Traveltime Detection Based Compensation Strategy for Incomplete Data in Time-Domain Full Waveform Inversion with Source Encoding

In Time-Domain Full-Waveform Inversion with Source Encoding (TDFWI-SE) for ultrasound computed tomography(USCT), incomplete data due to missing near-field signals cause artifacts and limit the FOV. Conventional methods using homogeneous models fail to recover structures beyond the FOV. This paper proposes a traveltime-based compensation strategy that identifies a critical early-time window [0, τ] dominated by missing off-axis signals. Within this window, measured data are replaced with synthetic waveforms; beyond τ, actual measurements are preserved. This ensures waveform consistency without homogeneous assumptions. Results show improved stability, accuracy, and successful reconstruction of targets outside the conventional FOV.