Sammendrag
The REFoCUS algorithm decomposes any arbitrary transmit wave into its Huygens-Fresnel components allowing Synthetic Transmit Aperture (STA) beamforming. The STA dataset is found by advancing the backscattered channel data by the applied transmit (Tx) delay and summing across Tx events. This simple advance-and-sum, also called adjoint inversion in frequency domain, has shown image quality similar to true STA beamforming for phased array sequences, but showed artifacts for sequences with walking aperture [1]. The artifacts were suppressed by regularizing the inversion at the cost of SNR [2]. Our time-domain implementation with pixel dependent apodization aims to generalize the REFoCUS method for all scan setups without introducing artifacts. The apodization is based on the directivity limitations of transducer elements, and it also works for 2D arrays using Sub-Aperture (SAP) technology.
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