Ch. 9 Image Quality and Characteristics Flashcards
any unwanted image on a radiographic image
artifact
number of bits that determines the amount of precision in digitizing the analog signal, and therefore the number of shades of gray that can be displayed in the image
bit depth
the amount of luminance (light emission) of a display monitor
brightness
differences in the brightness levels to differentiate among the anatomic tissues
contrast
used to describe the ability of the imaging system to distinguish between small objects that attenuate the x-ray beam similarly in digital imaging
contrast resolution
a method of describing the contrast resolution compared with the amount of noise apparent in a digital image
contrast-to-noise ratio
a measurement of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image
detective quantum efficiency (DQE)
results from the radiographic misrepresentation of either the size (magnification) or shape of the anatomic part
distortion
the range of exposure intensities that an image receptor can respond to and acquire image data
dynamic range
refers to image of objects that appear longer than the true objects
elongation
provides a numeric value indicating the level of radiation exposure to the digital image receptor
exposure indicator
the dimensions of an anatomic area displayed on the monitor
field of view
refers to images that appear shorter than the true objects
foreshortening
the number of different shades of gray that can be stored and displayed by a computer system in digital imaging
grayscale
tissues that attenuate the x-ray beam very differently
high subject contrast
tissues that attenuate the x-ray beam similarly
low subject contrast
an increase in the image size of an object compared with its true, or actual, sizes; also known as size distortion
magnification
combination of rows and columns (array) of pixels that make up a digital image
matrix
a measure of the ability of the system to reserve signal contrast (display the contrast of anatomic objects varying in size), and the value will be between 0 (no difference in brightness levels) and 1.0 (maximum difference in brightness levels)
modulation transfer function (MTF)