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29 Cards in this Set
- Front
- Back
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Pixel |
picture element |
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Pixel Size |
smaller pixel size means more pixels in a matrix, better detail |
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Matrix |
a series of rows and columns of numbers (pixels) that corresponds to the intensity of the xray beam that strikes a particular area |
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Voxel |
3D volume of tissue that corresponds to a pixel |
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Spatial resolution |
the ability of a system to accurately display objects in 2 dimensions |
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information consent |
megabytes/image or storage requirements |
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bit depth |
how many unique shades of gray are avaliable in an image's palette. We only see about 32 but digital imaging detectors are sensitive to about 1000. total # of shades avaliable = 2^b |
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Digitall imaging receptors: cassete based -referred to as |
computed radiography |
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psp plates stand for |
photostimulable phosphor imaging plate |
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layers of Photostimulable phosphor imaging plate |
-protective layer -phosphor layer -conductor layer -support layer -light shield layer -backing layer |
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protective layer |
protects from handling |
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phosphor layer |
holds phosphor |
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conductor layer |
grounds plate to avoid electrostatic problems and absorbs light to increase sharpness |
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support layer |
base on which layers are added |
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light shield layer |
prevents light from erasing data on the imaging plate |
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turbid phosphors |
random placement of phosphor crystals in the phosphor layer |
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structured phosphors |
phosphor layer with columnar phosphor crystals within the active layer |
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digital imaging receptors - non cassette based -different types |
PSP-photostimulable phosphor imaging plate flat panel image receptors Charged coupled device |
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PSP (photostimulable phosphor imaging plate) |
fixed in piece of equipment. Technologist never handles this kind of PSP |
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scintillator based flat panel image receptors |
uses amorphous silicon and a TFT array light, and then converts the xray beam to light, and then converts the light into electrons to create the image |
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non-scintillator based flat panel image receptors |
uses amorphous selenium and a TFT xrays are directly converted to electrons to create image |
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TFT stands for |
thin film transistors |
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Thin film transistors use __________________________ |
both scintillator and non scintillator based systems |
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define TFT |
a complex circuit device that collects electrons emitted from either amorphous selenium or amorphous silicon. Within that assembly are areas referred to as DELs |
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DELs -what do they do |
Detector elements collect electrons which represent the individual components within a digital image |
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Charge coupled device uses ________________ |
a scintillator |
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components of a charged coupled device |
scintillator mirror focusing lens integrated circuit device |
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Charge coupled device -process |
light form the scintillator material strikes the silicon in the Charged Coupled Device silicon chip. The electrons are then collected by the Charged coupled Device chip elements we refer to as pixels the electrons the the CCD captures are analyzed and assigned digital values based on how many electrons each pixel captures |
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advantages of digital |
-each pixel is a specific #, shade of gray, which directly correlate with the amount of xrays it receives -ability to used one exposure to create multiple images (bone vs soft tissue) -improved structure visualization due to increased contrast resolution
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