769. How do ultrasound scans work?
Ultrasound procedures are used for a number of medical reasons, most commonly to monitor the development of a foetus. Ultrasonography sends high-frequency sound waves through the body and measures their refl ected echoes to create a 2D image of internal structures. The transducer probe, which is placed on the skin, is specially designed to create and receive these waves. It does this using a principle called the piezoelectric eff ect. Quartz crystals – piezoelectric crystals – inside the transducer probe rapidly change shape and vibrate when an electric current passes through them. This causes sound waves to be produced, which travel freely through fl uid and soft tissue inside the body. However, once they reach a denser structure they will bounce back to the transducer as an echo. As a result, the crystals inside the probe emit electrical currents, which pass up to the central processing unit (CPU). The information gathered then forms an image on screen.