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Artefakter I ultralydbilder

Hans Torp NTNU, Norway. Artefakter I ultralydbilder. Hans Torp Department of Physiology and Biomedical Engineering NTNU Norway. Artefakter I ultralydbilder. Anisotropi og speckle Hindringer for ultralydbølgene Nær probe - -> redusert lateral oppløsning

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Artefakter I ultralydbilder

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  1. Hans Torp NTNU, Norway Artefakter I ultralydbilder Hans Torp Department of Physiology and Biomedical Engineering NTNU Norway

  2. Artefakter I ultralydbilder • Anisotropi og speckle • Hindringer for ultralydbølgene • Nær probe - -> redusert lateral oppløsning • Avstand fra probe -> Skygge • Reverberasjoner • Aberasjoner

  3. Punktspeder-funksjon

  4. Hindring i avstand fra transducergir skygge i ultralydbildet • videoklipp

  5. Hindring nær transducergir redusert effektiv aperture • videoklipp

  6. Probe-diameter D F: Fokaldybde L Oppløsning (skarphet) D Blenderåpning F-tall f# = F/D Bølgelengde: L Lateral oppløsning: f#  L F: Fokaldybde Eksempel Foto: L = 0.9 e-3 mm f# = 5.6 Oppløsning: 0.005 mm ~ 50000 dpi Eksempel Ultralyd: L = 0.5 mm (3 MHz) f# = 8cm/2cm= 4 Oppløsning: 2 mm ~ 125 dpi Større probe -> Bedre oppløsning Høyere frekvens -> Bedre oppløsning

  7. Reverberasjoner

  8. Sidelober

  9. Gitterlober Gitterlobe Kraftig ekko

  10. Acoustical noise due to - reverberations - aberrations Cardiac ultrasound imaging

  11. Pulse after 6cm propagation Hans Torp NTNU, Norway Pulse at transducer surface Non-linear acoustics in Ultrasound Imaging Transducer Nonlinear propagation Body wall

  12. 2. harmonic Hans Torp NTNU, Norway Fundamental and second harmonic signal separated by filter 50 100 150 200 250 300 350 400 450 20 40 60 80 100 Fundamental Signal from septum Noise from LV cavity

  13. Hans Torp NTNU, Norway Second harmonic imagingReverberation noise is suppressed 80 60 40 20 0 -20 0 1 2 3 4 5 6 x 10 Frequency 2.harmonic Bmode imaging ftx=1.7 MHz, frx=3.4 MHz Conventional Bmode imaging ftx=3.4 MHz, frx=3.4 MHz Signal Noise

  14. Hans Torp NTNU, Norway Cardiac examples 5 MHz probe Octave Fundamental

  15. Hans Torp NTNU, Norway Cardiac examples 5 MHz probe Fundamental Octave

  16. Hans Torp NTNU, Norway Brain - neonatal 5 MHz probe Fundamental Octave

  17. Hans Torp NTNU, Norway Brain - 18 week fetus 5 MHz probe Fundamental Octave

  18. Hans Torp NTNU, Norway Brain - 18 week fetus 5 MHz probe Fundamental Octave

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