Doppler Instrumentation Part Two

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Doppler Instrumentation Part Two
2012-09-26 05:05:15
Sonographic Instrumentation

Doppler Instrumentation Part Two
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  1. What is Quadrature Phase Detection?
    Signal processing to identify the forward and receive components of the complex Doppler signal.
  2.  What is transmit power?
    • Varies the power applied to a txdr.
    • Higher power setting result in larger amplitude signals and increased acoustic exposure to patients.
  3. What is Doppler gain?
    • Adjusts the amt of amplification or gain of the receive signals.
    • Does not increase patient exposure.
    • Increases the brightness of the spectrum; the brightness can be referred to as the magnitude or amplitude.
  4. What is volume?
    Adjusts the volume of the Doppler audio.
  5. What is PRF/Velocity scale?
    • This controls the PRF and therefore the velocity limits of the display.
    • Uses a higher PRF to detect higher velocities
    • Uses a lower PRF to detect lower velocities.
  6. What is Wall Filter?
    • It removes these low frequency signals from the display. 
    • It does not affect the higher peak Doppler shifts.
  7. What is sample volume, range gate, sample gate or gate?
    • The depth, size and position of the range gate is adjustable.
    • It is determined by: beam width, gate length and pulse length.
  8. What is Flow angle cursor/angle correction cursor?
    • Angle cursor is positioned by the operator so that it follows the direction of flow (parallel to vessel wall).
    • Angle correction bar is seen diagonally through the range gate relatively parallel to the vessel walls.
  9. What is Sweep?
    • Adjusts the scrolling speed of the Doppler spectrum.
    • Adjusts the horizontal axis (time) of the spectral display.