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WorksheetsCT intro
Total questions: 60
Worksheet time: 35mins
The sagittal plane divides the body into the right and left sections.
True
false
What is the thickness of a cross-sectional CT slice called?
X axis
Y axis
Q axis
Z axis
Why does using a small pixel size reduce the likelihood of volume averaging?
A) It limits the amount of data to be volume averaged.
B) It decreases the thickness of the plane.
C) It changes the temporal resolution.
D) It increases beam attenuation.
To differentiate adjacent objects on a CT image, there cannot be a density difference between the two objects.
A) True
B) False
The degree to which an x-ray beam is reduced by an object is known as attenuation.
A) True
B) False
Which is not an advantage of CT over conventional radiography?
A) The elimination of superimposed structures
B) The ability to differentiate small differences in density of anatomic structures and abnormalities
C) The depiction of a three-dimensional object as a two-dimensional image
D) The superior quality of the images
What can be used to create a temporary artificial density difference between two objects on a CT image?
A) Low-energy x-ray photons
B) Contrast agents
C) High-energy x-ray photons
D) Artifacts
What is the primary reason for changing the image plane from axial to coronal?
A) The anatomy of interest lies vertically rather than horizontally
B) To eliminate volume averaging
C) To reduce artifacts created by surrounding structures
D) To attenuate the x-ray beam
How are metals represented on a CT image?
A) As white areas
B) As black areas
C) As grey areas
What is the term for the ability of an x-ray tube to withstand resultant heat?
A) Thermal energy
B) Heat dissipation
C) Kinetic energy
D) Heat capacity
(a) is the directional term that refers to movement towards the sides of the body.
The larger the object being scanned, the thinner the CT slice required.
A) True
B) False
Which is a drawback of using thicker CT slices when imaging?
A) They increase the likelihood of missing very small objects.
B) They increase radiation dosage.
C) They decrease the pixel size.
D) They increase the number of slices that are produced.
What is the name for each two-dimensional square in a CT slice?
A) pixel
B) cube
C) cross-section
D) matrix
What is the most common matrix size in CT?
A) 256
B) 128
C) 512
D) 1024
In which part of the CT process are the data converted into shades of gray for viewing?
A) Image reconstruction
B) Image display
C) Data acquisition
Which directional term refers to movement towards the feet?
A) Posterior
B) Anterior
C) Superior
D) Inferior
What is density?
A) The degree to which matter is concentrated
B) The number of photons that pass through a structure
C) The amount of x-ray beam that is absorbed per unit of thickness
D) The degree to which an x-ray beam is reduced by an object
An x-ray beam consists of bundles of energy known as (a)
What is the name of the process in CT by which different attenuation values are averaged to produce one less accurate pixel reading?
A) Volume averaging
B) Z axis averaging
C) Pixel averaging
D) Image averaging
The terms scan data and (a) data are used interchangeably to refer to the computer data waiting to be processed to create an image.
What is another name for step-and-shoot scan mode?
A) Axial
B) Spiral
C) Helical
D) Volumetric
Which directional term refers to movement towards the head?
A) Posterior
B) Anterior
C) Superior
D) Inferior
Artifacts always degrade the quality of an image.
A) True
B) False
(a) artifacts appear as dark streaks or vague areas of decreased density on a CT image. (two words)
What determines the shades of gray on a CT image?
A) The scanning protocol
B) The thickness of the CT slice
C) The quantity of x-ray photons
D) Air-filled structures
What is the name for the area of the anode where the electrons strike and the x-ray beam is produced?
A) gantry
B) reconstruction processor
C) focal spot
D) space cloud
(a) resolution describes the ability of a system to define small objects distinctly.
What are used to quantify the degree that a structure attenuates an x-ray beam?
A) Pixels
B) Contrasting agents
C) Attenuation coefficients
D) Hounsfield units
What are image artifacts?
A) The photons in an x-ray beam
B) Substances used to create a temporary artificial density between objects
C) The data that form the CT slice
D) Objects seen on a CT image that are not present in the object scanned
Which generation of scanners used a thin x-ray beam passed linearly over the patient with a single detector following on the opposite side of the patient?
A) First-generation
B) Second-generation
C) Third-generation
D) Fourth-generation
Collimators control the slice thickness by narrowing or widening the x-ray beam.
A) True
B) False
Detectors restrict the x-ray beam to a specific area, reducing scatter radiation.
A) True
B) False
The (a) is the ring-shaped part of the CT scanner.
What is the unit of measure for the power capacity of the generator?
A) KHU
B) kW
C) MHU
D) HU
What does the source collimator do?
A) It limits the amount of x-ray emerging to thin ribbons.
B) It captures transmitted photons and changes them to electronic signals.
C) It ionizes Xenon gas.
D) It cools the imaging components.
What measures the number of photons that strikes the detector, converts the information to a digital signal, and sends the signal to the computer?
A) A Xenon gas detector array
B) High-frequency generators
C) The data-acquisition system
D) A solid-state detector array
Which is not a usual degree of tilt for a CT gantry?
A) +15 °
B) -5°
C) +35°
D) -25°
What is an overscan?
A) A thin x-ray beam passed linearly over the patient
B) The occurrence of ring artifacts
C) A tube arc greater than 360°
D) Streaking on the CT image
Which is not a component of a CT scanner?
A) Camera
B) Operator's console
C) Scanning gantry
D) Computer system
What determines the shades of gray on a CT image?
A) The quantity of x-ray photons
B) Air-filled structures
C) The scanning protocol
D) The thickness of the CT slice
Which is not part of a solid-state detector array?
A) Circuit board
B) Scintillator crystal
C) Photodiode
D) Amplifier
If the patient's weight exceeds the specified limits, scanning is not possible.
A) True
B) False
Which is not a characteristic of a pressurized Xenon gas detector?
A) No afterglow
B) Low-density material
C) High photon absorption
D) High stability
(a) is often used for the anode target material because it produces a higher-intensity x-ray beam.
Which is a disadvantage of using Xenon gas detectors?
A) They are more difficult to calibrate than the solid state variety.
B) Xenon gas must be kept under pressure in an aluminum casing.
C) They are highly unstable.
D) They are the most expensive type of detector to produce.
A microphone is a component of the gantry.
A) True
B) False
Which is a benefit of filtering the x-ray beam?
A) It decreases the time of CT imaging.
B) It increases the intensity of the beam.
C) It reduces scatter radiation.
D) It reduces overscan.
What is another name for incrementation?
A) feed
B) overscan
C) repositioning
D) detection
Which is not a desired characteristic of a detector?
A) High stability
B) High efficiency
C) Low afterflow
D) Low scatter suppression
Which is not a segment of the CT process?
A) Image display
B) Data acquisition
C) Data dispersal
D) Image reconstruction
The process of moving the table by a specified measure is most commonly called (a)
What determines the number of detector elements?
A) The gantry
B) The cooling system
C) The fan beam
D) The slip rings
Which generation of scanners uses a detector array that is fixed in a 360° circle within the gantry?
A) First-generation
B) Second-generation
C) Third-generation
D) Fourth-generation
The term detector (a) is used to describe the entire collection of detectors included in a CT system.
What is another name for solid-state detectors?
A) Detector bank
B) Apertures
C) Detector array
D) Scintillation detectors
(a) permit the gantry frame to rotate continuously? (two words)
What do current systems use to rotate the gantry frame?
A) Recoiling system cables
B) Collimators
C) Detectors
D) Slip rings
High-frequency generators are currently used in CT.
A) True
B) False
What is the range of aperture size for a gantry?
A) 60 cm - 70 cm
B) 70 cm - 90 cm
C) 70 cm - 80 cm
D) 90 cm - 100 cm
