kats final 14
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_____ System is Counting that starts with 0 to 1 and then counts over again
Binary Number System
In computer language, a single binary digit, 0 or 1, is called a___
emission of light in response to exposure to x-rays is called_____
emission of light during and after being exposed to x-raysaka, lag or after glow
What type of matieral should the front (or tube side) of the IR cassttee be made of?
The front of the cassttee should be made with material with a low atomic number such as plastic.Correct Answer: absorbs very little of the x-ray beam
Suspended with in the binder matierial of the SP scrren, what are the two main components of the CR phosphor layer?
barium fluorohalide with europium
How is the CR latent image formed?
by electrons being trapped in the phosphor layer
What does the DR detector array take the place of?
the Bucky tray
Define photostimulable luminescence. In CR, what causes it in the reader?
emission of light as a result of stimuation by a light sourcein CR, it is caused by the laser beam
In CR, when the ______________ are absorbed by the phosphor, the _____________ atoms become ionized.
In CR, what is the relationship between the trapped electrons and tissue absorption (differential absorption)?
trapped electrons are produced in proportion to the tissue's absorption. Direct relationshipproportional relationship
Define pixel pitch.
distance between two adjacent pixels
What would happen to the pixels and spatial resolution if the fixed matrix was spread out over a larger image plate (the field of view would stay the same)?
the pixels would become larger and decrease spatial resolution
Define pixel depth
ablility to display a range of shades of gray
In indirect conversion, what is the purpose of the scintillator?
to convert x-rays to light
Which is preferred high or low SNR?
High SNR is preferred because it means more photons have hit the IP then were lost
If quantum noise has increased, what has happened to the overall brightness of the digital image?
it has also increases due to loss of signal or fewer photons exposing the IR
What will cause distortion in an digital image?
the same causes as film/screen - OID/SID, alignment, magnification, foreshortening
What would be some ways to increase the signal to noise in an digital image?
simialr to film/screen, increasing mAs and kVp will result in more x-ray photons reaching the IR. Also, a thinner patient
Explain direct conversion in digital imaging in 4 basic steps.
- 1. exit radition is converted to an electrical charge which is briefly stored in the TFT arrary
- 2. electrial signal goes to the ADC to be digitized
- 3. the digital information is used to form the image matrix
- 4. the image is displayed on the monitor
Explain the relationship between pixel bit depth and shades of gray to be used.
the greater the pixel bit depth, the more shades of gray that can be found in a pixel
After secondary excititation in the reader, the photomultipler tube creates an electrical signal that is proportional to what?
to the light incident on the photocathode
During stimulation of the latent image, as the laser beam penetrates into the PSP, what also happend to the lazer beam? And what will cause this to increase?
it will increase as PSP thickness increases
According to the article, what design component of the CR reader/scanner allows for only the emitted light from the stimulation of the SPS to enter the photodetector?
the optical filter
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