Measurement of diagnostic electronic linear arrays by miniature hydrophone scanning

Ultrasonic pressures, intensities and power were computed using a calibrated miniature hydrophone scanning system. To accomplish these measurements, the electronically scanned beam was stopped, and raster scans were made with the hydrophone over a number of planes perpendicular to the beam axis. Ultrasonic power also was measured using a radiation force balance, and the results compared well with those obtained using the hydrophone. Spatial average-temporal average intensities for the stopped beam ranged from 0.13 to 3.71 mW/cm/sup 2/ (for a -40-dB beam area), and spatial peak-temporal peak intensities varied from 8.31 to 45.2 W/cm/sup 2/. Such measurements are important in setting equipment safety standards, in encouraging minimum use of ultrasonic exposures, and in quantifying exposure levels that may result in harmful biological effects.<>