ESTRO 2024 - Abstract Book

S757

Clinical - CNS

ESTRO 2024

visualized on the early onset of RT course: at week 1, the median GTV46Gy and GTV_60Gy relative reductions were 32.6% (R: 22 to 70%) and 17.9% (R: 15 to 40.4%), at week 2, 34.4% (R: 30.8 to 69.6%) and 26.8% (R: 20.5 to 47.1%), respectively, and for weeks 3, 4, 5, and 6, the relative volumes reductions were 42.6% (R: 37 to 80%) and 35.2% (29.7 to 54.1%); 38.2% (R: 35.9 to 81.5%) and 50% (R: 34.6 to 54.7%); 40.4% (R: 28.7 to 81.8%) and 54.5% (36.4 to 59.4%), and 42.1% (R: 8.3 to 86.5%) and 44.4% (R: 33.1 to 67.5%), respectively. (Figure 2). When comparing to the immediate prior MR scan, the median relative volume reductions were 2.6% (R: -28.6 to 70%) for GTV_46Gy and 10.2% (R: -23.2 to 40.4%) for GTV_60Gy. The median GTV_46Gy and GTV_60Gy centroid migration during RT, when comparing each MR with the baseline were 7.4 mm (R: 2.0-10.8 mm) and 3.6 mm (R: 1.3-8.8 mm), respectively, and when comparing with the immediate previous MR, 1.2 mm (R: 0-8.5 mm), and 1.1 mm (R: 0.1-4.2 mm), respectively.