Artifacts, Quality Assurance & Bioeffects Flashcards
You are most likely to encounter the range ambiguity artifact in Doppler under which of the following conditions
Pulsed wave Doppler, PRF 22 kHz, 3 MHz Doppler frequency
From a SAFETY standpoint, which one of the following methods is the best
Low transmit output and high receiver gain
Sometimes this can be interpreted as an additional vessel which has a spectrum similar to that of the real vessel.
Doppler Mirror Image
When you increase the PRF in an attempt to solve the problem of aliasing, you can encounter
Range Ambiguity
An artifact that gives rise to a double or duplicated image is called
Split Image / Refraction
The most likely cause for a beam thickness artifact is
Volume Averaging
With this artifact, the correct number of echoes appear on the image; there is less than average attenuation of a structure; and the artifact is parallel to the sound beam
Enhancement
This artifact causes a sound beam to bounce off a reflector and be redirected. It places the artifact deeper than the true reflector
Mirror Image
This artifact places structures much closer to the surface than they should be.
Propagation Speed Error
With this artifact, there is high attenuation, absence of true anatomy on the scan, and structures that lie deeper than the original structure are not imaged
Shadow
The most common type of artifact encountered in patients with a shotgun wound is
Commet Tail Artifact
At this point, aliasing begins
The Nyquist Limit
With this color representation, low velocity red is separated from low velocity blue by a black line
Flow Reversal
With this color representation, high velocity red and high velocity blue are shown directly next to one another with no black line in between
Aliasing
If the wires in an AIUM test object do not appear in the same place as on the display, what is the issue
Registration Accuracy
A shadow artifact occurs behind a gallstone as a result of
Higher than usual attenuation
True or False: If sound is traveling faster than the machine expects, it places the structure shallower than it should be
True
A quality assurance program is:
Needed by all labs
The force exerted by a sound beam on an absorber or a reflector is called
Radiation Force
- Explain the ALARA principle.
- What does ALARA stand for?
- How can we observe the principle for which ALARA stands (give at least 3 examples)
-Power is set AS LOW AS REASONABLY ACHIEVABLE (while still getting diagnostic information).
-As Low As Reasonably Achievable.
-See below:
Minimize exposure time (but perform a complete diagnostic exam).
Use minimum output power & highest receiver gain required to produce optimal images.
Do not prolong studies without reason.
Do not perform studies without reason.
Which of the following best describes an ideal epidemiologic bioeffects study
Randomized and prospective
All of the following statements regarding in-vitro bioeffects are true EXCEPT:
In vitro bioeffects conclusions are clinically relevant
Two things that can help reduce grating lobes are
The two things are subdicing and apodization
True or False: A mirror image artifact can appear along side of the true anatomy
False. This artifact is always deep to the true anatomy.
True or False: No known bioeffects are proven to occur at the levels used in diagnostic ultrasound
True
What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects
100 mW/cm2
If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased by
100 times
Which type of artifact appears most commonly with highly reflective objects
Shadowing
Of the following choices, which is considered most important for the sonographer with regard to bioeffects
Duration of study
Which one of the following sets of properties of a test phantom is most relevant when assessing depth calibration accuracy
Reflector spacing & Propagation speed
The temperature increase depends on what factors
- Applied intensity or power
- Frequency (absorption is directly proportional to frequency)
- Beam focusing
- Tissue perfusion
With this artifact, the correct number of echoes appear on the image; there is less than average attenuation of a structure; and the artifact is parallel to the sound beam
Enhancement
An artifact that is produced from interaction of the incident beam with a curved surface and results in an acoustic shadow is
a refractive edge shadow artifact
You are performing a QA test on an US system using a tissue equivalent phantom. You make an adjustment using a knob on the system console that changes the appearance of reflector brightness from fully bright to barely visible. You are evaluating what?
Sensitivity
Which artifact has a grainy appearance and is caused by the interference effects of scattered sound
Speckle
True or False: Generally, linear array transducers have excellent elevational resolution
False. The elements in a linear array transducers tend to be wide. This artifact can be rectified by using a one and a half dimensional array transducer, which makes thinner slices.
Under which circumstances is cavitation most likely to occur
High pressure; low frequency
The propagation speed of US in the AIUM test object is
1.54 mm/microsec
At what location in a sound beam is the SPTA intensity the highest
The focal point
True or False: Mirror image artifact is often seen around the pancreas
False
How is range ambiguity artifact eliminated
Lower the PRF
Side lobes are caused by the use of
single crystal transducers
Grating lobes are caused by the use of:
Arrays
A mirror image artifact is a result of the machine’s assumption that
Sound travels directly to the reflector and then back to the transducer
True or False: With transient cavitation, the bubble bursts.
True
When producing an ultrasound image, all of the following assumptions are made except
all structures create reflections of equal magnitude
