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40 Cards in this Set
- Front
- Back
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The ability to display two or more closely spaced objects as separate images
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Spatial Resolution
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The size of the relevant image displayed on the cathode ray tube (CRT)
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FOV
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Through application of software programs, possible to assign pixels a different gray scale value
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Gray scale enchancement
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Mathematically measures image against original object: 0 represents no image, 1 represents perfect image
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Modulation transfer function
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Aberrant movements of electrons in electonic equipment seen as flashes of light (snow) that degrades the image
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Electronic noise
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Analog signal sampled twice per cycle by ADC to gain accurate digital signal
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Nyquist Criterion
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Displaying small differences in subject contrast
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Contrast resolution
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The number of shades of gray assigned to the pixles
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Dynamic range
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Determines the number of density values available in each pixle. If affects density (brightness) and contrast of system and is controlled by the ADC
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Pixle Depth
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Loss of image quality caused by random variations in the number of photons striking the IR
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Quantum Mottle
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The number of densities from black to white on the x axis, the number of each density on the y axis
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Histogram
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A pre-set "ideal histogram" for each projection
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Look up table (LUT)
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CR provides optimal brightness and enhanced contrast
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Normalization
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A high "S" number indicates a need to move the center point (Sm) over ____.
a. more b. less |
a. more
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"S" values greater than 400 indicates _______________.
a. Overexposure b. Underexposure c. Perfect exposure |
b. Underexposure
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"S" values greater than 400 will demonstrates _________.
a. Quantum Mottle b. Improved MTF c. Lose of contrast |
a. Quantum mottle
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Three different type of reference histogram models used for LUT's include one that must have a direct exposure "spike" to locate S2. This is a:
a. Type 1 b. Type 2 c. Type 3 |
a. Type 1
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Histogram shape is NOT influenced by...
a. Type of exam b. Patient positioning c. mAs d. Type of generator |
c. mAs
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Which of the following does NOT use thin film transistors (TFTs).
a. Indirect photostimuable phospher imaging plate system b. Direct selenium flat panel imaging plate system c. Indirect silicon flat panel imaging plate system |
a. Indirect photostimulable phospher imaging plate system
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CR or DR?
Uses cassettes- more familiarity for technologists More adaptability for positioning and technique |
Computed Radiography
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CR or DR?
Direct hookup to the computer- no cassettes Attached to a table/chest bucky, contains a grid, and AEC sensors Flexibility of positioning limited No ability to split fields for multiple views Increased patient throughput Higher detective quantum efficiency (DQE) |
Digital Radiography
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Does comptued or digital radiography use Indirect Photostimulable
Phosphor Imaging Plate Systems (Computed Radiography)? |
Comptued Radiography
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The_______ _____ ______ is
designed to look and act to perform many functions of standard cassette |
Computed Radiography
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The computed radiographic (CR) cassette....
a. Comes in many of the same sizes as standard film cassettes b. Can be used with tabletop or bucky c. Can be used with manual or AEC techniques d. All of the above |
d. All of the above
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Name some features of a CR cassette
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Aluminum or plastic
Low absorbing carbon front Back panel has lead foil- backscatter Has a memory chip in one corner to download information on the exam and patient Front and back lined with felt to reduce static electricity and cushion plate |
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PSP stands for...
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Photostimulable phosphor
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IP stands for...
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Imaging plate
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How thick is an CR plate?
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1mm in thickness
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Which layer in a CR plate is supported by a firm base and protected by a thin plastic layer?
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The active phosphor later
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Name the following Layers
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The ______ layer and/or __________ layer grounds static charge; reverses light emissions
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Refletive and or conductive layer
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What type of emulsion must be facing forward?
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Single emulsion
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What are some common phosphers?
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Europium activated barium fluorohalides
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What is the average energy (keV) of 80 KVP beam?
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35
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True or false: Digital screens will absorb more low energy scatter thus the plate is senesitive
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True
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Since Photostimulable phosphor (PSP) absorb more low energy radiation
than radiographic film they are more........ |
More sensitive to scatter both before and
after exposure than radiographic film. Thus, Masking is needed to achieve optimal images |
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In a Latent image, where are the electrons stored?
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Electron pattern is stored in active layer of
exposed IP |
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How is a latent image made?
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Energy transferred to photoelectrons
Several photoelectrons liberated Liberated electrons have extra energy Blue-violet light given off by fluorescence More electrons freed by photoelectrons |
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In a latent image Fluorohalides absorb beam through ____________ interactions
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Photoelectric
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In a Latent Image Production,
Some electrons get trapped in the fluorohalides to create holes at the Europium site, this is called...? |
Electron Holes
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