Effect of Geometric and Transmit Corrections on Global Speed of Sound Estimation

For real-time ultrasound reconstruction a global speed of sound (SoS) has to be assumed. A common strategy to determine an estimate for this global SoS is to scan a range of candidate SoS and choose the one yielding highest image quality with respect to a specific metric. However, this strategy usually does not consider secondary geometric effects of changes in SoS which affect the reconstruction grid as well as the transmitted angles in plane wave imaging. This paper investigates how to correct these effects and what influence such corrections can have on the optimization of the global SoS. To this end, phantom data from the public CUBDL dataset is evaluated using different subsets of angles and different quality metrics for the SoS optimization. It will be shown that the corrections impact the SoS optimization and can lead to less ambiguous estimates and sharper reconstructions, especially when the tissue SoS deviates from the transmit SoS.