Mosby CT Registry Review Exam 2026
Questions and Answers
What is the smallest component of a digital image - Correct answer-pixel
How many CT numbers are assigned to each pixel in the image matrix? - Correct
answer-One
In a CT image, the CT number - Correct answer-Of a material is dependent on its
linear attenuation coefficient
Each two-dimensional square of data that make up the CT image is called a -
Correct answer-pixel
What is an element of the digital image - Correct answer-pixel
Which of the following influences the spatial resolution in cardiac CT imaging -
Correct answer-*detector size
*reconstruction interval
*pitch
As patient motion increases spatial resolution decreases - Correct answer-TRUE
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,Which is an advantage of using a small focal spot - Correct answer-increased
spatial resolution
Increasing the CT image matrix from 256x256 to 512x512 will likely improve? -
Correct answer-High-contrast spatial resolution
The practical limiting spatial resolution of a CT scanner is 3.6 lp/cm. What size
object does this correspond to? - Correct answer-1.4 mm
Use of a bone filter, as opposed to a soft tissue filter, to reconstruct CT images
would likely improve? - Correct answer-Spatial resolution
The spatial resolution of a typical CT scanner is on the order of? - Correct answer-
1 mm
A 512 x 512 matrix CT image over a 30-cm field of view could show a spatial
resolution of no better than ? lp/cm? - Correct answer-8.5
When comparing a 512x512 matrix to a 1024x1024 matrix, the 1024x1024 matrix?
- Correct answer-Contains four times as many pixels: 1024 x 1024 =1048576 then
512 x 512= 262144...then divide 1048576 /262144 = 4
High contrast spatial resolution and low contrast resolution are typically measured
baseline and ? thereafter - Correct answer-Biannually
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,To improve the high contrast spatial resolution of a CT study, one would increase
_____ while keeping all other factors the same. - Correct answer-Matrix size
(128x128 to 512x512)
A radiologist wants to improve the high-contrast spatial resolution of anatomy
which he/she is examining by CT. The change which would best lead to this
improvement is - Correct answer-Increase the matrix size
To improve the high-contrast spatial resolution of a CT study, one could increase ?
while keeping all other factors the same? - Correct answer-Matrix size
A voxel contains 25% air, 50% water and 25% bone. The CT number for this voxel
would be expected to be _____ HU? - Correct answer-0
How many pixels are contained in a 1,024 matrix image? - Correct answer-D.
1,048,576
MATH 1024 X1024
It is located in a matrix and is a two dimensional representation of a voxel -
Correct answer-pixel
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, When CT numbers are calculated for voxels (volume elements) of tissue what is
assigned the calculated number and a subsequent shade of gray - Correct answer-
pixel
What is defined as a picture element or the smallest component of the digital image
- Correct answer-pixel
A CT scan produces a 512x512 matrix transverse image of a 30 cm diameter FOV.
Each pixel is approximately _____ mm on a side. - Correct answer-0.6 equation:
30cm/512= .058cm convert to mm and its .58 which is approximately 0.6
The ability of a system to define small objects distinctly is referred to as which of
the following? - Correct answer-spatial resolution
Which of the following terms is/are commonly used to describe a CT scanner's
ability to differentiate objects with similar linear attenuation coeffiecents - Correct
answer-*spatial resolution
*sensitivity
Which of the following factors have an affect on contrast resolution - Correct
answer-*patient size
*slice thickness
*pixel size
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Questions and Answers
What is the smallest component of a digital image - Correct answer-pixel
How many CT numbers are assigned to each pixel in the image matrix? - Correct
answer-One
In a CT image, the CT number - Correct answer-Of a material is dependent on its
linear attenuation coefficient
Each two-dimensional square of data that make up the CT image is called a -
Correct answer-pixel
What is an element of the digital image - Correct answer-pixel
Which of the following influences the spatial resolution in cardiac CT imaging -
Correct answer-*detector size
*reconstruction interval
*pitch
As patient motion increases spatial resolution decreases - Correct answer-TRUE
©COPYRIGHT 2025, ALL RIGHTS RESERVED 1
,Which is an advantage of using a small focal spot - Correct answer-increased
spatial resolution
Increasing the CT image matrix from 256x256 to 512x512 will likely improve? -
Correct answer-High-contrast spatial resolution
The practical limiting spatial resolution of a CT scanner is 3.6 lp/cm. What size
object does this correspond to? - Correct answer-1.4 mm
Use of a bone filter, as opposed to a soft tissue filter, to reconstruct CT images
would likely improve? - Correct answer-Spatial resolution
The spatial resolution of a typical CT scanner is on the order of? - Correct answer-
1 mm
A 512 x 512 matrix CT image over a 30-cm field of view could show a spatial
resolution of no better than ? lp/cm? - Correct answer-8.5
When comparing a 512x512 matrix to a 1024x1024 matrix, the 1024x1024 matrix?
- Correct answer-Contains four times as many pixels: 1024 x 1024 =1048576 then
512 x 512= 262144...then divide 1048576 /262144 = 4
High contrast spatial resolution and low contrast resolution are typically measured
baseline and ? thereafter - Correct answer-Biannually
©COPYRIGHT 2025, ALL RIGHTS RESERVED 2
,To improve the high contrast spatial resolution of a CT study, one would increase
_____ while keeping all other factors the same. - Correct answer-Matrix size
(128x128 to 512x512)
A radiologist wants to improve the high-contrast spatial resolution of anatomy
which he/she is examining by CT. The change which would best lead to this
improvement is - Correct answer-Increase the matrix size
To improve the high-contrast spatial resolution of a CT study, one could increase ?
while keeping all other factors the same? - Correct answer-Matrix size
A voxel contains 25% air, 50% water and 25% bone. The CT number for this voxel
would be expected to be _____ HU? - Correct answer-0
How many pixels are contained in a 1,024 matrix image? - Correct answer-D.
1,048,576
MATH 1024 X1024
It is located in a matrix and is a two dimensional representation of a voxel -
Correct answer-pixel
©COPYRIGHT 2025, ALL RIGHTS RESERVED 3
, When CT numbers are calculated for voxels (volume elements) of tissue what is
assigned the calculated number and a subsequent shade of gray - Correct answer-
pixel
What is defined as a picture element or the smallest component of the digital image
- Correct answer-pixel
A CT scan produces a 512x512 matrix transverse image of a 30 cm diameter FOV.
Each pixel is approximately _____ mm on a side. - Correct answer-0.6 equation:
30cm/512= .058cm convert to mm and its .58 which is approximately 0.6
The ability of a system to define small objects distinctly is referred to as which of
the following? - Correct answer-spatial resolution
Which of the following terms is/are commonly used to describe a CT scanner's
ability to differentiate objects with similar linear attenuation coeffiecents - Correct
answer-*spatial resolution
*sensitivity
Which of the following factors have an affect on contrast resolution - Correct
answer-*patient size
*slice thickness
*pixel size
©COPYRIGHT 2025, ALL RIGHTS RESERVED 4
