Ultrasonic Imaging Systems

Slides on diagnostic ultrasound, which excels because it is non-invasive, externally applied, non-traumatic and safe. Explains that ultrasound is a mechanical vibration and so needs a medium to travel through, and that its velocity of propagation is almost constant across body tissues, which is what makes depth of penetration a function of transit time. Sets out the pulse-echo technique, transmitting a train of short bursts and receiving the echoes, which is far easier to measure than a continuous wave and is the basis of both echoencephalographs and echocardiographs, and closes on biological effects, where the consensus of repeated studies is that no significant hazard attaches to diagnostic levels of ultrasound.