ESTRO 2025 - Abstract Book

S1826

Clinical – Upper GI

ESTRO 2025

For all nominal plans, V95% iCTV >99% on pCT. Robustness evaluations of the recalculated treatment plans on cCTs demonstrated acceptable dose coverage for ten PT and seven XT patients. However, one PT patient (pt2) showed underdosage on one cCT, and for two XT patients (pt3+6), V95% iCTV underdosage was observed on one cCT each. Two of these patients were re-planned, while the third (XT) was not re-planned as only two respiratory phases showed underdosage (see Figure 1). For all patients, V95% iCTV >99% for the accumulated CBCT doses (Figure 2). Differences between the accumulated doses and nominal dose calculated on pCT, cCT, and rCT were minimal, deviating <1%, except for pt2, who had an adaptive re-plan based on underdosage on one cCT. Conclusion: Robustness evaluation on weekly cCT scans for 20 PROTECT trial patients showed acceptable target coverage in 85% of patients, while re-planning was prompted in 10%, and minor deviations were seen in 5% of the patients. The