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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To hide a column, click on the column name.
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You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
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