ESTRO 2025 - Abstract Book

S1393

Clinical - Lung

ESTRO 2025

Results: Dose falloff is characterised by s=1cm in-plane, s=0.64cm out-of-plane (Fig.1). To arrive at a clinical realistic TCP of 95%, nodules must be placed at a distance of 1.7cm from the GTV. Varying dose spill in the axial plane shows saturation of TCP at 97% for 30% background dose. Adding 30% dose spill 1 cm outside the PTV perpendicular to the axial plane brings the TCP over 99% (Fig.2). Larger respiration motion also leads to higher TCP due to the dosimetrically over-conservative ITV margin (Fig.2).