Chapter 12: Two Dimensional Imaging
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
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| What two characteristics of sound must be overcome to create high quality 2D images? | show 🗑
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| show | Multiple pulses
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| What is a single, circular, disc-shaped element that is physically moved to create scan planes? | show 🗑
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| How many active elements does mechanical transducers have and what does it resemble? | show 🗑
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| show | fan or sector-shaped
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| show | Pulses radiate out like bicycle spokes from PZT;
"Wiper blade on windshield"
Crystal rotates around a single point
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| How is the beam steered with a mechanical transducer? | show 🗑
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| show | Has fixed focal depth
Conventional, mechanical or fixed focusing with internal or external
Occurs in horizontal and vertical plane-hourglass beam shape
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| With a mechanical transducer, what happens if the PZT crystal is damaged? | show 🗑
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| With modern TDs what is the single slab of PZT cut into separate pieces called? | show 🗑
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| show | channel
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| What are some different types of array transducers? | show 🗑
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| show | Phased array
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| what is it called when a beam is focused or steered electronically? | show 🗑
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| What are some characteristics of a linear phased array transducer? | show 🗑
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| Describe the active elements in (linear) phased array TD. | show 🗑
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| show | fan or sector-shaped
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| How is the beam steered with a linear phased array? | show 🗑
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| show | Phased array
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| show | electronically; control can be adjusted by the sonographer (depth and amount); multi-focusing
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| What is multi-focusing? | show 🗑
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| show | inconsistent/erratic beam steering and focusing; effect of damage is not precise due to complex sound pulse interactions from the many elements
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| How many elements are excited to create sound beam in phased array? | show 🗑
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| What determines the beam's direction and focus in the linear phased array? | show 🗑
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| How is the beam direction determined with linear phased array? | show 🗑
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| show | sound beam directed downward
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| show | sound beam directed upward
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| show | variations in slope
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| show | unfocused sound beam
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| show | the beam is steered
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| With linear phased array, when the electrical pattern is curved, the beam is what? | show 🗑
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| show | a shallower focus
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| How is multi-focusing done with phased array? | show 🗑
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| show | Dynamic Receive Focusing
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| show | elements are disc-shaped concentric rings cut from the same circular slab of PZT
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| How are the active elements arranged in a annular array? | show 🗑
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| show | fan or sector-shaped
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| show | mechanical steering;
physically rotates the ringed-element to transmit sound in different directions
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| How is the annular array focused? | show 🗑
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| show | horizontan band dropout; only portion of image lost side to side; If innermost ring lost-lose superficial data; if outer ring lost-lose deeper data
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| show | Linear Switched Array
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| show | elements arranged in a line with a larger acoustic footprint
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| How are the elements arranged in a linear sequential array? | show 🗑
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| How is the beam steered with Linear Switched Array? | show 🗑
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| How is the beam focused with linear sequential array? | show 🗑
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| What is the image shape of a linear sequential array? | show 🗑
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| What happens with linear sequential array if there is a damaged PZT? | show 🗑
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| show | to overcome divergence and produce well-defined beam
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| show | beam is electronically steered creating a parallelogram shaped image that is steered by slope delay in electrical excitation of elements; steered left or right; Grayscale anatomic image no slope, rectangular straight down; Doppler portion have slope
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| What are Curved Array Transducers? | show 🗑
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| show | rectangular shaped strips of PZT arranged side by side in bowed line; 120-250 elements; large footprint array; elements about 1 wavelength in width
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| show | some but not all crystals fired at once to create sound beam; beam directed straight out of crystal; travel in different directions due to arc shape; sound beams are not parallel to each other
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| How is the beam focused with curved array? | show 🗑
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| What is the image shape of a curved array? | show 🗑
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| What happens in a curved array whenthere is a damaged PZT? | show 🗑
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Created by:
quietone055
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