CT Registry Certification Test Quiz!
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The Computed Tomography (CT) quiz has been developed to test your knowledge of different techniques and procedures used in the CT Scan. This exam is conducted by the American Registry of Radiologic Technologists (AART). Take this quiz to test your knowledge and learn about new topics. Read the questions carefully and answer.
- 1.
The 'filter' in filtered back-projection refers to:
- A.
Bowtie filter between the beam and patient
- B.
Conversion between attenuation and Hounsfield units
- C.
Conversion between fan-beam and parallel geometry
- D.
Fix for the blurring inherent to backprojection
Correct Answer
D. Fix for the blurring inherent to backprojectionExplanation
The filter in filtered back-projection compensates for blurring or smearing inherent to the process of back-projection.Rate this question:
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- 2.
Changing filters (aka kernels) in filtered back-projection results in:
- A.
Trade-off between image sharpness and noise
- B.
Different window levels in CT images
- C.
Different patient dose
- D.
 Different reconstructed field of view (FOV)
Correct Answer
A. Trade-off between image sharpness and noiseExplanation
Changing the filter in the filtered back-projection allows more or less high-frequency features. High frequencies (just like the periphery of k-space in MRI) are responsible for image sharpness - but also noise.Rate this question:
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- 3.
In helical CT, a single transverse slice represents:
- A.
A plane through the body perpendicular to the scan axis
- B.
A plane through the body oblique to the scan axis
- C.
A reconstruction made from projections at neighboring scan axis positions
- D.
None
Correct Answer
C. A reconstruction made from projections at neighboring scan axis positionsExplanation
In helical CT, the scanner never images a single slice. Instead, the slice is reconstructed by averaging CT projections taken 180 degrees apart - which are separated along the scan-axis based on the value of the pitch.Rate this question:
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- 4.
In helical CT, a pitch is defined as:
- A.
Table movement in 360 degrees / beam width
- B.
Patient dose in 360 degrees / beam width
- C.
Reconstructed slice thickness / beam width
- D.
Gantry angle with respect to the scan axis
Correct Answer
A. Table movement in 360 degrees / beam widthExplanation
Pitch is defined by how much the table moves during the time it takes to cover 360 degrees divided by the width of the beam.Rate this question:
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- 5.
High-pitch techniques are useful for:
- A.
Very small findings (e.g. nondisplaced fracture)
- B.
Gated cardiac CT
- C.
Accurate multiplanar reconstructions
- D.
Fast scans
Correct Answer
D. Fast scansExplanation
High-pitch techniques are useful for fast scans because they allow for rapid image acquisition. This is particularly beneficial in situations where quick imaging is required, such as in emergency cases or when scanning patients who are unable to hold their breath for an extended period. By reducing the scan time, high-pitch techniques help to minimize motion artifacts and improve image quality. Additionally, fast scans can enhance patient comfort and throughput in busy clinical settings.Rate this question:
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- 6.
Which of the following numbers reported by the scanner best reflects the total amount of radiation delivered to the patient?
- A.
Dose
- B.
CT Dose Index (CTDI)
- C.
Pitch
- D.
Dose-length product (DLP)
- E.
Effective mAs
Correct Answer
D. Dose-length product (DLP)Explanation
The Dose-length product (DLP) is the best reflection of the total amount of radiation delivered to the patient. The DLP takes into account both the dose of radiation delivered during each scan (dose) and the length of the scan (length). By multiplying these two factors together, the DLP provides a comprehensive measure of the total radiation exposure the patient received during the entire scan. The other options listed, such as CT Dose Index (CTDI), Pitch, and Effective mAs, do not provide a complete measure of the total radiation delivered to the patient.Rate this question:
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- 7.
Decreasing kV in CT is advantageous because:
- A.
X-ray penetration improves
- B.
Tissue contrast improves
- C.
Scan times are reduced
- D.
Metal streak artifacts are improved
Correct Answer
B. Tissue contrast improvesExplanation
Decreasing kV in CT is advantageous because it improves tissue contrast. Lowering the kV setting allows for better differentiation between different types of tissues in the body, making it easier to identify abnormalities or diseases. This is because lower kV settings result in a higher absorption of X-rays by the tissues, leading to greater contrast between them. By enhancing tissue contrast, healthcare professionals can obtain clearer and more accurate images, aiding in diagnosis and treatment planning.Rate this question:
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- 8.
The goal of automated exposure compensation is:
- A.
To generate images of similar noise in different patient sizes
- B.
To scan patients of different sizes with the same kV and mAs settings
- C.
To obtain pretty, low-noise images
- D.
To eliminate the radiation risks from CT examinations
Correct Answer
A. To generate images of similar noise in different patient sizesExplanation
Automated exposure compensation is used to adjust the exposure settings in order to achieve consistent image quality across patients of different sizes. Since larger patients may require more radiation dose to obtain a diagnostic image, automated exposure compensation ensures that the noise level in the image remains similar regardless of patient size. This helps in maintaining image quality and reducing the need for repeat scans.Rate this question:
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- 9.
Which of the following is NOT an advantage to performing a CT scan for stroke?
- A.
CT can be rapidly performed
- B.
It is always possible to distinguish between old and new infarcts
- C.
CT allows easy exclusion of hemorrhage.
- D.
CT allows the assessment of prenchymal damage
Correct Answer
B. It is always possible to distinguish between old and new infarctsExplanation
Performing a CT scan for stroke has several advantages, such as rapid execution, easy exclusion of hemorrhage, and assessment of parenchymal damage. However, it is not always possible to distinguish between old and new infarcts using a CT scan. This is because the appearance of infarcts on a CT scan may not provide enough information to determine their age accurately. Therefore, the inability to distinguish between old and new infarcts is not an advantage of performing a CT scan for stroke.Rate this question:
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- 10.
Which of the following is NOT true concerning CT?
- A.
CT is the imaging modality of choice for the detecting subarachnoid hemorrhage
- B.
Small subarachnoid bleeds may be inapparent.
- C.
On CT, subarachnoid hemorrhage appears as high density within sulci and CSF cisterns.
- D.
CT becomes more sensitive days to weeks after the acute phase of a subarachnoid hemorrhage.
Correct Answer
D. CT becomes more sensitive days to weeks after the acute pHase of a subarachnoid hemorrhage.Explanation
CT is actually most sensitive in the acute phase of a subarachnoid hemorrhage, typically within the first 24 hours. As time passes, the blood can become less dense and more difficult to detect on CT scans. Therefore, the statement that CT becomes more sensitive days to weeks after the acute phase of a subarachnoid hemorrhage is not true.Rate this question:
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Current Version
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Mar 22, 2022Quiz Edited by
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Feb 27, 2008Quiz Created by
Wright08
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