Transducers Acoustic Artifacts
118 Lumify Ultrasound System
Philips Healthcare 4535 618 58571_A/795 * MAY 2016
• Incorrect object location due to refraction, multi-path reflections, side lobes, grating lobes,
speed error, or range ambiguity
• Incorrect object size due to poor resolution, refraction, or speed error
• Incorrect object shape due to poor resolution, refraction, or speed error
Acoustic saturation occurs when received signals reach a system's high-amplitude limit. At that
point the system becomes unable to distinguish or display signal intensities. At the point of
saturation, increased input will not increase output.
Aliasing occurs when the detected Doppler frequency exceeds the Nyquist limit. It is
characterized on the spectral display by the Doppler peaks going off the display, top or bottom,
and then continuing on the other side of the baseline. On the Color display an immediate
change in color from one Nyquist limit to the other is seen.
Comet tail is a form of reverberation artifact produced when two or more strong reflectors are
close together and have a high propagation speed. In this case, sound does not travel directly to
a reflector and back to the transducer; and a strong linear echo appears at the reflector and
extends deeper than the reflector.
Enhancement is an increased relative amplitude of echoes caused by an intervening structure
of low attenuation.
Focal enhancement, also known as focal banding, is the increased intensity in the focal region
that appears as a brightening of the echoes on the display.
Mirror imaging artifact is most commonly seen around the diaphragm; this artifact results from
sound reflecting off another reflector and back.
Mirroring is the appearance of artifacts on a spectral display when there is improper separation
of forward and reverse signal processing channels. Consequently, strong signals from one
channel mirror into the other.
Multi-path positioning and refraction artifacts describe the situation in which the paths to and
from a reflector are different. The longer the sound takes traveling to or from a reflector, the
greater the axial error in reflector positioning (increased range). Refraction and multi-path
positioning errors are normally relatively small and contribute to general degradation of the
image rather than to gross errors in object location.
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