Pixels
A larger bit depth results in (less, more, no effect on) shades of gray being available to display on a computer monitor.
more
Increasing the number of pixels (increases, decreases) the quality of the image.
increases
Refers to the range of exposures that should be used to produce a diagnostic image.
Exposure latitude
Immediately before leaving the CR reader unit, the IP is erased by using an intense ________ ________.
White light
The ________ array is divided into square detector elements (DELs).
TFT
If the FOV is increased for a fixed matrix size, then the pixel size is (increased, decreased, unaffected).
increased
Due to direct relationship!
An MTF that provides a maximum of difference in brightness levels is _____.
1.0
A method of describing the strength of the radiation exposure compared with the amount of noise apparent in the digital image
Signal-to-noise ratio (SNR)
CR IP’s should be processed within ____ hour(s) after exposure to prevent latent image deterioration.
1 hour
What material do direct conversion detectors use that indirect detector don’t?
Amorphous selenium
What is the relationship between matrix size and pixel size for a fixed FOV? (Direct, Inverse, Unrelated)
Inverse
A system that can digitize and display a greater number of shades of gray will have what affect on contrast resolution? (increase, decrease, no effect)
increase
This is used to absorb exit radiation and convert it into visible light
Scintillator
What two materials make up the CR phosphor layer?
Barium fluorohalide and europium
An indirect conversion detector uses a _________ to convert x-rays to light and then to electrical charges using a __________.
Scintillator; photodetector
Pixel bit depth is determined by __________.
ADC
What is the advantage of a higher system DQE?
Less x-ray exposure is required to produce a quality radiograph which lowers patient dose
The measurement of the efficiency of an IR in converting the x-ray exposure it receives to a quality radiographic image
Detective quantum efficiency (DQE)
With a fixed matrix CR reader system, changing to a larger IP, for the same FOV, will result in (smaller, larger, unchanged) pixels.
larger
What is the main difference between indirect and direct conversion detectors when it comes to image production?
Direct conversion converts the exit radiation straight to an electrical charge, skipping scintillation altogether.
What happens to pixel size if the matrix size is increased for a fixed FOV? (increased, decreased, unaffected)
decreased
Increasing the number of line pairs per millimeter resolved in the imaging system results in (increased, decreased) spatial resolution and (increased, decreased) spatial frequency.
increased, increased
The ability of the detector to accurately capture the variety of photon intensities in the remnant radiation
Dynamic range
List the sequence of events, from beginning to end, of what happens in the CR reader unit.
IP is removed from cassette,
IP is scanned by helium-neon laser,
stored higher-energy state of the electrons in the phosphor layer is released as visible light,
PMT converts the light energy to an electrical signal,
the signal is digitized by the ADC.
List the sequence of events for production of a DR image using direct conversion detectors.