RVT Ultrasound Physics and Instrumentation 4

Question 1

Which artifact appears as a bright echogenic line with posterior shadowing caused by total reflection at a gas interface?

Accepted Answer

Dirty shadowing

Answer

Dirty shadowing (reverberation shadowing) occurs at gas interfaces where multiple reflections create a heterogeneous shadow with internal echoes.

Question 2

The time-gain compensation (TGC) control is used primarily to:

Accepted Answer

Compensate for attenuation of sound with depth

Answer

TGC amplifies returning echoes from deeper structures to compensate for the progressive attenuation of ultrasound as it travels through tissue.

Question 3

In pulsed-wave Doppler, aliasing occurs when the Doppler shift frequency exceeds:

Accepted Answer

Half the pulse repetition frequency (Nyquist limit)

Answer

Aliasing occurs when the Doppler shift exceeds the Nyquist limit (PRF/2), causing the waveform to wrap around and appear on the opposite side of the baseline.

Question 4

Which transducer design uses multiple elements fired in sequence to create a rectangular field of view?

Accepted Answer

Linear array

Answer

Linear array transducers fire elements sequentially across the footprint to produce a rectangular image with consistent width at all depths.

Question 5

The acoustic impedance of a medium is determined by:

Accepted Answer

Density and propagation speed

Answer

Acoustic impedance (Z) equals the product of the medium's density (ρ) and the speed of sound (c) in that medium: Z = ρc.

(RVT) Registered Vascular Technologist Practice Test

(RVT) Registered Vascular Technologist Practice Test

RVT Ultrasound Physics and Instrumentation 4