A Method for Direct Localized Sound Speed Estimates Using Registered Virtual Detectors

Brett C. Byram, Gregg E. Trahey, Jørgen Arendt Jensen

Research output: Contribution to journalJournal articleResearchpeer-review

287 Downloads (Pure)

Abstract

Accurate sound speed estimates are desirable in a number of fields. In an effort to increase the spatial resolution of sound speed estimates, a new method is proposed for direct measurement of sound speed between arbitrary spatial locations. The method uses the sound speed estimator developed by Anderson and Trahey. Their least squares fit of the received waveform’s curvature provides an estimate of the wave’s point of origin. The point of origin and the delay profile
calculated from the fit are used to arrive at a spatially registered virtual detector. Between a pair of registered virtual detectors, a spherical wave is propagated. By beamforming the data, the time-offlight between the two virtual sources can be calculated. From this information, the local sound speed can be estimated. Validation of the estimator is made using phantom and simulation data. The set of test phantoms consisted of both homogeneous and inhomogeneous media. Several different inhomogeneous phantom configurations were used for the physical validation. The
simulation validation focused on the limits of target depth and signal-to-noise ratio on virtual detector registration. The simulations also compare the impact of two- and three-layer inhomogeneous media. The phantom results varied based on signal-to-noise ratio and geometry. The results for all cases were generally less than 1% mean error and standard deviation. The simulation results varied somewhat with depth and F/#, but primarily, they varied with signal-tonoise
ratio and geometry. With two-layer geometries, the algorithm has a worst-case spatial registration bias of 0.02%. With three-layer geometries, the axial registration error gets worse with a bias magnitude up to 2.1% but is otherwise relatively stable over depth. The stability over depth of the bias in a given medium still allows for accurate sound speed estimates with a mean relative error less than 0.2%.
Original languageEnglish
JournalUltrasonic Imaging
Volume34
Issue number3
Pages (from-to)159–180
ISSN0161-7346
DOIs
Publication statusPublished - 2012

Keywords

  • Ultrasound
  • Sound speed
  • Beamforming
  • Channel data

Fingerprint Dive into the research topics of 'A Method for Direct Localized Sound Speed Estimates Using Registered Virtual Detectors'. Together they form a unique fingerprint.

Cite this