ESTRO 2024 - Abstract Book

S1694

Clinical - Lung

ESTRO 2024

Mauro Buono, Valerio Nardone, Roberta Grassi, Emma D'Ippolito, Federico Gagliardi, Dino Rubini, Vittorio Menditti, Salvatore Cappabianca

University of Campania “L. Vanvitelli”, Department of Precision Medicine, Naples, Italy

Purpose/Objective:

To evaluate the role of FFF and non-coplanar VMAT SBRT of lung lesions, with a template using software optimization of a commercial treatment planning system.

Material/Methods:

A retrospective analysis was performed on lung SBRT patients planned with standard planar SBRT. All the patients were retrospectively replanned using a template for software optimization that was developed on Monaco v. 5.51, relying on non-coplanar arcs and FFF. For each patient, non-coplanar FFF-VMAT, coplanar VMAT with and without flattening filter were also generated and compared. Statistical significance of differences was performed using non parametric test for related samples (Friedman test). Template optimized (TO) plans were analyzed in terms of PTV coverage and maximum doses (gradient and conformity), doses to organs at risk (OARs), giving priority to lungs, heart and chest wall. Subset analysis according to target localization (wall-seated, island and central targets) was performed.

Results:

Twenty-six patients were included for the present analysis. No differences were seen in terms of target coverage. Significant differences were seen for Dmax (central targets) and Conformity Index (for wall-seated and island targets). PTV Dmax was lower in noncoplanar treatments (p = 0,023). Regarding OARs, a significant difference was seen for Heart Dmax in central tumors, in Lungs V13.5 for island tumors and for chest wall V30 in wall-seated targets.

Conclusion:

The knowledge of differences of lung SBRT approaches can be useful in clinical practice. Non-coplanar VMAT SBRT in central targets can achieve a lower PTV Dmax and a lower heart Dmax, whereas in Island tumors can achieve a lower lungs V13.5. Conversely, in wall-seated targets a coplanar approach can achieve a lower Chest Wall V30.The investigation of the role of non-coplanar as well as FFF plans need to be analyzed in a larger dataset.

Keywords: SBRT, VMAT, lung radiotherapy

References:

1. Stereotactic Ablative Body Radiotherapy (SBRT): A Resource (2019).