Ch. 22 Physics Flashcards
Routine, periodic evaluation of an ultrasound system to gaurantee optimal image quality
quality assurance
Who is responsible for implementing a QA action plan
sonographer
What are the 4 requirements for a QA program
assessment of system components, repairs, preventative maintenance, record keeping
What are the Goals of a QA program
guarantee proper operation of the system, detect gradual changes, minimize downtime, reduce number of non-diagnostic exams, reduce number of repeat exams
What are the QA devices
tissue equivalent phantom, doppler phantom, slice thickness phantom (beam profile)
Phantoms are an ______ standard
objective
completely unbiased, not affected by individuals preference, factual, repeatable, able to be counted
objective
Influenced by someone’s opinion or beliefs, results vary
subjective
Have ultrasonic features similar to soft tissue, used to evaluate characteristicsof gray scale, texture, multifocus
tissue equivalent phantom
With tissue equivalent phantom, _____ is evaluated with this phantom since it contains small scatters that act like _______
gray scale, soft tissue
Evaluating ALL doppler components such as color, cw, pw, power
doppler phantom
What are the 3 doppler phantoms
vibrating strings, moving belt, flow phantom
Assesses the slice thickness and its effect upon image accuracy
slice thickness phantom
Slice thickness determines
elevational resolution
Slice thickness is most likely to _____ image quality because the imaging plane is _____ than either the beam width or pulse length
degrade, thicker
Slice thickness measures the beam geometry _____ to the imaging plane
perpendicular
Thicker slices _____ spatial resolutions and ____ the ability to visualize small, low contrast reflectors
diminish, reduce
When beam is too thick, cystic structures
may appear filled in
Refers to the ability of a system to display LOW LEVEL ECHOES
sensitivity
Sensitivity evaluated in what two forms
normal, maximum
Region close to the transducer where images are inaccurate
dead zone
Dead zone extends from the transducer to the _______ from which meaningful reflections appear
shallowest depth
With dead zones, what can help allow accurate imaging of important superficial structures
acoustic standoff/gel pad
Ability of the system to place reflections in proper positions while imaging from different orientations
registration accuracy
Another name for Range accuracy
vertical depth
Describes the systems accuracy in placing reflectors at correct depths located PARALLEL to the sound beam
calibration
Describes the systems ability to place echoes in their correct position when the reflectors are PERPENDICULAR to the sound beam
horizontal calibration
Smallest distance at which two SIDE BY SIDE pins are displayed as two distinct images (perpendicular to the sound beam)
lateral resolution
Smallest distance at which two pins positioned PARALLEL to the sound beam are displayed as two distant echoes
axial resolution
Describes the systems ability to display similar reflectors in the phantom with echoes of equal brightness
uniformity
