Determination of Acoustic Power and Intensity Levels from Diagnostic Ultrasound Machines

The average acoustic power and intensity levels from diagnostic ultrasound machines at five major Hospitals in Benue State were measured using ultrasound power meter UPM-DT-10AV. The ultrasound machine at Christian Hospital Mkar, Immaculate Conception Hospital Makurdi, Federal Medical centre Makurdi, Myom Hospital Gboko and Lobi Specialist Hospital Makurdi were used for the research work. The ultrasound power meter measures the out-put acoustic power from the ultrasound beams which were converted to intensity level, three set of readings were taken for each of the pre-timed duration of 5,10,15,20 and 25 minutes, the average values were then found. The results shows that the acoustic power and intensity levels from the measured ultrasound machines were not stable over time and that the intensity level increases exponentially with increase in the scanning duration. From the measured acoustic outputs, it was seen that the diagnostic ultrasound machine model EMP-860 located at Lobi Specialist Hospital Makurdi has the highest average intensity value of 0.51±0.01W/cm 2 for an exposed duration of 25 minutes and a minimum value of 0.06±0.003 W/cm 2 for an exposed duration of 5 minutes while the diagnostic ultrasound machine model SonoAce 8000 located at Federal Medical Centre Makurdi has the lowest measured average intensity value of 0.0067±0.0009 W/cm 2 and higher intensity value of 0.099±0.0012 W/cm 2 at an exposed duration of 5 and 25 minutes respectively. This work aims will assess ultrasound dosimetry compliance in our Hospitals and provides database for diagnostic ultrasound quality control in Benue State and Nigeria. The work has shown that some of the ultrasound machines have output intensities beyond the maximum safety limit of 0.094 W/cm 2 as recommended by WFUMB (1998) and FDA (1993) for fetal and abdominal scan.