Physics, Techniques and ProceduresSide lobe
unwanted emission of
ultrasound in a direction at an angle from the main
ultrasound beam (see
ultrasound beam (I), Fig. 1). Side lobes are due to radial vibration of the transducer crystal (as opposed to vibration in the thickness direction causing the main beam). Transducer crystals are designed with a diameter at least 10 times larger than the
ultrasound wavelength to reduce side lobe emission. The multiple small crystal elements of
electronic array transducers may have the effect of a grating; sound beams emitted at an angle from the main beam in this situation are called grating lobes. Side lobes and grating lobes may cause anatomical features lying outside the field of view to be displaced into the image (
side lobe artefact).
HJS