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WorksheetsQuality Assurance
Total questions: 35
Worksheet time: 18mins
Click on the image that displays the following artifact: Tube arching. Select the tile position from the 3×3 grid of CT images (top-left to bottom-right).
Top-left
Top-middle
Middle-middle
Bottom-right
Click on the image that displays the following artifact: Out of Field Artifact. Select the tile position from the 3×3 grid of CT images (top-left to bottom-right).
Top-left
Top-middle
Top-right
Middle-right
Click on the image that displays the following artifact: Aliasing Effect. Select the tile position from the 3×3 grid of CT images (top-left to bottom-right).
Bottom-left
Bottom-middle
Middle-right
Top-right
Click on the image that displays the following artifact: Partial Volume Artifact. Select the tile position from the 3×3 grid of CT images (top-left to bottom-right).
Middle-left
Top-left
Bottom-right
Top-middle
Click on the image that displays the following artifact: Beam Hardening. Select the tile position from the 3×3 grid of CT images (top-left to bottom-right).
Bottom-right
Top-right
Middle-middle
Bottom-middle
What type of artifacts are shown in the diagram?
Ring artifacts
Streak artifacts
Windmill artifacts
________ refers to the relationship between CT numbers and the linear attenuation values of the scanned object at a designated kVp value.
Linearity
Uniformity
Accuracy
Spatial resolution
________ refers to the ability of the scanner to yield the same CT number regardless of the location of an ROI within a homogeneous object.
Uniformity
Linearity
Spatial resolution
Contrast resolution
Who often share the responsibility for performing and documenting quality control tests?
CT technologists and physicians
CT technologists and medical physicists
Physicians and medical physicists
Medical physicists and scanner manufacturers
The range of x-ray intensity values to which the scanner can accurately respond is called the ________.
Dynamic range
Window Width
Index range
Window Level
Insufficient projection data are called ________.
Undersampling
Cupping
Beam-Harding
Ring
Which is not a typical classification for the causes of artifacts?
Physics based
Equipment induced
Patient based
Technologist based
Which is not a manifestation of patient motion?
Streaking
Blurring
Ghosting
Concentric rings
Which is not a feature CT systems use to minimize beam hardening?
Filtration
Calibration correction
Slowing gantry rotation speed
Beam-hardening correction software
Which describes a cupping artifact?
When the object appears in only a small number of views collected from the tube's 360° path
When there is an appearance of dark bands or streaks between dense objects in the image
When the periphery of the image is lighter
When fine stripes appear to be radiating from a dense structure
Which classification of image artifacts causes ring artifacts?
Physics based
Patient based
Equipment based
Where are laser lights located?
Inside the gantry
Outside the gantry
Both inside and outside the gantry
What is the maximum variation from the intended slice thickness for a slice thickness of 5 mm or less?
±0.5 mm
±1 mm
±0.5 cm
±1 cm
What is the maximum variation from the intended slice thickness for a slice thickness of 5 mm or greater?
±0.5 mm
±1 mm
±0.5 cm
±1 cm
What is the best way to reduce metallic artifact?
Select an SFOV that is larger than the patient.
Recalibrate the scanner.
Give the patient clear breathing instructions.
Minimize the metal present in the SFOV.
What is ghosting?
A type of image artifact where objects appear to have a shadow
A type of filter used to eliminate beam hardening
Another name for the edge gradient effect
Another name for tube arcing
What causes the edge gradient effect?
Irregularly shaped objects that have a pronounced difference in density from surrounding structures
More than one type of tissue is contained within a voxel
Patient motion
Anatomy that extends outside of the selected SFOV
What causes spiral interpolation artifacts?
Too few samples.
Images are created from views not in the same plane.
Patient motion.
The x-ray beams are composed of different energies.
True or False? Tube arcing is patient-induced artifact.
True
False
True or False? There is always the same specific pattern in the appearance of tube arc artifacts.
True
False
True or False? The American College of Radiology CT accreditation phantom is a solid phantom that contains four modules and is constructed primarily from a water-equivalent material.
True
False
True or False? Ring artifacts appear only on MDCT helical systems.
True
False
True or False? An undesired surge of electrical current within the x-ray tube causes tube arcing.
True
False
How often should noise and uniformity testing be done?
Weekly
Monthly
Semiannually
Annually
How often is slice thickness accuracy testing performed in most quality assurance programs?
Weekly
Monthly
Semiannually
Annually
How often is direct spatial resolution testing using a line pairs phantom performed in most quality assurance programs?
Daily
Weekly
Monthly
Annually
How is noise is measured?
By finding the standard deviation of the CT numbers within the region of interest of an object known to have a uniform density
By finding the mean of the CT numbers within any region of interest
By finding the standard deviation of the CT numbers within the region of interest of a phantom that contains multiple densities
By counting the line pairs visible in a scan of a water phantom
Concentric rings appear on a CT slice. Which is a likely cause?
One or more detectors are miscalibrated
Electrical surge within the x-ray tube
A partial scan was used resulting in too few samples
Patient motion
Any object seen on the image that is not present in the object scanned is considered an (a) .
According to the ACR reference CTDI, what is the recommended radiation dose for an adult head?
20 mGy
25 mGy
50 mGy
75 mGy
