Doppler Mode – Spectral Doppler 153
Chapter 11
Doppler Mode – Spectral Doppler
Overview
Doppler mode (spectral Doppler mode) scanning displays information about the
spectrum of flow velocities as a function of time. It is sometimes called FFT (Fast
Fourier Transform) because the information is presented as a frequency spectrum
indicating velocity components.
Pulsed Wave Doppler (PW)
PW Doppler is the primary Doppler mode. In PW Doppler, short bursts (pulses) of
ultrasound waves are transmitted at regular intervals and analyzed as they return. The
received signals are detected and sent to amplifiers for audio output as well as
displayed on the screen for a visual presentation of the frequency components.
Adjusting the Thermal Index Limit
Before you use Doppler mode, check that the TI settings are appropriate. The current
TI tissue type and limit are displayed just under the B-K Medical logo in the upper
left corner of the screen.
For information about adjusting the TI, see “Adjusting the Thermal Index Limit” on
page 138.
Adjusting MI
You can adjust the maximum allowed MI (mechanical index).
To adjust the MI limit:
•
Click MI above Gain on the left side of the screen and drag the slider.
Turning Doppler Mode On or Off
When you turn on Doppler mode, B-mode must be scanning.
To turn on Doppler mode:
•
Press
[
k
]
.
The Doppler indicator, including both the Doppler line and the Doppler gate,
appears superimposed on the B-mode image and the Doppler spectrum appears.
To position the Doppler gate on a larger B-mode image, press
[
m
]
and position the
Doppler gate before you press
[
k
]
.
Содержание Pro Focus 2202
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Страница 49: ...Part 2 Working with the Image ...
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