Intercomparison of acoustic output measurements of a diagnostic ultrasounddevice

An intercomparison of acoustic output measurements,I with 9 participants fr om four countries was performed. A commercial diagnostic ultrasound device including a 3.5-MHz M-mode transducer was circulated for that purpose. The acoustic output of the device was measured and the temporal-average power o utput, peak-negative acoustic pressure, output beam intensity, spatial-peak temporal average derived intensity and arithmetic-mean acoustic-working fr equency were determined. Although the majority of results were in good agre ement with one another, there were also some significant deviations from th e corresponding grand mean values, and the overall ranges of the participan ts' reported measurement results were as follows, Temporal-average power ou tput: 3.8 mW to 9.0 mW; peak-negative acoustic pressure: 1.50 MPa to 2.86 M Pa; output beam intensity: 7.3 mW/cm(2) to 13.2 mW/cm(2); spatial-peak temp oral-average derived intensity: 72 mW/cm(2) to 176 mW/cm(2); arithmetic-mea n acoustic-working frequency: 3.27 MHz to 3.33 MHz. The reasons for the occ urrence of significantly low or high values could be identified by the part icipants concerned. The results show that correct ultrasonic measurements a re not easy to conduct and strongly advise periodically checking the measur ement tools and procedures. (C) 1999 World Federation for Ultrasound in Med icine & Biology.