When creating an ultrasound image, all of the following assumptions are made except.A. Sound travels in a straight lineB. Sound travels at 1.54 km/sC. The sound beam is extremely thin D. All structures create reflections of equal magnitude
D. All structures crate reflections of equal magnitudeThe magnitude of a reflection is related to the scattering strength of the anatomic structure that creates it. For example, reflections from bone are usually strong, whereas reflections from soft tissue are normally weak.
Which statement regarding axial resolution is incorrect?A. Axial resolution artifact is related to beam diameterB. Higher quality images are associated with smaller numbersC. Axial resolution may be reported in units of metersD. Numerically, axial resolution equals one-half the pulse lengthE. Too few reflects appear on the image
A. Axial resolution artifact is related to beam diameter
An ultrasound pulse has a width of 4 mm, a length of 2 mm, and is produced by a transducer 3,000 times per second. What is the best estimate of the system's axial resolution?A. 4 mmB. 2 mmC. 1 mmD. 1,500 Hz
C. 1 mmAxial resolution is equal to approx. one-half of the pulse length. The length is 2 mm, therefore the axial resolution is 1 mm.
Which of the following statements is true about lateral resolution?A. It is also called angular, transverse , and depth resolutionB. It is reported in units of timeC. It is the same at all depthsD. It can be improved by focusing
D. It can be improved by focusing
All of the following artifacts result in the placement of too many echoes on the image except:A. shadowingB. reverberationC. mirror imageD. Grating lobes
A. Shadowing
Which of the following determines the spatial resolution of a display?A. number of pixelsB. number of lines on the displayC. number of bits per pixelD. spatial pulse length
B. number of lines on the display
Which of the following determines the spatial resolution of a digital display?A. pixel densityB. number of lines on the displayC. number of bits per pixelD. spatial pulse length
A. pixel density
Which artifact produces an image with an incorrect number of reflectors?A. propagation speed errorB. multipathC. enhancementD. side lobes
D. side lobes
T or F. Mirror image artifacts always appear deeper than the true anatomy.
TRUE
Which artifact is unrelated to the dimensions of an ultrasound pulse?A. lateral resolutionB. depth resolutionC. slice thicknessD. refraction
D. Refraction
T or F. It is common to visualize artifacts when the dimension of the sound beam is larger than the reflector's dimension.
TRUE
Two reflections, one true and one artifact, are displayed on an ultrasound image. In the body, only one anatomic structure is present. The correct reflection and the artifact are found side by side. What is the most likely cause of this artifact?A. mirror imageB. grating lobeC. enhancementD. multipath
B. grating lobe
Two distinct reflections are observed on an image, but they actually arise from a single anatomic structure. The artifact is positioned deeper than the correct reflection. What is the most likely cause of this artifact?A. grating lobeB. side lobeC. refractionD. mirror image
D. mirror image
Which one of these artifacts does not result from multiple reflections?A. comet tailB. reverberationsC. ring downD. enhancement
D. enhancement
Whil using a linear sequential array transducer during a color doppler exam, the shape of the gray scale image is mot often _____, whereas the shape of the color doppler portion of the image is _____.A. rectangular, parallelogramB. rectangular, sectorC. sector, trapezoidD. square, rectangular
A. rectangular, parallelogram
What is the meaning of the term "analysis" in the context of spectral analysis of doppler signals?A building a sophisticated signal from componentsB. building a simplified signal from componentsC. identifying the building blocks or components of a complex signalD. measuring a complex signal, then modifying its information content
C. identifying the building blocks or components of a complex signal
The analysis of doppler spectra using ___ is most accurate.A. zero-crossing detectorsB. FAst Fourier TransformsC. time interval histogramsD. Chirp-Z transforms
B. Fast Fourier Transforms
Spectral analysis of color flow doppler is most commonly performed by which of the following techniques?A. zero-crossing detectorsB. Fast Fourier TransformsC. autocorrelationD. Chirp-Z transforms
C. autocorrelation
Acoustic artifacts include: (More than one answer may be correct)A. images of reflectors in an inappropriate positionB. images of reflectors with improper shapeC. images of reflectors with incorrect brightnessD. images that do not correspond to anatomical structures
A, B, C, and D.An artifact is an error in imaging. All of the choices indicate a type of error, and therefore, are artifacts
Which of the following is not a potential cause of artifact in diagnostic imaging?A operator errorB. equipment malfunctionC. patient motionD. ultrasound physicsE. none of the above
E. none of the above
Ultrasound systems are designed to automatically _____.A. display similar structures with equal brightness, regardless of depthB. position structures at the correct depth, regardless of the mediumC. display all reflections on a line corresponding to the main axis of the sound beam, regardless of refractionD. select the optimal beam width based on the clinical application
C. display all reflections on aline corresponding to the main axis of the sound beam, regardless of refraction
Six distinct, equally spaced reflections appear on an image a ever increasing depths. What type of artifact is this?A. reverberationB. ring downC. mirror imagingD. longitudinal resolution
A. Reverberation
Which situation will commonly produce reverberation artifact?A. two masses that lie perpendicular to the sound beam's main axisB. two weak reflectors that lie close to each other along the axis of the beamC. two strong reflectors that lie along the main axis of the beamD. a single highly reflective mass
C. two strong reflects that lie along the main axis of the beam
What are the characteristics of a medium that produces comet tail artifact?A weak reflectors, closely spaced, low propagation speedsB. strong reflectors, widely spaced, high propagation speedsC. strong reflectors, closely spaced, low propagation speedD. strong reflectors, closely spaced, high propagation speed
D. strong reflectors, closely spaced, high propagation speed
What is the most likely cause of ring down artifact?A. refractionB. inversionC. reabsorptionD. reflection
D. reflection
Where are shadowing artifacts commonly seen on an acoustic scan?A. deeper than a structure with a high impedanceB. shallower than a structure with a low propagation speedC. deeper than a structure with a high attenuationD. alongside of a structure with a low elastance
C. deeper than a structure with high attenuation
How is shadowing artifact expressed?A. positioning structures too deep on the imageB. locating structures in improper lateral positionC. placing reflections in multiple locationsD. reflectors being absent on the image
D. reflectors being absent on the image
Which of these produces shadowing?A. reverberationB. multipathC. reflectionD. attenuation
D. attenuation
What causes enhancement artifact?A. sound beams bendingB. linear array transducer architectureC. unexpectedly low acoustic attenuationD. acoustic energy radiating in a direction other than the beam's main axis
C. unexpectedly low acoustic attenuation
Unexpectedly low attenuation results in which of the artifacts listed below?A. refractionB. attenuationC. enhancementD. shadowing
C. enhancement
When enhancement occurs, where does it appear on the image?A. in the near fieldB. deeper than a weak attenuatorC. in the far fieldD. shallower than a weak reflector
B. deeper than a a weak attenuator
Acoustic focusing of an ultrasound beam may create which artifact?A. side lobesB. refractionC. speckleD. enhancement
D. enhancement
Which process causes mirror image artifact?A. reflectionB. refractionC. propagation speed errorD. attenuation
A. reflection
Where is a mirror image artifact located?A. sometimes shallower on the image than in the bodyB. always deeper on the image than in the bodyC. sometimes the same depth on the image as in the bodyD. never deeper on the image than in the body
B. always deeper on the image than in the body
Which artifact is not affected by the shape or dimensions of an ultrasound pulse?A. lateral resolutionB. slice thicknessC. mirror imagingD. longitudinal resolution
C. mirror imaging
Which artifact is created by sound moving through a medium with a propagation speed less than soft tissue?A. vertical misregistrationB. horizontal misregistrationC. lateral resolutionD. ring down
A. vertical misregistrationVertical misregistration occurs when pulses do not travel at the speed of sound in soft tissue (1,540 m/sec)
While imaging is a test object, an ultrasound system displays one image 1.8 cm deeper than another. Upon measuring the test object, it is found that it is actually 2.0 cm deeper. What conclusion can be drawn from this?A. speed of sound in the test object is the same as soft tissueB. speed in the test object is less than that in soft tissueC. attenuation of sound in the test object is less than that in soft tissueD. speed in soft tissue is less than that of the test object
D. speed in soft tissue is less than that of the test object
If an ultrasound pulse travels through a large mass in the body at a speed of 1.2 mm/us, what happens to the position of all echoes produced from reflectors shallower than the mass?A. they are placed in too shallow a location on the imageB. they are placed in too deep a location on the imageC. they are likely to be placed at the correct depth
C. they are likely to be placed at the correct depth
If a sound pulse travels through a large mass at a speed of 1.2 mm/us, what happens to the position of echoes from reflectors deeper than the mass?A. they are placed in too shallow a location on the imageB. they are placed in too deep a location on the imageC. they are likely to be placed a the correct depth
B. they are placed in too deep a location on the image
What type of artifact causes a reflection to be placed at an incorrect depth?A. lateral incertitudeB. shadowingC. range ambiguityD. indeterminate relaxation
C. range ambiguity