ARDMS SPI - ARDMS Sonography Principles and Instrumentation Attenuation, Reflection, and Refraction Questions and Answers

Question 1

A sonographer is imaging a patient with a high-frequency linear transducer.
They notice that the far field of the image is significantly darker than the near field.
Which of the following is the primary reason for this observation?

Accepted Answer

The attenuation coefficient is directly proportional to frequency.

Answer

Increased refraction in the far field.

Answer

Specular reflection is stronger in the near field.

Answer

The acoustic impedance of deeper tissues is lower.

Question 2

An ultrasound wave travels from a medium with an acoustic impedance of 1.5 MRayls to a medium with an acoustic impedance of 1.7 MRayls. What will occur at the boundary between these two media?

Accepted Answer

A portion of the sound will be reflected back to the transducer.

Answer

All of the sound will be transmitted.

Answer

Refraction will not occur, regardless of the angle of incidence.

Answer

The frequency of the ultrasound wave will increase.

Question 3

For refraction of an ultrasound beam to occur at an interface between two tissues, which two conditions must be met?

Accepted Answer

Different propagation speeds and an oblique angle of incidence.

Answer

Different acoustic impedances and a 90-degree angle of incidence.

Answer

Identical propagation speeds and an oblique angle of incidence.

Answer

Different propagation speeds and a 90-degree angle of incidence.

Question 4

While performing a Doppler study of the red blood cells, a sonographer notes that the strength of the returning echoes increases significantly when they switch from a 3 MHz transducer to a 6 MHz transducer. This is best explained by:

Accepted Answer

Rayleigh scattering.

Answer

Specular reflection.

Answer

Acoustic enhancement.

Answer

Refraction.

Question 5

A sonographer observes a strong, bright reflection from the diaphragm-lung interface, with a complete loss of signal (acoustic shadow) posterior to it. This is primarily due to:

Accepted Answer

A large mismatch in acoustic impedance.

Answer

High absorption in the lung tissue.

Answer

Significant refraction at the curved diaphragmatic surface.

Answer

The critical angle being exceeded.

Question 6

Which of the following is a primary component of attenuation?

Accepted Answer

Conversion of sound to heat

Answer

Amplification

Answer

Refraction

Answer

Increased propagation speed