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Contrast Media > CT Registry > Flashcards

CT Registry Flashcards

1
Q

Computed Tomography uses what

A

X-Rays to image individual slices through the body

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2
Q

X-Rays are directed

A

Into a localized section of the patient

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3
Q

How is an image seen (simple)

A

Detected signals are constructed into an image

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4
Q

CT system console controls what

A

Information about the pt
specific imaging parameters
post-processing techniques
filming and arching instructions

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5
Q

CT Console information goes…

A

To the Host computer, translated into systems machine language then to scan controller.

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6
Q

Scan Controller controls what

A

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

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7
Q

How is information from the scan controller sent

A

Electronic signals are converted into analog (continuous) waveform. DAS converter accomplishes this.

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8
Q

What does the Gantry contain

A

CT X-Ray tube

Detectors

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9
Q

The technique that allows the user to select the range of pixel values used in a 3D ct reformation is termed

A

Thresholding

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10
Q

A voxel’s dimension may be decreased by

A

Decreasing the section width

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11
Q

What may cause abnormal findings and will reduce the density of the liver?

A

Fatty Infiltrate

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12
Q

Patients whose posterior descending artery branches from the right coronary artery, and whose left posterior ventricle branches arise from the left circumflex artery, are said to be

A

Codominant

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13
Q

What does it mean to be Codominant

A

7% of the population is said to be codominant, meaning that the posterior descending artery (PDA) is supplied by the right coronary artery (RCA) and the left posterior ventricular branches arise from the left circumflex artery (LCA)

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14
Q

The articulation between the distal tibia and the fibula is called the

A

Syndesmoisis

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15
Q

For MDCT identified areas of calcium must demonstrate relative attenuation values greater than

A

+130 HU

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16
Q

1st generation scanner produced what type of x-ray beam:

A

Thin “pencil beam”

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17
Q

How many detectors did a 1st generation ct use

A

One detector

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18
Q

How did the tube/detectors assembly work/move in a 1st generation scanner

A

Across the patient then rotated by 1 degree

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19
Q

Total scan time for 1st generation ct

A

5 mins per image

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20
Q

Anatomy scanned on 1st generation

A

Head

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21
Q

2nd generation scanners produced what type of x-ray beam

A

Fan Beam

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22
Q

How many detectors did a 2nd generation use

A

Multiple @30, in a straight line called an array

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23
Q

How did the tube/detector assembly on a 2nd generation scanner work/move

A

Across the patient, then rotated by 5 degrees

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24
Q

Total scan time on a 2nd generation scanner

A

20 seconds per image

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25
Q

3rd generation scanners produce what type of x-ray beam

A

Fan Beam

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26
Q

How many detectors will a 3rd generation scanner have

A

Multiple detectors along an arc

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27
Q

How does the tube detector assembly move/work on a 3rd generation

A

The tube/detector assembly rotates around the patient.

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28
Q

Total scan time on a 3rd generation

A

Faster than 1 second per image

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29
Q

Most scanners today are based on what generation of CT scanner

A

3rd

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30
Q

4th generation scanners produces what type of x-ray bea

A

Fan Beam

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31
Q

How many detectors will a 4th generation have

A

Multiple detectors encircle the patient and do not rotate

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32
Q

How does the tube/detector assembly move/work on a 4th generation

A

Only the tube rotates around the patient.

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33
Q

Total scan time on a 4th generation

A

Faster than 1 second per image

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34
Q

The Slip Ring transfers the following information between stationary components and the rotating gantry

A

Electrical power
Scanning instructions
detected signals

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35
Q

Multirow detectors collect information from _____ and how does this affect the scanned anatomy

A

Multiple anatomical slices in each rotation.

Anatomy can be scanned faster without increasing the slice thickness or varying the pitch

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36
Q

MDCT

A

Multi-row Detector Scanners

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37
Q

MSCT

A

Multi-array Scanner

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38
Q

MDCT Systems use what type of x-ray beam

A

Cone Beam

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39
Q

Describe an electron beam CT scanner and it’s use

A

Alternative design that has no x-ray tube

Very fast scan times making it suited for cardiac and coronary artery imaging.

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40
Q

What is fusion imaging and what is most commonly associated with it

A

Comparison of two imaging modalities yielding co-registered images.
PET/CT scanners

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41
Q

What does PET stand for

A

Positron Emission Tomography

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42
Q

PET images are sensitive to changes in…

A

Metabolism associated with malignant tissues

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43
Q

What is the value of overlaying PET images with High-Resolution CT images

A

Best to associate a change in metabolism with a specific structure.

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44
Q

How is cone beam CT associated with oncology

A

Cone beam CT is being used in the oncology department in order to verify patient positioning prior to receiving radiation therapy.

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45
Q

CT Colonography images are best displayed in what window settings:

A

“lung-type” -400L/1600W

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46
Q

____ is a term that refers to an excessive amount of nitrogenous materials in the blood and is a symptom of renal failure.

A

Azotemia

AKA uremia Azotemia

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47
Q

How do you determine the linear dimension of each pixel?

A

DFOV/Matrix size

*convert cm-mm /add zero to end of cm

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48
Q

What measuring unit is used to quantify effective dose?

A

Sieverts

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49
Q

What does Effective Dose Mean

A

ED approximates the relative risk from exposure to ionizing radiation and is based on the radiosensitivity of a given tissue type.

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50
Q

Phantom measurement of the uniformity of a CT system is performed primarily to assess the negative effets of

A

Beam Hardening

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51
Q

As low-energy x-ray photons are absorbed when the beam passes through the patient, the average photon energy of the beam increases along the path and may result in a loss of system uniformity. This is known as

A

Beam Hardening

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52
Q

The type of hemorrhage that occurs between the skull and outer layer of the dura in traumatic brain injury is referred to as

A

Epidural Hematoma

53
Q

The type of hemorrhage that occurs between the dura matter and the inner layer of meninges known as the arachnoid is called

A

Subdural Hematoma

54
Q

Increased section width or increased table speed will play a roll in increasing

A

Pitch

55
Q

An increase in Pitch is the result of

A

An increase in section width or increase in table speed

56
Q

The process of scanning a phantom device of known density to improve the accuracy of CT attenuation measurement maybe referred to as

A

Calibration

57
Q

What type of artifact manifests as a streaking effect at areas of extremely-high-density interfaces

A

Edge Gradient

58
Q

The soft center of each inter-vertebral disc is called the

A

Nucleus Pulposus

59
Q

How do you calculate DFOV (display field of view)

A

Pixel dimension X matrix size
ex: 320 matrix, 0.75 mm x 0.75mm pixel dimension
320X.75=240/24cm

60
Q

A high-osmolar contrast material has an average osmolality of

A

1000-2400 mOsm/kg Water

61
Q

Operator’s console

A

Key point of interaction between the technologist and the imaging system

62
Q

Host computer

A

Primary link between technologist and the other components of the imaging system

63
Q

Gantry houses

A

X-Ray tube
Detectors
Slip Rings
High voltage generator

64
Q

Patient table

A

Controlled by software according to tech instruction.

65
Q

Patient coordinates “Axis”

A

X: Left to Right
Y: Anterior to Posterior
Z: Head to Feet

66
Q

Tungsten Atomic Number

A

High 74

67
Q

The average CT value for blood is @

A

+45

68
Q

Pulmonary nodes assumed to be benign have an average density within what range?

A

+164 and higher

69
Q

The normal range for the International Normalized Ratio (INR) for Prothrombin Time (PT) results in

A

-0.8- -1.2

70
Q

INR stand for and is what

A

International Normalized Ratio

INR compares a patients PT with a control sample for more accurate results.

71
Q

An increase in Sample Frequency results in

A

an Increase in Spatial Resolution

72
Q

Describe the relationship between Slice Sensitivity Profile (SSP) and dose profile

A

Dose profile is always HIGHER than SSP

73
Q

High resolution CT examinations of the temporal bones and internal auditory canal should include

A 
Thin sections (1-2mm)
Small targeted DFOC (less than 10cm)
High Resolution algorithm (kernal) for reconstruction
74
Q

A good display field of view (DFOV) for a thorasic spine would be:

A

15 cm

75
Q

Calculate beam pitch

A

Total # of sections (detectors) multiplied by the detector dimension, then divide the table movement by answer above.

76
Q

What measuring units Quantify absorbed dose?

A

Greys

*absorbing x-rays give shades of gay (Greys)

77
Q

The approximate inherent filtration of the CT x-ray amounts to an aluminum equivalent of

A

3.0mm

78
Q

What term describes a condition in which cerebral ischemia is caused by systemic hypertention

A

Vasovagal reaction

79
Q

What phase of renal contrast enhancement provides maximum sensitivity for parenchymal lesions?

A

Nephrographic

70-90 seconds after injection

80
Q

Multiplanar reformations (MPR) images along the long axix of the optic nerve would be best described by which of the the following anatomic planes?

A

Oblique Sagittal

81
Q

The ability of CT system to reduce involuntary motion artifacts and provide CT images free of motion artifact is determined by which of the the following components of image quality

A

Temporal resolution

Temporal resolution=stop motion/no blurring

82
Q

What mathematical functions may be used to quantify the spatial resolution of a CT scanner

A

PSF (Point Spread Function)
MTF (Modulation Transfer Function)
LSP (Line Spread Function)

83
Q

In multislice CT (MSCT) the beam of pitch is equal to the table feed per rotation divided by the

A

Total collimation

84
Q

A decrease in matrix size will

A

Decrease Noise

85
Q

The Iliac artery bifurcates at

A

L5-S1

86
Q

Pathway of blood

A
  • From Superior & Inferior Vena Cava’s (and coronary sinus) to-
  • Right Atrium, through the tricuspid valve to-
  • Right Ventricle, through the Pulmonary Semilunar Valve to-
  • Pulmonary Trunk, Rt and Lt pulmonary Arteries to lungs, from lungs to-
  • Heart, through Plumonary Veins to-
  • Left Atrium, through bicuspid (mitral) valve to-
  • Left Ventricle, through aortic semilunar valve to-
  • Ascending aorta
87
Q

Collimation restricts x-rays to only the selected cross-sectional region. How does this affect the pt.

A

It minimized the dose to the pt and reduces scatter.

88
Q

Pre-patient collimation is a factor indetermining the slice thickness in _____ dectector CT, but NOT in _____ detector CT

A

Single-row

Multi-detector

89
Q

In order for an x-ray photon to generate a signal, it must

A
  • enter the detector
  • collide with a detector atom
  • produce a measurable event
90
Q

What type of detectors are the most prevalent type used on today;s CT scanners?

A

Solid State

91
Q

What happens when a photon strikes a solid state material/detector?

A

It emits a flash of light which is converted into an electrical impulse by a photodiode.

92
Q

How do you calculate acquired slice thickness on a MDCT scanner?

A

The thickness of the x-ray beam is divided by the total number of slices acquired in a single rotation.

93
Q

What is the primary function of the array processor?

A

Reconstruction of the projected attenuation raw data into CT images

94
Q

In radiology, a network refers to

A

A number of interconnected digital devices that need to share information

95
Q

How many bits are in a byte?

A

8

96
Q

Which stage following renal contrast enhancement provides maximum sensitivity for parenchymal lesions?

A

Nephrographic (70-90 minutes after injection)

*PN (like PM-time of day)

97
Q

The ability of an object to attenuate the x-ray beam is assigned a value known as the

A

Linear attenuation coefficient

98
Q

An increase in detector pitch does what

A

Raises the rate at which the patient moves through the gantry during data acquisition, thus lowering patient dose.

99
Q

In CT a decrease in KVp does what to patient dose?

A

Decreases patient dose, (opposite of x-ray)

100
Q

Ischemic brain tissue is identified as an infarct core when cerebral blood volume (CBV) falls below:

A

2.5 ml/100g

101
Q

What terms are commonly used to describe a CT scanners ability to differentiate objects with similar linear attenuation coefficients?

A

Sensitivity

Contrast Resolution

102
Q

Which of the following components of CT image quality may be controlled by the technologist:

  • Spatial Resolution
  • Contrast Resolution
  • Noise
A

ALL OF THEM

103
Q

Spatial resolution is affected by what geometrical factors?

A

Focal Spot Size

Slice Thickness

104
Q

Contrast Resolution may be altered by

A

Size Thickness
Algorithm Selection
Noise

105
Q

The Basilary artery and Middle (Rt & Lt) cerebral arteries are NOT part of what part of the brain?

A

Circle of Willis

106
Q

Phantom measurement of the uniformity of a CT system is performed primarily to assess the negative effects of

A

Beam Hardening

107
Q

The best method of reducing the risk of contrast induces rephrocity (CIN) is

A

Adequate patient hydration

108
Q

What type of image reconstruction was used in the first prototype CT scanner

A

Iterative technique

109
Q

The degenerative pathologic process of the spine known as spondyloysis involves a defect in the

A

Pars Interarticularis

110
Q

The process of scanning a phantom device of known density to improve the accuracy of CT attenuation measurement may be referred to as

A

Calibration

111
Q

The ability of a CT scanner to image a small high-density object is controlled by the _____ of the scanner

A

Spatial Resolution

112
Q

Areas of a CT image containing abrupt changes in tissue density are electronically represented by

A

High Spatial Frequencies

113
Q

A grid of pixels comprise a

A

Matrix

114
Q

The width of a CT window controls

A

The range of pixel values

115
Q

When one is choosing a window to display a CT image, the width defines

A

The range of CT numbers (pixels) to be displayed

116
Q

In patients who are right dominant, the posterior descending artery branches from the

A

Right Coronary Artery

117
Q

The full width at half maximum (FWHM) of a slice sensitivity profile diagram indicates the

A

Effective Section Width

118
Q

The quantity of radiation dose received by the pt from a series of CT scans is referred to as

A

MSAD (Multi Slice Average Dose)

119
Q

The calculation of the average cumulative dose to each section within an acquisition of Multiple Sections is termed the

A

MSAD (Multi Slice Average Dose)

120
Q

The approximate radiation dose measured during a scan of a 100-min pencil ionization chamber is the

A

CTDI

121
Q

Technological factors that exhibit an effect upon Longitudinal Spatial Resoultion

A
  • Detector Pitch

- Interpolation algorithm

122
Q

Glimoa tumors are found in the

A

Brain

123
Q

A decrease in apperature size will increase

A

Noise

124
Q

PET system absorbs what type of radiation

A

Annihilation Photons

125
Q

Agaston Scores for MDCT cardiac examination

1-10

A

Min

126
Q

Agaston Scores for MDCT cardiac examination

11-100

A

Mild

127
Q

Agaston Scores for MDCT cardiac examination

101-400

A

Moderate

128
Q

Agaston Scores for MDCT cardiac examination

>400

A

Extensive

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