S2413
Physics - Radiomics, functional and biological imaging, and outcome prediction
ESTRO 2026
redistribution of radiation dose toward less perfused lung regions.
Digital Poster 390
Perfusion-guided re-optimization of lung SBRT using 68Ga-MAA PET/CT to reduce acute radiation- induced lung toxicity Malik Nebbache 1 , Pierre-Yves LE ROUX 2 , François LUCIA 1 1 Radiation Oncology, University Hospital, Brest, France. 2 Nuclear Medicine, University Hospital, Brest, France Purpose/Objective: Gallium-68–labeled macroaggregated albumin (68Ga- MAA) perfusion PET/CT enables regional assessment of pulmonary function and may refine dose distribution in stereotactic body radiotherapy (SBRT). This study evaluated the feasibility of systematic SBRT plan re-optimization according to predefined perfusion-based functional dose constraints, aiming to selectively spare highly perfused lung regions most predictive of acute radiation-induced lung toxicity (RILT). Material/Methods: Fifty-five patients treated with SBRT for primary or secondary lung tumors were included. Functional subvolumes were derived from 68Ga-MAA PET/CT as FV50%, FV70%, and FV90%, encompassing 50%, 70%, and 90% of total perfusion activity. The low-functional volume (LFV = anatomical lung volume - FV90%) represented the least perfused lung regions.Functional re-optimization applied three quantitative constraints: mean dose to FV70% <3 Gy (optimal threshold, 4 Gy acceptable), volume of FV50% receiving ≥ 20 Gy <4% (optimal, 7% acceptable), and volume of FV70% receiving ≥ 5 Gy <10% (optimal, 20% acceptable).The objective was to maximize compliance with these thresholds while preserving target coverage and standard organ-at-risk (OAR) constraints. The primary endpoint was the proportion of patients meeting optimal or acceptable functional thresholds. A secondary analysis evaluated the subgroup who developed grade ≥ 2 acute RILT (n = 10). Results: Functional re-optimization significantly improved compliance with all perfusion-based constraints compared with anatomical plans. The proportion of patients meeting optimal thresholds increased from 50.9% to 70.9% for MD_FV70% (p = 0.0026), from 61.8% to 76.4% for V20_FV50% (p = 0.013), and from 30.9% to 45.5% for V5_FV70% (p = 0.013).Target coverage and OAR doses remained unchanged in all cases.In patients with grade ≥ 2 RILT, compliance improved from 3 to 7 for MD_FV70%, 4 to 8 for V20_FV50%, and 1 to 4 for V5_FV70%, showing consistent trends despite limited statistical power.In the overall cohort, a mean dose increase of +0.11 Gy to the LFV (p = 0.016) confirmed the effective
Conclusion: Systematic SBRT plan re-optimization guided by 68Ga- MAA perfusion PET/CT is feasible and enhances compliance with perfusion-derived functional dose constraints predictive of acute RILT, without compromising target coverage or OAR safety. This approach provides a reproducible framework for individualized, functionally guided SBRT and supports prospective validation of perfusion-based planning to mitigate pulmonary toxicity and preserve post- treatment lung function. References: 1. Bailey DL et al. Semin Nucl Med 2016;46:428–35.2. Hofman MS et al. J Nucl Med 2011;52:1513–9.3. Le Roux PY et al. Cancer Imaging 2016;16:24.4. Bucknell NW et al. Radiother Oncol 2018;129:196–208.5.
Midroni J et al. Int J Radiat Oncol Biol Phys 2024;120:370–408.6. Lucia F et al. Cancers
2023;15:1726.7. Lucia F et al. Int J Radiat Oncol Biol Phys 2024;118:952–62.8. Lucia F et al. Phys Imaging Radiat Oncol 2025;34:100786.9. Pinot F et al. Cancers 2023;15:2166.10. Kadoya N et al. Int J Radiat Oncol Biol Phys 2016;96:422–31.11. Matsuo Y et al. Int J Radiat Oncol Biol Phys 2012;83:e545–9.12. Kong FM et al. Int J Radiat Oncol Biol Phys 2021;110:172–87.13. Takeda A et al. Br J Radiol 2012;85:636–42. Keywords: functional planning, 68Ga-MAA PET/CT, lung SBRT
Made with FlippingBook - Share PDF online