1|Page
CT Registry Exam 2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS
WILL COME FROM HERE (100% Latest Already Graded
A+
1. In computed tomography, the primary purpose of the bowtie filter is
to:
A. Increase spatial resolution
B. Reduce patient dose by equalizing x-ray intensity across the detector
array
C. Enhance contrast resolution
D. Decrease image noise
Answer: B
The bowtie filter is shaped to compensate for the varying thickness of
the patient. It attenuates the x-ray beam more at the edges than at the
center, equalizing the intensity reaching the detectors and significantly
reducing overall patient dose.
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2. The mathematical technique used to reconstruct CT images from
projection data is known as:
A. Fourier transform
B. Filtered back projection
C. Iterative reconstruction
D. Maximum likelihood expectation maximization
Answer: B
Filtered back projection remains the standard reconstruction algorithm
in most clinical CT systems. It applies a mathematical filter to the
projection data before back-projecting it to generate a cross-sectional
image.
3. The CT number of water on the Hounsfield scale is:
A. -1000
B. 0
C. +1000
D. +500
Answer: B
The Hounsfield scale is defined such that water has an attenuation
value of 0 Hounsfield units (HU). Air is -1000 HU, and dense bone is
approximately +1000 HU, though this can vary.
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4. Partial volume artifact occurs when:
A. The patient moves during the scan
B. A single voxel contains multiple tissue types
C. The x-ray tube is overheated
D. The detector array is misaligned
Answer: B
Partial volume averaging occurs when a voxel includes two or more
different tissues with significantly different attenuation coefficients. The
resulting CT number is the weighted average of these tissues, which
may not accurately represent either one.
5. In helical CT, the term pitch is defined as:
A. Table travel per rotation divided by beam collimation
B. Beam collimation divided by table travel per rotation
C. Rotation time divided by table speed
D. Table speed multiplied by beam collimation
Answer: A
Pitch is the ratio of table movement per gantry rotation to the x-ray
beam collimation width. A pitch of 1.0 means the table advances
exactly one beam width per rotation.
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6. The primary advantage of multidetector CT (MDCT) over single-slice
CT is:
A. Lower patient dose
B. Faster scan times and improved longitudinal resolution
C. Higher tube voltage
D. Simpler reconstruction algorithms
Answer: B
MDCT allows for much faster scanning of larger volumes with thinner
slices, improving both temporal and longitudinal resolution. It enables
cardiac, trauma, and whole-body angiography examinations.
7. The relationship between spatial resolution and the reconstruction
matrix is:
A. A 512x512 matrix provides the same resolution as a 1024x1024
matrix
B. A 1024x1024 matrix may provide better spatial resolution
C. A smaller matrix always improves resolution
D. Matrix size has no effect on resolution
Answer: B
A larger reconstruction matrix (e.g., 1024x1024) results in smaller pixel
sizes, potentially improving spatial resolution. However, this requires
more data and increases image noise unless dose is increased.
CT Registry Exam 2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS
WILL COME FROM HERE (100% Latest Already Graded
A+
1. In computed tomography, the primary purpose of the bowtie filter is
to:
A. Increase spatial resolution
B. Reduce patient dose by equalizing x-ray intensity across the detector
array
C. Enhance contrast resolution
D. Decrease image noise
Answer: B
The bowtie filter is shaped to compensate for the varying thickness of
the patient. It attenuates the x-ray beam more at the edges than at the
center, equalizing the intensity reaching the detectors and significantly
reducing overall patient dose.
,2|Page
2. The mathematical technique used to reconstruct CT images from
projection data is known as:
A. Fourier transform
B. Filtered back projection
C. Iterative reconstruction
D. Maximum likelihood expectation maximization
Answer: B
Filtered back projection remains the standard reconstruction algorithm
in most clinical CT systems. It applies a mathematical filter to the
projection data before back-projecting it to generate a cross-sectional
image.
3. The CT number of water on the Hounsfield scale is:
A. -1000
B. 0
C. +1000
D. +500
Answer: B
The Hounsfield scale is defined such that water has an attenuation
value of 0 Hounsfield units (HU). Air is -1000 HU, and dense bone is
approximately +1000 HU, though this can vary.
,3|Page
4. Partial volume artifact occurs when:
A. The patient moves during the scan
B. A single voxel contains multiple tissue types
C. The x-ray tube is overheated
D. The detector array is misaligned
Answer: B
Partial volume averaging occurs when a voxel includes two or more
different tissues with significantly different attenuation coefficients. The
resulting CT number is the weighted average of these tissues, which
may not accurately represent either one.
5. In helical CT, the term pitch is defined as:
A. Table travel per rotation divided by beam collimation
B. Beam collimation divided by table travel per rotation
C. Rotation time divided by table speed
D. Table speed multiplied by beam collimation
Answer: A
Pitch is the ratio of table movement per gantry rotation to the x-ray
beam collimation width. A pitch of 1.0 means the table advances
exactly one beam width per rotation.
, 4|Page
6. The primary advantage of multidetector CT (MDCT) over single-slice
CT is:
A. Lower patient dose
B. Faster scan times and improved longitudinal resolution
C. Higher tube voltage
D. Simpler reconstruction algorithms
Answer: B
MDCT allows for much faster scanning of larger volumes with thinner
slices, improving both temporal and longitudinal resolution. It enables
cardiac, trauma, and whole-body angiography examinations.
7. The relationship between spatial resolution and the reconstruction
matrix is:
A. A 512x512 matrix provides the same resolution as a 1024x1024
matrix
B. A 1024x1024 matrix may provide better spatial resolution
C. A smaller matrix always improves resolution
D. Matrix size has no effect on resolution
Answer: B
A larger reconstruction matrix (e.g., 1024x1024) results in smaller pixel
sizes, potentially improving spatial resolution. However, this requires
more data and increases image noise unless dose is increased.
