D
IRECTION
5771498-100, R
EVISION
6
V
ENUE
™ S
ERVICE
M
ANUAL
4-18
Section 4-3 - Functional Checks
P R E L I M I N A R Y
4-3-5-3
Using PW/CW Doppler Modes
4-3-5-3-1
Alternative 1
1) Press
PW
or
CW
. A scanning screen is displayed with a Doppler cursor on the 2D mode image and
a Doppler spectrum in the lower part of the screen.
2) Position the Doppler cursor line and in PW the sample volume location over the area of interest.
3) In PW, adjust the
Sample Volume
.
NOTE:
Sample Volume adjustment may affect the Scale, Frame rate and LV rej. settings.
4-3-5-4
Optimizing PW/CW Doppler Modes
The use of preset gives optimum performance with minimum adjustment. If necessary, the following
controls can be adjusted to further optimize the PW/CW modes display:
•
Adjust the
Active mode gain
to set the gain in the spectral Doppler area.
•
Adjust
Low velocity reject
to reduce unwanted low velocity blood flow and tissue movement.
•
In PW mode, adjust
Sample volume
to low setting for better resolution, or higher setting to more
easily locate the disturbed flows. Adjustment of the Sample volume may affect the PRF (Nyquist
limit) settings.
•
Adjust the
Compress
setting to balance the effect of stronger and weaker echoes and obtain the
desired intensity display.
•
Adjust
Frequency
to optimize flow display. Higher setting will improve resolution and the lower
setting will increase the depth penetration.
•
Adjust
Frame rate
to a higher setting to improve motion detection, or to a lower setting to improve
resolution.
NOTE:
Frequency and Frame rate settings may affect the Low Velocity Reject.
•
Adjust
Power
to obtain an acceptable image using the lowest setting possible. This is particularly
important in CW mode, as the energy duty cycle is 100% (constant).
NOTE:
The Doppler Power setting affects only Doppler operating modes.
Adjust the following settings to further optimize the display of the image.
•
Use the
Horizontal sweep
to optimize the sweep speed.
•
To view signal detail, adjust
Scale
to enlarge the vertical spectral Doppler trace. Velocity range
directly controls the pulse repetition frequency, which is responsible for the setting of the Nyquist
limit (the ability to detect maximum velocity without aliasing).
•
Use
Invert
to reverse the vertical component of the spectral Doppler area of the display.
CAUTION
Use all noise reduction controls with care. Excessive
application may obscure low level diagnostic information.
Summary of Contents for H45051VN
Page 477: ......
