ESTRO 2025 - Abstract Book

S1425

Clinical - Lung

ESTRO 2025

Results: Compared with 3DCRT, VMAT significantly reduced mean doses to the right PV including Dmean (31,6 Gy versus 28,4 Gy, p=0,03), V30Gy (40,8 Gy versus 48,4Gy, p=0.002), V46Gy (34,4 Gy versus 41Gy, p= 0.002), V55Gy (23 Gy versus 31,7 Gy, p=0.02) and V60Gy (15,3Gy versus 22,5 Gy, p=0.04). Dmax to the right PV and doses to the left PV were not improved in patients treated with VMAT compared with 3DCRT. Conclusion: VMAT treatment with PV sparing can significantly reduce the dose to the PV as compared to 3DCRT technique. Preserving the PVs could reduce the incidence of AF. Therefore, PVs should be assigned to organ at risk for patients receiving thoracic RT and dose-sparing of the PVs should be considered.

Keywords: Lung cancer, radiotherapy, cardiac toxicity

4098

Digital Poster Case report of the first-in-human two modality radiotherapy treatment in a single plan using biology-guided radiotherapy Henry S. Park 1 , Huixiao Chen 1 , Emily Draeger 1 , Lauren Tressel 1 , John J. Kim 1 , Kimberly L. Johung 1 , Melissa R. Young 1 , Karine A. Al Feghali 2 , Dorine de Jong 2 , Zhe J. Chen 1 , David J. Carlson 1 1 Radiation Oncology, Yale School of Medicine, New Haven, USA. 2 Medical Affairs, RefleXion Medical, Hayward, USA Purpose/Objective: Technological advancements have enabled the simultaneous treatment of multiple lesions in a single or multi-plan approach, termed multi-target treatment (MTT). We present the first clinical case combining biology-guided radiotherapy (BgRT) and SBRT within a single treatment plan for lung and kidney metastases, highlighting key technical and clinical considerations. Material/Methods: A patient with an oligoprogressive 3.8 cm ultra-central right lung metastasis of thymic origin was evaluated for BgRT eligibility (tumor size 2-5 cm, SUVmax >6, >2 cm away from FDG-avid critical structures). Another oligoprogressive 2.4 cm left kidney lesion was incidentally found. The treatment plan prescribed 40 Gy in 5 fractions with BgRT for the lung and SBRT for the kidney (Figure 1). For BgRT, the PTV was defined as a 5mm expansion of the GTV on a single phase (i.e. 50%) on 4D scan. Joint optimization of the two targets in a single treatment plan was performed. The functional PET modeling scan and each fraction started with a 15 mCi FDG injection followed by a PET prescan 60 minutes post-injection, confirming adequate FDG activity for precise BgRT delivery. The BgRT target was treated before the SBRT target.