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Chap 5 Flat-panel DR Test

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1.
EI does or does not represent an equivalent for patient dose entrance exposure?
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2.
Direct TFT: the photoconductor (a-Se) does what?
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3.
High frequencies contain _____, low frequencies contain ______.
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4.
Fill factor is expressed how?
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5.
Csi crystals (______ phosphor). Gradolinium oxysulfide (_____ phosphor).
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6.
x-ray attenuation depends on what 3 factors?
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7.
Indirect flat panel TFT detectors: following the x-ray scintillator (x-ray detection medium) is what?
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8.
(indirect flat panel (TFT) detectors) ______ crystals are deposited in a needle like fashion (_______ phosphor) and run in the direction of the x-ray beam.
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9.
Indirect TFT: the purpose of the a-Si photodiode layer is ?
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10.
You base scaling the histogram on what?
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11.
X-ray scintillators are what for indirect flat panel TFTs?
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12.
Fill factor affects what 2 things?
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13.
Systems that use phosphor (indirect detectors) and systems that use photoconductors (direct) differ by converting x-rays to electrical how?
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14.
Image lag is aka
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15.
Scintillator screen does what in CCD detectors? ****
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16.
4 main components of a CCD detector?
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17.
High MTF value at lower spatial frequencies means that the detector provides better _____.
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18.
2 types of indirect digital detectors?
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19.
What is exposure latitude?
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20.
3 tests to measure spatial resolution?
A.
an a-Si photodiode flat-panel layer
B.
spatial resolution and contrast resolution (detail and signal-to-noise)
C.
detects x-rays and converts them into light
D.
the exposure falling on the detector.
E.
cesium iodide (Csi) crystals are deposited in needle like fashion, (structured phosphors)
F.
x-ray absorber, scintillator, light optics, the CCD. (which is a sensor chip.. or many...)
G.
detects x-ray photons from the patient and converts them directly into electrical charges.
H.
examines the response of the image receptor to the radiation falling upon it.
I.
CsI and Gd2O2S (gradolinium)
J.
contrast resolution
K.
fine details, contrast.
L.
as a percentage. (Fill factor of 80% means that 20% of the pixel area is occupied by the detector electronics and 80% is sensing area)
M.
Csi- structured, Gradolinium- turbid
N.
charged coupling device (CCD) digital detector, and the flat-panel thin film transistor (TFT) digital detector. (difference between them is technical factors on how to convert light to electrical)
O.
memory effect
P.
atomic number (Z#), density, and thickness of attenuating material.
Q.
phosphor (indirect)- convert x-ray energy into electrical through an intermediate stage of light photons, photoconductors (direct) convert energy energy directly into electrical charge without the intermediate stage.
R.
bar test pattern, sharp-edged object, narrow slit.
S.
does not
T.
To convert th elight from the x-ray detection scintillator into electrical charges.
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21.
TFT stands for?
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22.
Direct TFT: the photoconductor is usually what substance?
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23.
Third step in image processing is ___________, where the adjusted or scaled raw data values are mapped to the "for presentation" values to display an optimum image.
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24.
the ability of the imaging system to resolve fine details present in an object is called
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25.
As the spatial frequencies increase, the DQE ______
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26.
A system that has a higher spatial frequency at an MTF of .1 will show _____ spatial resolution than a system with below MTF of .1.
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27.
Detectors with ____ fill factors (____ sensing areas) will provide better spatial and contrast resolution.
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28.
Image obtained initially from the detector is referred to as what?
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29.
Before the flat panel detector can be used, it must be prepared. This is referred to as __________.
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30.
During readout, system electronics provide systematic collection of changes on each chip in a manner referred to as a “bucket brigade”. (the charge pattern from the readout of pixels is sent to the ADC for digitization)

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