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Advanced Imaging > Midterm > Flashcards

Midterm Flashcards

1
Q

What are four appearances of artifacts?

A

Ring
Band
Streak
Shading

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2
Q

What is the start and end location for a CT routine chest?

A

Just above lung apices to Kidneys

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3
Q

Name two patient induced artifacts in CT?

A

Motion & Metal & Out of field

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4
Q

Name the two correction/remedy for ring artifacts in CT?

A

detector calibration
detector replacement

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5
Q

The only CT procedures that you have learned that is scan in Axial is?

A

Head

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6
Q

What is the definition of the term “slice” in relationship to CT?

A

One 360 degree rotation around the patient pieced together

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7
Q

What is the CT number for bone?

A

400 to 1000

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8
Q

What is the CT number for air?

A

-1000

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9
Q

What is the CT number for water?

A

0

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10
Q

What is the CT number for lung?

A

-200

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11
Q

Name the four step process of a conventional CT scanner?

A

1- start; tube and detectors are accelerated to const. speed
2- x-ray tube energized data collected for 360 degree
3-stop; tube and detectors slow down & stop
4-table & patient indexed to the next scanning position

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12
Q

What is the display field of view?

A

the area at which the tube is imaging

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13
Q

What is another name for a conventional CT scanner?

A

Slice by Slice scanner

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14
Q

Name two requirements for a Spiral/Helical CT unit

A

-Complete a full 360 degree rotation continually
-Table move through the gantry continuously

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15
Q

What is a pixel?

A

a 2 dimensional area of an image

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16
Q

What is a matrix?

A

rows and columns of pixels together

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17
Q

What are two advantages of a multi-slice CT scanner?

A

-Faster scan time- easier with single breath for patient
-Better spatial resolution

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18
Q

Name the three steps for formation of CT images by a CT scanner?

A

-Data acquisition
-Image resolution
-Image display

DII ARD FORM

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19
Q

Spiral CT was made possible because of what new technology?

A

Slipring technology

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20
Q

What are two important features of the gantry?

A

-Apperature
-Tilting of the gantry

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21
Q

Who was the person who developed the mathematics used to reconstruct the CT images?

A

Radon/Cormack

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22
Q

Name the generation scanner that used a rectilnear pencil beam?

A

1st gen

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23
Q

Name the generation scanner that used spiral?

A

6th gen

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24
Q

Name the generation that used rotate-rotate?

A

3rd gen

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25
Q

Name the generation that used translate rotate?

A

2nd gen

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26
Q

What is the purpose of the detectors?

A

To capture the beam to help create the image

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27
Q

Name the two types of collimators in a CT unit?

A

-Precollimator
-Predetector

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28
Q

What is the most significant development in radiology in the past 40 years?

A

CT

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29
Q

When does tomography trace back to?

A

1920’s

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30
Q

What does a CT scanner do?

A

Looks at a specific layer or section of the body

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31
Q

Conventional Tomography uses what type of tomography?

A

Axial

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32
Q

Computed Tomography uses what type of tomography?

A

Transverse image

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33
Q

How many major design advancements has Ct gone through since 1970’s?

A

5

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34
Q

What type of beam did the 1st generation CT scanner use?

A

pencil beam

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35
Q

How much did the 1st generation scanner rotate?

A

180 degrees

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36
Q

What kind of scan was the 2nd generation?

A

translate rotate

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37
Q

How much did the 2nd generation CT scanner rotate?

A

180 degrees

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38
Q

How many detectors did the 2nd generation CT scanner have?

A

5 to 30 detectors

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39
Q

What was special about the 2nd generation over the 1st generation?

A

It had a faster scan time

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40
Q

What kind of scan did the 3rd generation use?

A

Rotate-Rotate

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41
Q

What kind of beam did the 3rd generation use?

A

A fan beam of 30-60 degrees for full patient coverage

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42
Q

What happens in the 3rd generation if one detector fails?

A

A ring artifact appears

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43
Q

How much did the 3rd generation scanner rotate?

A

360 degrees

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44
Q

Why didn’t the 4th generation CT scanner last long?

A

-Cost of detectors
-Too much scatter given off

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45
Q

How did the tube rotate in 4th generation scanners?

A

Rotates around a stationary ring of detectors

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46
Q

What type of beam was used in the 4th generation scanner?

A

Fan beam

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47
Q

How many detectors did the 4th generation use?

A

8,000 detectors

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48
Q

What is the 5th generation scanner used for?

A

Heartscan

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49
Q

What was special about the 5th generation scanner?

A

Allowed for continuous rotation of the tube for spiral
The continuous motion made no interscan delay b/c as the tube moves the table moves

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50
Q

What made Spiral CT possible?

A

Slipring technology

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51
Q

What is another name for 6th generation scanner?

A

Spiral CT

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52
Q

What were benefits of Spiral CT?

A

-Less motion artifacts
-Improved lesion detection because the reconstructed image can be at arbitrary intervals
-Reduced scan time
-Advances in computer processing allows for multi-planar reconstruction and even 3D reconstruction

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53
Q

What are basic CT scanner components?

A

-Gantry includes the pedestal or table, tube, collimators, detectors, and high voltage generator
-Operators Console
-Computer

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54
Q

What are the three steps of the formation of CT images by a CT scanner?

A

1- Display Acquisition
2- Image Reconstruction
3-Image Display

DII ARD FORMATION

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55
Q

What is image acquisition?

A

Refers to the collection of x-ray transmission measurements from the patient

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56
Q

How many layers of laser are on the gantry?

A

3 layers

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57
Q

What is the tilt range for the gantry?

A

+/- 12 to +/- 30 degrees

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58
Q

Table weight limits vary from ____ to ____ lbs.

A

300 ; 600

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59
Q

What is Slice by slice data acquistion?

A

Conventional CT, the tube rotates around the patient to collect data from a single slice of tissue, followed by table moving so that the next contiguous slice can be scanned

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60
Q

What are the four steps of Interscan delay?

A

1- Tube must be accelerated to constant speed of rotations
2- Tube produces x-rays that are transmitted through the patient to fall on the detectors
3- patient resumes breathing while the tube slows down and comes to a stop
4- Unwind the cable so another 360 degree slice can be scanned

61
Q

Is interscan delay in Spiral CT?

A

No, the scan stops and the patient moves

62
Q

What are limitations of interscan delay?

A

-Longer exam times
-Omission of certain portions of anatomy b/c patient respiration phase may not be consistent
-Inaccurate generation of 3D images and multiplanar reformatted images, also from inconsistent levels of inspiration

63
Q

How does Spiral-Helical CT work?

A

The tube rotates continuously around the patient

64
Q

Why is Spiral Ct called Spiral CT?

A

The geometry describes a spiral or winding

65
Q

The geometry of Spiral-Helical CT also is called? Why?

A

Spiral-helical Volume CT; It defines a volume of tissue

66
Q

What are requirements for Spiral-Helical CT?

A

-Continuously rotating scanner based on slip ring technology
-Continuous table movement
-Increase load ability of the x-ray tube
-Spiral-Helical Algorithm
-Mass memory buffer to store the vast amount of data collected
-Increased cooling capacity of the x-ray tube
-Slip rings replaced the high tension cables and allowed for the continuous rotation of the tube
-Volume scanning, Spiral Helical Scanning are the same

67
Q

What are advantages of Spiral CT?

A

-Multiplanar reconstruction
-Shorter scan times
-Artifacts reduced

68
Q

When was multislice CT scanners announced?

A

1998

69
Q

What were multislice CT scanners capable of?

A

Imaging four slices simultaneously per x-ray tube rotation

70
Q

At the present time, multislice scanner are available to image how many slices per x-ray tube rotation?

A

320

71
Q

What are the advantages of multislice scanners?

A

-Shorter acquisition time
-Decreased amount of contrast medium
-Improved spatial resolution
-Improved image quality

72
Q

What is Raw Data?

A

The signal data from all of the detector responses and contain the most information for image production

73
Q

What is another name for Raw Data?

A

Scan Data

74
Q

What is Image Data?

A

Reconstructed data; The result of raw data undergoing computer computations and filtered back projection to produce the image

75
Q

What is a matrix?

A

Grid formed from rows and columns of pixels

76
Q

What is a pixel?

A

Two dimensional square picture element utilized toe display a digital image

77
Q

What is a voxel?

A

A 3D cube of anatomy

78
Q

What is a CT number/ Hounsfield number?

A

The number assigned that is related to the linear attenuation coefficient of the tissue within each voxel of the image

79
Q

What is the CT number for fat?

A

-80 to -120

80
Q

What is SFOV?

A

Area within the gantry from which the raw data are acquired

81
Q

What is DFOV?

A

Determines how much of the raw data are used to create and image

82
Q

What is ROI?

A

A display function available on all scanners defining and area on the image

83
Q

What is algorithm?

A

set of mathematical calculations and processes applied in image reconstruction

84
Q

What is the linear attenuation coefficient?

A

Numeric expression of the decrease in radiation intensity that follows transmission through matter

85
Q

What is slice?

A

Section of the object that is being scanned

86
Q

What are slip rings?

A

Devices that transmit electrical energy and allow continuous rotation of the x-ray tube for volumetric acquisition

87
Q

What is volume scanning?

A

Refers to the acquisition of a volume of CT data, the patient moves through the gantry with uninterrupted rotation and output of the x-ray tube

88
Q

What are indications for Head CT without contrast?

A

-Intracranial hemorrhage
-Early infarction
-Dementia
-Hydrocephalus
-Cerebral trauma
-Headaches
-Seizure

89
Q

What are indications for Head CT with contrast?

A

-Mass
-Lesion
-AVM
-Aneurysm
-Metastasis

90
Q

What ae indications for Chest CT with contrast?

A

-Infection
-Mass
-Emphysema
-Evaluation of abnormalities discovered on chest radiographs
-Evaluation of know or suspected congenital thoracic anomalies
-Evaluation of trauma

91
Q

What are indications for Abdomen and Pelvis CT with contrast?

A

-Suspected abdominal mass
-Tumor staging
-Abscess
-Infection
-Pelvic mass
-Hematuria
-Renal Mass

92
Q

What are indications of Renal stone study without contrast?

A

Suspected renal or ureteral calculi

93
Q

What are indications for Cervical Spine CT?

A

Fracture or Dislocation

94
Q

What are indications for Lumbar Spine CT?

A

Fracture or Dislocation

95
Q

What are the scouts for Head CT?

A

AP & Lateral

96
Q

What is the scan type for Head CT?

A

Axial

97
Q

Where is the start and end location for Head CT?

A

Just below skull base (C1-C2)
Just above vertex

98
Q

What are the window settings for Head CT?

A

-Soft Tissue
-Bone

99
Q

What reconstructions are made for Head CT?

A

Sagittal & Coronal

100
Q

How does the patient go in for Head CT?

A

Head first

101
Q

What scouts are done for Chest CT?

A

AP & Lateral

102
Q

What is the scan type for Chest CT?

A

Helical

103
Q

Where is the start and end location for Chest CT?

A

Just above lung apices
To top of kidneys

104
Q

What are the window settings for Chest CT?

A

Soft Tissue & Lung

105
Q

What reconstructions are made for Chest CT?

A

Sagittal & Coronal

106
Q

How does the patient go for Chest CT?

A

Goes in feet first with arms over head

107
Q

What scouts are done for Abdomen & Pelvis CT?

A

AP & Lateral

108
Q

What is the scan type for abdomen & pelvis CT/

A

Helical

109
Q

Where is the start and end location for abdomen and pelvis CT?

A

Just above Diaphragm
Just below Symphysis pubis

110
Q

What Contrast is used for abdomen and pelvis CT?

A

Iv and Oral

111
Q

What are the window settings for abdomen and pelvis CT?

A

Soft Tissue
Lung
Liver

112
Q

What reconstructions are made for abdomen and pelvis CT?

A

Sagittal & Coronal

113
Q

How does the patient go in for abdomen and pelvis CT?

A

Goes in feet first with arms over head

114
Q

What scouts are done for renal stone studies?

A

Ap & Lateral

115
Q

What scan type is renal stone studies?

A

Helical

116
Q

Where is the start and end location for renal studies?

A

Just above diaphragm
Just below Symphysis Pubis

117
Q

Why don’t you use contrast for renal stone studies?

A

Both stones and contrast appear white; making it difficult to see a stone

118
Q

What are the window settings for renal stone studies?

A

Soft Tissue

119
Q

What reconstructions are made for renal stone studies?

A

Sagittal & Coronal

120
Q

How does the patient go for renal stone studies?

A

feet first with arms over head

121
Q

What scouts are done for Cervical Spine CT?

A

Ap & Lateral

122
Q

What is the scan type for Cervical Spine CT?

A

Helical

123
Q

Where is the start and end location for Cervical Spine CT?

A

Just below Skull base (C1-C2)
Middle of T2

124
Q

What are the window settings for cervical spine ct?

A

Soft Tissue
Bone

125
Q

What reconstructions are made for Cervical Spine CT?

A

Sagittal & Coronal

126
Q

How does the patient go for Cervical Spine CT?

A

Head first

127
Q

What scouts are done for Lumbar Spine CT?

A

AP & Lateral

128
Q

What scan type is Lumbar Spine CT?

A

Helical

129
Q

Where is the start and end location for Lumbar Spine CT?

A

T12
S1

130
Q

What are the window settings for Lumbar Spine CT?

A

Soft Tissue
Bone

131
Q

What reconstructions are made for Lumbar Spine CT?

A

Sagittal & Coronal

132
Q

How does the patient go for Lumbar Spine CT?

A

Feet first

133
Q

What is an artifact?

A

Any discrepancy between the CT numbers represented in the image and the expected CT number based on the linear attenuation coefficient

134
Q

What are the 4 appearances of artifacts?

A

-Streaks
-Band
-Shading
-Rings

135
Q

What are sources of artifacts?

A

-Patient
-Imaging Process and Equipment

136
Q

What are patient induced artifacts?

A

-Motion
-Metal Artifacts
-Out of field artifacts

137
Q

Motion artifacts are caused by?

A

Voluntary and Involuntary Motion

138
Q

What is the remedy for voluntary motion? involuntary motion?

A

voluntary: explanation of procedure and good communication

involuntary: short scan time

139
Q

How does metal artifacts manifest itself?

A

Start Streaking

140
Q

What is the remedy for metal artifacts?

A

-Removal of external metallic objects
-Mar Software
-Gantry angulation

141
Q

What is out of field artifact?

A

Patient is not entirely enclosed in the scanning field of view

142
Q

What is the remedy for out of field artifacts?

A

-Selection of larger SFOV
-Taping patient tissue
-Raising patients arms above their head on the scan of chest and abdomen

143
Q

What are equipment imaging process artifacts?

A

-Ring
-Line in Topogram
-Staircase

144
Q

What is ring?

A

Malfunction of a detector in a third generation scanner

145
Q

What are the remedies for ring?

A

-Detector calibration
-Detector replacement

146
Q

What is Line in Topogram?

A

Bad detector causes continuous line on the topogram

147
Q

What is the remedy for Line in Topogram?

A

Detector Replacement

148
Q

What is staircase?

A

Improper selection of slice thickness and slice incrementation when generation MPR and 3D images

149
Q

What is the remedy for staircase?

A

-Thin Slice use
-50% overlap on recon slice incrementation

Advanced Imaging (11 decks)

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