GE Medical Systems 500, User Manual, Page: 173 / 636

Doppler
LOGIQ 500 Basic Users Manual
2276612–100 Rev. 0
5–61

Controls (cont’d)
Doppler Spectral Gain Theta Angle Correction
Description
Amplifies the overall strength of the
echoes being processed in the
Doppler spectral trace. Estimates the flow velocity in a direction at an
angle to the Doppler vector by computing the
angle between the Doppler vector and the flow
to be measured.
Estimated flow velocity equals the velocity
toward the probe divided by the COS
q
.
Accessing/
Changing Gain (DG#) values are shown on the
left side of the display. The initial
gain value is selected in the Set
Up/Custom Display menu page 4. Flow towards the probe is mapped above the
baseline of the spectral display and left speaker.
To adjust the angle clockwise relative to the
probe face, turn
θ
Angle clockwise.
To adjust the angle counterclockwise relative to
the probe face, turn
θ
Angle counterclockwise.
Press M/D Cursor to quickly return the angle
correction to zero degrees and erase the angle
correction cursor from the display.
The initial angle value is selected in the Set Up/
Custom Display menu page 4.
Benefits Fills in or cleans out spectrum
information. Optimizes the accuracy of the flow velocity. This
is especially useful in vascular studies where it
is necessary to measure velocity.
Values 0 to 32 in increments of 2.
Usually set in the middle of the
range.
For optimum velocity measurements, the angle
of incidence should be less than 20
°
for cardiac
applications. The usual setting is between 45
°
and 65
°
for vascular applications.
1
°
increments from 0
°
to 80
°
.
Bioeffects Doppler spectral gain has no affect
on acoustic output. However, with
increased Doppler spectral gain, the
output level can usually be reduced
to produce an equivalent spectrum
image quality.
PW Doppler CW Doppler
Angle Correction
Cursor
Figure 5–26. Phased Array Doppler Display with Angle Correct