Digital Rad
Year digital radiography first began in clinical settings
1980s
How small of an object can a digital system resolve that has a spatial resolution of 5 lp/mm
0.1 mm
Solved: a spatial resolution of 5 lp/mm resolves 10 objects per mm, each object being 1/10 mm or 0.1 mm
gray scale and matrix
lumen per square meter and lux
basic units for level of illumination
True or False: Digital mammography has the largest image files compared to NMT, computed tomography, digital or computed radiography
True
Relationship between spatial frequency and object size and spatial resolution
As frequency increases:
object size decreases
spatial resolution increases
Ratio used to determine spatial resolution
FOV to matrix size
The use of two screen in imaging results in ________
MTF
PACS replaces what?
film storage
A software correction done in preprocessing that equalizes the response of each pixel to a uniform exposure
flatfielding
Three classifications of digital imaging artifacts
image receptor
software
object
what is ergonomics
match workers to work environment to maximum efficiency
Two principle characteristics of a medical image
contrast resolution and spatial resolution
Spatial resolution is also called ______________
image detail
Material used in almost all medical flat panel digital display devices
monochrome liquid crystal displays
Flatfielding is done during ____________
Partitioning is done during ____________
Lossless compression is done during ____________
Flatfielding is done during preprocessing
Partitioning is done during imaging
Lossless compression is done during post-processing
True or False: A digital display with higher megapixels has worse resolution
False
the image brightness of digital
In digital radiography where is the latent image formed
radiation detector
Dynamic range of 1000
screen-film radiography
Preprocessing the digital image is done __________ and post-processing is done __________
automatically; manually
When is a histogram selected and by whom
before each exam by the technologist
Why are collimated margins on fours side of a DR image important
to prevent errors in the histogram analysis
limitation of spatial resolution in digital imaging
size of pixel
The type of IR used when computed radiography was developed in the 1970s
phophor
line pairs is defined as:
a unit to describe spatial frequency or resolution
Image receptor with a high DQE will result in __________ patient dose
lower (inversely proportional)
Average size of DR and CR image files
200 MB
Most recent development in digital radiography image receptors
direct capture solid state devices
test tool for MTF
bar test pattern
definition of dynamic range
number of gray shades that an imaging system can reproduce
type of digital imaging that uses the highest dynamic range
mammography
reading area ambient light levels requirement
near darkness
daylight vision
photopic vision
parts of the retina that detect light
cones and rods
relationship of SNR and mAs
direct: as mAs is increased, SNR increases