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41 Cards in this Set
- Front
- Back
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T/F
APR & AEC depend upon each other to work. |
F
they work independently. however AEC can be pre-programmed into APR |
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if a digital image is grainy will it be over exposed or under exposed?
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under exposed. However,digital will try to compensate resulting in quantum mottle
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T/F
direct readout digital radiography is cassettless |
True
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__________ is the range of exposure intensities an image receptro can accurately detect.
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Dynamic range
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film screen receptors have _______ dynamic range (wide or narrow)
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narrow
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digital dynamic rage is ___________ (linear or sloped).
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linear
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T/F
film screen receptors accurately detech very low & very high intensities |
False-
DIGITAL receptors detect very high and very low intensities |
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List some similarities between film screen & digital systems:
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mA, time, kVp, accurate positioning, positioning, grids, collimators, IR
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list some differences between film screen & digital systems:
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~digital IR = wide dynamic range
~post processing (only associated w/ digital - i.e. subtraction, edge enhancement) ~digital images are composed of numerical data (easily manipulated by computer - brightness, contrast) |
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what creates the manifest image for film screens?
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black metallic silver
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what creates the manifest image for digital images?
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numerical values.
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numerical information divided into squares is called what?
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pixels
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a combination of rows and columns (pixels together) is called what?
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matirx
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what is the smallest component of a matrix
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pixel
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T/F
matrix size does not affect image quality |
F
increasing matrix size = increased spacial resolution |
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____________ is the smallest detail seen on an image
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spacial resolution
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fewer pixels does what to the resolution
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decreases spacial resolution
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the larger the matrix size the ______ the pixels; which increases quality and _________ spacial resolution
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increases; increases
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what are the 3 primary stages for digital imaging?
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1. image acquisition 2. image processing 3. image display
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the purpose of using AEC w/ film-screen imaging is to control
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density
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AEC devices work by measuring
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radiation that exits the patient
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how many detectors are typically found in an AEC system?
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3
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minimum response time refers to
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the shortest exposure time possible when an AEC device is used
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T/F
adjusting the density controls affects image density |
T
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T/F
phototimers measure radiation before it interacts with the image receptor |
F ~ however, ionization chamber systems measure radiation before it interacts w/ the image
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the purpose of the backup timer is ...
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to limit unnecessary xray exposure
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what happens if AEC is activated for a stretcher chest study?
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an inappropriate long exposure occurs
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the purpose of anatomical programming is to
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present the radiographer with a preselected set of exposure factors
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What is the limitation of conventional radiograph?
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poor soft tissue differentiation
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computed radiography has the advantage of...
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wide dynamic range
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what occurs when the exit radiation interacts with a photostimulable image plate?
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Energy absorption
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a geometric chracteristic of a computerized image is known as...
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spatial resolution
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image brightness on a display monitor is adjusted by?
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window level
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radiographic contrast on a display monitor is adjusted by?
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window width
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image noise can be decreased by...
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increasing xray dose
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increasing th window width of a digital image on a display monitor...
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decreases the contrast
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the smallest component of a matrix image that represents an xray intensity is called a(n)
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pixel
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the mathematical formula used to construct a gdital image is called a(n)
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algorithm
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digital radiography includes image acquisition methods that include:
~computed radiography; ~flat panel direct capture detectors, ~ charged-coupled devices or ~ what combination? |
all of them
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a disadvantage of flat panel direct capture detectors is
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difficulty in mobile imaging
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in order to change the visibilit of a digital image, lookup tables (LUT) alter the....
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pixel value
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