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68 Cards in this Set
- Front
- Back
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The two principal characteristics of a medical image are _____.
a. spatial resolution and noise b. spatial resolution and contrast resolution c. contrast resolution and modular transfer function d. contrast resolution and dynamic range |
b. spatial resolution and contrast resolution
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Spatial frequency is used to describe the quality of spatial resolution in terms of _____.
a. pixel size b. modular transfer function c. line pairs d. contrast resolution |
c. line pairs
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In digital imaging, spatial resolution is ultimately limited by _____.
a. focal spot size b. spatial frequency c. contrast resolution d. pixel size |
d. pixel size
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What is the spatial frequency of a digital system that can resolve 100 um?
a. 5 lp/mm b. 10 lp/mm c. 50 lp/mm d. 100 lp/mm |
b. 10 lp/mm
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If a digital system has a spatial resolution of 4 lp/mm, it can resolve an object as small as _____ mm.
a. 8 b. 4 c. 0.25 d. 0.125 |
d. 0.125
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As spatial frequency increases the object size _____ and the spatial resolution _____.
a. increases, increases b. decreases, decreases c. decreases, increases d. increases, decreases |
c. decreases, increases
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If there were such thing as a perfect imaging system, the MTF would be equal to _____.
a. 5 b. 1 c. 2 d. 4 |
b. 1
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A _____ test tool is used to acquire data for an MTF (Modulation transfer function) curve.
a. bar pattern b. post processing c. signal-to-noise ratio d. contrast-detail curve |
a. bar pattern
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11.The human visual system can distinguish _____ shades of gray.
a. 10 b. 30 c. 300 d. 1000 |
b. 30
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The number of gray shades that an imaging system can reproduce is called its _____.
a. spatial frequency b. contrast c. spatial resolution d. dynamic range |
d. dynamic range
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Screen-film radiography has a dynamic range of _____.
a. 10 b. 100 c. 1,000 d. 10,000 |
c. 1,000
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The bit capacity of each pixel identifies the _____ of a digital imaging system.
a. dynamic range b. grey scale c. spatial frequency d. MTF |
a. dynamic range
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The _____ digital imaging system uses the highest dynamic range.
a. computed tomography b. mammography c. magnetic resonance d. angiography |
b. mammography
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The portion of useful image-forming x-rays is referred to as the _____.
a. frequency b. MTF c. signal d. noise |
c. signal
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Recent studies have shown that denser breast tissue is best imaged with _____.
a. xerography b. computed tomography c. screen-film mammography d. digital mammography |
d. digital mammography
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As mAs is increased the signal to noise ratio is _____.
a. decreased b. increased c. not affected d. doubled |
b. increased
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Image detail is also called _____.
a. spatial resolution b. spatial frequency c. signal to noise ratio d. dynamic range |
a. spatial resolution
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Of all radiographic imaging systems, _____ has the best contrast resolution.
a. digital radiography b. mammography c. magnetic resonance imaging d. computed tomography |
d. computed tomography
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With digital imaging, patient dose can be reduced by using higher _____ techniques.
a. mAs b. kVp c. optical density d. contrast |
b. kVp
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DQE is _____.
a. density quantum effect b. direct quantum efficiency c. detective quantum efficiency d. detective quantum energy |
c. detective quantum efficiency
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If an image receptor has a high probability of interacting with the x-ray beam, then it has a high _____.
a. DQE b. SNR c. MTF d. lp/mm |
a. DQE
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The use of an image receptor with _____ DQE can result in _____ patient doses.
I. low, lower II. high, lower III. high, higher IV. low, higher a. I b. II c. I & III d. II & IV |
d. II & IV
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Digital radiography images should be repeated if there is a problem with _____.
a. contrast b. overexposure c. brightness d. none of the above |
d. none of the above
Patient motion would be a reason for repeating a digital image |
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the science of ______ is the study of visible light
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photometry
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what is a basic photometric unit?
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lumen
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decreasing luminous intensity with increaing distance from the source of light follows the ______
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inverse square law
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a digital display monitor is best viewed
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straight on
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a digital display device with higher megapixels has better spatial resolution
TF |
True
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an advantage to viewing the AMLCD screen is that the image quality is equally good viewed from any angle
TF |
False
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the luminance of a digital display device is measured in units of
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candela
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___ is an auto preprocessing func that recalibrates image data to achieve uniform response across the image receptor
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flatfielding
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reregistering an image to correct for patient motion is done with
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pixel shift
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within a PACS network a single workstation is referred to a _____
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client
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the national standard for image transmission in teleradiogy is the ____ format
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DICOM
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a graph of the frequency of occurence versus digital value intervals is called a _________
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histogram
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Each anatomical part has an image histogram with a ________
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Characteristic shape
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lossy compression reduces data files to
a. 10:1 b. 100:1 c. 1000:1 d. none of the above |
b. 100:1
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lossless compression reduces data files
a. 10:1 b. 30:1 c. 100:1 d. none of the above |
b. 30:1
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what size is the average CR or DR image file
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20 MB
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a ghost image can occur in digital imaging because of _______
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incomplete erasure
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The purpose of the TFT (thin film transistor) is to ________
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convert x-ray photons into light photons
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the principle source of noise in CR is
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scatter
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The computed radiography reader is made up of _____, _____, and _____ modules.
I. mechanical II. chemical III. optical IV. computer a. I, II, III b. II, III, IV c. I,III, IV d. I, II, IV |
c. I,III, IV
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In digital radiography, the brightness of the image is determined by _____.
a. pixel values b. Hounsfield units c. automatic brightness control d. film contrast |
a. pixel values
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Image-forming x-rays include those which have been _____.
a. transmitted without interaction b. scattered through Compton interaction c. absorbed through photoelectric interaction d. both A and B |
d. both A and B
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Which kVp selection would result in the most scattered x-rays in the image-forming beam?
a. 90 kVp b. 75 kVp c. 60 kVp d. 50 kVp |
a. 90 kVp
The percentage of Compton interaction increases as kVp increases |
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The x-ray interaction that contributes to the clear parts of the image is _____.
a. coherent scatter b. Compton interaction c. photoelectric interaction d. pair production |
c. photoelectric interaction
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Computed radiography screens respond to radiation with _____.
a. fluorescence b. electron emission c. photostimulable luminescence d. biological phosphorescence |
c. photostimulable luminescence
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Optical filters are used to filter out the _____ light and allow the _____ light to reach the photodetector
a. stimulating, emitted b. emitted, stimulated c. emitted, monochromatic d. stimulating, monochromatic |
a. stimulating, emitted
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What is the most recent development in digital radiography image receptors?
a. fanned x-ray beams b. linear array radiation detectors c. photostimulable phosphors d. direct capture solid-state devices |
d. direct capture solid-state devices
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Conventional x-ray tubes and cassettes holders can still be used with _____ radiography systems.
a. computed b. computed tomography c. direct capture d. all of the above |
a. computed
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Component used to convert radiation to visible light in DR is the
a. charge coupled device b. scintillator c. RIS d. PACS |
b. scintillator
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Automatic Brightness Stabilization adjusts _______ to maintain image brightness
a. kV b. mA c. mAs d. time |
c. mAs
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Contrast resolution is limited by noise or _______
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SNR
signal to noise ratio |
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Mammo has the best spatial resolution because of _____
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small focal spot size
(0.1 mm) |
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If mAs is increased in digital radiography _____ remains the same but _____ is improved with increased mAs
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spatial resolution , contrast resolution
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Objects with ____ spatial frequency are harder to image than objects with _____ spatial frequency
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high , low
small objects are harder to image bony trabecula is hard / a liver is easy |
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As the spatial frequency becomes _____, the objects become ______.
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larger , smaller
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Higher spatial frequency indicates better ________
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spatial resolution
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Trabeculae = (high / low) spatial frequency.
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high
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No digital imaging system can image an object smaller than one ____
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pixel
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Blur occurs over __ lp/mm for radiography (limit)
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8
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Reduced Amplitude =
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BLUR
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The dynamic range for digital imaging is greater than _______
a. 10,000 b. 35,000 c. 55,000 d. 65,000 |
d. 65,000
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______is that portion of the image forming x-rays that represents anatomy
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Signal
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Most x-rays have energy matching the __________energy of the capture element
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k-shell binding
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What is a capture element in CR
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the capture element is the photostimulable phosphor
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The use of 2 screens in imaging results in a higher ____.
a. spatial frequency b. pixel size c. MTF d. spatial resolution |
c. MTF
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