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Computed Tomography (CT) > CT Glosssary > Flashcards

CT Glosssary Flashcards

1
Q

The reformatting of cross-sectional images to produce images of the surfaces of anatomical structures

A

3D Surface Rendering

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2
Q

A mechanism of attenuation in which x-ray photons interact with the patient’s tissues and never leave the body

A

Absorption

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3
Q

A hardware component used to increase the strength of a signal

A

Amplifier

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4
Q

Information expressed in a continuous fashion

A

Analog

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5
Q

The component that converts the analog data into digital information to be temporarily stored in the raw data file

A

Analog-to-Digital Converter (ADCs)

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6
Q

The positive terminal of the CT x-ray tube and the part of the tube where the target material is located

A

Anode

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7
Q

Saving the patient’s digital images on a long-term storage device

A

Archiving

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8
Q

A specialized computer component used to reconstruct the CT images

A

Array Processor

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9
Q

Annoying anomalies which sometimes appear in CT images

A

Artifacts

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10
Q

A reduction in the number of photons in the x-ray beam as it passes through the tissues in the patient’s body

A

Attenuation

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11
Q

A calculation used for reconstructing the final CT images from the raw data by adding together the attenuation information collected from all of the projections

A

Back Projection

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12
Q

A type of oral contrast agent known for providing very good opacification of the bowel, but is slower moving through the GI tract compared to iodinated agents

A

Barium Sulfate Oral Contrast Agent

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13
Q

The increase in the average energy of the x-ray beam as it penetrates tissues

A

Beam Hardening

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14
Q

Refers to the timing immediately following an IV contrast injection defined by at least a 30 HU difference between the abdominal aorta and the inferior vena cava

A

Bolus Phase of Enhancement

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15
Q

X-rays produced as a result of an electron colliding with or passing near the nucleus of an atom in the target

A

Bremsstrahlung (braking radiation)

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16
Q

The negative terminal of the CT x-ray tube and the part of the tube where the negatively charged electrons flow into the tube from the high voltage generator

A

Cathode

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17
Q

X-rays produced as a result of an electron in the target replacing one ejected by a fast-moving incoming electron

A

Characteristic Radiation

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18
Q

Components on the CT scanner that restrict the path of the x-ray photons

A

Collimator

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19
Q

An x-ray tomographic technique which uses computers to reconstruct the images

A

Computed Tomography

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20
Q

A calculation used for reconstructing the final images from the raw data used on multi-row detector scanners with the capability of collecting more than four slices in a single rotation

A

Cone Beam Reconstruction

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21
Q

Having no gaps between adjacent slices

A

Contiguous

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22
Q

Conditions that would preclude a patient from having a CT study performed in a given manner (i.e. with contrast)

A

Contraindications

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23
Q

The ability to differentiate small differences in density on the image

A

Contrast

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24
Q

A compound, usually pharmaceutical in nature, which when administered to a patient, may improve the sensitivity and specificity of the clinical diagnosis

A

Contrast Agent

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25
Q

A study of cross-sectional images characterized by an increment of the patient table after each x-ray tube rotation

A

Conventional Scan

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26
Q

The process of applying a reconstruction filter to the raw data

A

Convolution

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27
Q

Aligned perpendicular to the axis which travels from anterior to posterior in the patient

A

Coronal

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28
Q

Sections made by cutting anything at right angles to any axis

A

Cross-sections

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29
Q

A number that correlates to the Hounsfield scale which ranks various materials by their attenuation properties

A

CT Number

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30
Q

A study which uses IV contrast media to visualize vascular structures

A

CT Angiography (CTA)

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31
Q

Indicator of radiation dose which includes the radiation located within the intended slice thickness as well as that from the penumbra

A

CT Dose Index (CTDI)

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32
Q

A CT hardware component which measures the x-rays that pass through the patient’s body

A

Detector

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33
Q

A group of detectors

A

Detector Array

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34
Q

The standard used for communicating digital medical image information, which was established to improve workflow efficiency between imaging systems in healthcare environments worldwide

A

Digital Imaging and Communications in Medicine (DICOM)

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35
Q

Information expressed in terms of discrete numbers

A

Digital

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36
Q

The components that convert the digital commands coming out of the scan controller into analog commands that can then be executed by the power-producing and mechanical components

A

Digital-to-Analog Converters (DACs)

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37
Q

A filter applied to the digital image data to further sharpen or smooth the appearance of the tissues

A

Display Filter

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38
Q

The amount of ionizing radiation absorbed by an object per unit mass

A

Dose

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39
Q

The best indicator of radiation dose reflecting the total energy from a CT scan absorbed by the patient

A

Dose Length Product (DLP)

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40
Q

A calculated sum of the absorbed dose of all of the tissues in the body, each individually multiplied by a weighting factor for that organ or region

A

Effective Dose

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41
Q

Stationary metal contacts through which electrical signals are transferred to and from the rotating slip ring

A

Electrical Brushes

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42
Q

A CT scanner that has no x-ray tube with fast scan time making it well-suited for cardiac and coronary artery imaging.

A

Electron Beam CT Scanner (EBCT)

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43
Q

Refers to the timing usually a few minutes after an IV contract injection defined by less than a 10 HU difference between the abdominal aorta and the inferior vena cava

A

Equilibrium Phase of Enhancement

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44
Q

The condition that occurs when the substance being injected misses the vein and instead goes directly into the soft tissue

A

Extravasation

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45
Q

An x-ray beam having a shape similar to an opened paper fan

A

Fan Beam

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46
Q

A structure on the cathode terminal of the CT x-ray tube from which the electron beam is released

A

Filament

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47
Q

The area on the anode target bombarded by the electron beam and a factor in determining the image resolution

A

Focal Spot

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48
Q

The comparison of two imaging modalities yielding co-registered images

A

Fusion Imaging

49
Q

The part of a CT scanner through which the patient table is advanced and the component that contains the CT x-ray tube and the detectors

A

Gantry

50
Q

A unit for measuring the absorbed radiation dose in which 1 Gy equals 100 rads

A

Gray (Gy)

51
Q

A continuous spectrum of shades of the color gray used to differentiate structures on a digital image

A

Gray Scale

52
Q

A study of cross-sectional images characterized by continuous patient table motion during x-ray tube rotation

A

Helical Scan

53
Q

The component that creates the high voltage that enables the CT x-ray tube to produce x-ray photons

A

High Voltage Generator

54
Q

The communications coordinator for the rest of the CT system

A

Host Computer

55
Q

The grid of rows and columns of pixels which forms the digital image

A

Image Matrix

56
Q

Compounds that are injected through the theca of the spinal cord into the subarachnoid space during a myelographic study of the spine

A

Intrathecal Contrast Agents

57
Q

Compounds, typically containing iodine, that are injected into the blood stream in order to better differentiate tissues and better delineate abnormalities on CT images

A

Intravenous (IV) Contrast Agents

58
Q

A type of oral contrast agent known for moving through the GI tract quickly compared to barium sulfate agents

A

Iodinated Oral Contrast Agent

59
Q

A type of IV contrast agent that breaks down in the blood stream

A

Ionic Contrast Agent

60
Q

A type of energy that can cause detrimental changes to occur in the atoms of living tissues

A

Ionizing Radiation

61
Q

A complex cycle of correction calculations which may be applied during the CT image reconstruction process to reduce image noise, and which allows a greatly reduce dose to be used without compromising image quality

A

Iterative Reconstruction

62
Q

The scan parameter which is the maximum energy of the x-ray photons and the parameter that controls the contrast in a CT image

A

kVp

63
Q

A single projection scan obtained with a stationary x-ray tube and a moving patient table generating the image used to position the cross-sectional slices

A

Localizer Scan

64
Q

The scan parameter which is the mathematical product of the tube current and the rotation time (in sec.) and which determines the number of photons the patient’s body is exposed to

A

mAs

65
Q

The post-processing algorithm used on CTA and MRA data to allow visualization of the complete vascular tree

A

Maximum Intensity Projection (MIP)

66
Q

Streaks that result from metal located within the scan field-of-view during a CT scan

A

Metal Artifact

67
Q

Streaks, blurriness, or ghosting that results from motion of any structure in or on the patient’s body during a CT scan

A

Motion Artifact

68
Q

An indicator of radiation dose which corrects the CTDI on conventional scans by factoring in gaps or overlaps between the slices as indicated by the selected table increment

A

Multiple Slice Average Dose (MSAD)

69
Q

The reformatting of images acquired in one orientation to produce images in other orientations

A

Multiplanar Reconstruction

70
Q

A CT scanner design that collects information from multiple anatomical slices in each rotation of the x-ray tube

A

Multi-row Detector CT Scanner (MDCT)

71
Q

A condition in an image that refers to electronic interference and which causes the appearance to be grainy

A

Noise

72
Q

Refers to the timing shortly after an IV contrast injection defined by a 10-30 HU difference between the abdominal aorta and the inferior vena cava

A

Non-equilibrium Phase of Entertainment

73
Q

Type of IV contrast that does not break down in the blood stream

A

Non-Ionic Contrast Agent

74
Q

The link between the technologist and the computerized electronic environment of the CT scanner hardware

A

Operator’s Console

75
Q

Compounds containing iodine or barium sulfate that are swallowed or administered rectally in order to opacify the gastrointestinal tract on CT images

A

Oral Contrast Agents

76
Q

The concentration of molecular particles in the contrast agent solution

A

Osmolality

77
Q

Results from selecting slices that are much thicker than the anatomy and pathology which we want to visualize

A

Partial Volume Artifact

78
Q

Results in blurring of the images and a decreased ability to visualize small structures when the slices are too thick

A

Partial Voluming

79
Q

A thin, focused beam of x-rays

A

Pencil Beam

80
Q

A tiny bit of energy contributing to the x-ray beam which travels at the speed of light

A

Photon

81
Q

The distribution, viewing and storage facility for digital images across an imaging facility’s computer network

A

Picture Archiving and Communication System (PACS)

82
Q

The extent to which the x-ray helix is stretched during a helical scan

A

Pitch

83
Q

A single picture element formed by the intersection of a row and column of the image grid

A

Pixel

84
Q

A restriction on unwanted x-rays entering the detector assembly from arbitrary angles

A

Post-patient Collimation

85
Q

Conditions that would warrant a medical decision as to whether the benefits of the exam outweigh the risks posted to the patient

A

Precautions

86
Q

A refinement of the thickness of the x-ray beam after it leaves the x-ray tube and before it enters the patient’s body

A

Pre-patient Collimation

87
Q

A view of the anatomical cross-section along the path of the x-ray beam from only one vantage point

A

Projection

88
Q

Position with the posterior side of the body facing up

A

Prone

89
Q

A pre-defined set of parameters that is used to run a CT scan for a specific clinical application

A

Protocol

90
Q

A unit for measuring the absorbed radiation dose

A

Rad

91
Q

Radiation that extends outside of the intended slice caused by imperfect collimation of the x-ray beam

A

Radiation Penumbra

92
Q

The measured x-ray photon information

A

Raw Data

93
Q

The number of millimeters of information reconstructed and displayed in the final image

A

Reconstruction Field-of-View (FOV)

94
Q

The filter applied to the raw data during image reconstruction

A

Reconstruction Filter

95
Q

The parameter that determines where helical slices will be reconstructed and if they will be overlapped

A

Reconstruction Interval

96
Q

A unit for measuring the radiation dose equivalent

A

Rem (1 rem = 1 rad)

97
Q

A measurement of the smallest structure that we can visualize, or resolve, in the image

A

Resolution

98
Q

The process of reconstructing images from the raw data using modified parameters, after the initial image reconstruction is complete

A

Retrospective Reconstruction

99
Q

Aligned perpendicular to the axis which travels from left to right in the patient

A

Sagittal

100
Q

The collection of anatomical information during the time the x-ray beam is on

A

Scan

101
Q

The component responsible for the timing and correct performance of each CT system component once the scan has been started

A

Scan Controller

102
Q

The number of millimeters of anatomy over which projection data is collected

A

Scan Field-of-View (FOV)

103
Q

A mechanism of attenuation in which x-ray photons interact with a dense structure and change the direction of their path

A

Scattering

104
Q

The process of determining the patient’s current condition and medical history in order to ensure eligibility for the scanning procedure

A

Screening

105
Q

The number of millimeters of anatomy, intersected by the thickness of the x-ray beam, which is represented in the CT image

A

Slice Thickness

106
Q

A large rotating ring on the CT scanner to which several hardware components are mounted and which eliminates the need for power and data cables

A

Slip Ring

107
Q

Positioned with the anterior side of the body face up

A

Supine

108
Q

The advancement, in millimeters, of the patient table between consecutive conventional slices determining the gaps or overlap between adjacent slices

A

Table Increment

109
Q

The material in the CT tube which is bombarded with fast-moving electrons to generate x-rays

A

Target

110
Q

Any imaging method in which the patient’s tissues are visualized by “cutting” them into sections

A

Tomography

111
Q

Aligned perpendicular to the axis which travels from head to foot in the patient

A

Transverse

112
Q

The parameter that determines the number of x-ray photons produced by the CT x-ray tube

A

Tube Current (mA)

113
Q

The parameter that determines the energy level of x-ray photons produced by the CT x-ray tube

A

Tube Voltage (kV)

114
Q

The thickness of a substance in reference to contrast media

A

Viscosity

115
Q

The center CT number around which the window width is positioned

A

Window Level

116
Q

The range of CT numbers that occupy the full gray scale on the image monitor

A

Window Width

117
Q

Adjusting the brightness and contrast of the shades of gray assigned to represent the tissues in the pixels of a CT image

A

Windowing

118
Q

The source of x-rays in a CT scanner

A

CT X-ray Tube

Computed Tomography (CT) (8 decks)

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