ARDMS SPI Transducer Construction and Function 3

Question 1

Which of the following BEST describes the piezoelectric effect as used in diagnostic ultrasound transducers?

Accepted Answer

Conversion of electrical energy to mechanical energy and vice versa

Answer

The piezoelectric effect allows certain crystals to convert electrical signals into mechanical (acoustic) vibrations and incoming pressure waves back into electrical signals.

Question 2

A phased array transducer steers and focuses the beam primarily by adjusting:

Accepted Answer

Time delays applied to individual element firings

Answer

Phased arrays use programmable electronic time delays across all elements to steer and dynamically focus the beam in real time.

Question 3

Increasing the diameter of a single-element unfocused transducer will:

Accepted Answer

Increase the near-field length

Answer

Near-field length = r²/λ; a larger radius (r) increases the near-field length, keeping the beam collimated for a longer distance.

Question 4

Side lobes in ultrasound transducers are most problematic because they:

Accepted Answer

Create artifact echoes that appear to originate from the main beam

Answer

Side lobes radiate energy off-axis; reflectors in their path produce echoes that the system incorrectly places along the main beam axis, creating artifacts.

Question 5

What distinguishes grating lobes from side lobes in array transducers?

Accepted Answer

Grating lobes arise from the periodic spacing of array elements, not from the element aperture

Answer

Grating lobes result from constructive interference due to the regular inter-element spacing of array transducers, while side lobes are inherent to any finite aperture.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI Transducer Construction and Function 3