Image Production Flashcards
X-ray tubes in CT are most similar to the radiation source used within which modality?
A. Diagnostic Radiography
B. Positron emission tomography (PET)
C. Ultrasonography
D. Magnetic Resonance Imaging (MRI)
A. Diagnostic Radiography
If milliamperage (mA) is decreased by a factor of 2, how is the radiation dose to the patient changed if other factors remain unchanged?
A. Dose is increased by a factor of 2
B. Dose is decreased by a factor of 2
C. Dose remains unchanged
D. Dose is decreased by a factor of 22
B. Dose is decreased by a factor of 2
Which of the following statements correctly describes the flow of electrons through the x-ray tube?
A. Cathode to anode
B. Anode to cathode
C. Positive to negative
D. Target to a filament
A. Cathode to anode
An increase of which of the following exposure factors would increase the total number of x-ray photons exposing the detectors? (Select three)
A. Increased milliamperage (mA)
B. Increased kilovoltage peak (kVp)
C. Increased pitch
D. Increased filtration
E. Increased rotation time
A. Increased milliamperage (mA)
B. Increased kilovoltage peak (kVp)
E. Increased rotation time
Which technical change is expected to increase the penetrating ability of an x-ray beam?
A. Increased kVp
B. Increased mA
C. Increased rotation time
D. All of the above
A. Increased kVp
Which of the following effects can occur when mA is increased in CT? (Select three)
A. Increasing dose to the patient
B. Increasing image contrast
C. Increasing the intensity of the beam
D. Increasing the exposure to the detector elements
E. Increased spatial resolution
A. Increasing dose to the patient
C. Increasing the intensity of the beam
D. Increasing the exposure to the detector elements
If the rotation time of a scan is decreased, what other exposure parameter should be changed to maintain the image quality?
A. Increased mA
B. Increased kVp
C. Decrease scan length
D. Decrease mA
A. Increased mA
The specific process that accelerates electron in an x-ray tube is:
A. Evacuation of air in the envelope
B. Thermionic emission
C. Application of a voltage
D. Bremsstrahlung electron interactions
C. Application of a voltage
Compared to general radiography, CT x-ray tubes require:
A. Large heat capacity
B. Shorter exposure time
C. Less radiation output
D. Lower mA settings
A. Large heat capacity
Production of x-rays in a CT machine requires a: (select three)
A. Source of electrons
B. Means of rapid acceleration of electrons
C. Means of rapid deceleration of electrons
D. Source of radioactivity
A. Source of electrons
B. Means of rapid acceleration of electrons
C. Means of rapid deceleration of electrons
The signal produced by a CT detector is a(n):
A. Analog electrical signal
B. Processed image data
C. Raw digital data
D. Unprocessed binary data
A. Analog electrical signal
The width of the x-ray beam is controlled by:
A. kVp
B. Collimation
C. Matrix size
D. mA
B. Collimation
Physical components located inside the CT gantry typically include which two of the following? (Select two)
A. X-ray tube
B. Computer system
C. High-voltage generator
D. Archive sensors
A. X-ray tube
C. High-voltage generator
The main difference between image production in CT compared to image production in radiography:
A. X-ray photons are collected by detectors
B. An unprocessed digital signal is converted to image data
C. Projections are compiled into a 3D volume of data
D. The x-ray beam is partially attenuated by the patient
C. Projections are compiled into a 3D volume of data
A single “view” acquired during a CT scan is also called a:
A. Slice
B. Projection
C. Detector
D. Attenuation reading
B. Projection
A common kVp setting used in CT is:
A. 20 kVp
B. 120 kVp
C. 200 kVp
D. 20-500 kVp
B. 120 kVp
The phrase “8-slice scanner” refers to a CT imaging system that has:
A. 8 detectors
B. 8 detector rows
C. 8 mm x-ray beam
D. An 8 second rotation time
B. 8 detector rows
The principal advantage of thin detector rows is:
A. Faster scan time
B. Lower patient dose
C. Lower x-ray output
D. Higher spatial resolution
D. Higher spatial resolution
Increasing the mA and kVp of a CT scan will usually result in which two of the following? (Select two)
A. Increased patient dose
B. Increased processing time
C. Decreased image noise
D. Decreased spatial resolution
A. Increased patient dose
C. Decreased image noise
Which component of the CT imaging system is responsible for creating reconstructed image data?
A. Computer system
B. Data acquisition system
C. Detector array
D. Array processor
A. Computer system
CT angiography imaging of the heart is sometimes performed with the CT scanner in the volume acquisition mode. This means that the:
A. Patient couch moves only between x-ray exposures
B. Patient table is in constant motion
C. Scan data is acquired in one rotation of the x-ray tube
D. Scan data is collected in one large helical pattern
C. Scan data is acquired in one rotation of the x-ray tube
What number represents the x-axis?
1
A CT scanning protocol is set to use a pitch of 0.79. This will result in:
A. Overlap in the scan data
B. Missing views in the scan data
C. Overlap and missing views in the scan data
D. Scan data without overlap or missing views
A. Overlap in the scan data
Helical scanning mode is usually preferred over axial scanning mode for what three reasons? (Select three)
A. Decreased scan time
B. Improved IV contrast timing
C. Increased spatial resolution
D. Improved post-processing
E. Decreased patient dose
A. Decreased scan time
B. Improved IV contrast timing
D. Improved post-processing
Increasing the acquisition thickness of a CT scan means:
A. Combining detector rows together as one detector row
B. Increasing the displayed slice thickness
C. Combining reconstructed slices together to form thicker slices
D. Increasing the space between spirals in the helix
A. Combining detector rows together as one detector row
During helical scanning, if the table moves a greater distance than the width of the beam the pitch will be:
A. Greater than 1
B. Less than 1
C. Equal to 1
A. Greater than 1
What portion of the patient can be visualized through the process of retrospective reconstruction?
A. Only parts of the patient within the display field-of-view (DFOV)
B. Only parts of the patient within the scan field- of-view (SFOV)
C. Only parts of the patient outside the scan-of-view (SFOV)
D. Only parts of the patient within the scanner gantry
B. Only parts of the patient within the scan field- of-view (SFOV)
The sequential acquisition mode is described by which of the following statements?
A. The patient table moves only between x-ray exposures
B. The patient table is in constant motion
C. The scan data is acquired in one rotation of the x-ray tube
D. The scan data is collected in one large spiral pattern
A. The patient table moves only between x-ray exposures
Under what two circumstances would it be impossible to reconstruct the additional brain anatomy missing from the image below? (select two)
A. The missing anatomy is outside of the original display field-of-view (DFOV)
B. The original image data has been deleted from the CT computer system
C. The original scan data has been deleted from the CT computer system
D. The missing anatomy is outside of the original scan field-of-view (SFOV)
C. The original scan data has been deleted from the CT computer system
D. The missing anatomy is outside of the original scan field-of-view (SFOV)
What CT data acquisition mode collects a series of adjacent axial sections?
A. Axial scanning
B. Helical scanning
C. Volume scanning
A. Axial scanning
Shifting the center of a sagittal image requires changes to which two data coordinates? (Select two)
A, X-axis
B. Y-axis
C. Z-axis
B. Y-axis
C. Z-axis
Which of the following statements accurately describes the orientation of the x-axis in CT imaging? (Select two)
A. Extends horizontally across the scanner
B. Extends vertically across the scanner
C. Represents data coordinates in terms of right and left
D. Represents data coordinates in terms of anterior and posterior
A. Extends horizontally across the scanner
C. Represents data coordinates in terms of right and left
What portions of a patient receive radiation exposure during CT scanning?
A. Any portion of the patient within the display field-of-view
B. Any portion within the scan field-of-view but outside the display field-of-view
C. Any portion of the patient outside the scan field-of view
D. Any portion of the patient within the scanner gantry
D. Any portion of the patient within the scanner gantry
What CT scan data acquisition mode is demonstrated in this illustration?
A. Axial mode
B. Helical mode
C. Volume mode
B. Helical mode
What axis position has changed in this series of axial images?
A. X-axis
B. Y-axis
C. Z-axis
C. Z-axis
Pitch is defined as the ratio of the table movement to the:
A. Beam width
B. Acquisition thickness
C. Tube rotation time
D. Radiation output
A. Beam width
What CT scanning mode may induce patient motion artifact from several stops and starts of the gantry table during data acquisition?
A. Axial mode
B. Helical mode
C. Volume mode
A. Axial mode
Which two of the following statements regarding the scan field-of-view (SFOV) are true? (Select two)
A. The SFOV is larger than the DFOV
B. Data in the SFOV is sent to the radiologist
C. Data in the SFOV is saved on the CT computed system
D. The size of the SFOV is set by the technologist using the scout images
A. The SFOV is larger than the DFOV
C. Data in the SFOV is saved on the CT computed system
What axis position has changed in this series of sagittal images?
A. X-axis
B. Y-axis
C. Z-axis
A. X-axis
If the pitch is equal to 1.1, how far is the far is the patient table moving during each rotation of the tube?
A. 1.1 times the beam width
B. 1.1 divided by the number of data channels
C. 1.1 times the number of detector rows
D. 1.1 divided by the acquisition thickness
A. 1.1 times the beam width
What portion of the CT data collected during a scan is saved by the scanner but not reconstructed for viewing?
A. Any portion of the patient within the display field-of-view
B. Any portion within the scan field-of-view but outside the display field-of-view
C. Any portion of the patient outside the scan field-of view
D. Any portion of the patient within the scanner gantry
B. Any portion within the scan field-of-view but outside the display field-of-view
What CT scanning method requires a large detector array with numerous data collection channels?
A. Axial scanning
B. Helical scanning
C. Volume scanning
C. Volume scanning
If a routine helical scan of the chest is pre-programmed to use 16 detector rows and a pitch of 1.13, how will the resulting views comprise the scan data?
A. Duplicate views of the same positions in the scan data
B. Missing views in the scan data
C. Overlapping and missing views in the scan data
D. No overlap of missing views in the scan data
B. Missing views in the scan data
What number represents the y-axis?
A. 1
B. 2
C. 3
B. 2
When the pitch is less than one, how do the resulting views comprise the scan data?
A. Overlapping views in the scan data
B. Missing views in the scan data
C. Overlap and missing views in the scan data
D. No overlap or missing views in the scan data
A. Overlapping views in the scan data
During which acquisition mode is the patient table in constant motion?
A. Axial scanning
B. Helical scanning
C. Volume scanning
B. Helical scanning
After completing a CT of abdomen, you noticed that your images do not include the entire abdomen. Which of the following methods can to retrieve this information?
A. Prospective reconstruction
B. Retrospective reconstruction
C. Multiplanar reformation
D. This information cannot be retrieved
B. Retrospective reconstruction
When imaging a patient in CT, what portion of the patient is processed for viewing on the technologist’s computer monitor?
A. Any part within the DFOV
B. Any part within the SFOV but outside of the DFOV
C. Any part of the patient outside of the scan of the DFOV
D. Any part of the patient within the scanner gantry
A. Any part within the DFOV
How is anatomical data from the SFOV used during CT image production?
A. Data from the SFOV is used for multiplanar reformations
B. Data from the SFOV is used for volume rendering (VR)
C. Data from the SFOV is used for long-term image archival
D. Data from the SFOV is used for image reconstruction
D. Data from the SFOV is used for image reconstruction
What number is the Z-axis?
3
Which of the following statements accurately describes the orientation of the z-axis in CT imaging? (Select two)
A. Extends vertically across the scanner
B. Extends longitudinally through the scanner
C. Represents data coordinates in terms of anterior and posterior
D. Represents data coordinates in terms of superior and inferior
B. Extends longitudinally through the scanner
D. Represents data coordinates in terms of superior and inferior
Which of the following two statements concerning the SFOV are true? (Select two)
A. The SFOV is usually larger than the DFOV
B. Data in the SFOV is sent to the radiologist
C. Data in the SFOV is saved on the CT computed system
D. The size of the SFOV is set by the technologist using the scout images
A. The SFOV is usually larger than the DFOV
C. Data in the SFOV is saved on the CT computed system
During an axial scan, the total amount of anatomical coverage per tube rotation is dependent on which of the following two variables? (Select two)
A. Number of activated detector rows
B. Tube rotation time
C. Pitch
D. Thickness of activated detector rows
A. Number of activated detector rows
D. Thickness of activated detector rows
The localizer images are used by the technologist to assign which variable of a CT scan?
A. DFOV
B, SFOV
C. Acquisition thickness
D. Reconstruction thickness
A. DFOV
Acquiring x-axis measurement of a pathology is possible in which two imaging planes? (Select two)
A. Sagittal
B. Axial
C. Coronal
A. Sagittal
C. Coronal
A CT detector configuration is changed from 0.625 mm x 16 rows to 1.25 x 8 rows. The change may result in:
A. Decreased patient dose
B. Increased spatial resolution
C. Increased beam coverage
D. Increased scan time
A. Decreased patient dose
Consider two identical scanning protocols, except one protocol uses a pitch of 0.73 and the other uses a pitch of 0.87. The protocol using of 0.87 will result in which of the following protocols?
A. Decreased scan time
B. Increased spatial resolution
C. Decreased patient dose
D. Increased scan time
A. Decreased scan time
C. Decreased patient dose
What is the primary reason for decreasing the detector thickness for CT angiography examinations?
A. Decreased patient dose
B. Increased spatial resolution
C. Increased beam coverage
D. Decreased scan time
B. Increased spatial resolution
The helical acquisition mode is the most common technique used for imaging which three body sections? (select three)
A. Cranium
B. Chest
C. Abdomen
D. Extremities
B. Chest
C. Abdomen
D. Extremities
The inner rows of a non-uniform detector array have the advantage of:
A. Increased spatial resolution
B. Increased contrast resolution
C. Decreased patient dose requirement
D. Decreased image noise
A. Increased spatial resolution
What is the relationship between acquisition thickness and spatial resolution?
A. As acquisition thickness increases, spatial resolution decreases
B. As acquisition thickness increases, spatial resolution increases
C. As acquisition thickness increases, spatial resolution remains constant
D. As acquisition thickness increases, spatial resolution remains constant in the inner detector rows.
A. As acquisition thickness increases, spatial resolution decreases
Based on feedback from an American College of Radiology (ACR) site-visit, your imaging department needs to design a new low-dose CT protocol for patients who weigh less than 30 pounds. Which of these detector configurations would be most suited for this protocol?
A. 1 mm x 16 rows
B. 2 mm x 8 rows
C. 4 mm x 4 rows
D. 0.5 mm x 8 rows
C. 4 mm x 4 rows
Acquisition thickness refers to the:
A. Number of active detector rows
B. Thickness of active detector rows
C. Thickness of reconstructed slices
D. Number of data collection channels
B. Thickness of active detector rows
The visible difference between these two images might be explained by which of the following?
A. Different slice thickness
B. Different slice interval
C. Different window width
D. Different contrast volume
A. Different slice thickness
These three images were created by scanning the same spherical object using the same CT system. The difference in appearance is a result of using a different:
A. Reconstruction algorithm
B. Number of projections
C. Interpolation algorithm
D. Windowing technique
B. Number of projections
What two combinations of reconstruction parameters could be used to create detailed images of the bony trabeculae? (Select two)
A. Thin slices
B. Thick slices
C. Edge-enhancing algorithms
D. Smoothing algorithms
A. Thin slices
C. Edge-enhancing algorithms
Which of the following accurately describes where raw CT data is stored?
A. It is not stored
B. In the CT computer system
C. In the picture archiving and communication system (PACS)
D. In the radiologists reading station
B. In the CT computer system
The process of assigning a specific level of edge-enhancement to the CT image data is controlled by mathematical filters called: (select three)
A. Reconstruction algorithms
B. Reconstruction filters
C. Reconstruction kernels
D. Filter back-projection
A. Reconstruction algorithms
B. Reconstruction filters
C. Reconstruction kernels
The mathematical filtration of CT data to enhance the appearance of specific tissue types is called:
A. Interpolation
B. Filtration
C. Convolution
D. Back projection
C. Convolution
Thick reconstruction slices (greater than 3 mm) are not suitable for which of the following? (Select all that apply)
A. Multiplanar reformations
B. Angiographic imaging
C. Abdominal imaging
D. Thoracic imaging
A. Multiplanar reformations
B. Angiographic imaging
The process of reconstruction in the CT computer system creates:
A. Image data
B. Scan data
C. Unprocessed data
D. Reformatted data
A. Image data
After performing a thoracic spine scan for trauma, the radiologist requests images of the entire bony thorax. The raw data is still saved on the CT scanner. This will require:
A. Rescanning the patient
B. Retrospectively reconstructing images with a different DFOV
C. Retrospectively reconstructing images with a different algorithm
D. Retrospectively reconstructing images with a different SFOV
B. Retrospectively reconstructing images with a different DFOV
Which two of these algorithms are preferred for viewing bone? (Select two)
A. Edge-enhancing algorithms
B. Standard algorithms
C. Smoothing algorithms
D. Bone algorithms
A. Edge-enhancing algorithms
D. Bone algorithms
Which three of these scan parameters can be changed retrospectively? (Choose three)
A. Scan start and end locations
B. Slice thickness
C. SFOV
D. DFOV
A. Scan start and end locations
B. Slice thickness
D. DFOV
Estimating an unknown value in a series of known values is a mathematical process called:
A. Interpolation
B. Filtration
C. Convolution
D. Back-projection
A. Interpolation
In this scan of the temporal bones, the initial images series (left) was rejected by the radiologist. The technologist retrospectively reconstructed the image series (right), which was then accepted by the radiologist. Based on the appearance of these images, what is one possible reason the initial image series (left) was rejected?
A. Incorrect reconstruction algorithm
B. Incorrect window width
C. Incorrect window level
D. Incorrect gantry tilt
A. Incorrect reconstruction algorithm
By definition, the acquisition thickness is the same as the:
A. Detector row thickness
B. Reconstruction slice thickness
C. Reconstruction slice interval
D. Acquisition mode
A. Detector row thickness
Which of these image-processing techniques in CT are only used in helical scanning?
A. Interpolation
B. Filtration
C. Convolution
D. Back-projection
A. Interpolation
Which of these scenarios will result in gaps in reconstructed image information?
A. When the slice interval is equal to the slice thickness
B. When the slice interval is greater than the slice thickness
C. When the slice interval is less than the slice thickness
B. When the slice interval is greater than the slice thickness