ESTRO 2023 - Abstract Book

S501

Sunday 14 May 2023

ESTRO 2023

Figure 1: Summary of the two cases provided to participants

Results Cumulative dose assessment was performed by 21 participants using rigid (RIR) or deformable image registration (DIR)- based summation of 3D dose or isodose contours, or summation of DVH metrics extracted from each course. Registration was global or OAR-based. Three participants used tissue recovery factors (TRF) of 25-50% for the spinal cord only (n=1) or all organs (n=2). There was large variation in non-recovery corrected near-maximum cumulative dose (inter-observer ranges 14.5-24.1Gy for HN, 2.4-33.8Gy for lung OARs), which for lung OARs increased when converting to EQD2 (inter-observer ranges 9.4-42.9 Gy EQD2) (Figure 2, a-d). Cumulative mean doses were more consistent than near-maximum doses. Improved consistency in near-maximum dose was observed using a standardised workflow with submitted spatially mapped doses (inter-observer range 10.7-13.5Gy for HN, 0.4-9.8Gy for lung OARs) (Figure 2, e-f).