Ambient Lighting
The level of light in the room while viewing images
Automatic Rescaling
occurs during histogram analysis and is employed to maintain consistent image brightness despite overexposure or underexposure of the digital image receptor
Bit
0 or 1 that refers to the computer's basic unit of information
Bit Depth
Number of bits
Brightness
The amount of luminance (light emission) of a display monitor
Byte
8 bits combined
Contrast Resolution
The ability of the image receptor to distinguish between objects having similar subject contrast
Contrast-to-Noise Ratio
A method of describing the contrast resolution with the amount of noise apparent in a digital image
Detective Quantum Efficiency (DQE)
A measurement of the efficiency of an image receptor in converting the x-ray exposure it receives to a quality radiographic image
Deviation Index (DI)
A value that reflects the difference between the desired or target exposure to the image receptor and the actual exposure to the image receptor
Digital Imaging and Communications in Medicine (DICOM)
A communication standard for information sharing between PACS and imaging modalities
Dynamic Range
Refers to the range of exposure intensities an image receptor can accurately detect
Electronic Masking
Also known as shuttering. A post processing function that can remove regions of the digital image
Fill Factor
the percentage of the x-rays reaching the sensitive area of the detector element (DEL)
Flat-Panel Detectors (FPD)
Solid-state image receptors using a large-area active matrix array of electronic components ranging in size from 43 x 35 cm to 43 x 43 cm
Grayscale
the number of different shades of gray that can be stored and displayed by a computer system
Histogram Analysis
Graphic display of the distribution of pixel values. Each image has its own histogram, & it is evaluated to determine the adequacy of the image receptor exposure to x-rays
Imaging Plate
Located in the CR image receptor, where the photon intensities are absorbed by the phosphor.
Latent Image
The invisible image within the image receptor
Lookup Tables (LUT)
provides a method of altering the image to change the display of the digital image in a variety of ways
Matrix
A digital image is displayed as a combination of rows and columns (array) of small, usually square, "picture elements" called pixels.
Modulation Transfer Function (MTF)
a measure of the imaging systems ability to display contrast of anatomic objects varying in size
Photostimulable Luminescence
The emission of visible light from the photostimulable phosphor when stimulated by a high-intensity laser beam.
Photostimulable Phosphor (PSP)
The phosphor layer of the imaging plate (IP) composed of barium fluorohalide crystals doped with europium
Picture Archival and Communication System (PACS)
A computer system designed for digital imaging that can receive, store, distribute, and display digital images
Pixel Density
number of pixels per unit area
Pixel Pitch
the pixel spacing or distance measured from the center of a pixel to an adjacent pixel
Pixels
The smallest component of the matrix. Also known as picture elements
Sampling Frequency
how often the analog signal is reproduced in its discrete digitized form
Sampling Pitch
distance between the sampling points
Scintillator
A phosphor material that converts the exit radiation into visible light
Signal-to-Noise Ratio
A method of describing the strength of the radiation exposure compared with the amount of noise apparent in a digital image
Spatial Frequency
variation in anatomic details imaged as white to black brightness levels that can be defined by the unit of line pairs per millimeter
Window Level
Sets the midpoint (center) of the range of brightness visible in the digital image
Window Width
The range or number of shades of gray visible on the digital image