Intercomparison of acoustic output measurements of a diagnostic ultrasound device

An intercomparison of acoustic output measurements with 9 participants from 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 output, peak-negative acoustic pressure, output beam intensity, spatial-peak temporal average derived intensity and arithmetic-mean acoustic-working frequency were determined. Although the majority of results were in good agreement with one another, there were also some significant deviations from the corresponding grand mean values, and the overall ranges of the participants' reported measurement results were as follows. Temporal-average power output: 3.8 mW to 9.0 mW; peak-negative acoustic pressure: 1.50 MPa to 2.86 MPa; output beam intensity: 7.3 mW/cm2 to 13.2 mW/cm2; spatial-peak temporal-average derived intensity: 72 mW/cm2 to 176 mW/cm2; arithmetic-mean acoustic-working frequency: 3.27 MHz to 3.33 MHz. The reasons for the occurrence of significantly low or high values could be identified by the participants concerned. The results show that correct ultrasonic measurements are not easy to conduct and strongly advise periodically checking the measurement tools and procedures.