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28 Cards in this Set
- Front
- Back
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Using the central region of the retina where cones are concentrated; bright light, or day vision
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photopic vision
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Electronic feedback mechanism that maintains constant brightness of the fluoroscopic image
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automatic brightness control
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Ability to distinguish very small objects and perceive fine detail
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Visual acuity
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the multiplication of light photons at the output phosphor compared with x-rays at the input phosphor, and the image minification gain is the ratio of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor.
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Flux Gain
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Minification gain × Flux gain. =
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Brightness Gain
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A type of television camera tube used in many fluoroscopic imaging systems
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Vidicon
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Imaging body vasculature radiographically by injecting a contrast medium into the vessel and making a series of radiographs
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Angiography
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The emission of electrons after light stimulation
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photoemission
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Protective barrier to intercept radiation scattered below the fluoroscopic tabletop
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bucky slot cover
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3.
What is the difference between Rod and Cone vision? With which is visual acuity greater? |
The rods are located on the periphery of the retina, and are the sensory cells responsible for scotopic or low-light vision. CONES are the sensory cells located centrally on the retina, and are responsible for photopic or bright-light vision and increased visual acuity.
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Does spatial resolution change when one is viewing in the magnification mode versus the normal mode?
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Yes, spatial resolution is improved in the magnification mode
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What is vignetting ?
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Reduced image intensity at the PERIPHERY of the field of view of an image intensifier tube
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What is the primary function of the fluoroscope ?
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To provide real-time dynamic images
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Who invented the fluoroscope in 1896 ? What phosphor was used on that original fluoroscopic screen?
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Thomas Edison. Zinc cadmium sulfide.
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What determines the image frame rate in video fluoroscopy ?
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Because we operate on 60 Hz electric power in the United States, each cycle is 33 ms, which results in
30 frames per second , the maximum frame rate available. |
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What limits the vertical resolution and horizontal resolution of a video monitor ?
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Vertical resolution is limited by the number of lines,
Horizontal is limited by bandwidth |
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What is the principal difference between a standard video system for fluoroscopy and a high resolution system ?
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More video lines and higher frequency bandpass
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What is the milliamperage (mA) used during conventional image intensified fluoroscopy?
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greater than or equal to 5mA
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The output phosphor of the image intensifier is composed of..
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zinc cadmium sulfide
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The input phosphor converts ____ to ____.
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x-rays, light
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The number of light photons emitted within the image intesifier is ____ ____ to the amount of x-ray photons exiting the patient.
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directly proportional
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The ratio of x-rays incident on the input phosphor to light photons exiting the output phosphor is called ____ gain.
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flux
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An image intensifier is identified by the diameter of its..
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input phosphor
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Brightness gain of most image intensifiers is ____ to _____, and it decreases with tube age and use.
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5000 to 30,000
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Fluoroscopy for an air-contrast barium enema is generally done at ____ kVp.
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80 - 90
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Automatic brightness control maintains the brightness of the image by varying..
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kVp & mA
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The SOD in fluoroscopy should not be less than ____ for mobile units.
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12 inches
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The CCD is mounted on the ____ phosphor of the image intensifier tube and is coupled by ____ ____ or a lens system.
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output, fiber optics
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