Classroom Activity for 14-16
Ultrasound imaging systems uses piezoelectric transducers as source and detector. Piezoelectric crystals vibrate in response to an alternating voltage, and when placed against a patient’s skin and driven at high frequencies produce ultrasound pulses that travel through the body.
As they travel outwards and encounter different layers within the body the ultrasound waves are reflected back towards the source.
The returning signal drives the crystals in reverse and produces an electronic signal that is processed to construct the image. Compared to MRI, ultrasound has the advantages of low cost and portability.
It is also preferred over x-ray imaging for procedures in which ionising radiation poses a significant risk, such as checking foetal development during pre-natal care.