ARDMS SPI Acoustic Waves and Properties 4

Question 1

Snell's Law in ultrasound describes the relationship between:

Accepted Answer

Incident and refracted beam angles at a tissue boundary

Answer

Snell's Law states that the sine of the angle of incidence to the sine of the angle of refraction equals the ratio of propagation speeds in the two media.

Question 2

What is the approximate average propagation speed of ultrasound assumed by diagnostic scanners in soft tissue?

Accepted Answer

1540 m/s

Answer

Diagnostic ultrasound machines assume 1540 m/s (1.54 mm/µs) as the average soft-tissue propagation speed for depth calculation.

Question 3

The reflection coefficient at a tissue interface is primarily determined by the difference in:

Accepted Answer

Acoustic impedances of the two media

Answer

The intensity reflection coefficient depends on (Z2 − Z1)² / (Z2 + Z1)², where Z1 and Z2 are the acoustic impedances of the two media.

Question 4

Increasing the amplitude of an ultrasound wave will directly increase its:

Accepted Answer

Acoustic power and intensity

Answer

Amplitude is proportional to pressure variation; acoustic intensity is proportional to amplitude squared, so larger amplitude means greater power and intensity.

Question 5

A sound wave with frequency of 5 MHz traveling through soft tissue (c = 1540 m/s) has a wavelength of approximately:

Accepted Answer

0.31 mm

Answer

λ = c / f = 1540 m/s ÷ 5,000,000 Hz = 0.000308 m ≈ 0.31 mm.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI Acoustic Waves and Properties 4