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SEM II - Exposure > CR Digital Imaging > Flashcards

CR Digital Imaging Flashcards

0
Q

Digital

A

Device or system that represents information as continuously variable numerical values.

Like a digital watch.

CR & DR are digital.

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1
Q

Analog

A

A device or system that represents information as continuously variable physical quantities.

Like a mechanical watch.

X-ray film is analog.

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2
Q

Binary code

A

Numerical form of digits 1 & 0 that computers are capable of processing, storing, and transferring information held in this numerical code.

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3
Q

Digitizing

A

Process if converting colors, shades, and shapes held as analog information into numbers, which is digital information.

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4
Q

PSP - Photostimulable Phosphor

A

Plate used in CR in place of film

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5
Q

IP Protective layer

A

Fluorinated polymer material

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6
Q

IP Phosphor layer

A

Europium barium fluorohalide crystals

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7
Q

IP Anti-halo/Reflective layer

A

Prevents laser light from penetrating;

Allow reflected light from the phosphor to pass through.

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8
Q

IP conductive layer

A

Removes static electricity

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9
Q

IP Base layer

A

PET - polyethylene terephthalate

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10
Q

IP backing layer

A

Protects base from handling damage, contains bar code label on IR

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11
Q

Capture element for CR

A

The imaging plate, part of the digital system, remnant X-ray energy is captured

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12
Q

Coupling element for CR

A

Part of the digital system, transfers X-ray generated signal to collection element.

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13
Q

Collecting element for CR

A

Part of digital system, which collects photons or electrons to be quantified and assigned a digital value

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14
Q

Fading

A

The process of image weakening from latent image being stored on a cassette and not processed immediately.

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15
Q

F-center

A

Electrons elevated out of their normal orbital rings into higher orbitals.

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16
Q

Readout

A

Scan of phosphor plate with helium-neon laser light and reads the latent image from the phosphor.

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17
Q

Raster pattern

A

A side to side pattern a laser uses to obtain an image.

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18
Q

HeNe - helium neon

A

Type of laser light used to read the latent image from the phosphor

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19
Q

PSL - photo stimulated luminescence

A

Has a wavelength of 390-400 nm whose intensity of light is directionally proportional to the amount of radiation absorbed.

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20
Q

PMT - photomultiplier tube

A

A device that converts light energy to electrical energy.

The “collection element” for CR.

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21
Q

ADC

A

Analog to digital converter

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22
Q

DAC

A

Digital to analog converter

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23
Q

PACS

A

Picture archiving and communication system

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24
Q

QDE

A

Quantum detection efficiency.

Measures the effective way of a CR system to convert remnant radiation into useful image signals

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25
Q

Exposure indicator

A

How much radiation actually got to the image receptor.

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26
Q

The perfect dose to to the imaging plate for CR is?

A

1 mR (miliroentgen)

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27
Q

The Fuji CR exposure indicator is the

A

“S” number.

Calculated by dividing 200 by the exposure amount.

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28
Q

The range of acceptable values for Fuji CR is

A

180-220

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29
Q

The perfect exposure indicator value for Fuji is

A

200

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30
Q

As the Fuji exposure indicator goes up, dose to the patient

A

Goes down.

31
Q

The Kodak CR exposure indicator is the

A

Exposure index number

32
Q

The range of acceptable values for Kodak CR is

A

1950-2050

33
Q

The perfect exposure indicator value for Kodak is

A

2000

34
Q

As the Kodak exposure indicator goes up, dose to the patient

A

Goes up (direct relationship)

35
Q

The Agfa CR exposure indicator is the

A

Log mean number (LGM)

36
Q

The range of acceptable values for Agfa CR is

A

1.9-2.5 LGM

37
Q

The perfect exposure indicator value for Agfa is

A

2.2 LGM

38
Q

As the Agfa exposure indicator goes up, dose to the patient

A

Goes up (direct relationship)

39
Q

Algorithm

A

A finite sequence of instructions, an explicit, step by step procedure for solving a problem, often used for calculation and data processing.

40
Q

Pixel

A

The smallest component of a picture, little squares, 2 dimensional, each corresponds to a shade of gray.

41
Q

Pixel size

A

Measured from side to side to the pixel

42
Q

Pixel pitch

A

Measured from the center of one pixel to the center of the adjacent one.

43
Q

Pixel density

A

/mm

The number of pixels per given area.

44
Q

Matrix

A

Layout of cells on rows and columns, many crossed and columns

45
Q

Voxel

A

Volume element, 3 dimensional (CT Scan), each voxel corresponds to a shade of gray representing a volume within a patient.

46
Q

Hounsfield unit

A

AKA CT numbers

A quantative scale for describing radio density

47
Q

CT Number

A

Aka Hounsfield units

A quantative for describing radio density calculated by comparing the linear attenuation coefficient of each pixel to the linear attenuation coefficient of water

48
Q

Bit range/bit level/bit depth

A

Measured in bits, pixels have a depth referring to the range of gray shades that can be assigned to a specific pixel.

The higher the dynamic range the more gray shades available to display the image.

49
Q

1 bit =

A

2 shades

50
Q

2 bit =

A

4 shades

51
Q

3 bit =

A

8 shades

52
Q

4 bit =

A

16 shades

53
Q

5 bit =

A

32 shades

54
Q

6 bit=

A

64 shades

55
Q

7 bit=

A

128 shades

56
Q

8 bit =

A

256 shades

57
Q

9 bit =

A

512 shades

58
Q

10 bit =

A

1024 shades

59
Q

11 bits =

A

2048 shades

60
Q

12 bits =

A

4096 shades

61
Q

Spatial resolution

A

Field of view, matrix size.

The ability to visualize small objects.

62
Q

Spatial resolution for digital imaging is measured in

A

lp/mm - line pair per millimeter

63
Q

Contrast resolution

A

The ability to distinguish adjacent structures that have similar densities

64
Q

SMTPE pattern

A

Contrast test tool; what tv stations used to end their daily programming with.

“Society of motion picture and television engineers”

65
Q

Automatic rescaling

A

If an image is grossly under/over exposed, preset rescaling will take place by software and presented to the monitor as a new image.

66
Q

Europium barium fluorohalide

A

X-ray energy enters these molecules, that energy is absorbed by the molecules

67
Q

CR identification terminal

A

Used to input patient and exam details with barcode reader and RF chip

68
Q

Tools for evaluating CR digital image quality

A

Exposure indicator

Magnification

“Tech eye”

69
Q

Exposure indicator

A

Know your “normal” range

Know direct vs indirect scale

70
Q

Magnification - evaluating CR digital image quality

A

Look for quantum mottle

71
Q

“Tech eye”

A

Knowledge of detail

Experience with digital imaging

72
Q

Advantages to digital imaging

A 
Post processing - can change manifest image (density, contrast, magnify, annotate)
No need to store film
Can transmit images remotely
Faster processing
Better contrast resolution
73
Q

Photomultiplier tube

A

A device that converts light energy to electrical energy.

The “collection element” for CR

74
Q

Three inherent factors responsible for image resolution capability

A

Image plate crystal size

Laser beam size

Monitor matrix size

75
Q

The speed of a digital imaging system is determined by

A

The level of exposure received at the image receptor. Varies by manufacturer.

76
Q

CR Image Formation

A

PSP plate absorbs remnant X-ray energy
Electrons are pushed away from nucleus
PSP plate is bombarded by red laser light (600nm)
Elevated electrons are “slapped” back into normal orbits
Stored energy released as bluish visible light (400nm)
Visible light sent to PMT by light gate
Visible light intensity converted to electron energy by PMT
Electrons quantified as a digital value (in binary code)

SEM II - Exposure (6 decks)

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