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PACS chapter 3

Key terms

Aliasing loss of digital information because of fluctuating signal; also known as foldover, biasing, or wraparound
Archive query Software function that allows historical information to be gathered from digital storage, such as multiple examinations, a range of dates, or by pathology
Automatic rescaling Occurs when exposure is greater or less than the optimal amount to produce a diagnostic image; It is the effort of the computer to "fix" exposure errors
Contrast manipulation Conversions of the digital image using contrast enhancement parameters
Critical frequency The frequency of a signal that exactly matches the nyquist frequency, resulting in a zero-amplitude signal caused by phase shifts
Edge enhancement Enhancement occurs when fewer pixels in the neighborhood are included in the signal average; the smaller the neighborhood, the greater the enhancement
High-pass filtering Technique for the enhancement of contrast and edge that amplifies the frequencies of areas of interest that are known and suppresses frequencies outside the area of interest
Histogram Graphic representation of all of the digitally recorded signals of a digital X-ray exposure
Image annotation Software function that allows text or markers to be digitally added to an image
Image orientation identification of the top or side of an image
Image stitching Process of "sewing" together multiple images to form one continuous image
Look-up table reference histogram of the luminance values derived during image acquisition
Low-pass filtering result of averaging each pixels frequency with surrounding pixel values to remove high-frequency noise; the result is a reduction of noise and contrast; useful for viewing small structures such as fine bone
Manual send computer function that allows images to be sent to specified reading stations
Nyquist theorem When sampling a signal such as the conversion from an analog to a digital image, the sampling frequency must be greater than twice the bandwidth of the input signal so that the reconstruction of the original image will be nearly perfect
Patient demographics input information regarding patient age, identifying number, ordering physician, and so on
Shuttering used to blacken out the white collimation borders in a digital image, effectively eliminating veil glare
Smoothing also known as low-pass filtering, the result of averaging each pixel's frequency with surrounding pixel values to remove high-frequency noise
Spatial frequency resolution amount of detail or sharpness in a digital image
Window level Image manipulation parameter that changes screen image brightness, usually through the use of a mouse
Window width image manipulation parameter that changes screen image contrast, usually through the use of a mouse
Created by: 2304598396295915