111- Digital Imaging Flashcards
Binary code uses what two symbols
0 & 1
How many bits make up a bite
8
What is a PSP made of
Barium fluorohalide with europium activators
What is the initial response with CR
Linear
When/how is the latent image made
After exposure, when electrons are trapped in a higher energy state in the phosphor
When/how is the manifest image made
When red laser scans plate, electrons give off blue light
When is a CR plate most sensitive to scatter
After exposure
What is the exposure data recognition
Useful Information used to create histogram
What are the useful values of a histogram
Minimum and maximum values
If a histogram can not detect collimated edges, what happens to the image
Too light or dark
CR reader process:
Cassette lowered into reader/laser beam scans cassette/blue light photons emitted/light photons picked up by photodiode/electrical signal is created/sent to ADC/digital data sent to computer
White and linear artifacts on images means:
A scratch was obtained in reader
Direct capture pathway
X-ray tube/beam/photoconductor (amorphous selenium)/ TFT/analog signal/ADC/digital signal
Indirect capture pathway
X-ray tube/beam/scintillator/light/CCD or CMOS (or photodiode;amorphous silicon and TFT) /analog signal/ADC/digital signal
What is the scintillator made of
Cesium iodide or gadolinium oxysulfide
When is a TFT used
In direct and indirect capture
What is the interphase message called between HIS and RIS
HL7
If you increase bit depth, what happens to resolution
Increases
Main controlling factor of resolution
Pixel size
Imaging system with best resolution (highest to lowest)
Film, CR(direct capture), DR
If you decrease pixel pitch, what happens to resolution
Increases
Is it more desirable to use a high or low kvp with DR
High
4 factors that control contrast
Kvp, WW, LUT, automatic rescaling
Insufficient light produced by the IP causes:
Graininess
An undesired effect with edge enhancement
Increase in noise
Undesired effect of low pass filtering
Loss of fine detail
What is masking
Suppressing pixel values
What does equalization do
Evens brightness
How to calculate size of pixels in a matrix
FOV / matrix
If the exposure is too high or too low, what can bring it back into diagnostic quality
Automatic rescaling
What does oversaturation look like on an image
Overall loss of contrast, very gray
What does MTF relate to
Speed class, fidelity, accuracy, absorption coefficient
What is the purpose of a reference histogram
To bring any exposure into the ideal brightness, density, and contrast levels
What causes a wraparound image
Aliasing, Moire effect
What is an exposure latitude
Multiple exposures on different patients that are all fit within diagnostic quality
What is quantization
Assigning of digital densities to each pixel
What layer of the IP is the “active layer”
Phosphor layer
What are the two types of phosphors
Turbid and needle
Does direct or indirect capture give the best spatial resolution
Direct
Does direct or indirect capture give the lowest patient dose
Indirect
What is the purpose of the DEL
Collect electrons and represent the exposure level, essentially pixels
What is DQE
Sensitivity and accuracy by which the IR converts incoming data to viewing device
What is the perfect DQE
100%
What happens to speed if you increase kvp
Increase
What type of detectors have the highest DQE
Amorphous selenium
What are the minimum values of the histogram
Whites
What are the maximum values of the histogram
Blacks
What are the two forms of histogram analysis
Priori and neural
Priori uses how many histograms
1
Neural uses how many histograms
Two or more
What determines the size of the pixels
The matrix
Spatial location domain is based on:
X and Y locations for each pixel
Spatial frequency domain is based on:
Number of cycles per unit length
What is the mathematical algorithm applied to change an image from spatial location domain to spatial frequency domain
Fourier transformation
If you increase window width, what happens to contrast
Decreases
If you increase window level, what happens to brightness
Gets darker
What is automatic shuttering
Blackening our the white collimation borders
High sampling frequency does what to detail and storage
Increase detail
Decrease storage
2.5 line pairs/mm sample at __pixels/mm
5
An S value of 200 indicates that the IP received about __mR
1
What refers to a gradual increase in patient exposure over time due to wide exposure latitude of digital processing
Dose creep
What does DAP mean, and what does it do
Dose area product, measures patient’s entrance skin dose
Where is the DAP located
Collimator box
What does the DAP not take into account
SID
What resolution monitors are used for CT
1K
What resolution monitors are used for general exams
2K 3K
What resolution monitors are used for mammography
5K
What is the purpose of DICOM
Standardized public format and protocol for communicating imaging files
What is a film digitizer
A device that converts an analog film image into a digital computer image
What is a hard copy of an image
Images produced on film using a laser printer
What is a soft copy image
Images viewed on a flat screen monitor
What is veiling glare
Light from inside the monitor that floods the retinas
What does the conductor layer of the IP do
Absorbs light to increase sharpness
What does the light shield layer of the IP do
Prevents light from erasing data
What does the backing layer of the IP do
Lined with lead to reduce backscatter
What is the factor that makes DR IR’s respond faster
Increases kvp
What imaging system has the best contrast resolution
DR
What is fast scan with digital imaging
Reading of the DEL’s
