Gammex 1425B, Руководство пользователя

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34 Appendix B: Harmonic Imaging
Figure B-2. B-Mode Images of Phantom, Imaging Comparison
Figure B-3 illustrates one trade-off to consider when selecting the mode for a particular examination:
though a.sharper image can be realized using harmonic imaging compared with the fundamental
mode, this enhanced sharpness comes with a loss of penetration.
Figure B-3. Fundamental Imaging (left) and Harmonic Imaging (right)
Figure B-4 shows the improved resolution seen in harmonic imaging of the phantom’s pin targets
(nylon fibers). The fibers appear nearly point-like in the harmonic imaging mode.
Figure B-4. Fundamental Imaging (left) and Harmonic Imaging (right), Phantom Pin Targets
Three tissue properties determine the effectiveness of harmonic imaging:
• Pulse propagation speed
• Attenuation (rate of pulse energy loss with depth)
• The value of the tissue's nonlinearity parameter (B/A)