Doppler angle

Doppler angle corrects for the usual clinical situation when an ultrasound beam is not parallel to the Doppler signal.

For instance, if one wants to evaluate an artery, the best angle for evaluation would be at zero degrees (parallel to the vessel). The strongest signal and best waveforms would be at zero degrees. Zero degrees is not usually clinically feasible, however, so instead the probe is at some angle between 0 (parallel) and 90 degrees (perpendicular) when evaluating the vessel (usually between 30 and 60 degrees).

The ultrasound machine can correct a Doppler signal appropriately if the transducer is angled less than 60 degrees from a vessel. It does not, however, know what angle you are using, so you have to provide this information to the machine, usually via a knob on the control panel.

If you try to correct for an angle above 60 degrees, then there will be a high rate of error with your spectra: up to 20% to 30% . If serially evaluating blood flow velocity in a vessel, try to maintain a similar Doppler angle from study to study .