ESTRO 2024 - Abstract Book

S2258

Clinical - Upper GI

ESTRO 2024

Results:

The adaptation rate using the new beam arrangement decreased by 36% compared to the current clinical approach. For 9/14 patients there was no difference in terms of adaptation rate, but for 2/14 patients one adaptation less was required, for 2/14 patients two adaptations less were required and for 1/14 patient three adaptations less were required with the 3Bnew compared to the 3Bclin. In terms of OAR, the differences between 3Bnew compared to 3Bclin, reported in Table 1 for the 14 patients, were on average 0.0±0.7 Gy in MHD (p=0.99), 0.6±1.1 % in Heart-V25Gy (p=0.052), 0.5±1.1 % in Heart-V40Gy (p=0.02), 0.1±0.4 Gy in mean lung dose (p=0.5), - 0.4±2.5% in Lungs-V5Gy (p=0.5), 0.6±1.3% in Lungs-V20Gy (p=0.1) and 0.7±0.7 Gy in Body-D0.03cc (p=0.002). Looking at the patient and tumor anatomy of this patient cohort, the patients that seem to benefit from the new beam arrangement are those whose diaphragm position and amplitude in the consecutive reCTs is higher compared to the planning CT.