Diagnostics
Longitudinal Delta-Radiomics Identifies Treatment-Fraction-Associated Features Linked to Outcomes After Carbon-Ion Radiotherapy for Head and Neck Cancer
By Xiangdi Meng, Zhuojun Ju, Nobuteru Kubo and 2 others.
Abstract
Background
Longitudinal imaging during carbon-ion radiotherapy (CIRT) may capture dose-related tumor evolution before clinical assessment. We investigated whether serial CT-based Δ-radiomic features follow treatment-fraction (dose escalation)-associated trajectories with prognostic relevance in patients with head and neck cancer (HNC) treated with CIRT.
Methods
We analyzed 167 HNC patients receiving 16-fraction CIRT. Features were extracted from plan-CT, confirm-CT, and weekly-CT scans after 5, 9, and 13 fractions. Δ-radiomic features were defined as time-normalized relative changes from confirm-CT. Linear mixed-effects models, paired Wilcoxon signed-rank tests, and monotonicity assessments identified features with systematic longitudinal changes. Endpoints were progression-free survival (PFS), overall survival (OS), and local recurrence (LR). Optimal prediction timing was determined using optimism-corrected C-indices. Bootstrap resampling and multivariable Cox models assessed cutoff stability and incremental value beyond clinical factors.