chap 20 physics 2
Terms
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copy deck
- (assumption 6), the intensity of a reflection is related to the characteristics of the tissue, is invalid that causes_____?
- enhancement artifact
- the opposite of the shallowing___?
- enhancement artifact
- enhancement artifact in clinic provides____?
- diagnostic information
- enhancement is unrelated to__?
- the speed of sound travel in a medium
- characteristics of enhancement artifact?
-
1. hyperechoic (appears the same as the foreground color)
2. too little attenuation
3. abnormally low attention - focal enhancement artifact____?
- side-to-side image that appear brighter than tissue at other depth
- focal enhancement artifact also called___?
- focal banding
- the most prominent at the focus is at____?
- banding
- characteristics of focal enhancement?
-
1. a hyperechoic side-to-side region(the same foreground color)
2. the result of increase intensity at the focus - sound reflect off of a strong reflector, and is redirected toward a second structure causes_____?
- mirror image artifact
- (assumption 1), sound travels in a straight line, and (assumption 2) sound travels directly to a reflector and back to the transducer, are invalid that cause______?
- mirror image artifact
- ____is placed deeper that the real structure?
- mirror artifact
- _____always located along a straight line between the transducer and the artifact?
- the mirror
- mirror image artifact appear____?
- in color Doppler
- characteristics of mirror image?
-
1. a second copy of a true reflector
2. the copy appear deeper than the true reflector
3. bright reflector the mirror lies on a straightline between artifact and transducer - mirror image artifact that appear on a spectral Doppler display is called____?
- crosstalk artifact
- if sound wave propagates with a speed higher than the speed of soft tissue (1.54km/s), then create____?
- speed error artifact
- speed errors appear as____?
- step-off, structure are split or cut
- if medium's speed is faster than speed in soft tissue, then____?
-
1. sound travels faster than ultrasound system
2. pulses return fast
3. go return time is too short
4. reflector is close to transducer
5. reflector is shallow on image
6. distance underestimated (too small) - if medium's speed is slower than speed in soft tissue, then_____?
-
1. sound travel slower than ultrasound system
2. pulse return slow
3. go-return time too long
4. reflector far from transducer
5. reflector too deep
6. distance overestimated - propagation speed errors also called____?
- range error artifact or range ambiguity artifact
- (assumption 3), sound travels at a speed of exactly 1,540m/s, is invalid that cause____?
- speed error artifact
- characteristics of speed error?
-
1. correct number or reflector
2. improper depth
3. appear as a step off - sound is transmitted in a direction other than along the beam's main axis, cause___?
- lobe artifacts
- lobe artifact degrade____?
- lateral resolution
- lopes are____than the primary beam and do not create____?
- weaker...reflection
- if strong reflector in the path of the lobe, then creating____?
- reflection
- (assumption 2), reflections arise from structures located along the beam's main axis, is invalid, then creates____?
- lobes artifacts
- characteristics of lobe artifact?
-
1. a second copy of the true reflector
2. the artifact and the true reflector are side by side at the same depth - lobes created by a single crystal transducer (a mechanical probe) are called___?
- side lobes
- lobes created by array transducers are called___?
- grating lobes
- dividing each PZT element into small piece called subdicing that reduces____?
- grating lobes
- apodization reduces____?
- grating lobes
- if a sound pulse changes direction during transmission, then creates___?
- refraction artifact
- a sound wave strike a boundary obliquely and with different propagation speed, it occurs___?
- refraction
- _____degrades lateral resolution?
- refraction artifact
- (assumption 1), sound travels in a straight line , is invalid that causes___?
- refraction artifact
- characteristics of refraction artifact?
-
1. a second copy of the reflector
2. the copy is side by side or the same depth - the image is neither___nor____?
- thin...uniform thickness
- _____is the dimension of the beam perpendicular to the imaging plane?
- slide thickness artifact
- ____determined by the thickness of the imaging plane?
- elevational resolution
- (assumption 5), the imaging plane is extremely thin, is invalid that cause
- slice thickness artifact
- _____lies outside of the imaging plane?
- the true reflector
- ______fills in hollow structure such as cysts?
- slice thickness
- if the beam dimension is greater than the reflector size, then appear____?
- slice thickness artifact
- ____reduced with thinner imaging planes by 1 and half dimensional array transducer?
- slice thickness artifact
- if beam is wider than the distance between two reflectors that located side by side or perpendicular to the beam, then cause_____?
- lateral resolution artifact
- lateral resolution artifact display a small____?
- reflector as a wide rather than a narrow dot
- lateral resolution artifact is least at____?
- the focus
- if a long pulse strike two closely spaced structure, then causes___?
- axial resolution artifact
- _____creates one reflection on the image from 2 closely spaced reflectors?
- axial resolution artifact
- if sound pulses glance off a second structure on the way to or from the primary reflector, then cause___?
- multipath artifact
- the transmit path length____from the return path length
- differ
- (assumption 2), a pulse travels directly to a structure and then back to the transducer, is invalid that causes___?
- multipath artifact
- if sound beam strikes_____, some of reflected sound directed away from transducer
- a curved or oblique reflector
- the ability to precisely position a moving structure is called____?
- temporal resolution
- temporal resolution determined by___?
- frame rate, best with high frame rate
- _____related to the overall detail in an image?
- spatial resolution artifact
- spatial resolution artifact determined by____?
- sound beam's spacing or line density
- Analog display (TV), spatial resolution is determined by____?
- TV scan lines per frame
- in the digital, spatial resolution is related to____?
- pixel density
- high pixel density creates___?
- good spatial resolution
- low pixel density creates___?
- bad spatial resolution
- ____appears as small amplitude echoes and result from electrical interference, signal process?
- noise
- ____,a form of noise, arises from small amplitude sound waves interfering with each other?
- speckle
- _____high tech solution for reducing an image's noise?
- harmonic imaging