Describe the basic principles of ultrasound imaging (2 marks)

Ultrasound is any frequency above that of human hearing - around 20 kilohertz.

Ultrasound imaging works by emitting a known intensity of ultrasound at a specific frequency, and capturing the reflected sound from whatever is being imaged.

At each boundary between different materials (whether manufactured or living tissues), a certain percentage of the ultrasound is transmitted and a certain percentage reflected.

By calculating the time between emission and the return of the reflected wave, the distance of that boundary can be found.