Transducer Construction and Function Flashcards

Which material property is most important for a transducer backing layer?

Answer: High acoustic impedance and high attenuation

The backing layer requires high acoustic impedance to load the crystal and high attenuation to absorb rearward-traveling energy and shorten pulse duration.

A transducer's Q factor is defined as the ratio of the operating frequency to the:

Answer: Bandwidth

Q factor = operating (center) frequency divided by bandwidth; a low Q indicates wide bandwidth and good axial resolution.

In a linear array transducer, electronic focusing in the elevation plane is achieved by:

Answer: A fixed acoustic lens

Elevation-plane focusing in a linear array is fixed and accomplished by a curved acoustic lens bonded to the transducer face.

What is the primary purpose of the matching layer in a transducer?

Answer: Reduce acoustic impedance mismatch between crystal and tissue

The matching layer minimizes reflection at the crystal-tissue interface by presenting an intermediate acoustic impedance, maximizing energy transmission.

Lateral resolution in a single-element focused transducer is BEST at the:

Answer: Focal zone

Lateral (azimuthal) resolution is best at the focal zone where the beam is narrowest.

Which transducer array configuration uses a convex curved surface to produce a fan-shaped image wider than the footprint?

Answer: Curvilinear array

A curvilinear (convex) array has elements arranged along a curved surface, producing a trapezoidal or sector image that widens beyond the transducer footprint.

The spatial pulse length of a transducer is determined by the number of cycles in a pulse multiplied by the:

Answer: Both B and C (they are equivalent)

Wavelength equals propagation speed divided by frequency, so spatial pulse length = number of cycles × wavelength = number of cycles × (speed/frequency).