University of Texas at San Antonio and medical physicists at University of Texas Health San Antonio's Mays MD Anderson Cancer Center. Macroscopic physical dose enhancement has been systematically determined using a novel measurement technique on a clinical brachytherapy setup. Experimentally determined dose enhancements of up to ~5% have been measured; these observed enhancements agree well with Monte Carlo simulations. Intriguingly, a macroscopic physical dose enhancement of 5% is a volume average—the dose enhancement in the microscopic vicinity of a nanoparticle is much higher. This microscopic enhancement may be determined via the radiobiological effects on cells. Recently we have investigated the radiobiological effects of irradiation in a brachytherapy setup for C33a cervical cancer cells treated with PEGylated gold nanoparticles. We have carried out imaging flow cytometry to quantify the effects of the treatment on cell viability and apoptosis, using Zombie Aqua and Annexin V staining, respectively. Cell survival curves were fit with the linear quadratic model. We then determined the radiation dose required to achieve the same cancer cell killing effect with vs. without the presence of gold nanoparticles.