Transcranial ultrasonic wave propagation simulation: skull insertion loss and recovery

Severe energy dissipation and waveform aberration in ultrasonic wave propagation due to the human skull remain major challenges to achieving good focus in high intensity focused ultrasound (HIFU) brain therapy and high-resolution thermoacoustic tomography (TAT) of the human brain. With the inclusion of the skull insertion loss, we numerically simulated the ultrasonic wave propagation using the pseudospectral time domain (PSTD) algorithm for TAT setup. We then applied the redatuming scheme through downward and upward continuation originated in seismic signal processing to eliminate the diffraction caused by the irregularity of the skull and to recover the insertion loss due mainly to the diploes layer of the skull. This approach, after further validation, is aimed to recover wave energy dissipation and waveform aberration in ultrasonic measurements applied to both trans-skull imaging (ultrasound propagates outward) and therapy (ultrasound propagates inward).