Which term best describes the property of a transducer that relates to its ability to limit ringing and improve axial resolution?

• A. Backing material
• B. Piezoelectric constant
• C. Impedance matching
• D. Damping factor

Answer: (A)

Damping the transducer’s vibrations after it’s excited is what limits ringing and shortens the emitted pulse, which in turn improves axial resolution. The backing material behind the piezoelectric element provides this damping by absorbing mechanical energy and quickly dissipating it. A shorter pulse means better separation of reflectors along the beam path, so the transducer can resolve structures that are closer together in the axial direction. That’s why the backing material is the term that best describes the property responsible for reducing ringing and boosting axial resolution. The piezoelectric constant mainly affects sensitivity and how efficiently electrical energy is converted to sound, impedance matching influences energy transfer to tissue, and while damping factor relates to how much damping occurs, the backing material is the practical, descriptive component used to achieve that damping.