Mosby's CT Registry Review 3rd Edition: Practice Exam #1, Exams of Science
education
What is the smallest component of a digital image - ANSWERpixel
How many CT numbers are assigned to each pixel in the image matrix? -
ANSWEROne
In a CT image, the CT number - ANSWEROf a material is dependent on its
linear attenuation coefficient
Each two-dimensional square of data that make up the CT image is called a -
ANSWERpixel
What is an element of the digital image - ANSWERpixel
Which of the following influences the spatial resolution in cardiac CT imaging
- ANSWER*detector size
,*reconstruction interval
*pitch
As patient motion increases spatial resolution decreases - ANSWERTRUE
Which is an advantage of using a small focal spot - ANSWERincreased spatial
resolution
Increasing the CT image matrix from 256x256 to 512x512 will likely improve?
- ANSWERHigh-contrast spatial resolution
The practical limiting spatial resolution of a CT scanner is 3.6 lp/cm. What size
object does this correspond to? - ANSWER1.4 mm
Use of a bone filter, as opposed to a soft tissue filter, to reconstruct CT images
would likely improve? - ANSWERSpatial resolution
The spatial resolution of a typical CT scanner is on the order of? - ANSWER1
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? - ANSWER8.5
When comparing a 512x512 matrix to a 1024x1024 matrix, the 1024x1024
matrix? - ANSWERContains 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 - ANSWERBiannually
To improve the high contrast spatial resolution of a CT study, one would
increase _____ while keeping all other factors the same. - ANSWERMatrix 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 - ANSWERIncrease the matrix size
To improve the high-contrast spatial resolution of a CT study, one could
increase ? while keeping all other factors the same? - ANSWERMatrix size
A voxel contains 25% air, 50% water and 25% bone. The CT number for this
voxel would be expected to be _____ HU? - ANSWER0
How many pixels are contained in a 1,024 matrix image? - ANSWERD.
1,048,576
MATH 1024 X1024
It is located in a matrix and is a two dimensional representation of a voxel -
ANSWERpixel
When CT numbers are calculated for voxels (volume elements) of tissue what
is assigned the calculated number and a subsequent shade of gray -
ANSWERpixel
, What is defined as a picture element or the smallest component of the digital
image - ANSWERpixel
A CT scan produces a 512x512 matrix transverse image of a 30 cm diameter
FOV. Each pixel is approximately _____ mm on a side. - ANSWER0.6 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? - ANSWERspatial 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 - ANSWER*spatial resolution
*sensitivity
Which of the following factors have an affect on contrast resolution -
ANSWER*patient size
*slice thickness
*pixel size
*mAs/dose
As mAs/dose increases contrast resolution decreases - ANSWERFALSE
As mAs/dose increases contrast resolution INCREASES - ANSWERTRUE
education
What is the smallest component of a digital image - ANSWERpixel
How many CT numbers are assigned to each pixel in the image matrix? -
ANSWEROne
In a CT image, the CT number - ANSWEROf a material is dependent on its
linear attenuation coefficient
Each two-dimensional square of data that make up the CT image is called a -
ANSWERpixel
What is an element of the digital image - ANSWERpixel
Which of the following influences the spatial resolution in cardiac CT imaging
- ANSWER*detector size
,*reconstruction interval
*pitch
As patient motion increases spatial resolution decreases - ANSWERTRUE
Which is an advantage of using a small focal spot - ANSWERincreased spatial
resolution
Increasing the CT image matrix from 256x256 to 512x512 will likely improve?
- ANSWERHigh-contrast spatial resolution
The practical limiting spatial resolution of a CT scanner is 3.6 lp/cm. What size
object does this correspond to? - ANSWER1.4 mm
Use of a bone filter, as opposed to a soft tissue filter, to reconstruct CT images
would likely improve? - ANSWERSpatial resolution
The spatial resolution of a typical CT scanner is on the order of? - ANSWER1
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? - ANSWER8.5
When comparing a 512x512 matrix to a 1024x1024 matrix, the 1024x1024
matrix? - ANSWERContains 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 - ANSWERBiannually
To improve the high contrast spatial resolution of a CT study, one would
increase _____ while keeping all other factors the same. - ANSWERMatrix 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 - ANSWERIncrease the matrix size
To improve the high-contrast spatial resolution of a CT study, one could
increase ? while keeping all other factors the same? - ANSWERMatrix size
A voxel contains 25% air, 50% water and 25% bone. The CT number for this
voxel would be expected to be _____ HU? - ANSWER0
How many pixels are contained in a 1,024 matrix image? - ANSWERD.
1,048,576
MATH 1024 X1024
It is located in a matrix and is a two dimensional representation of a voxel -
ANSWERpixel
When CT numbers are calculated for voxels (volume elements) of tissue what
is assigned the calculated number and a subsequent shade of gray -
ANSWERpixel
, What is defined as a picture element or the smallest component of the digital
image - ANSWERpixel
A CT scan produces a 512x512 matrix transverse image of a 30 cm diameter
FOV. Each pixel is approximately _____ mm on a side. - ANSWER0.6 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? - ANSWERspatial 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 - ANSWER*spatial resolution
*sensitivity
Which of the following factors have an affect on contrast resolution -
ANSWER*patient size
*slice thickness
*pixel size
*mAs/dose
As mAs/dose increases contrast resolution decreases - ANSWERFALSE
As mAs/dose increases contrast resolution INCREASES - ANSWERTRUE
