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CVS203: Final Exam

Terms in this set (171)

artifacts are something in our image that does not accurately represent _______ being imaged
anatomy
the following are examples of what?

-reflectors that are not real
-not seen on the image
-incorrect shape or size
-incorrect position
-incorrect brightness
artifacts
what are the four (4) causes of artifacts?
1. violation of "assumptions"
2. equipment malfunction/poor design
3. physics of ultrasound
4. operator error
<dropping the transducer crystals will break and create fall out>

what is the above an artifact example of?
equipment malfunction
<under color gaining creates an error in out imaging>

what is the above an artifact example of?
operator error
it's important to understand artifacts in order to _____ and _____ them
eliminate; correct
-sound traveling in a straight line
-sound travels directly to a reflector and back
-sound travels in soft tissue at exactly 1540m/sec
-reflections arising only from structures positioned in the beams main axis
-imaging plane is very thin
-strength of a reflector is related to the characteristics of the tissue creating the reflection

the above are examples of what?
assumptions of the systems
The Six Assumptions of imaging system:
1. sound travels in a ________ line
2. sound travels directly to a ___________ and back
3. sound travels in soft tissue at exactly _________m/s
4. reflections only arise from structures positioned in the ____________
5. the imaging plane is __________
6. the strength of reflection is related to the characteristics of _____________
1. straight
2. reflector
3. 1540
4. beams main axis
5. very thin
6. tissue creating the reflection
actual anatomy always remains ____
visible
What are corrective actions?
-slightly change position of the angle of insonation
-change window
-gains
-change patient positioning
-instrument malfunction when artifacts remain
reverberations appear as __________ bouncing between two (2) strong reflectors
multiple, equally spaced echoes
ARTIFACTS: REVERBERATION is assumption #____
2
Reverberations appear _____ and ______
1. multiples
2. equally spaced
reverberations are located _____ to the sound beams main ______
1. parallel
2. axis
With reverberation, the first 2 reflectors are _____ and the remaining which are deeper are _____
1. real
2. not real
with reverberations, the first 2 reflections are closer/farther to the transducer
closer
a corrective measure for artifact reverberation is _____
change angle
reverberations resemble _____
A ladder or Venetian blind
Comet tail artifact is also known as ____
ring-down artifact
define comet tail artifact
solid hyperechoic line coming straight down
comet tail appears when the _______ surfaces are located in a medium with high propagation speeds, such as a mechanical ______
1. reflecting
2. heart valve
comet tail also arise from _______, or ______ of small structures such as gas bubbles after they are bombarded by sound pulse
1. resonance
2. vibrations
comet tail is located ________ to the sound beam's main axis
parallel
comet tail is assumption #____
2
what is a corrective measure for comet tail artifact?
changing the window
shadow artifact is assumption #___
6
Hypoechoic or anechoic region extending downward when attenuation is higher in the above tissue than the surrounding tissues is what type of artifact?
shadowing
shadowing has no _______ lines
hyperechoic
shadowing artifact is located _______ the structure
beneath
shadowing prevents ______ of true anatomy on the scan
visualization
Shadowing may provide valuable information that characterize _______ (gallstone shadows)
tissue
what is a corrective measure for shadowing?
1. leave it
2. TGCs
3. different angle
4. new window
is shadowing entirely related/unrelated to speed of sound in a medium?
unrelated
________ artifact is a special form of shadowing that appears as a hypoechoic region extending down from the edge of a curved reflector
edge shadow
with edge shadow, the beam ______ at the edge of a curved reflector
refracts
edge shadow extends ______ from the edge _______ to the sound beam
1. downward
2. parallel
with edge shadowing, the beam ______ resulting in a drop in intensity
diverges
edge shadowing prevents _________ of true anatomy
visualization
edge shadowing is also known as what?
shadowing by refraction
what is a corrective measure to edge shadowing artifacts?
TGCs, change angle, or new window
Enhancement artifact appears as what?
hyperechoic region beneath tissues with abnormally low attenuation
enhancement artifact is the opposite of _______ artifact
shadowing
enhancement artifacts are located _____ the structure
beneath
enhancement artifact can provide valuable diagnostic information that helps to _________ the tissue
characterize
enhancement is related/unrelated to speed of sound in the medium
unrelated
what are the corrective measures for enhancement artifact?
TGCs, change angle or leave it
focal enhancement artifact is assumption #____
6
what artifact is the following definition?

"side-by-side region of an image that appears brighter than the tissues at other depths
focal enhancement
with focal zone, the entire _____ region of tissue appears _______
1. horizontal
2. hyperechoic
with focal enhancement, when the beam is strongly focused the intensity in the focal zone is decreased/increased
increased
with focal enhancement artifact, reflections at the focal zone may be ________
abnormally strong
what are the corrective measures for focal enhancement artifacts?
turn down TGCs, change focal zone
mirror artifact is assumption #____ and ____
1 and 2
Mirror image artifact is created when the sound reflects of a strong/weak reflector (mirror) and is redirected toward a second structure
strong
what does the redirection of a reflector cause with mirror artifact?
replica or second copy
a mirror artifact is deeper/shallower than the true reflector
deeper
mirror artifact can concur in _____, _____ mode and ______
1. B mode
2. color mode
3. doppler
decrease the gain which will just decrease the strength of the returning echoes, decrease the power, change the angle of insonation

is the above a corrective measure for mirror artifact?
yes
crosstalk artifact is a _____ image artifact that appears on a ______ display
1. mirror
2. spectral doppler
the crosstalk identical doppler spectrum both above and below the baseline appearing ______ on the spectral display
bidirectional
crosstalk appears when doppler grain is too high/low or when flow is at the beam ______ near ___ degrees
1. high
2. focus
3. 90
decrease the gain which will just decrease the strength of the returning echoes, decrease the power, change the angle of insonation

is the above a corrective measure for crosstalk artifact?
yes
speed error artifact is assumption #___
3
Speed errors appears when the mediums speed is slower/faster than the speed in the soft tissue appears as a step off (go return time)
slower or faster (both)
if there is a longer time of flight there will be a _____ image
deeper
if there is a shorter time of flight there will be a ______ image
shallower
state the artifact:
information is placed from the sides of the beams into the main beam axis
side lobes and grating lobes
________ lobes is created by a single crystal transducer such as a mechanical probe
side
___________ lobes is created by array transducers
grating
harmonics gets rid of _____ level echoes
low
Grafting lobes can be reduced or cured by dividing each element into smaller, miniature pieces this is called __________________
subdicing
__________alters the electrical spike voltages and reduces lobe strength
apodization
what is the corrective measures for artifact lobes (side lobes/grafting lobes)
harmonics
artifact lobes (side lobes/grafting lobes) is assumption #____
4
identify the artifact:
a second copy of a true reflector incorrectly appears on the image the artifact is at the same depth as the true reflector or the copy is side by side
refraction
refraction artifact is assumption #_____
1
what is the corrective measure for artifact refraction?
change window or change angle of insonation
identify the artifact:

-low level echoes are integrated into the anechoic area of the image
- section thickness artifact or partial volume artifact
slice thickness (elevation)
slice thickness artifact can affect scan of cysts in what way?
fills in hollow structures
slice thickness (or slice elevation) is assumption #____
5
what is the corrective measure for slice thickness? (2)
-lower TGCs,
-harmonics
identify the artifact:

Occurs when a pair of side by side reflectors are closer than the width of the sound beam
lateral resolution artifact
lateral resolution artifact affects images how?
two images appear as one
where does lateral resolution artifact most likely occur?
where the beam is wide
what is the corrective measure for lateral resolution artifact?
change depth
identify the artifact:
a long pulse strikes two closely placed structures, where one is in front of the other, Only one reflection will appear if the structures are closer together than one-half the spatial pulse length
axial resolution artifact
An axial resolution artifact occurs when structures are ________ to the main axis
parallel
higher/lower frequency has better axial resolution
higher
identify the artifact:
when sound pulses glance off a second structure on the way to or from the primary reflector, combination of mirror and lobe
multipath
mutlipath is assumption #___
2
what is the corrective measure for multipath?
change angle
identify the artifact:
when a beam strikes a curved structure or oblique reflector
curved and oblique reflectors
what assumption is curved and oblique reflectors #___ & ____
1 & 2
how can you correct the artifact of curved and oblique reflectors?
change angle
identify the artifact:

With low line density image exhibits less detail and the spatial resolution is poor
spatial resolution artifact
identify the artifact:
Occurs when a reflecting structure is located deeper than the imaging depth of the image. (incorrect depth for image)
range ambiguity artifact
what is the corrective measure for a range ambiguity artifact?
increase PRP
identify the artifact:
occurs at the very top of the sector in the nearfield and does not depict the anatomy correctly
speckle
the routine evaluation performed periodically and routinely which is a medical and legal necessity for every laboratory is _______ _________
quality assurance
who is responsible for implementing a quality assurance action plane?
the sonographer
state the 3 quality assurance requirements
1. assessment of system components
2. preventive maintenance
3. record keeping
what 3 device enable the sonographer to perform quality assurance?
1. Tissue equivalent phantom
2. Doppler phantom
3. Beam profile/slice thickness phantom
state the 4 proper methods for quality assurance programs:
1. Test under known, defined conditions
2. Use constant instrument settings
3. Use a phantom with measurable characteristics
4. Image in an identical environment
for quality assurance purposes what is used to evaluate greyscale?
tissue equivalent phantoms
what phantoms are used for quality assurance testing purposes? (3)
1. tissue equivalent phantoms
2. doppler phantoms
3. slice thickness phantom
which phantom for quality assurance includes a circulation pump that propels fluid through vessels some contain vibrating string or moving belt instead of pump
doppler phantom
which quality assurance phantom checks elevational resolution
slice thickness phantom
the ability of a system to display low-level echoes is _____________
sensitivity
what are the 2 forms of sensitivity?
normal and maximum
maximum/normal sensitivity settings include all the pins, solid masses, and cystic structures in the test phantom are accurately displayed
normal
All quality assurance and performance measurements are made at the _______ sensitivity
normal
maximum sensitivity is evaluted with two settings
1. output power
2. amplification
what is measured on the display with maximum sensitivity ?
depth of tissue like texture
Maximum visualization _____ is used to assess sensitivity
depth
the region close to the transducer where images are inaccurate is known as ____________
dead zone
the dead zone extends from transducer to __________
shallowest depth
the dead zone results from transducer ringing and the time it takes the system to do what?
switch from the transmit to receive mode
Higher frequency transducer have a thinner/thicker dead zone than lower frequency transducers
thinner
state the four major principles of medial ethics
1. respect of autonomy
2. nonmaleficence
3. beneficence
4. justice
true or false:
Ordering or cancelling an exam is within the sonographers scope of practice
false
quality of being, worthy, honored, or esteemed includes patient's perception of being in control and having self worth is _______
patient dignity
Proper body mechanics to reduce the number of injuries is _________
erogonomics
the list below are examples of __________

-Wrist support braces
-Cable braces
-Ergonomic transducer design
-Chairs with adjustable armrests and footrests
-Control panel and monitor (swivel and extension)
adaptive ergonomic device
should the sonographer follow best practices?
yes, all the time
some examples of best practices a sonographer should follow are:
-positioning the systems monitor directly in front of you and at eye level
-limit the amount twisting and bending over
-proper sitting positions
-proper foot support

what other 2 best practices should the sonographer also follow?
1. arm close to body
2. staying close to the patient
laboratory policies and procedures:
routine lab operation should include _________ programs, proper use of _______ and ________ concern
1. educational
2. equipment
3. safety
laboratory policies and procedures: in order to reduce workplace injuries, effective _______________ is needed/recommended
patient scheduling
what should the sonographer incorporate in order to minimize strain, injury, and repetitive motion in the workplace?
non-scanning activities between studies
_________________ are a set of guidelines to minimize the exposure and risk of health care workers when in contact with a patient
standard precautions
all patients should be treated as _____________
potentially infectious
what preventative measures can health care workers take to prevent skin and mucus membrane exposure during contact with patients' blood or body fluids?
1. hand washing
2. barrier precautions
3. PPE
Standard Precautions apply to a broad range of substances. what are they? (6)
1. body fluids
2. secretions
3. excretions
4. mucus membranes
5. airborne particles
6. non-intact skin
Standard Precautions also applies to any items ___________ with body fluids, secretions, mucus membranes, etc.
soiled
What does OSHA stand for?
Occupational Safety and Health Administration
OSHA presents the following implementation of the universal precautions -- what are they?
1. gloves (at minimum)
2. protective clothing
3. eye protection must be worn at all times
OSHA requires Standard Operating Procedures (SOPs) for all activities that have the potential for exposure, plus a ________________ program, and _______________ procedures
1. worker educational
2. records documenting
several instruments measure the ____________ produced by transducers
sound energy
hydrophone (microprobe) is similar to a small __________ needle with a tiny piece of PZT crystal attached to its end
hypodermic
a wire connects the crystal to an ___________ in a hydrophone
oscilloscope
Since the hydrophone is small, the _______________ and _____________ is measured
1. acoustic pressure
2. voltage created by PZT
what uses a calibrated hydrophone?
intensities and other outputs
Three (3) devices measure the output of the ultrasound transducers by absorption, the conversion of sound energy into heat: what are they?
1. calorimeter
2. thermocouple
3. liquid crystal
a primary mandate regarding clinical ultrasound is that the benefits to the patient must outweigh the risks of the exam is known as what relationship?
risk-benefit
low density ultrasound has no known ________
bioeffects
the science of identifying and measuring the characteristics of the ultrasound beam that are relevant to its potential for producing biological effects is known as what?
dosimetry
research is performed within the living body of an animal or a plant - this is known as what?
in vivo
research is performed outside the living body and in an artificial environment - this is known as what?
in vitro
what two techniques are used to study bioeffects?
mechanistic approach and empirical approach
__________ has greatest effect on patient exposure
Exam duration
__________________ are used with pulsed Doppler
highest output intensities
______________ are with grey scale imaging
lowest output intensities
_________________ searches for a relationship between cause and effect
mechanistic approach
_________________searches for a relationship between exposure and response
empirical approach
what are the two (2) mechanisms of bioeffects?
thermal and cavitation
Related to the likelihood of harmful bioeffects from cavitation is.....?
mechanical index
bioeffects from tissue temperature elevation is....?
thermal index
the interaction of sound waves with microscopic, stabilized, gas bubbles in tissue is....?
cavitation
____________ is the interaction of sound waves with microscopic, stabilized, gas bubbles in tissue
TI
_____________ is an intensity related to the sound beams
SPTA
No confirmed bioeffects have been reported for temperature elevations of up to ____*C above normal for exposures <____ hours
1. 2
2. 50
__________________appear less tolerant of tissue heating than adult-fetal defects have resulted from temperature elevation -fetus keep temp <39°C
fetal and neonatal tissues
_____________ is the creation of gaseous nuclei from dissolved gases in a fluid
cavitation
cavitation is found in the _________ and are different than the gas bubbles introduced into the body as _____________
1. tissues
2. contrast agents
The only cavitation bioeffect identified at intensities typical of diagnostic ultrasound are in ________ with a well defined population of stabilized ______________ such as the lung
1. tissues
2. gas bodies
what are the two forms of cavitation?
stable and transient
__________ relates to pressure and frequency
MI
high MI has more __________, _________ and low __________
cavitation, pressure, frequency
in transient cavitation, High MI (Mechanical Index) levels create bubble-bursting or termed _________ or ____________
inertial or normal cavitation
The cavitation produces highly localized violent effects including what 2 things with transient cavitation?
shock waves and colossal temperatures
with transient cavitation, _________ effects are not considered clinically important since they are localized
destructive
1. Low MI levels creates bubbles that are a few millimeters in diameter which oscillate or expand and contract that do not burst

2. The fluids surrounding the cells undergo microstreaming and cells are exposed to sheer stresses

the above are examples of ___________ cavitation
stable
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