PTA Physical Therapy Assistant

Answer: B - The percentage of time that ultrasound energy is being emitted from the sound is called duty cycle.

If the duty cycle is 100%, then the ultrasound output is constant and results in primary thermal effects.
Consistency of the ultrasound output as ratio between the spatial peak intensity and spatial average intensity is called beam non-uniformity ratio (BNR).

The area of the sound head that produces the ultrasound waves is called effective radiating area.

The amount of power generated by the ultrasound unit is called intensity.