Full Digital Color Doppler Ultrasonic Diagnostic Instrument (Vet) User’s Manual V1.00
- 27 -
First, sampling detection should be on the major axis of the vessel, not on the minor axis or inclined
axis, so the ratio between the detected vessel length and diameter is as large as possible.
Second, the major axis of the vessel should be parallel with the scanning section, the angle between
beam and blood flow is as small as possible, the maximum not more than 60 degrees. Angle
correction is performed only based on meeting above requirements; the measurement error can be
controlled within the allowable range. (The smaller the Doppler angle is, the smaller the error is.
When the Doppler angle is greater than 60° and the error is rapidly increasing. The measured flow
velocity is relatively accurate with small angle scanning, so in the clinical diagnosis, try to use the
Doppler angle less than 60°).
Ultrasound angle is not greater than 20° in the cardiovascular examination; in the examination of
abdomen, limbs and other peripheral vascular, ultrasound angle is not greater than 60°, if the actual
angle is greater than 60°, it must be corrected to 60°.
3). Move the baseline. The position of baseline moves up or down at the maximum, the velocity range of
blood flow can be increased twice.
4). Spectral Doppler filter, also known as wall filter. The role and adjustment principles are described the
same as above.
5). Spectral Doppler gain. The spectrum having appropriate gain should have bright and clear velocity
curves, sharp edges, clean background. If the gain adjustment is too large, the brightness of spectrum is
saturated, dispersion loses layering, edge is rough, and the background appears clutters liking snowflakes.
Gain adjustment is too small, spectral curve is dim, depicting unclear.
1. PW mode operation
Press
key, first enter B/PW mode, user selects the sample position in PW spectrum according
to the displayed reference CFM or PDI images, and sets the sample volume of PW and correctional
angle of blood flow direction. Press
【
Update
】
key to enter PW mode. When you need to re-adjust the
position, press
【
Update
】
key again to return to B/PW mode, re-select and re-set parameters. So forth.
2. Display adjustable parameters in PW mode
For B/PW mode, through “Parameters” menu user can adjust “D Freq”, “PRF”, “Wall Filter”,
“Sensitivity”, “Persistence”, “Threshold”, “Balance”, “Color Smooth”, “Artifact Remove”, “Dyn
Range”, “Edge”, “Comp Curve”, “IP”, “Frame Avg” and “Image Opt”. For PW mode, through
“Parameters” menu user can adjust “Dyn Range”, “PW Freq”, “Wall Filter” and “Noise Reject”.
Parameters adjustment table in PW mode
No. Items
Parameters
Value/Status
Descriptions
Remark
Doppler
Frequency
3.5MHz probe 2
levels
6.5MHz probe 2
level
7.5MHz probe 2
levels
3.5MHz probe CFM frequency:
2.5MHz, 3.3 MHz
6.5MHz probe CFM frequency:
5.0MHz, 5.7MHz
7.5MHz probe CFM frequency:
5.0MHz, 6.5MHz
PRF
11-level, 350
～
7500Hz
Adjusting velocity range acturally adjusts
the PRF. Velocity range is set too high, the
blood flow is not satisfied, particularly
difficult to detect low-velocity blood flow;
be set too low, it will occur color aliasing.
Velocity range should be adjusted to
maximize the display of low-velocity blood
flow, but not to appear color inversion.
1
B/PW
mode-
Menu
item
Wall Filter
8-level, 50
～
350Hz
Filter out low-frequency echo signal not
generated by blood flow; so that the blood
Attention:
In real time PW mode, only has “Parameters” menu.