Phys Med. 2026 Jun 23;148:105858. doi: 10.1016/j.ejmp.2026.105858. Online ahead of print.
ABSTRACT
PURPOSE: Drug-eluting stents fail in up to 20% of patients. In failed cases, intravascular brachytherapy (IVBT) is administered with β-emitting 90Sr90Y through a guidewire. Current clinical dosimetry is water-based, neglecting attenuation from patient-specific materials such as plaques, stents, and the off-centered guidewire, leading to a discrepancy between prescribed and delivered dose. This study retrospectively performed patient-specific IVBT dose calculations using Optical Coherence Tomography (OCT) to quantify uncertainties in clinical dosimetry.
METHODS AND MATERIALS: Dose calculations on OCT images from ten patients were performed using RapidBrachyIVBT, a Monte Carlo-based dose calculation software. Heterogeneities, including guidewire(s), stents, and fibrotic and calcified plaques, were contoured and assigned material properties; surrounding tissue was modeled as smooth muscle. Absorbed dose to water and medium were calculated. The prescribed dose to water was 18.4 or 23 Gy at 2 mm from the source, depending on lumen diameter. The dose homogeneity index was defined as the ratio of the maximum to the minimum dose in the target volume.
RESULTS: When heterogeneities were included, median maximum dose attenuation was 76.7% (75.0-77.1) in the artery segment and 56.2% (52.2-65.1) in the target volume. The median dose homogeneity index increased from 1.29 in water to 2.93 (2.44-3.33) with patient-specific materials. The guidewire produced asymmetric dose distributions in all patients, with the greatest attenuation where it opposed thick calcified plaques.
CONCLUSIONS: Standard water-based IVBT dosimetry is inaccurate due to dose-attenuating materials present during treatment. Personalized, image-guided IVBT planning that accounts for patient-specific heterogeneities may improve treatment accuracy and clinical outcomes.
PMID:42335519 | DOI:10.1016/j.ejmp.2026.105858