There was a startup in Shanghai in the early 2000. Their device used multiple transducers. The probe was at least 40 cm in diameter. They did trials on uterine fibroids, among other diseases. One of the difficulties was while it looks good in theory, but the path ultrasound travels in the body is more complicated than, say x-ray or gamma ray. They expected a fine focal zone, but sometimes the focal zone was much larger than expected. This new wave of ultrasound equipment may have discovered better ways to control the sound beam.