ESTRO meets Asia 2024 - Abstract Book

S62

Interdisciplinary – Brachytherapy

ESTRO meets Asia 2024

Table 1: Summary of dosimetry results, displaying the maximum percentage dose difference in the entire artery segment and at the target volume, and the target homogeneity index. In Patients 2 and 3, each guidewire added a cold spot at the target volume. Percent dose difference plots for Patient 3 are shown in Figure 1.

Figure 1: The percent dose difference between water-based and patient-specific dosimetry on an example slice of Patient 3's OCT images with one (left), two (middle), and three (right) guidewires present in the lesion area. For patients 4 and 5, the dose attenuation at the target volume was up to 53.3% and 65.1% in segments where the guidewire was facing away from and towards calcification, respectively.

Conclusion:

The dose at the target volume in IVBT is significantly reduced by guidewires which cause cold spots amplified by calcifications. Limiting the number of guidewires present during irradiation and having guidewires facing away from calcification could reduce the cold spot effect and dose inhomogeneity at the target volume. Retrospective dosimetry considering the differences between prescribed and delivered dose can allow clinicians to guide re-treatment and patient follow-ups.

Keywords: Intravascular brachytherapy, in-stent restenosis

References:

1. Lee M, Banka G. In-stent restenosis. Interv Cardiol Clin 2016;5: 211e220.

2. Negi S, Torguson R, Gai J, et al. Intracoronary brachytherapy for recurrent drug-eluting stent failure. JACC Cardiovasc Interv 2016; 9:1259e1265.