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17 Cards in this Set
- Front
- Back
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What is digital radiography?
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recording a map of x-ray transmission throught patient in a digital file
-file is viewed as a digital image -conventional x-ray machines are used it is not photopgraphing radiographs with a digital camera or running rads through a scanner |
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How is a digital image made?
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computer prepares a row by colume matrix of digital data file
-each row X column intersection is termed a pixel (picture element) -each pixel is assigned a color in a digital camera and a shade of grey in a radiograph rows X columns = matrix size more pixels/area = greater detail more pixels = bigger file size |
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What is a DICOM file?
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Digital Imagine COmmunications in Medicine
-need DICOM viewing software to view -very large files |
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What is digital radiography
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computer radiography - image plate in cassette like housing
direct digital radiography - flat panel detector |
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How does computer radiography work?
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x-ray -> patient -> detector -> reader -> digital signal -> computer DICOM file output
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How does direct digital radiography work?
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x-ray -> patient -> detector -> digital signal - > DICOM file output
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What are the components of computer radiography?
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-cassettes appeal similar to film-screen
-cassettes must be processed in plate reader; 90sec/plate -images better than film -most labor intensive digital system |
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What are the components direct digital radiography?
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-no cassette to process
-image available immediately -types --CCD (charged couple device) --Flat Panel -indirect digital detector -direct digital detector |
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What is the benefit of a CCD system?
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-image quality is a function of light collection, lens and number of pixels in camera chip
-light collection and lens is most crucial *hard to retrofit so usually have to purchase entire unit including x ray tube and table |
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What are the benefits of flat panel digital radiographs?
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-no cassettes, camera or lens
-immediately after exposure, image is viewable and ready to archive -excellent quality image -image plate is portable but subject to damage |
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What is the detail with digital imaging?
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detail as good with digital although it looks it at first glance
there are other advantages that offset the slight reduction in spatial resolution |
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What are the advantages of digital imaging if the detail isn't better?
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-no darkroom, film, envelopes
-no exposure latitiude -contrast optimization -post processing -consultation -professional image |
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What is exposure latitude?
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the extent to which a film, image or flat panel can be over or underexposed and still achieve an acceptable result
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What is contrast optimization?
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the range of light intensities a medium can capture
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T/F
Low exposure image is more grainy appearance or more noise on digital imaging? |
true
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What is the advantage of imaging post processing?
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ability to change image contrast and blackness after acquisition
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What are still problems of digital imaging like with traditional radiographs?
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positioning
motion radiation safety |
