Evaluating Stent-Induced Dose Perturbations in Intravascular Brachytherapy with EBT4 Films 📝

Author: Yijian Cao, Jenghwa Chang, Nicholas Coupey, Lyu Huang, Jessica Jung 👨‍🔬

Affiliation: Northwell, Hofstra University Medical Physics Program 🌍

Abstract:

Purpose:
The Synergy bioabsorbable polymer (BP) stent, made of Platinum Chromium Alloy, is widely utilized in treating coronary artery disease. This study investigates dose perturbations caused by this stent during intravascular brachytherapy (IVBT) using Gafchromic EBT4 films within a custom 3D-printed phantom
Methods:
EBT4 films were calibrated with the 6MV photons of a TrueBeam at 5 cm depth in a solid water phantom, covering doses from 0 to 40 Gy. Films were scanned 24 hours post-irradiation using the Epson 10000XL scanner and analyzed with the RIT v6.8.64. A 3D-printed phantom simulated the clinical setup in water, with the β-Rail 3.5F catheter in the center of the Synergy XD stent. EBT4 films were positioned in contact with the stent and at identical locations after stent removal. Percent depth dose (PDD) curves were extracted from films and fit with the fifth-order exponential polynomial equations. Dose perturbation was evaluated using a dose reduction factor (DRF) defined as 1-Dose_with_Stent / Dose_without_Stent.
Results:
Exponential polynomial fitting yielded R² values of 0.99939 (no stent) and 0.99918 (with stent). The Root Mean Square Error and Mean Absolute Error were slightly higher for the with-stent PDD (0.0384 and 0.0355) compared to Monte Carlo simulations. DRF values at 2, 3, 4, and 5 mm were 5.7%, 3.9%, 2.7%, and 2.6%, respectively with an average dose reduction of 4.5 ± 2.2% at 2 to 5 mm and a maximum dose reduction of 7.9% at 2.68 mm.
Conclusion:
The Synergy stent introduces dose perturbations in IVBT in clinically significant regions from 2 to 5 mm. Further studies are needed to explore the implications of these dose perturbations in clinical practice to better inform treatment planning and delivery.

Back to List