Premium
Challenges and Regulatory Considerations in the Acoustic Measurement of High‐Frequency (>20 MHz) Ultrasound
Author(s) -
Nagle Samuel M.,
Sundar Guru,
Schafer Mark E.,
Harris Gerald R.,
Vaezy Shahram,
Gessert James M.,
Howard Samuel M.,
Moore Mary K.,
Eaton Richard M.
Publication year - 2013
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.7863/ultra.32.11.1897
Subject(s) - hydrophone , mechanical index , acoustics , ultrasound , medicine , context (archaeology) , calibration , repeatability , distortion (music) , measurement uncertainty , deconvolution , optics , statistics , computer science , physics , telecommunications , microbubbles , mathematics , paleontology , amplifier , bandwidth (computing) , biology
This article examines the challenges associated with making acoustic output measurements at high ultrasound frequencies (>20 MHz) in the context of regulatory considerations contained in the US Food and Drug Administration industry guidance document for diagnostic ultrasound devices. Error sources in the acoustic measurement, including hydrophone calibration and spatial averaging, nonlinear distortion, and mechanical alignment, are evaluated, and the limitations of currently available acoustic measurement instruments are discussed. An uncertainty analysis of acoustic intensity and power measurements is presented, and an example uncertainty calculation is done on a hypothetical 30‐MHz high‐frequency ultrasound system. This analysis concludes that the estimated measurement uncertainty of the acoustic intensity is +73%/−86%, and the uncertainty in the mechanical index is +37%/−43%. These values exceed the respective levels in the Food and Drug Administration guidance document of 30% and 15%, respectively, which are more representative of the measurement uncertainty associated with characterizing lower‐frequency ultrasound systems. Recommendations made for minimizing the measurement uncertainty include implementing a mechanical positioning system that has sufficient repeatability and precision, reconstructing the time‐pressure waveform via deconvolution using the hydrophone frequency response, and correcting for hydrophone spatial averaging.