ESTRO 2024 - Abstract Book

S370

Beachytherapy - Physics

ESTRO 2024

3 Poher A, Berumen F, Ma Y, Perl J, Beaulieu L. « Validation of the TOPAS Monte Carlo toolkit for LDR brachytherapy simulations ». Phys Medica 2023;107:102516.

4 The authors acknowledge the valuable contribution of Dr.Baljeet Seniwal to this work.

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Digital Poster

RapidBrachyIVBT: A dosimetry software for personalized image-guided intravascular brachytherapy

Maryam Rahbaran 1,2 , Jonathan Kalinowski 1,2 , Joseph DeCunha 3,4 , Kevin Croce 5 , Brian Bergmark 5 , Philip Devlin 6 , James Tsui 7 , Shirin A. Enger 1,2 1 McGill University, Department of Oncology, Montreal, Canada. 2 Jewish General Hospital, Lady Davis Institute for Medical Research, Montreal, Canada. 3 University of Texas MD Anderson Cancer Center, Department of Radiation Physics, Houston, USA. 4 University of Texas MD Anderson Cancer Center, Department of Medical Physics, Houston, USA. 5 Harvard Medical School, Department of Cardiology, Boston, USA. 6 Harvard Medical School, Department of Radiation Oncology, Boston, USA. 7 McGill University, McGill University Health Centre, Montreal, Canada Cardiovascular disease is the leading cause of death in the United States (1) and second cause of death in Canada (2). Coronary artery disease is the most common form of cardiovascular disease, caused by excess plaque along the arterial wall, blocking blood flow to the heart (stenosis). The most common treatment option for partial obstructions is a percutaneous coronary intervention, which widens the arterial wall with the inflation of a balloon inside the lesion area and leaves behind a metal stent to prevent re-narrowing of the artery (restenosis). However, in-stent restenosis may narrow the artery again by neointimal hyperplasia, producing fibrotic and calcified plaques due to damage to the arterial wall tissue. Drug-eluting stents, which slowly release medication to inhibit neointimal hyperplasia, are used to prevent in-stent restenosis but fail for up to 20% of cases (3). Intravascular brachytherapy (IVBT) uses β-emitting radionuclides to prevent in-stent restenosis and is used in failed cases (4). However, current clinical dosimetry for IVBT is water-based per the American Association of Physicists in Medicine Task Group 149 report (TG-149), i.e., absorbed dose in the region of interest is calculated by assuming that the patient’s artery, calcified plaques, metallic stents, and guidewire from the IVBT delivery system are all water with unit mass density. The attenuation of the dose by these heterogeneities is not considered (5). In-stent restenosis recurs for one third of IVBT patients, which could be attributed to inaccurate dosimetry (6, 7, 8). In fact, previous studies by our group, performed with Monte-Carlo simulations in an artery model, have shown that including such heterogeneities may attenuate absorbed dose to the region of interest by up to 50% compared to dose calculations in water (9). Vascular optical coherence tomography (OCT) is an imaging modality that utilizes near-infrared light to image the IVBT treatment area, visualizing calcification, stents, and the guidewire (10). It has been shown that intravascular image-guidance improves IVBT patient outcomes (11). The purpose of this study was to develop a Monte Carlo based software to investigate the uncertainties in water-based IVBT dosimetry by extending our previous software to account for patient-specific geometry from OCT images. Purpose/Objective:

Material/Methods: