ARDMS SPI Principles of Image Resolution 5

Question 1

A 5 MHz transducer in soft tissue (c = 1540 m/s) produces a wavelength of approximately:

Accepted Answer

0.31 mm

Answer

λ = c/f = 1540/5,000,000 ≈ 0.308 mm ≈ 0.31 mm.

Question 2

Which statement correctly compares axial and lateral resolution at a specific depth?

Accepted Answer

Axial resolution is typically better than lateral resolution

Answer

Axial resolution (determined by SPL) is generally superior to lateral resolution because the beam width is almost always wider than the SPL.

Question 3

Coded excitation (e.g., chirp pulses) is used in ultrasound primarily to:

Accepted Answer

Improve signal-to-noise ratio and penetration while maintaining resolution

Answer

Coded excitation transmits a long modulated pulse and uses pulse compression on receive to achieve high SNR with good axial resolution.

Question 4

Spatial compounding improves image quality by:

Accepted Answer

Averaging frames from multiple steering angles to reduce speckle and improve contrast resolution

Answer

Compounding averages images steered from several angles, reducing coherent speckle and improving contrast and boundary definition.

Question 5

Which parameter does NOT directly affect axial resolution?

Accepted Answer

Active aperture width

Answer

Active aperture width affects lateral resolution (beam width), not axial resolution, which depends solely on spatial pulse length.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test