5 parts of image intensifier

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chapter 15 fluoro

Question	Answer
mA for fluoroscopy	0.5-5 mA
length and diameter of image intensifier tube	50cm long, 15-58cm diameter
5 parts of image intensifier	1. input phosphor 2. photocathode 3. focusing lenses 4. accelerating anode 5. output phosphor
material of input phosphor	cesium iodide
material of output phosphor	silver-activated zinc cadmium sulfide
brightness gain	expression of ability of image intensifier tube to increase image brightness
flux gain	ratio of number of light photons at output phosphor to number of light photons emitted in input phosphor + represents tube's conversion efficiency
conversion factor	expression of luminance at output phosphor divided by input exposure rate
Automatic Brightness Control (ABC)	function of fluoro unit adjusting kVp, mA, or both
magnification mode	increases voltage to electrostatic focusing lenses
in magnification mode, the focal point is shifted _______ from output phosphor	farther
trifocus image intensifier ________________ can be operated in any of these 3 modes	30/23/15
distortion:	misrepresentation of true size or shape of object
2 types of distortion from fluoro:	unequal magnification (pincushion) and loss of brightness around periphery (vignetting)
image noise:	results when insufficient info is present to create image (not enough xrays expose input phosphor)
image noise is fixed by ______ __	increasing mA
2 tv cameras:	camera tube and Charge-Coupled Device (CCD)
image intensifier can resolve ______lp/mm	5
monitor can resolve ___to___lp/mm	1 to 2
cassette spot filming	static imaging process using radiographic cassette to obtain an image
Flat-Panel Detectors are used in ________ fluoroscopy	digital
Flat-panel detectors:	cesium iodide amorphous silicon indirect capture detector
Application-Specific Integrated Circuits (ASIC):	minimize noise, maximize readout speed, allow switching from low to high dose
Backlighting:	erase detector between frames, preventing ghosting
advantages of flat panel detectors in place of image intensifiers:	reduce bulk+weight don't degrade w/age more durable less artifacts reduce dose 50% better contrast resolution postprocessing options
fluoro features:	Last Image Hold (LIH) for virtual collimation frame averaging, reducing pt dose option to include grid selection of added filtration
frame averaging __________spatial resolution	decreases

Created by: JuliaW2003

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