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OOGA_Digital X-ray Chapter 4 Digital Detector Arrays

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1. The phosphor most likely to be used in indirect Digital Radiography (DR) is:
Gd2O2S. A-Se. CsI BaFlBr.
2. The a-Si material in a Digital Detector Array (DDA) refers to:
the type of initial conversion material the thin film transistor (TFT) photo-diode array semi-conductor composition. the specific model number for the device or imaging system. the physical size of discrete internal detector elements
3. Linear Diode Array (LDA) detectors are most often used in:
real time radioscopy. micro-focus inspection of aerospace castings. pipeline weld inspection application baggage inspection systems.
4. Which digital modality is less prone to radiation damage?
Amorphous Selenium Amorphous Silicon Linear Diode Array (CMOS) CCD Panels
5. The abbreviation TFT stands for:
Tiny Field Transistor. Thin Filter Transmission. Thin Film Transistor Tiny Filter Transistor.
6. Initial sensing medium (converter) in the Digital Detector Array (DDA) is typically a:
aSi aSe PSL Phosphor or scintillator. Electronic signal.
7. Current Digital Detector Array (DDA) technology provides a minimum pixel pitch of _____________ in a-Si DDA panel.
1 micron 10 microns. 100 microns. 1000 microns
8. Digital Detector Array (DDA)s (DDA) systems are available from:
Only a few manufacturers/vendors/integrators. Dozens of suppliers North American merchants. Europium dealers
9. Cesium Iodide (Csl) provide a different and typically better response mechanism compared to GdSO in that:
Their light emission is focused and less diffused. Csl has a higher atomic weight. The Csl conversion layer is typically grown onto the photo-diode array. All of the above
10. Amorphous Silicon (a-Si) semi-conductor materials are classified as having:
A narrow band gap A wide band gap An overlapping band gap No band gap of any kind
11. A transistor can be best described as:
A digital transformation tool. A valve that allows current to flow when triggered A filter for electronic charge A narrow band gap material.
12. The SMTR (specific material thickness range) for a particular Digital Detector Array (DDA)
Could be considered the effective inspection range for the DDA. Is the same for all detectors Is of no particular importance. Only applies to DDAs using Csl conversion.
13. Higher Signal-to-Noise Ratio (SNR) in an image acquired with a Digital Detector Array (DDA)
Indicates the largest resolvable feature the DDA can detect Indicates the smallest resolvable crack a DDA can detect. Indicates the largest resolvable crack a DDA can detect Results in lower contrast sensitivity.
14. Contrast-to-Noise Ratio (CNR) in a Digital Detector Array (DDA) image is closely related to:
SNR Subject contrast System noise. All of the above. None of the above
15. Larger pixel sizes (Pitch) in a Digital Detector Array (DDA) will typically:
Decrease spatial resolution. Increase SNR. Decrease image file size All of the above None of the above
16. All Digital Detector Array (DDA)s have a peak efficiency typically related to:
The focal spot size of the X-ray system. The initial conversion material (primary X-ray capture medium). Electronic amplification. The DDA manufacturer.
17. Any image from any Digital Detector Array (DDA) in order to be usable requires:
Offset calibration Gain calibration Offset/gain calibration. None of the above
18. A Digital Detector Array (DDA) gain calibration image:
Is obtained with the DDA exposed to radiation. Is obtained with the DDA exposed to light. Is obtained monthly. Is obtained by offset.
19. A Digital Detector Array (DDA) offset calibration image:
Is otherwise known as a “dark” image. Measures the DDAs response to noise in the X-ray beam. Measures the DDAs response to contrast sensitivity. Is otherwise known as the “bright” image.
20. Offset and gain calibrations for the Digital Detector Array (DDA) panel:
Increase image quality. Correct for certain bad pixels or erroneous DDA response. Increase DDA sensitivity. All of the above
21. Most Digital Detector Array (DDA)s are:
Impervious to radiation. Impervious to energy less than 100 kVp. Rated for certain X-ray energy levels. Always good for 10K exposures at prescribed energy levels.
22. Radiation damage to the digital X-Ray detector:
Is a cumulative effect. Is never a consideration. Is readily apparent. Should be brought to the manufacturer’s attention immediately.
23. A common method for increasing or improving the spatial resolution within a Digital Detector Array (DDA) system is:
Using a larger focal spot Applying geometric magnification Applying maximum contrast during image processing Decreasing the SOD
24. Digital Detector Array (DDA) imaging device types can include:
TFT read-out devices combined with a conversion material (typically a phosphor or scintillator) An LDA A CCD or CMOS type detector All of the above
25. A relevant bad pixel cluster:
Contains at least 5 bad pixels Contains pixels that are considered CKPs Is comprised of all CKPs Is corrected with the duplex wire gauge
26. A dead pixel is one that
Provides no response Provides an intermittent response Provides a constant response a and c All of the above
27. A bad neighborhood pixel is a functional pixel where ____________ adjacent pixels are bad:
4 8 12 16
28. CKP stands for
Contaminated Centered Kilobyte Pixel Cluster Kernel Pixel Concept Knowledge Processing
29. SNR stands for:
Syncopated Noise Reduction. System Noise Reduction Safety Net Review Signal to Noise Ratio
30. Bad pixels can look like defects on the image:
True False
31. CSA stands for
Chemical Safety Assessment. Contrast Sensitivity Achievable. Compliance Safety Accountability Cloud Security Alliance.
32. Which material is a photoconductor?
Gad-Ox Selenium Cesium Iodide Barium Fluorohalide a and c
33. Csl (scintillators) typically provide a more efficient X-ray quanta response and conversion mechanism compared to Gadox (phosphors) in that:
Csl has a powdered, turbid structure Csl has a lower atomic weight. the Csl conversion layer is typically grown onto the photo-diode array (directly coupled to the photo-diode array). Csl has excessive lag lending to extremely high resolution.
34. Cluster Kernel Pixel (CKP) refers to a pixel with less than _______________ good neighbors.
3 4 5 10
35. Bad pixels on a Digital Detector Array (DDA) panel:
Cannot be corrected Can hide a defect Are cause for panel replacement Cannot be fixed by the manufacturer Will affect defect POD
36. Any digital detector or conversion material is:
damaged by background radiation. degraded by radiation exposure accumulation. easily repaired if image quality degrades. exposed only for the maximum number of times as determined by the manufacturer.
37. Which material is more efficient and will provide a better Signal-to-Noise Ratio (SNR)
Gad-Ox Cesium Iodide
38. While using a Digital Detector Array (DDA) device, shading, ghosting, or gray value fluctuation across or within the image indicates:
an increase in detector performance that a new gain and offset calibration should be performed the monitor/display needs adjustment X-ray tube replacement is necessary.
39. A 2048 x 2048 pixel matrix Digital Detector Array (DDA) would have:
Over 4,000 pixels Over 40,000 pixels Over 400,000 pixels Over 4 million pixels
40. Which scintillator requires a greater exposure time compared to the other?
Gad-Ox Cesium Iodide
41. Which scintillator has a lower cost?
Gad-Ox Cesium Iodide
42. Which scintillator provides more light output for the same radiation dose?
Gad-Ox Cesium Iodide
43. A technique to compensate for Cluster Kernel Pixels (CKP)s that may hide a small defect is to use:
Various filters Geometric magnification Increase kV Perform offset/gain calibration.
44. What type of “bad pixel” cannot be corrected through calibration?
Noisy pixel Pixel cluster Relevant cluster Bad line segment Cluster kernel pixel
45. For pixel correction, a calibration is performed with no object under the X-Ray beam. This exposure is called the:
Gain image Dark image Air image Offset image a and c
46. The effects of bad pixels can be reduced by:
calibration smaller focal spot size replacing the panel magnification all of the above
47. Afterglow or ghosting is ultimately caused by:
Quantum noise Using improper machine settings Radiation damage The scintillator material aging Under responding pixels
48. Which scintillator has a columnar structure?
Gad-Ox Cesium Iodide
49. Indirect conversion in flat-panel detectors is a ______-step process.
One Two Three Four
50. The component within the Digital Detector Array (DDA) pixel that produces a digital signal is the:
scintillator photoconductor FET Storage capacitor
51. Amorphous Digital Detector Array (DDA) panels may encounter hysteresis effects which result in:
Dead pixels CKP pixels Ghosting Longer exposure times Shorter exposure times
52. “Amorphous” means what in regard to amorphous silicon and amorphous selenium panels?
crystaline direct non-crystaline in-direct
53. A 14” x 17” Digital Detector Array (DDA) panel contains ___________________ of pixels.
thousands tens of thousands hundreds of thousands millions
54. What controls the address of each individual pixel in a Digital Detector Array (DDA) panel?
Software Pixel Gate Modular Pixel FET
55. Which Digital Detector Array (DDA) variation is the most prone to radiation damage?
CMOS direct non-crystaline in-direct
56. Which Digital Detector Array (DDA) variation has a thicker scintillator layer?
Gad-Ox Cesium Iodide
57. In direct Digital Detector Array (DDA) panels, electron hole pairs are created within the:
FET Gad-ox scintillator Cesium iodide scintillator Selenium
58. Which variation of Digital Detector Array (DDA) panel is delivered with no dead pixels?
Gad-Ox Selenium Cesium Iodide CMOS CR
59. Amorphous silicon panels are impervious to moisture.
True False
60. When X-rays interact with a Digital Detector Array (DDA) panel, ________________ is/are created within the Field Effect Transistor (FET.)
light electron mismatch electron hole-pairs a voltage drop
61. Which Digital Detector Array (DDA) modality is not indirect?
Amorphous selenium CMOS CCD None of the above
62. Which variation of Digital Detector Array (DDA) panel does not suffer from ghosting?
Gad-Ox Selenium Cesium Iodide CMOS CR
63. The size of each pixel derived from exposing a Digital Detector Array (DDA) panel is based upon:
The size of the silver halide grain The size of the pixel in the panel. The viewing monitor capability The magnification applied to the image.
64. Which variation of Digital Detector Array (DDA) panel is least affected by temperature variations?
Gad-Ox Selenium Cesium Iodide CMOS CR
65. Which variation of Digital Detector Array (DDA) panel is able to better tolerate harder radiation?
Gad-Ox Selenium Cesium Iodide CMOS CR
66. _____________ is used to restore an estimate of a pixel value from surrounding good pixels.
Interpolation Binning Frame averaging Geometric magnification None of the above
67. In regards to having enough pixels to encompass the smallest defect size, the Digital Detector Array (DDA) system is dependent upon the:
Monitor resolution Pixel pitch Geometric magnification Geometric magnification b and c
68. A bad line segment has _____ or more bad pixels connected in a row or column where no more than 10% of this line has adjacent bad pixels.
5 10 15 20
69. Which Digital Detector Array (DDA) option is not considered a scintillator?
CCD Gad-ox Cesium iodide Selenium
70. On an offset corrected image
Under-responding pixels are compensated for. Over-responding pixels are compensated for. Irrelevant clusters are compensated for Bad neighborhood pixels are compensated for. All of the above.
71. A good pixel that is surrounded by all bad pixels is called a:
Lagging pixel. Bad neighborhood pixel. Non-uniform pixel. Cluster kernel pixel.
72. Ideally, the inspector wants at least _______ pixel(s) to cover the smallest defect to be encountered in the inspection.
1 2 3 4
73. In a Charge Coupled Device (CCD), the amount of electron/holes generated is related to the amount of:
Electric charge. Light absorbed. Reflected light. Incident X-rays.
74. The layer in a Charge Coupled Device (CCD) chip that contains the electron gates is the:
Silicon diode layer. Polysilicon layer. Silicon substrate. All of the above.
75. The insulating layer in a Charge Coupled Device (CCD) chip is the:
Polygonal layer. Silicon dioxide layer. Silicon substrate. Monosilicon layer.
76. Which of the following can be done to decrease the chance of having image lag occur in the next image?
Decrease the amount of time between exposures. Increase the amount of time between exposures. Leave the collimation open to allow a wider X-ray beam. Acquire the image with the higher kV first.
77. Which Digital Radiography (DR) modality is not amorphous in nature?
CMOS Cesium Oxide Gad-Ox CR IP
78. Amorphous silicon panels are sensitive to:
Light. Gamma rays. X-Rays. Ultraviolet radiation. b and c All of the above
79. The portion of the amorphous silicon panel that can be damaged by radiation is the:
Gad-Ox scintillator. Cesium Oxide scintillator. The electronics within each pixel. The read/control electronics.
80. Using the software to increase the pixel binning:
increases the resolution of the resultant image. decreases the frame rate of the resultant image. ungroups several pixels that were grouped together. decreases the resolution of the resultant image.
81. The effect of applying a binning operation is to create a:
better pixel. smaller pixel. larger pixel. super pixel.
82. Which of the following measures the efficiency of a system to convert ionizing radiation input signal into a useful output image?
DQE MTF Exposure latitude Spatial resolution
83. Contrast sensitivity is the digital system’s ability to:
show small differences in gray levels. record noise interference. allow lower kVp and higher mAs. separate structures from noise.
84. The number of electron/hole pairs created during the exposure of an amorphous silicon panel is related to the:
amount of light absorbed. amount of incident X or Gamma rays. electric charge applied to the panel. amount of reflected light.
85. Offset calibration is used to remove inherent signals, such as ghosting/image lag, that remain in a detector.
True False
86. A solid chemical element or compound doped with impurities that make it highly conductive is known as a
Dopant. Semi-conductor. Transistor. Capacitor.
87. Which of the two technologies, Charge Coupled Device (CCD) or Complementary Metal-Oxide Semi-conductor (CMOS), is more susceptible to noise, has a lower light sensitivity, uses very little power, and is inexpensive to manufacture?
CMOS CCD
88. Which of the following is not a scintillator used for Digital Radiographic (DR) plates?
Gd2O2S. A-Se. CsI. All of the above are used as scintillators.
89. What does a photoconductor do?
It produces light when absorbing X-rays. It produces X-rays when absorbing light. It absorbs light and produces electric charges. It absorbs X-rays and produces electrical charges.
90. Gain calibration will remove inherent detector artifacts from an image.
True. False.
91. Which imaging modality can compensate for variations in the X-ray beam coverage?
Film. Computed Radiography. Digital Detector Array. Real Time X-ray.
92. Which type of absorbing material requires a capacitor as the storage element?
CCD CMOS Amorphous silicon Amorphous selenium
93. A Gad-ox scintillator is known as what type of phosphor?
Turbid Unstructured Structured Both a and b Both a and c
94. The type of flat-panel detector that uses thin films of silicon integrated with arrays of photodiodes is known as a:
CsI detector CMOS Charge-coupled device Amorphous silicon detector
95. Cesium Iodide (Csl) detectors use:
thin crystalline needles. rare-earth scintillators. miniature cameras. specialized pixel sensors.
96. In Cesium Iodide (CsI) detectors,
there is a great deal of light spread crystalline needles block light from the detector. light hitting the photodiode reduces the charge in the FET. light spread causes the image resolution to decrease.
97. A device that includes a photosensitive array and small pixels that convert light into electrical charges is known as a ___________ transistor.
Thin-field Thin-film Field-effect Field-energy
98. A device that acts like a switch to send electrical charges to the image processor in a direct conversion flat panel detector is known as a ___________ transistor.
Thin-field Thin-film Field-effect Field-energy
99. Flat-panel detectors that use indirect conversion technology convert:
X-rays to visible light. Electrical signals to light. X-rays to electrical signals. Visible light to X-rays.
100. Pixel binning ___________ the resolution of the resultant image.
increases decreases Pixel binning has no effect upon the resolution of the digital image.
101. When specialized pixels in a complementary metal oxide silicon system are struck with X-ray photons:
The X-ray photons are converted into light. Light photons are stored in capacitors. Light photons are converted into electrical charges. All of the above.