Not trying to sound alarmist at all but I am wondering if ultrasounds are safe to be used like this? My understanding is it's basically a high-frequency sound wave which is probably fine for most tissue usage, however here it says it's scattering off of red blood cells. I don't know why that feels so unsettling to me.
Waves scatter off of everything so that's not of concern. Depending on the intensity, frequency, and tissue in question ultrasound can have an effect. Someone elsewhere linked to a couple academic papers on the topic.
I share your hesitation about using this on the brain, at least barring exhaustive long term animal model trials. Subject a mammal to this every day for 10 years and show that there are no negative effects relative to the control.