Ch 20, 21 & 22 (CR & DR) Flashcards

1
Q

In what order was X-rays produced (CR, DR, film screen)

A

Film screen - CR - DR

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2
Q

PSP stand for

A

Photostimulable Phosphor Plate

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3
Q

What is CR processed by

A

A reader

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4
Q

What is the heart of CR

A

PSP

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5
Q

Direct conversion detectors do what

A

Convert photons straight to electronic signals

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6
Q

Indirect conversion detectors do what

A

Take photons & convert them to light by way of a scintillator before a photodetector converts the light to an electronic signal.

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7
Q

Which type of digital imagining is instantaneous

A

DR

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8
Q

The image that has been captured has been stored by the IP but not processed

A

Latent Image

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9
Q

An image that has been converted into numerical values for transmission or processing

A

A digital image

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10
Q

Analog signals are converted to a binary language called what

A

Analog to Digital Converter

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11
Q

Each binary digit/number is called a what

A

Bit

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12
Q

A number of pixels laid out in rows or columns

A

Matrix

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13
Q

Pixels represent what

A

Varying shades of grey

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14
Q

Grey scale bit depth range

A

8 - 32 bits

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15
Q

Depth in the matrix is called what

A

Voxel

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16
Q

The size of the detector determines what

A

Field of View size

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17
Q

Another word for spatial resolution

A

Detail

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18
Q

The larger the matrix, spatial resolution is better or worse

A

Better

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19
Q

The smaller the matrix, spatial resolution is better or worse

A

Worse

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20
Q

The larger the matrix the smaller the what

A

Pixels

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21
Q

Spatial resolution is measured in what

A

Line pairs per millimeter (lp/mm)

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22
Q

LUT stands for

A

Look Up Table

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23
Q

Grey scale processing is done by what 3 things

A

Histogram
LUT
Windowing

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24
Q

Which processing feature is post processed

A

Windowing

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25
Q

How is a a histogram formed

A

Digital system finds the min/max signal within the anatomical region of interest in the image & if it’s out of range it rescales it to be within range

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26
Q

Without LUTs what would the image show

A

Low contrast images

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27
Q

Window Width is what

A

Contrast

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28
Q

Window level is what

A

Brightness

29
Q

What are the 3 types of noise

A

System noise - comes from the system (usually doesn’t effect image)
Ambient noise - scatter (effects image)
Quantum mottle - not using the correct KVP/mAs (effects image - grainy)

30
Q

How accurate the IR is at converting the incoming signal to the outgoing viewing device

A

Detective Quantum Efficiency (DQE)

31
Q

What do you want the DQE to be & what is it realistically

A

1 but it is typically 30%-70%

32
Q

The number that the system gives that tells you if your image is within an acceptable range - based on exposure factors and image quality

A

EI

33
Q

How many bits are required to form a byte

A

8

34
Q

How do you figure out how many pixels are in a matrix

A

Length x width

35
Q

What is the relationship between the bit depth and the density resolution of a digital image

A

The higher the bit depth the more shades of grey that are visible

36
Q

Low window level =

A

Light image

37
Q

High window level

A

Dark image

38
Q

What is a del/array

A

3 or more pixels in a row

39
Q

What is pixel pitch

A

Center of one pixel to center of next

40
Q

Signal to noise ratio - what is ideal

A

High signal, low noise

41
Q

Deviation Index

A

Comparison between actual exposure and the proper exposure received by the IR

42
Q

Where is the latent image held

A

In the PSP

43
Q

What is read on DR vs CR

A

CR - the entire IP is read
DR - only reads the part that was exposed by radiation

44
Q

Selecting what projections your doing based on which parts are being imaged

A

APR - Anatomically Programmed Radiography

45
Q

Parts of the CR

A

Cassette
PSP
Plate Reader
Computer Workstation

46
Q

What is the purpose of the felt in the cassette

A

To collect dust and particles & keeps static electricity down

47
Q

What is the cassette backed with

A

Aluminum

48
Q

What is the purpose of the aluminum backing of the cassette

A

Assists with eliminating back scatter

49
Q

Layers of PSP

A

Protective
Phosphor
Reflective
Conductive
Supportive

50
Q

Purpose of reflective layer in PSP

A

Reflects light when IP is being scanned

51
Q

Purpose of conductive layer of PSP

A

Conducts electricity away

52
Q

Supportive layer purpose of PSP

A

Gives it rigidity so it’s not floppy

53
Q

What is the red light in the reader

A

Laser light - caused the trapped photons to be released

54
Q

What is the blue light in the reader

A

The luminescence - emitted by the IP during processing

55
Q

Why do CR plates need to be read immediately

A

The image starts deteriorating immediately

56
Q

What is used to guide the controlled laser in the CR reader

A

Optical subsystem

57
Q

What is in the PSP that causes the PSP to fluoresce

A

Barium fluorohalide

58
Q

Spatial resolution for CR vs DR

A

DR has better spatial resolution than CR

59
Q

What is a TFT

A

Thin Film Transistor

60
Q

What does a TFT do

A

Discharges dels/array (pixels grouped together) to the computer workstation

61
Q

What absorbs light & converts to the electrical charges in the indirect conversion using a TFT array

A

The photodiode / Amorphous Silicone

62
Q

What does del stand for

A

Detector Elements

63
Q

What is a DEL

A

3 or more pixels grouped together that are discharged out by row

64
Q

What absorbs light & converts it to an electric charge in indirect conversion (NON TFT)

A

CCD converts it to electrical charges & also sends it to the computer

65
Q

What is the difference between TFT & CCD

A

TFT uses photodiodes in the form of a matrix. CCD uses fiberoptic wires

66
Q

What does CCD stand for

A

Charge Coupled Device

67
Q

What is a scintillator made of

A

Cesium iodine (CsI)
OR
gadolinium oxisulfide (Gd2O2S)

68
Q

What is the photoconductor made of that is used in direct conversion

A

Amorphous Selenium

69
Q

What is the 3rd indirect option that isn’t normally used

A

CMOS - complimentary metal oxide semiconductors