Exactly my concern too. There are techniques like synthetic aperture focusing which can correct some of these errors to some degree but they're complex and have harsh limits of their own. It's always better to not have the errors introduced by the distance and water volume in the first place. The thing which makes no sense about this entire approach is we already can not have those errors.

I've been looking up relevant data and reading some papers to determine if I'm missing something there but, so far, the approach looks pretty much 'all downside' with the few upsides being: 1. Faster to image full body, 2. Don't have to have some technician poking you with an ultrasound wand, 3. Looks cool?

But I'm just an imaging and DSP guy, you're the actual radiologist. If you don't mind there's one question I'm not sure about. Trying to 'strong-man' the product concept, the only potential benefit of the approach I haven't crossed out is if there's any meaningful value from having additional simultaneous receivers off-axis from the emitter? I mean value which can't be gained from just moving a single emitter to another axis, grabbing more images and then cross-registering those. Even then, the off-axis receivers are always co-planar with the emitter, which seems like it would greatly limit any utility.

The downside column I've got so far is vast... and it's not just distance, there's also the turbulance in the water, micro-bubbles from the ongoing submersion of body and platform into the tank, the thermal disruption at the boundary layer, the fact the human is freestanding with no support while being submerged means they'll be far less stationary than a human comfortably reclined on a ultrasound table, it goes on and on.