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Ct Review Class > Ch 1 System Operation And Components > Flashcards

Ch 1 System Operation And Components Flashcards

1
Q

Ct uses X-rays to image individuals at different

P 1

A

Cross sectional anatomy

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2
Q

Reconstructed image

A

Measurement of photons of xray beam in which each tissue has its own characteristic intensity

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3
Q

Overview of Ct system

A 
Control panel
Computer 
Scan controller 
Digital analog converter 
Gantry 
High voltage 
Generator 
Info converted into tiny electrical signals 
Pass through amplifier 
Analog signal sampled 
Then digitized by analog digital converter
Data stored temporarily in raw data file
Calculated image by array processor
Image transferred to host computer
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4
Q

Scan controller

A

Responsible for timing and operation of patient table , gantry , and high voltage generator

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5
Q

Digital analog converter (dac)

A

Electronic signal converted into analog or continuous waveform

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6
Q

Gantry

A

Contains X-ray tube and detectors

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7
Q

High voltage generator

A

Generates high voltage potential between cathode and anode

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8
Q

1st commercial scanner

A

1973

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9
Q

First gen scanner

Type beam?
What does?
Scan time?

A

Pencil beam
Single detector moved 180 degrees
Tube detector moved across patient then rotated 1 degree
Scan time : 5mins

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10
Q

2nd gen Ct

Type beam?
What does?
Scan time?

A

Fan beam
Multiple detectors in straight line
Tube detector moved across patient then rotated 5 degrees
Total scan time : 20 sec per image

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11
Q

3rd gen Ct

Type beam?
What does?
Major difference?
What does difference help with?
Scan time?
A

Fan beam geometry

Detector array rotates with tube in tube/detector assembly within gantry

Detector array curved arc

Arc arrangement improves reproducibility across array and minimize artifacts

Scan time: less 1 sec per image

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12
Q

Scanners today mostly based off?

A

3rd gen scanner

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13
Q

Scan

A

Collection of anatomical information during time X-ray beam is on

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14
Q

4th gen scanner

A

Similar to 3rd gen

Tube generates X-rays in fan beam geometry , rotates about gantry same as 3rd

Difference: detectors don’t travel with tube in 4th. Circle around patient. Many more detectors

Same time: less 1 sec per image

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15
Q

Slip ring technology

A

Large rotating ring surrounds gantry aperture

Eliminates winding of high tension cables from high frequency generator

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16
Q

Electrical brushes

A

Conveys electrical power and data to components on rotating ring

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17
Q

Slip rings conveys scanning instructions from _______to gantry component in order preform scan

Conveys measure attenuation data from patient to computer and _______ in order facilitate and image

A

Host computer

Array processor

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18
Q

Sling ring transfers

A

Electrical signal
Scanning instructions
Detected signal between stationary components and rotating gantry components

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19
Q 
Multi row detectors
 From?
Scan time vs?
Type beam?
Aka?
A

Collect from multi slices

Faster scan without increase in slice thickness or varying pitch

Very thick X-ray beam and multiple detector arrays

Aka : mdct, msct, multi array scanners

Each parallel detector array composed hundreds scanners along arc

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20
Q

Single row detector

A

Detector array aligned in one row

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21
Q

Multi row detector scanner

Detectors/ why?

Equation

A

Multiple parallel detector arrays in order to vary the number of slices collected in single,rotation and to vary slice thickness

When thick X-ray beam is measured by multiple parallel detector array , thickness of beam \ total number detectors = desired slice thickness

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22
Q

Mdct beam is ____ shape?

A

Cone

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23
Q

___ detector scanners collect info from multiple anatomical slices in each rotation of the X-ray tube

A

Multirow detector scanner

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24
Q

Benefits of multi row detector scanner

A

Fast scans

Increased anatomical coverage

Scanner with thinner slices to improve resolution along slice direction

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25
Q

Electron beam Ct (ebct)

A

No X-ray tube

Very fast scan times: good for cardiac Ct and coronary artery imaging

Produce electron beam that streams from electron gun and which I electromechanical directed toward an army of tungsten anodes.

X-ray beam generated when electron beam strikes anode

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26
Q

Pet/Ct scanner

A

Nuclear imaging modality that involved injection of slightly radioactive pharmaceutical

Malignant tissue characterized by rapid growth and high metabolism , agent accumulation in abnormal tissue

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27
Q

Fusion imaging

A

Comparison of two imaging modality yielding coregistered images

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28
Q

Value in pet image resulting Ct

A

Associate change in metabolism with a specific structure

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29
Q

Attenuation correction

A

S

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30
Q

Cone beam oncology

A

Verifies patient positioning before radiation therapy

High quality 3D image while patient positioning in linear accelerator

Clinicians can compare images for patients treatment plan and positioning adjustment that puts tumor in direct in X-ray beam path

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31
Q

Operator console

A

Key point of interaction between technologist and imaging system

Consists of: keyboard, monitor, and mouse

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32
Q

Keyboard

A

Alphanumeric keys to type

System command for post processing

Image manipulation/ archiving

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33
Q

Mouse/ trackball

A

Graphic input device purpose of planing a scan, selecting image parameters, displaying images, selecting post processing parameters

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34
Q

Monitor

A

Provides feedback on data entry and displaying images

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35
Q

Host computer

A

Primary link between tech and other components of imaging system. Also controls storage devices

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36
Q

Host computer storage devices

A

Hard discs and removable media

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37
Q

Gantry contains

A

Ct tube
Detectors
Slip ring
High voltage generator

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38
Q

Patient table fed through _____ of the gantry

A

Aperture

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39
Q

Rotating frame assembly location

A

Located central aspect of gantry

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40
Q

Rotated assembly frame gantry contains

A

Tube, detector array, data acquisition system

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41
Q

Gantry tilts

A

+ or - 30

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42
Q

Gantry tilt

A

Tilting rotational angle of detector array and Ct tube as it moves around patient
- result: generating attenuated projection along slice plane that is encircled by the tube as it evolves around patient

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43
Q

Patient table movement

A

Controlled by software according to instructions entered by tech

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44
Q

Patient coordinate system

A

Z axis
Y axis
X axis

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45
Q

Z axis

A

Long axis of patients body( along table)

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46
Q

X axis

A

Extends patients left and right

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47
Q

Y axis

A

Extends posteriorly to anteriorly of patient

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48
Q

Ct tube located

A

In rotating frame assembly of the gantry

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49
Q

Electrons of X-ray charge?

A

Negative

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50
Q

Most X-ray reaction in Ct?

A

Bremsstahlung

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51
Q

Bremsstahlung radiation

A

Breaking radiation in which electrons Lose energy of X-ray photons

52
Q

Characteristic radiation % or Ct X-rays?

A

10-12%

53
Q

Characteristic radiation

A

Electron Collides with inner electron shell of target atom ejected, outer shell electron shifts positions , then X-ray photon produced . X-rays produced when fast moving electrons collide with target material and lose energy

54
Q

X-ray tube two electrodes

A

Anode and cathode

55
Q

Electron beam flow?

A

Cathode to anode

56
Q

Cathode contains

A

Filament heating wires

57
Q

Filament is in cup shaped _____

A

Cathode

58
Q

Cup shaped region part cathode

A

Focuses electron beam to anode target material

59
Q

Filament temp controlled by?

A

Ma selected by tech

60
Q

Ma

A

Tube current that determines number of X-ray photons produced

61
Q

Kv

A

Tube voltage that controls photo energy level selected by tech

62
Q

Ma=_____ ampere

A

1/1000

63
Q

Ct voltage range

A

90-140

64
Q

Space charger compensator

A

Applied to tube filament which cools filament slightly as tube voltage increases in order to prevent an unwanted elevation in tube current in response to higher kv levels

65
Q

X-ray photons produced at?

A

Anode

66
Q

Target material

A

Tungsten

67
Q

Whyntungsten target material?

A

High atomic number #74

Withstand heat

Melting point 3400degree c

68
Q

Target located

A

Rotating anode

69
Q

Why anode rotates

A

Avoid excess heat and extends life tube

70
Q

Cathode of Ct tube

A

Contains more than one filament

Small filament - smaller area covered- determines focal spot

71
Q

Focal spot

A

Area of target from which useful X-rays emitted

72
Q

Small focal spot

A

Thin slices, higher resolution

73
Q

Interscan delay

A

Minimum amount of time frame that must transpire between one scan and initiation of next

Shorter the better

74
Q

Window of tube

A

X-ray beam exits

Filter restricts low level X-ray photons

75
Q

Beam hardening

A

Filter out low energy rays to lessen patient dose and improve image quality

76
Q

Collimation

A

Restricts X-rays only to selected cross section region thereby minimizing patient dose and reducing scatter

77
Q

Scatter radiation

A

X-rays that are deflected at many angles

- degrades image

78
Q

Two types collimation

 -
A

Pre patient

Post patient

79
Q

Pre patient collimating

A

Restricts X-ray beam to thickness of the slice in single row detector
- made of thick metal plates attached to bottom tube housing

80
Q

Multi row detector pre patient collimating

A

Select thickness of X-ray beam which spreads over multiple detectors
- reduces dose

81
Q

Slice thickness in mdct

A

Determined by image reconstruction

82
Q

Post patient collimating

A

Further refines the path of X-ray photons after they pass through the patient and before they enter detectors

83
Q

Two main purposes of post collimtion

A

Conjunction with pre patient collimator assembly to provide better definition of slice thickness ( single slice Ct)

Reduce scatter radiation to detectors

84
Q

Detectors

A

First component of data acquisition system (das)

Measures in coming X-rays

85
Q

In order X-ray photon to generate a signal

A

X-ray must be able to enter the chamber of the detector and be captured

X-ray collides with atom in detector material

Collision of X-ray photon and detector material must produce a measurable event( electricity or light)

86
Q

Two categories :

A

Gas and solid state

87
Q

Gas detector

A

Large detector array with hundreds of chambers with the array ( gas detectors)

88
Q

Gas used in gas detector

A

Xenon

89
Q

Pressure to compress gas?

A

Decrease vacant space and increase probability X-ray photons collide with xenon atom

90
Q

Collision of X-rays gas detector

A

Xenon atom splits into xenon ion and an electron which migrates to detector electrode plates which detects event

91
Q

Gas detector located

A

In stationary ring around the gantry in 4th gen

92
Q

Gas chambers and collimating

A

Provides own post collimation

93
Q

Must prevalent type detector

A

Solid state detector

94
Q

Solid state detectors

A

Scitilation detectors

95
Q

Solid state detector material

A

Solid crystalline

96
Q

Solid state detector photon collision

A

Photon and detector atom occurs closer to surface then gas detector

97
Q

Solid state detector arrangement

A

Multiple detector arrays , uses flash of light which is sensed by photodiode

98
Q

Photodiode

A

Photon strikes the solid state material emits flash of light which converted into electrical pulse by

  • attached to bottom of solid state material on detector
99
Q

Single row detector arrays

A

Have single row array of detectors arranged along curved arc- opposite X-ray tube

100
Q

On single row detector scanner _____ of X-ray determines final slice thickness

A

Collimation

101
Q

Multiple parallel rows detector elements arranged along

A

Curved arc opposite X-ray tube

102
Q

Mdct X-ray beam collimated

A

Thickly

103
Q

Acquired slice thickness formula

A

Thickness of beam
_______________________
Total number of slices acquired in single rotation

104
Q

How many adjacent multi row detectors in mdct

A

64

105
Q

Thinner slices

A

Attenuation info for one slice can be measured by detectors in single detector array

106
Q

Thicker slices

A

Measured by detectors in several adjacent detector arrays

107
Q

Types detector arrays

A

Symmetric and asymmetric

108
Q

Symmetric detector array

A

Size each detector is identical

109
Q

Assymetric detector array

A

Detector size varies

110
Q

Mdct several channels of measured attenuation info can be added together to generate

A

Slice thickness

111
Q

Array processor

A

Primary location for all complex mathematical calculations involved in generation of Ct

Reconstruction of projected attenuation raw data into Ct images

Site to generate retrospective reconstruction and sometimes post process image data

112
Q

Picture archiving and communication system( PACS)

A

Connects operator console to storage system and distribution images
- also patient list for console

113
Q

Dicom- digital imaging and communications in medicine

A

Goal is to achieve compatibility and workflow efficiency between imaging systems in healthcare environments worldwide

114
Q

Specified protocol for dicom

A

Tcp/ip

115
Q

Network

A

A number of interconnected digital devices that need to share information

Devices operators consoles of digital imaging modalities , image workstations , image viewing stations, image storage devices, printers and personal computers

116
Q

A network comprised of:

A

Server and client

117
Q

Server

A

Archive device that stores image

118
Q

Client

A

Image workstation which needs to access the images that are stored on a server

119
Q

Hub

A

Receives incoming packets of data , amplifies electrical signal and then it broadcasts these packets out to all devices on the network

Includes one that originally sent packet

120
Q

Network switch

A

Connects multiple clients to a server but individual traffic elements and selectively forwarding data to the one device that actually needs it

121
Q

Bandwidth

A

Rate of transfer which in bits per second

122
Q

File sizes denoted

A

MB( megabytes)

123
Q

Bandwidth denoted in

A

Mb ( megabits)

124
Q

Virtual private networks (vpn)

A

Allows remote authorized individuals to connect in secure fashion to server located in a location , using the routing infrastructure provided by public network

125
Q

Electronic health network (ehr)

A

Contains and shares information from all providers involved in patient care

126
Q

Electronic medical record ( emr)

A

Contains standard medical data gathered from a patient in a single provider office
- electronic medical records

Ct Review Class (7 decks)

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