5 Medical Imaging Informatics Flashcards
represented by physical quanity whose allowed values are continuous
Analog form of data
number or other unit of infor such as letter of alphabet is represented by a sequence of digits, each of which is limited to a defined number of values
Digital form of data
- rectangular sometimes square array of picture elements
- its size must be half or less than the size of he smallest object to be seen
pixel
- largest number that can be stored in a single pixel is determined by ______
- 1 byte (8 bits)
- 2 bytes (16 bits)
- the no of bits or bytes used for each pixel
- 255 maximum number
- 65,535 maximum number
- reads or writes data in any order
- accesses data in a searial manner only
- random access (solid state memories, magnetic diskc, optical disks
- sequential access (magnetic tape)
Photometric quantity descibing thee brightness of a monitor.
rate of light nergy mitted or reflected from a surface per unit area, per unit solid anlee, correected for he photopic spectral sensitivity of the human eye
candela per square meter (cd/m2)
Luminance
ACR Technical Standar for Electronic Practice of Medical Imaging Maximal luminance for workstation: for mammography for optimal contrast
- at least 171 cd/m2
- at least 250 cd/m2
- at least 450 cd/m2
Gray scale LCD monitors provide about ===== times larger maximal luminances than color LCD
3X
BECAUSE RED, GREEN AND BLUE FILTERS IN COLOR lcdS ABSORB LIGHT OT CREATE COLOR IMAGES
minimal luminance of a monitor, measured in total darkness, entire screen black
black level
maximal luminance divided by the black level
contrast ratio
stray light from the face of the monitor that occurs when an image is displayed
veiling glare
Typical Radio Image formats PET Digital Fluoroscopy Xray CT MRI Utz
pixel format bits per pixel
- 128 to 336 16
- 512 or 1024 8 to 12
- 512 12
- 64 to 1024 12
- 512 8
luminance produced as a function of the magnitude of the digital or analog signal sent to the monitor
Display Function
dicom
gsdf
Digital Imaging and Comunications in Medicine
Grayscale Standard Display Function
Goals of DICOM GSDF
Which on is not achieved
- Provide applications with a predictable transformation of digital pixel values
(called “presentation values,” abbreviated as “P-values”) to luminance - similar display of contrast on display monitors and
printed media - provide perceptual linearization, that is, equal differences in the
pixel values received by the display system should be perceived as equal by the
human visual system (NOT ACHIEVED)