ARDMS SPI Ultrasound Bioeffects and Safety 2

Question 1

Which index displayed on modern ultrasound systems specifically relates to the risk of acoustic cavitation?

Accepted Answer

Mechanical Index (MI)

Answer

The Mechanical Index (MI) quantifies the likelihood of cavitation by comparing peak negative pressure to the square root of frequency.

Question 2

Stable cavitation differs from inertial cavitation in that stable cavitation involves:

Accepted Answer

Bubbles oscillating in a sustained, non-destructive manner

Answer

Stable (non-inertial) cavitation describes gas bubbles that oscillate repetitively without collapsing, whereas inertial cavitation involves violent implosion.

Question 3

The ALARA principle in diagnostic ultrasound means the operator should:

Accepted Answer

Use the lowest output that still yields diagnostic information

Answer

ALARA (As Low As Reasonably Achievable) requires minimizing acoustic exposure while still obtaining the necessary diagnostic image quality.

Question 4

Which ultrasound mode typically produces the highest time-averaged acoustic intensity and greatest potential for thermal bioeffects?

Accepted Answer

Pulsed-wave Doppler

Answer

Pulsed-wave Doppler has a high duty factor and focuses the beam on a small sample volume, resulting in the highest time-averaged intensity and greatest heating potential.

Question 5

A Thermal Index value of 2.0 indicates that the ultrasound system is capable of raising tissue temperature by approximately:

Accepted Answer

2.0°C

Answer

The TI is defined as the ratio of acoustic power to the power needed to raise tissue temperature by 1°C, so TI = 2.0 suggests a potential 2°C rise.

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI - ARDMS Sonography Principles and Instrumentation Practice Test

ARDMS SPI Ultrasound Bioeffects and Safety 2