UTC Ultrasound Physics & Instrumentation 2

Question 1

In pulsed wave Doppler, the Nyquist limit represents which value?

Accepted Answer

Half the pulse repetition frequency (PRF/2), the maximum detectable Doppler shift without aliasing

Answer

Maximum imaging depth achievable

Answer

Minimum frequency required for tissue imaging

Answer

Maximum acoustic power output of the transducer

Question 2

Which transducer type fires elements sequentially to produce a rectangular field of view, making it ideal for vascular and musculoskeletal imaging?

Accepted Answer

Linear array

Answer

Phased array

Answer

Curvilinear (convex) array

Answer

Annular array

Question 3

The Doppler effect used in ultrasound refers to which phenomenon?

Accepted Answer

Change in received frequency caused by relative motion between the sound source and a moving reflector

Answer

Attenuation of sound waves as they travel through tissue

Answer

Reflection of sound waves at tissue boundaries

Answer

Focusing of the sound beam by the transducer lens

Question 4

What is the primary advantage of tissue harmonic imaging over fundamental (conventional) imaging?

Accepted Answer

Reduced near-field artifacts and improved contrast resolution

Answer

Increased penetration depth for deep structures

Answer

Higher frame rates for moving structures

Answer

Better sensitivity for low-velocity Doppler flows

Question 5

A phased array transducer is most commonly used for which clinical application?

Accepted Answer

Cardiac (echocardiographic) imaging through narrow intercostal windows

Answer

Peripheral vascular imaging of leg veins

Answer

Musculoskeletal imaging of superficial tendons

Answer

Breast mass characterization

Question 6

Aliasing in Doppler ultrasound is best described as occurring when:

Accepted Answer

The detected Doppler shift frequency exceeds the Nyquist limit (PRF/2)

Answer

The overall system gain is set too high

Answer

The Doppler angle exceeds 60 degrees from the direction of flow

Answer

The transducer frequency is too low for the depth of interest

Question 7

What is the primary purpose of time gain compensation (TGC) in ultrasound imaging?

Accepted Answer

To amplify returning echoes from deeper tissues and compensate for acoustic attenuation

Answer

To increase the frame rate for real-time imaging

Answer

To reduce the depth of the displayed image

Answer

To narrow the beam width at a specific focal depth