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34 Cards in this Set
- Front
- Back
tesla =
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10,000 gaus
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precision
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wobble
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larmor frecuency
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all protons in the nucleus will rotate with the same frequency
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gyromatic ratio
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a moment of inertia of a spinning nuclei in a magnetic field
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type of coils to control pulsing
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gradient
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coils close to the body part
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surface or radiofrecuency coils
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coils in the wall that evens out the magnetic field
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shim
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heavy magnet, .3 T
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permanent
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magnet that produces lots of heat due to lots of resistance. .02-.4 T
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resistive
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uses liquid cryogen in thermos like container (dewar)
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superconductive
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layering of cryogens is
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ramping
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when boiling point is reached and safety valves release the gas
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quenching
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stainless steel staples or surgical implants gt hot
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tourqing
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scans head only
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first generation
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first to scan whole body
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second generation
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rotates 360 degrees within gantry. 4 scans per minute.
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third generation
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15 scans per minute. scans both clockwise and counterclockwise
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fourth generation
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dedicated to cardiac imaging. also referred to as electron beam tomography
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fifth generation
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helical/spiral. uses slip ring technology to allow continuous rotation around gantry. entire abdomen scanned in 30-40 seconds
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sixth generation
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MSCT. entire chest or abdomen scanned in 15-20 seconds.
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seventh generation
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software allowing data to be changed from transverse to coronal. also used for targeting.
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reformation
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where the beam is collimated in CT
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at the tube and detector
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type of detector used in most modern day CT scanners
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solid state
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3 attributes to detectors
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high stability, fast response time, wide dynamic range
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motion artifact
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result of scan time
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when 2 adjacent object have more than 60% difference in attenuation coefficients is also known as
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star/interface artifacts
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looks like quantum mottle
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too much noise not enough data
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section interval
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difference between scan sections
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problem with biplane vascular imaging
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increased scatter radiation. eliminated by alternating the exposures.
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vascular generators operate at
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higher mA and low kVp
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pulsing of the beam in a grid controlled tube is done using
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third electrode located inside the tube that briefly turns the focusing cup positive.
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visualization is of a contrast filled vessel is better with
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low kVp
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98.6 degrees farenheight is = to _____ degrees celsius
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37
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biplane imaging refers to
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2 c arms 90 degrees from one another
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