Transducer Construction and Function Flashcards
7 cards from real ARDMS SPI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Transducer Construction and Function flashcards as text
Dynamic receive focusing in modern array transducers improves lateral resolution by:
Answer: Continuously adjusting the receive focus as echoes return from increasing depths
During reception, time delays are updated in real time to focus at the depth from which echoes are currently returning, providing optimum lateral resolution at all depths.
A transducer labeled '5-12 MHz' is best described as a:
Answer: Broad-bandwidth transducer capable of operating across that frequency range
Modern broadband transducers have wide bandwidths allowing the operator to select or the system to use frequencies across the stated range for different imaging needs.
Acoustic impedance (Z) is calculated as the product of:
Answer: Density and propagation speed
Z = ρ × c, where ρ is the medium's density and c is the speed of sound in that medium.
In a 1.5D array transducer compared to a standard 1D array, the key improvement is:
Answer: Limited electronic control in the elevation dimension to improve slice-thickness resolution
A 1.5D array adds a few rows of elements in the elevation direction, allowing limited electronic focusing to reduce slice-thickness artifacts compared to a fixed lens.
The phenomenon of pulse ring-down (ringing) in a transducer is reduced by:
Answer: Using a heavily damped backing layer with high attenuation
A heavily damped (high-attenuation) backing layer absorbs the residual mechanical energy of the crystal quickly, shortening ring-down and improving axial resolution.
Which formula correctly describes the optimal thickness of a single matching layer?
Answer: One-quarter wavelength at the center frequency
The matching layer thickness is set to one-quarter wavelength at the center frequency, creating a quarter-wave transformer that maximizes power transmission.
When comparing continuous-wave (CW) to pulsed-wave (PW) Doppler transducer designs, CW transducers differ in that they:
Answer: Use two separate elements—one dedicated to transmitting and one to receiving—operating simultaneously
CW Doppler transducers have two separate crystal elements operating simultaneously—one continuously transmitting and one continuously receiving—with no range gate.