(ITA) The time average intensity is the average ultrasound intensity calculated over the time between pulses.
Time average intensity = Pulse average intensity x Duty factor
For ultrasound systems, the instantaneous intensity is averaged over one or more scan repetition periods for a specified scan mode.

Power in ultrasound describes the energy generated by a wave or in a signal per unit of time. The power is measured in watts (W) and is proportional to the square of the amplitude.

See also Spatial Average Intensity, Ultrasound Radiation Force and Time Average Intensity.

(I-SPTA) Spatial peak time averaged intensity is the measure most associated with temperature rise.

See also Thermal Effect, and Time Average Intensity.

See Time Average Intensity.

(ITP) The temporal (instantaneous) peak intensity is the maximum intensity during the ultrasound pulse.
The formula is: P2/rc
P is the instantaneous acoustic pressure, r is the density of the medium and c is the speed of sound in the medium.

See also Temporal Average Intensity (Time Average Intensity).