ESTRO 2024 - Abstract Book

S4364

Physics - Intra-fraction motion management and real-time adaptive radiotherapy

ESTRO 2024

a systematic 0.7 mm longitudinal discrepancy (targeting error in superior direction respectively without and with Synchrony: FID: 0.3 vs. 1.1 mm; FIDResp: 0.15 vs. 0.88 mm, -0.62 vs. 0.39 mm). With more complex scenario including motion during delivery, applying MLC corrections led to TTE >2 mm (Fig.1). The systematic shift of 0.7 mm in the longitudinal direction can be explained by the different kV reconstructions used for the kV/MV alignment (based on 3D-kV acquisitions) and used for the Synchrony tracking (based on 2D-kV acquisitions). Assuming that this issue will be quickly solved by the company, we obtain TTE values below 1 mm for each tracking modality if we apply corrections only with the jaws. When applying corrections with the MLC to correct a 3 cm displacement of the target in the vertical direction, TTE values remain between 1.7 and 2.1 mm.