Measured acoustic intensities for clinical diagnostic ultrasound transducers and correlation with thermal index.
OBJECTIVE
To investigate if the thermal index for bone (TIB) displayed on screen is an adequate predictor for the derated spatial-peak temporal-average (ISPTA.3) and spatial-peak pulse-average (ISPPA.3) acoustic intensities in a selection of clinical diagnostic ultrasound machines and transducers.


METHODS
We calibrated five clinical diagnostic ultrasound scanners and 10 transducers, using two-dimensional grayscale, color Doppler and pulsed-wave Doppler, both close to and far from the transducer, with a TIB between 0.1 and 4.0, recording 103 unique measurements. Acoustic measurements were performed in a bespoke three-axis computer-controlled scanning tank, using a 200-μm-diameter calibrated needle hydrophone.


RESULTS
There was significant but poor correlation between the acoustic intensities and the on-screen TIB. At a TIB of 0.1, the ISPTA.3range was 0.51-50.49 mW/cm2and the ISPPA.3range was 0.01-207.29 W/cm2. At a TIB of 1.1, the ISPTA.3range was 19.02-309.44 mW/cm2and the ISPPA.3range was 3.87-51.89 W/cm2.


CONCLUSIONS
TIB is a poor predictor for ISPTA.3and ISPPA.3and for the potential bioeffects of clinical diagnostic ultrasound scanners. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.
Department of Obstetrics and Gynecology, Helse Stavanger, Stavanger, Norway.
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K
Retz
National Centre for Ultrasound in Gastroenterology, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Medicine, University of Bergen, Bergen, Norway.
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S
Kotopoulis
Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
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http://orcid.org/0000-0003-1825-1660
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Kiserud
Department of Obstetrics and Gynecology, Haukeland University Hospital, Bergen, Norway.
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K
Matre
Centre for Clinical Research, Haukeland University Hospital, Bergen, Norway.|Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
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GE
Eide
Department of Obstetrics and Gynecology, Helse Stavanger, Stavanger, Norway.|Department of Clinical Science, University of Bergen, Bergen, Norway.
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R
Sande
D000162:Acoustics; D002138:Calibration; D004867:Equipment Design; D004869:Equipment Safety; D005260:Female; D006801:Humans; D011247:Pregnancy; D013696:Temperature; D014159:Transducers; D016216:Ultrasonography, Prenatal / Q000295:instrumentation*
in vitro; intensity measurements; thermal index; ultrasound safety