Which artifact causes a reflector to be improperly positioned on the display?
Answer(s): D
Acoustic Shadowing: This artifact occurs when a structure absorbs or reflects most of the ultrasound waves, causing a shadow behind the structure. It does not cause improper positioning of a reflector on the display.Speckle: This is a form of noise in ultrasound imaging that appears as granular texture. It can affect image quality but does not lead to improper positioning of reflectors.Enhancement: This artifact occurs when the area behind a weakly attenuating structure appears brighter. It affects the brightness of the image but does not affect the position of reflectors.Range Ambiguity: This occurs when an echo is received after the next pulse has been sent out, causing the reflector to be placed at an incorrect depth on the display. This is because the system assumes the echo came from the most recent pulse.
"Ultrasound Physics and Instrumentation" by Frank MieleARDMS Sonography Principles and Instrumentation study materials
Which adjustment resulted in the change from image A to image B?
Answer(s): C
Increased Transmit Frequency: This would generally improve the resolution of the image but does not directly correlate to the changes seen in the provided image link.Increased Scale: Adjusting the scale changes the velocity range displayed but does not directly affect the speckle or noise reduction.Decreased Color Gain: Reducing the color gain can decrease the amount of color noise, making the blood flow regions more defined, which aligns with the change observed from image A to image B.Decreased Acoustic Power: This reduces the overall intensity of the ultrasound beam, affecting penetration depth and overall brightness but is less likely to result in the specific improvements seen.
"Understanding Ultrasound Physics" by Sidney K. EdelmanARDMS Sonography Principles and Instrumentation study materials
What are two types of cavitation in tissue?
Heat and Transient: Heat and transient are not classifications of cavitation.Thermal and Mechanical: These terms refer to different bioeffects of ultrasound but are not types of cavitation.Stable and Transient: These are the two types of cavitation observed in tissues during ultrasound. Stable cavitation involves the oscillation of gas bubbles without collapse, while transient cavitation involves the violent collapse of gas bubbles, which can generate high temperatures and shock waves.Thermal and Stable: Thermal effects are a different concept related to tissue heating, not a type of cavitation.
"Diagnostic Ultrasound: Principles and Instruments" by Frederick W. KremkauARDMS Sonography Principles and Instrumentation study materials
Which change was made after acquiring image A to produce image B?
Answer(s): B
Increased Sweep Speed: This affects the display of the waveform over time but does not impact the appearance of the spectral Doppler signal in the way shown.Decreased Pulse Repetition Frequency (PRF): Lowering the PRF can lead to aliasing, which is evident as the waveform wrapping around in the spectral display from image A to image B. This makes the velocity appear higher than it actually is.Decreased Wall Filter: This adjustment primarily affects the elimination of low-frequency Doppler signals but does not typically cause the kind of changes seen in the images.Increased Spectral Gain: Increasing the gain would result in a brighter spectral display but not the wrapping of the signal as seen.
Which machine setting could cause aliasing to occur?
Doppler Scale Too High: This would prevent aliasing but could result in loss of low-velocity signals.Doppler Scale Too Low: When the scale is set too low, velocities exceed the Nyquist limit, resulting in aliasing where the Doppler signal wraps around the baseline.Doppler Gain Too High: High gain may result in noise and overamplified signals but does not directly cause aliasing.Doppler Gain Too Low: Low gain results in weak signal detection but does not cause aliasing.
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