Gammex 1425A, User Manual

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Doppler Quality Control Instruments

Flow instruments and string test objects are two types of Quality Control test tools for Doppler 
ultrasound scanners. Flow instruments, such as the Gammex 1425A, produce physiological flow 
rates and can be used to perform the full range of quality and acceptance tests. “Flow phantoms 
provide a more realistic signal environment in which a spectrum of velocities is produced across 
the flow profile of a simulated vessel. Flow instruments can be calibrated in terms of absolute flow 
rates (and, therefore, maximum velocities).”

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 Flow phantoms mimic blood flow in the body; the 

continuous stream simulates venous flow.

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The angled vessel is used to measure sensitivity for different frequency transducers and accuracy 
of the Doppler angle. The variable flow speeds test the accuracy of the Doppler shift. Good flow 
instruments are self-contained and provide an accurate speed of sound. They are also practical for 
routine quality control and comparison of ultrasound systems as well as teaching the principles of 
Doppler ultrasound.

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String phantoms are not physiological.

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 String phantoms display a specular-like reflection from the 

string surface which could produce uncertainties in specifying the exact Doppler angle.

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 The knot 

signal on the spectral display shows as a regular spike, this can interfere with visualization of the 
Doppler spectrum.

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 Also, the water tank can produce unwanted reverberations and reflections.

Doppler Guided Tour

Using the Preset Flow Rates

The microprocessor-based flow controller produces flow rates from 1.7 to 12.5 ml/s. To select con-
tinuous flow, select a preset. The Optimizer displays the flow rate in ml/s and a calculated velocity 
in cm/s. There are five user-programmable presets for continuous flow rates.

These presets can be adjusted in 0.1 ml/s incremental steps. To adjust the flow rate, use the 
“INCREASE” and “DECREASE” buttons. To save a new flow rate as a preset flow rate for future 
use, press the SAVE PRESET button and select from the preset buttons numbered 1-5.

The Pulse mode presets are hard set and cannot be adjusted.