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Three-dimensional Quantitative Ultrasound Imaging

Three-dimensional Quantitative Ultrasound Imaging. Tonydev2@aol.com. Devaney@ece.neu.edu. A.J. Devaney Department of electrical and computer engineering Northeastern university Boston, MA 02115. “Acoustical Holography,” Encyclopedia of Applied Physics, Americal Institute of Physics 1993.

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Three-dimensional Quantitative Ultrasound Imaging

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  1. Three-dimensional Quantitative Ultrasound Imaging Tonydev2@aol.com Devaney@ece.neu.edu A.J. Devaney Department of electrical and computer engineering Northeastern university Boston, MA 02115 “Acoustical Holography,” Encyclopedia of Applied Physics, Americal Institute of Physics 1993. A.J. Devaney Associates, Inc. 295 Huntington Ave-suite 208. Boston, MA 02115

  2. Sensor system Insonifying waveform Scattered wavefield Canonical Imaging Configuration Quantitative imaging problem: Given set of scattered field measurements determine object function

  3. Data Model • Nonlinear and nonlocal mapping from object function to scattered field • Mapping from 3D to 2D thus non-unique Born approximation Rytov approximation

  4. “Lens” outgoing spherical wave Incoming spherical wave . scattering point Image point Born Approximation Imaging

  5. Analog Two-dimensional Imaging x,y x,y Lens Object Image Lens converts outgoing spherical waves into incoming spherical waves to produce the image field.

  6. Scattered wavefield Object Sensor system aperture • Measure wavefield over aperture • Compute plane wave amplitude (FFT) • Perform plane wave expansion (FFT) Backpropagation Imaging Backpropagated wavefield Image Sensor system aperture

  7. Sensor system Object Image Scattered wavefield Backpropagated wavefield Single experiment generates image of the product Backpropagation--the Acoustic Lens

  8. The backpropagation Algorithm Scattered wavefield Object Sensor system aperture Backpropagated wavefield Image Sensor system aperture

  9. Wave aberration function models sensor and computational inaccuracies The backpropagation Point Spread Function spherical wave Sensor system aperture backpropagated spherical wave Point spread function is the image of a point (delta function) scatterer

  10. Ideal Case : Zero aberration and = 4steradians Point Spread Function Point spread function Coherent transfer function

  11. source array detector array High quality image Improving Image Qualityconfocal Ultrasound Imaging Focus-on-transmit and focus-on-receive Confocal mode: r=r0

  12. Plane wave insonification Diffraction tomography source array detector array Partial image

  13. Image Quality Point spread function Transfer function

  14. Image Processing • Image processing performed directly on 3D image in confocal system • Image processing performed on raw data in diffraction tomography • (yields filtered backpropagation algorithm)

  15. Summary and Conclusions • Single experiment ultrasound imaging of 3D objects yields extremely low image quality • Multiple experiments via confocal scanning or diffraction tomography yields high image quality • Post image processing and algorithm optimization can improve image quality • Born approximation not adequate for strong scattering and/or extended objects • Conventional (optical) measures of image quality not appropriate for 3D ultrasound

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