ESTRO 2025 - Abstract Book

S946

Clinical – Head & neck

ESTRO 2025

microdosimetric kinetic model (mMKM). MTS constraints for LEM-I: D0.1cc<70 Gy , D5%<68 Gy and D10%<64 Gy (Figure 1d). In LEM-I optimized CIRT-plans mMKM hotspots are frequently observed at the end of beam-range which overlaps on pharyngeal mucosa causing toxicity. Hence, mMKM dose constraints for MTS were added [D0.1cc<70 Gy , D5%<68 Gy , Figure 1e]. LEM-I re-optimization was triggered in case of suboptimal mMKM dose distribution. To account for high dose-averaged linear energy transfer (LETd) of CIRT, D RBE -filtered-LETd analysis was conducted (Figure 2a-b).

Results: