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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show | one
resembles a coin
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show | fan or sector-shaped
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How is the image shape created with mechanical transducers? | show 🗑
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show | It mechanically steered
the 2D image is built by rotating the crystal with a motor
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How is the beam focused with a mechanical transducer? | show 🗑
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show | the entire image is lost because it only has one crystal
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show | elements
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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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show | many (100-300) elements along the probe face side by side shaped rectangular and narrow; element's width is about 1/4 to 1/2 of the sounds wavelength
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What is the image shape of the (linear) phased array transducer? | show 🗑
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show | phased; electronically transmitted in different directions with no moving parts; "wiper blade" or "bicycle spokes"
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What always means adjustable or multi-focus? | show 🗑
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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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What happens with a linear phased array transducer if their is a damaged PZT? | show 🗑
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How many elements are excited to create sound beam in phased array? | show 🗑
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show | pattern of electrical signals
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show | draw a line connecting spikes; draw another line perpendicular to original line extending out of TD; the direction of this second line indicates sound beam direction
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show | sound beam directed downward
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show | sound beam directed upward
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What creates the sector shaped image in the linear phased array? | show 🗑
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In linear phased array, a straight electrical spike line is what kind of beam? | show 🗑
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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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With linear phased array, a more pronounced curve means what? | show 🗑
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show | multiple sound beams sent down each scan line; distinct pulses are transmitted with differing patterns; each electrical spike pattern will have different degree of curvature; least curve produces deepest focus
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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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show | multiple ring-shaped elements with common center similar to "bulls eye target"
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show | fan or sector-shaped
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How is the beam steered with annular array? | show 🗑
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show | multiple transmit focal zones; "multi-focus"
Smaller diameter ring-shallower focus, diverge rapidly; collects data from the shallowest depth; only information from the focal zone stored; this repeated for each ring; focusing on all planes at all depths;
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What happens with a damaged PZT with annular array? | show 🗑
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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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show | elements are rectangular; 120-250 elements; larger elements than linear phased array; size is about 1 wavelength
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show | some but not all crystals are fired simultaneously to create beam; beams are parallel to each other-directed straight ahead; first group of crystals fired, then another
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How is the beam focused with linear sequential array? | show 🗑
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show | rectangular image; image never wider than TD; can produce smaller width image; sound beams are emitted from small groups of crystals at different locations along face of TD
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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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What occurs with Phased Linear Sequential Array? | show 🗑
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show | convex, curved or curvilinear array; bowed, arched shaped; similar operational characteristics to linear array
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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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show | blunted sector shape with arc at top of image corresponds to directly curved array footprint
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show | dropout directly below element; portion affected from top to bottom; only scan lines from defective crystal are affected
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quietone055
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