Resonance by rod-shaped reflectors in ultrasound test objects.

Rod-shaped reflectors such as those used in the AIUM test object resonate at medical ultrasound frequencies, producing artifacts posterior to the reflector. Rods of various diameters and materials were examined to determine their resonant properties, and the effect of the Plexiglas scanning surface of the enclosure on image quality was studied. A theory predicting the resonant frequencies of rods is proposed, and methods of eliminating resonance artifacts are discussed.