A comparison of ultrasound exposure in therapy and pulsed Doppler fields.

A detailed comparison of the ultrasound exposure in water from a therapeutic beam and a pulsed Doppler beam was carried out. A significant overlap in acoustic power was found between therapy intensity levels used clinically and the upper end of the diagnostic range, between approximately 100 mW and 200 mW. In addition, pulse pressure amplitudes in the range 0.5-1.0 MPa were measured close to the transducer on both units. It is common to use physiotherapy equipment at pulse average intensities of 0.5 W/cm2 or less, and at these levels exposures of similar magnitude may be obtained with beams currently defined as therapeutic and those available from pulsed Doppler equipment.