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WorksheetsChapter 5 Radiographic Image Production – Key Terms
Total questions: 15
Worksheet time: 8mins
Which device forms large-area pixel arrays that read X-ray absorption signals in digital radiography?
Active matrix flat panel imagers
Hydrogenated amorphous silicon
Thin-film transistor arrays
Field effect transistor grids
At the pixel level, which component acts as a switch to control signal readout?
Scintillator crystal
Gadolinium oxysulfide
Photoconductor layer
Thin-film transistor
In direct conversion, how are X-rays transformed by the detector?
Converted to heat then current
Stored as latent image signal
Converted first to visible light
Converted directly to electrical charge
In indirect conversion, how are X-rays transformed by the detector?
Converted to light then electrical charge
Converted directly to electrical charge
Converted to mechanical vibration
Converted to secondary radiation
Which material converts X-rays directly into electrical charge within the detector?
Gd2O2S powder
a-Si:H photodiode
Scintillator
Photoconductor
Which material converts X-rays into visible photons as an intermediate step?
Field effect transistor
Thin-film transistor
Photoconductor
Scintillator
Which scintillator type is unstructured and tends to increase light spread?
Selenium photoconductor
Gadolinium oxysulfide
Cesium iodide with thallium
Hydrogenated amorphous silicon
Which scintillator is structured with needle-like crystals and associated with high DQE?
Thallium-doped cesium iodide
Gadolinium oxysulfide layers
Hydrogenated amorphous silicon
Polycrystalline selenium
Hydrogenated amorphous silicon in a detector primarily serves which role?
Layer blocking X-ray scatter
Photodiode converting light to charge
Scintillator converting X-rays to light
Switch isolating pixel charge
Which calibration process corrects for detector nonuniformity using flat-fielding?
Dead pixel mapping
Image lag removal
Offset correction
Gain calibration
Which correction removes the inherent detector signal present without exposure?
Offset correction
Gain calibration
Lag mitigation
Dead pixel interpolation
Residual signal carried over from a previous exposure is termed what?
Readout noise
Pixel crosstalk
Dark current
Image lag
Nonfunctioning detector elements are typically handled by which method?
Gain scaling of neighbors
Offset subtraction globally
Hardware replacement only
Interpolation of dead pixels
Detective quantum efficiency (DQE) most directly describes which characteristic of a detector?
Resistance to radiation damage over time
Rate of pixel readout per second
Efficiency of converting X-rays into useful image signal
Uniformity of scintillator crystal alignment
Match each component or process to its primary function.
TFT
Pixel-level switch for readout
FET
Isolates and holds pixel charge
Scintillator
Converts X-rays to visible light
Photoconductor
Converts X-rays to electrical charge
Gain calibration
Corrects detector nonuniformity
