Physics-Artifacts

When creating an ultrasound image, all of the following assumptions are made except:
A. sound travels in a straight line
B. sound travels at 1.54 km/s
C. reflections arise only from structures in the pulse's main beam
D. the sound beam is extremely thin
E. all structures create reflections of equal magnitude

Which statement regarding axial resolution is incorrect?
A. axial resolution artifact is related to beam diameter
B. axial resolution may be reported in units of meters
C. higher quality images are associated with small numbers
D. too few reflectors appear on the image
E. numerically, axial resolution equals one-half the pulse length

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. 1 mm
B. 1500 Hz
C. 4 mm
D. 2 mm

Which of the following statements is true about lateral resolution?
A. it is the same at all depths
B. it is reported in units of time
C. it can be improved by focusing
D. it is alos called angular, transverse, and depth resolution

All of the following artifacts results in the placement of too many echoes on the image except:
A. shadowing
B. reverberation
C. mirror image
D. grating lobes

Which of the following determiens the spatial resolution of an analog display?
A. number of lines on the display
B. spatial pulse length
C. number of pixels
D. number of bits per pixel

Which of the following determines the spatial resolution of a digital display?
A. pixel density
B. number of lines on the display
C. number of bits per pixel
D. spatial pulse length

Which artifact produces an image with an incorrect number of reflectors?
A. side lobes
B. multipath
C. enhancement
D. propagation speed error

True or false.
Mirror image artifacts always appear deeper than the true anatomy.
True False

Which artifact is unrelated to dimensions of an ultrasound pulse?
A. refraction
B. depth resolution
C. lateral resolution
D. slice thickness

True or False.
It is common to visualize artifacts when the dimension of the sound beam is larger than the reflector's dimension.
True False

Two reflection, one true and one artifact, are displayed on an 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. multipath
B. mirror image
C. enhancement
D. grating lobe

Two distinct reflections are observed on an image, but they actually arise form a single anatomic structure. The artifact is positioned deeper than the correct reflection. What is the most likely cause of this artifact?
A. mirror image
B. grating lobe
C. side lobe
D. refraction

Which of these artifacts does not result from multiple reflections?
A. ring down
B. reverberations
C. enhancement
D. comet tail