ARDMS SPI Principles of Image Resolution 4

Question 1

Increasing transducer frequency to improve resolution is limited primarily by:

Accepted Answer

Greater acoustic attenuation reducing penetration depth

Answer

Higher frequencies are attenuated more rapidly in tissue, limiting the usable imaging depth.

Question 2

Which component in a modern ultrasound system performs dynamic aperture control?

Accepted Answer

The beamformer

Answer

The beamformer applies time delays and apodization across elements, enabling dynamic aperture and focusing.

Question 3

In harmonic imaging, the image is formed from the _____ harmonic frequency.

Accepted Answer

Second (2f₀)

Answer

Tissue harmonic imaging uses the second harmonic (twice the transmitted frequency) generated by nonlinear propagation.

Question 4

Tissue harmonic imaging improves lateral resolution compared to fundamental imaging because harmonic signals:

Accepted Answer

Are strongest near the beam axis where pressure is highest, reducing side lobes

Answer

Harmonic energy is concentrated near the beam axis, reducing clutter from side lobes and grating lobes.

Question 5

The far field (Fraunhofer zone) of an unfocused transducer is characterized by:

Accepted Answer

Beam divergence and degrading lateral resolution

Answer

In the far field the beam diverges, widening the beam and worsening lateral resolution.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test