  Row-column arrays have shown to be able to generate 3-D ultrafast ultrasound
images with an order of magnitude less independent electronic channels than
classic 2D matrix arrays. Unfortunately row-column array images suffer from
major imaging artefacts due to the high side lobes. This paper proposes a
row-column specific beamforming technique that exploits the incoherent nature
of certain row column array artefacts. The geometric mean of the data from each
row and column pair is taken prior to summation in beamforming, thus
drastically reducing incoherent imaging artefacts compared to traditional
coherent compounding. The effectiveness of this technique was demonstrated in
silico, and the results show an average fivefold reduction in side-lobe levels.
Significantly improved contrast was demonstrated with Tissue-to-noise ratio
increasing from $\sim$10dB to $\sim$30dB and Tissue Contrast Ratio increasing
from $\sim$21dB to $\sim$42dB when using the proposed new method compared to
Delay and Sum. These new techniques allowed for high quality 3D imaging whilst
maintaining high frame rate potential.
