GE LOGIQ 7, Basic User Manual

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Contrast resolution
Description Contrast resolution is the ability of an imaging system to detect
and display the shape and echogenic characteristics of a
structure. See Figure 18-11 for more information.
Specific values measured are less important than stability over
time. Routine tests at the same settings should produce the
same results.
Benefit A correct diagnosis is dependent upon an imaging system's
ability to differentiate between a cystic or solid structure versus
echo patterns from normal surrounding tissue.
Method A phantom with echogenic targets of different sizes and depths
should be used.
Procedure To measure contrast resolution:
1. Set the front panel TGC slide pots to their center (detent)
position. Set dynamic range to 54 db.
2. Gain and acoustic output can be adjusted, as necessary,
since these values are displayed on the monitor.
3. Scan a test phantom with echogenic targets at the depths
available.
4. Evaluate the echogenic targets for contrast between each
other and between the surrounding phantom material.
Remember, TGC slide pots are centered and should remain
fixed. This may NOT provide an optimal scan image.
5. Document all results for future reference and comparison.
Contact a Service Engineer if the echogenic characteristics or
shapes of the targets appear distorted.