A comparison of the AIUM/NEMA, IEC and FDA (1980) definitions of various acoustic output parameters for ultrasonic transducers.

Comparison is made between the values obtained for the acoustic output from different types of medical ultrasonic equipment when determined according to the definitions given in different documents. In particular, the American Institute of Ultrasound in Medicine with the National Electrical Manufacturers Association Safety Standard for Diagnostic Ultrasound Equipment, the U.S. Food and Drug Administration Diagnostic Ultrasound Reporting Guide (1980) and the proposed International Electrotechnical Commission standard are compared for pulse-echo and Doppler equipment. Differences of up to 40% in the spatial-average temporal-average and spatial-peak pulse-average intensities are shown to be a result of the different definitions of beam area and pulse duration.