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DMI 15 > Quiz 2 > Flashcards

Quiz 2 Flashcards

0
Q

Turbid

A

•crystals distributed throughout a phosphor layer

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1
Q

A layer that traps images/electrons

A

•phosphor layer

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2
Q

Reflective layer

A

•sends light in a forward direction

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3
Q

Conductive layer

A

•absorbs & reduces static electricity

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4
Q

What is the phosphor layer made of

A

•barium fluorohalide

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5
Q

How are images acquired & formed

A
  • Attenuated beam interacts with electrodes in the crystals

* crystals contain F Traps that hold electrons & elevate to a high state creating a latent image

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6
Q

Laser scanning

A
  • scans in a Raster pattern

* releasing electrons from F-Traps causing emitted light

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7
Q

Translation

A

•The process of scanning the moving imaging plate is known as

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8
Q

Digitization

A

•when a light photon is assigned a number

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9
Q

Optical mirror

A

•directs the laser beam onto the imaging plate

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10
Q

Erasing the imaging plate

A

•imaging plate is run under bright light to release any remaining electrons trapped in the F-Traps

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11
Q

PSL

A
  • photostimuable luminescence
  • amount of light emitted by the plate during reading process
  • level of exposure indicates speed class
  • high kVp low mAs produces increase speed class & reduces pt. Exposure
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12
Q

What is a picture element

A

•pixel

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13
Q

A group of pixels are arranged in a grid pattern

A

•matrix

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14
Q

Bit depth

A

•The number of bits per pixel

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15
Q

When laser scan the imaging plate it gives off light. what color is this light?

A

•blue

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16
Q

Quantum mottle caused by

A

•Technique to low
•specifically low mAs
•not enough photons reach the plate
Thus insufficient light for the reader to interpret

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17
Q

A range of KV that works will with CR

A
  • 45-120

* but 60-110 is optimal

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18
Q

What does mAs give you

A
  • Selecting the amount of photons
  • to little will be grainy “quantum mottle”
  • back scatter from cassette will influence amount of mAs
19
Q

Spatial resolution

A
  • amount of detail present in an image

* the thinner the phosphor layer the higher the resolution

20
Q

Moiré pattern

A

•wavy artifacts caused by grid lines

21
Q

Grid ratios for portable/department use

A
  • portable 6:1

* department 12:1

22
Q

A graphic representation of the optimal densities within the collimated area

A

•histogram

23
Q

Grid orientation

A
  • should be perpendicular

* if parallel can cause Moiré effect

24
Q

TFT

A
  • thin film transistor
  • acts as a switch
  • absorbs electrons & generating an electrical charge
25
Q

indirect conversion

A
  • old system uses scintillator to produce light to be captured & digitized by CCD
  • converts X-ray into visible light
26
Q

CCD

A

•charged couple device

27
Q

Direct conversion

A

•photons are converted to electrons & stored in TFT

28
Q

CMOS

A
  • Complimentary metal oxide silicon

* newer systems use CMOS instead of CCD

29
Q

DQE

A
  • detective quantity efficiency
  • measures the percentage of photons absorbed when they hit the detector
  • high DQE=higher quality images at lower dose
30
Q

Noise

A
  • the main factor that limits cassette less image acquisition
  • the main limiting factor for quality
  • caused by scatter
31
Q

Rapid sequence exposures

A
  • double exposure

* electronic memory artifact

32
Q

Is the shape of the histogram anatomically specific

A

•Yes it is important to choose correct anatomical region

33
Q

Automatic rescaling

A

• images are produced with uniform density & contrast

34
Q

Latitude

A
  • amount of error that will still produce a quality image

* DR & CR have a wide latitude

35
Q

If sampling occurs less than twice per cycle what might happen

A

•wrap around images are aliasing

36
Q

What would be the perfect MTF for an imaging system

A
  • 100% of what u take get transferred would be ideal

* modulation transfer function

37
Q

What do you lose when you manipulate an image

A

• You lose information/data

38
Q

Smoothing

A
  • Low pass filtering

* reduces noise & contrast good for small structures

39
Q

Edge enhancement

A
  • Amplifies the frequencies of the areas of interest
  • high pass filtering
  • good for large structures
40
Q

Veil glare

A
  • excessive light on the view box

* reduces information on the image

41
Q

Shuttering

A

•unexposed borders of the image is blackened to avoid veil glare

42
Q

Display workstation

A
  • any computer in the hospital that you can display an image on
  • a computer connected to PACS
43
Q

Manual send function

A

•allows images to be sent to different workstations

44
Q

DICOM

A

•The accepted system that allows different modalities to communicate through PACS

45
Q

Importance of film orientation

A

•Must be orientated correctly so it is displayed properly

46
Q

Is it ok to annotate right or left marker

A

•No lead marker should always be displayed

DMI 15 (5 decks)

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