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Personalized lung dosimetry evaluated by 90Y PET/CT in radioembolization: dosimetric correlations and exploratory
Yi-Chieh Chen1, Po-Chin Liang2, Chih-Horng Wu2,3,4
1Department of Nuclear Medicine, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan.
Purpose:
To evaluate whether personalized lung mass improves pre-treatment lung dose estimation accuracy compared to the 1000-g lung model, using post-treatment 90Y PET/CT as the reference. Sex-specific anatomical differences and dosimetric factors associated with radiation pneumonitis (RP) were also explored.
Materials And Methods:
A retrospective analysis was conducted on 100 patients treated with 90Y radioembolization from 2018 to 2025. Pre-treatment lung dose estimates were derived using both the standard 1000-g lung mass model and CT-based personalized lung mass. Post-treatment lung absorbed doses were quantified via 90Y PET/CT. Dosimetric and clinical variables were compared between patients with and without RP, and sex-specific differences in lung anatomy and dose distribution were evaluated.
Results:
The mean lung mass (760.11 ± 144.89 g) was significantly lower than the 1000-g model (P < 0.001). Two patients (2%) developed RP, and both had baseline lung metastases (28% overall). Although limited by the small number of events, the RP group showed a trend toward higher median administered activity (4425 MBq [range, 3000-5800 MBq] vs. 1300 MBq [range, 400-4900 MBq]) and lung absorbed dose, whereas no similar trend was observed for lung shunt fraction (LSF) (7.6% [range, 5.1-10.0%] vs. 4.3% [range, 1.0-14.5%]). Personalized lung dose showed a stronger correlation with 90Y PET/CT than the 1000-g model (r = 0.678 vs. r = 0.612; P = 0.009), while LSF showed no correlation (r = 0.150). Sex-based dose differences seen with the 1000-g model were absent with personalized lung mass, which showed significantly lower lung mass in females (810.78 ± 126.21 g vs. 636.05 ± 109.33 g, P < 0.001).
Conclusion:
Personalized dosimetry improves predictive accuracy and mitigates sex-related dosimetric bias, suggesting CT-derived lung mass should be considered to optimize 90Y radioembolization precision. Given our limited sample size, the association between pre-existing lung metastases and RP warrants further investigation.
