True, but ultrasound isn't entirely benign. Depending on what frequency and what power it can crack solid parts of the body (its used to break up kidney/gall stones) it also can heat things up (which is, assuming my understanding is correct, why doppler scans for blood flow are not done on <18 week pregancy)
My point is, phased arrays of ultrasound have the ability to be destructive. In the same way that a single MIMO wifi AP isn't going to cook you, but 10,000 MIMO arrays steering coherently over you will.
True, but ultrasound isn't entirely benign. Depending on what frequency and what power it can crack solid parts of the body (its used to break up kidney/gall stones) it also can heat things up (which is, assuming my understanding is correct, why doppler scans for blood flow are not done on <18 week pregancy)