7 Safety of ultrasound

Question 1

What are the 2 potential negative effects of ultrasound?

Answer 1

Thermal effects (conversion of mechanical energy to thermal energy).

Mechanical effects (e.g. cavitation in which bubbles of gas are created which can cause structural damage, and resonance).

Question 2

How is ultrasound intensity measured?

Answer 2

The intensity of the exposure to ultrasound is the spatial peak temporal average (SPTA) which is the maximum ultrasound intensity (spatial peak) averaged over the exposure duration (temporal average), measured in power per unit area (watts/cm2).

Question 3

How is safety increased when using ultrasound?

Answer 3

Minimise the duration, reposition the probe and minimise the power (particularly in TOE).