VT Ultrasound Physics & Doppler Principles 3

Question 1

What is the approximate speed of sound in soft tissue used as the standard for ultrasound imaging?

Accepted Answer

1,540 m/s

Answer

Most diagnostic ultrasound systems assume a propagation speed of 1,540 m/s in soft tissue.

Question 2

The term 'wall filter' in Doppler ultrasound is used to eliminate signals from:

Accepted Answer

Slow-moving vessel walls and tissue

Answer

Wall filters (high-pass filters) remove low-frequency Doppler shifts caused by slow-moving vessel walls and surrounding tissue clutter.

Question 3

When the angle of insonation is 0° in the Doppler equation, the cosine value is:

Accepted Answer

1.0

Answer

cos(0°) = 1.0, meaning the beam is perfectly parallel to flow, yielding maximum Doppler frequency shift.

Question 4

Which transducer design provides the best near-field resolution for superficial vascular structures like the carotid artery?

Accepted Answer

Linear array

Answer

Linear array transducers produce a rectangular field of view and superior near-field resolution ideal for superficial vessels.

Question 5

Increasing the pulse repetition frequency (PRF) in pulsed Doppler will:

Accepted Answer

Increase the maximum detectable velocity

Answer

A higher PRF raises the Nyquist limit (PRF/2), allowing detection of higher velocities before aliasing occurs.

(VT) Vascular Technician Certification Practice Test