MODEL RELEASE AVAILABLE. Young woman undergoing abdominal ultrasound examination. Ultrasound scanning is used to image many organs in the body and is believed to be so safe that, unlike X-rays, it is widely used for scanning pregnant women. The scanner's probe contains a crystal that is made to vibrate & emit a high frequency sound pulse. The probe also acts as a receiver, detecting the echo of each pulse as it is reflected from the structures it encounters. Echos are created as the pulse meets interfaces between different tissue densities - the surface of bone, for example. The machine in background plots echoes against time to produce an image slice" into the body."