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Davies SPI REVIEW Already Rated A+ What action below would be most in keeping with the ALARA principle while performing a diagnostic ultrasound examination? A: Allow multiple students to scan an obstetrical patient because the fetus is in a good position for imaging. B: Prolong the sonogr...

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  • October 29, 2024
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  • 2024/2025
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Davies SPI REVIEW Already Rated A+

What action below would be most in keeping with the ALARA principle while performing a diagnostic
ultrasound examination?
A: Allow multiple students to scan an obstetrical patient because the fetus is in a good position for
imaging.
B: Prolong the sonogram to make videos of the fetus for each family member.
C: Complete the diagnostic scan in a timely fashion at the lowest output power that achieves a quality
image.
D: Maximize the acoustic output to brighten the overall image.
E: Extend the sonogram beyond the intended scope of the exam requisition.

C: Complete the diagnostic scan in a timely fashion at the lowest output power that achieves a quality
image.

What is the primary function of the backing material in a transducer?

✔️✔️The backing material dampens the vibrations of the piezoelectric crystal, reducing pulse duration
and improving axial resolution.



How does the aperture size affect beam width in ultrasound imaging?

✔️✔️A larger aperture reduces beam width, improving lateral resolution and focus, especially at
greater depths.



What is the purpose of apodization in ultrasound?

✔️✔️Apodization reduces side lobe artifacts by adjusting the strength of the signal across the
transducer elements, improving image quality.



How does the scan line density impact spatial resolution?

✔️✔️Higher scan line density increases spatial resolution, providing finer detail in the image but
potentially lowering frame rate.



What causes ring-down artifact?

✔️✔️Ring-down artifact occurs when sound waves interact with gas bubbles, creating continuous
echoes that appear as a solid line extending from the source.

,Explain the significance of the pulse repetition frequency (PRF) in Doppler imaging.

✔️✔️PRF determines the number of pulses sent per second and affects the maximum detectable
Doppler shift, which impacts aliasing risk.



What is beam divergence, and how does it affect image resolution?

✔️✔️Beam divergence is the spreading of the ultrasound beam with depth; increased divergence
decreases lateral resolution in the far field.



Describe how increasing frequency affects attenuation.

✔️✔️Higher frequencies experience greater attenuation, resulting in decreased penetration but
improved resolution in superficial tissues.



What does lateral resolution depend on?

✔️✔️Lateral resolution depends on beam width; a narrower beam provides better side-by-side detail.



How does the Fresnel zone differ from the Fraunhofer zone?

✔️✔️The Fresnel zone (near field) has better resolution and minimal divergence, while the Fraunhofer
zone (far field) has increased divergence and reduced resolution.



What is an acoustic window, and why is it important?

✔️✔️An acoustic window is a pathway with minimal obstruction for sound waves to reach target
tissues, important for clear imaging, especially in areas like the abdomen.



Explain how time-of-flight is used in ultrasound.

✔️✔️Time-of-flight measures the time it takes for sound waves to travel to a structure and back,
helping calculate distance and create accurate images.



What is the purpose of adjusting the baseline in Doppler ultrasound?

✔️✔️Adjusting the baseline shifts the zero point on the display, preventing aliasing and allowing
better visualization of flow direction.

,How does lateral gain compensation differ from TGC?

✔️✔️Lateral gain compensation adjusts gain across the width of the image to correct for intensity
variations, while TGC compensates for depth attenuation.



What is the main effect of frame averaging on an ultrasound image?

✔️✔️Frame averaging reduces random noise by averaging consecutive frames, resulting in a
smoother image but with decreased temporal resolution.



What is slice thickness artifact?

✔️✔️Slice thickness artifact occurs when echoes from structures outside the imaging plane are
included, potentially blurring or distorting the image.



Why is PRF adjusted in spectral Doppler imaging?

✔️✔️PRF is adjusted to match the expected blood flow velocities; too low a PRF may cause aliasing,
while too high a PRF may miss slower flows.



How does increasing focal zones impact frame rate?

✔️✔️Increasing focal zones reduces frame rate, as the system spends more time focusing on each
depth, enhancing resolution at those points.



What does color priority do in ultrasound imaging?

✔️✔️Color priority adjusts the balance between color Doppler and grayscale, controlling which is
given display priority in mixed regions.



Why is it important to minimize the Doppler angle in vascular studies?

✔️✔️Minimizing the Doppler angle (ideally below 60°) improves accuracy in blood flow velocity
measurements.



How does acoustic impedance influence reflection?

, ✔️✔️Greater differences in acoustic impedance between tissues increase reflection, producing
stronger echoes for clearer imaging boundaries.



Explain the purpose of using a standoff pad in ultrasound imaging.

✔️✔️A standoff pad enhances imaging of superficial structures by creating distance, allowing better
focus on small, near-surface details.



What is the difference between real-time and static imaging?

✔️✔️Real-time imaging displays moving images continuously, useful for observing dynamic processes,
while static imaging captures a single frame.



How does elevational resolution differ from axial and lateral resolution?

✔️✔️Elevational resolution is the ability to distinguish structures in the third dimension (thickness of
the slice), impacting image clarity in the out-of-plane dimension.



What is clutter artifact in Doppler imaging?

✔️✔️Clutter artifact consists of low-frequency noise caused by tissue or wall motion, which can
obscure true blood flow signals in Doppler imaging.



What does the ALARA principle stand for?

As Low As Reasonable Achievable



During performance of an obstetrical ultrasound exam you adjust the system parameters to improve the
image. Which of the following parameters would increase acoustic exposure?
A: Increase gain
B: Increase TGC
C: Increase frequency
D: Increase transmit power
E: Increase frame averaging

D: Increase transmit power

While performing a sonogram to minimize risk to the fetus which imaging mode trade off would be most
applicable?
A: Use M-mode instead of pulsed-wave Doppler to measure the fetal heart rate.

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