Mosby CT Registry Review Questions With
Complete Solutions
What is the smallest component of a digital image - VERIFIED ANSWER✔✔-pixel
How many CT numbers are assigned to each pixel in the image matrix? - VERIFIED ANSWER✔✔-One
In a CT image, the CT number - VERIFIED 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 - VERIFIED ANSWER✔✔-pixel
What is an element of the digital image - VERIFIED ANSWER✔✔-pixel
Which of the following influences the spatial resolution in cardiac CT imaging - VERIFIED ANSWER✔✔-
*detector size
*reconstruction interval
*pitch
As patient motion increases spatial resolution decreases - VERIFIED ANSWER✔✔-TRUE
Which is an advantage of using a small focal spot - VERIFIED ANSWER✔✔-increased spatial resolution
Increasing the CT image matrix from 256x256 to 512x512 will likely improve? - VERIFIED 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? -
VERIFIED ANSWER✔✔-1.4 mm
Use of a bone filter, as opposed to a soft tissue filter, to reconstruct CT images would likely improve? -
VERIFIED ANSWER✔✔-Spatial resolution
The spatial resolution of a typical CT scanner is on the order of? - VERIFIED 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? - VERIFIED ANSWER✔✔-8.5
When comparing a 512x512 matrix to a 1024x1024 matrix, the 1024x1024 matrix? - VERIFIED 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 -
VERIFIED ANSWER✔✔-Biannually
To improve the high contrast spatial resolution of a CT study, one would increase _____ while keeping all other
factors the same. - VERIFIED 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 - VERIFIED 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? - VERIFIED 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? - VERIFIED ANSWER✔✔-0
,How many pixels are contained in a 1,024 matrix image? - VERIFIED ANSWER✔✔-D. 1,048,576
MATH 1024 X1024
It is located in a matrix and is a two dimensional representation of a voxel - VERIFIED ANSWER✔✔-pixel
When CT numbers are calculated for voxels (volume elements) of tissue what is assigned the calculated number
and a subsequent shade of gray - VERIFIED ANSWER✔✔-pixel
What is defined as a picture element or the smallest component of the digital image - VERIFIED 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. - VERIFIED 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? - VERIFIED
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 - VERIFIED ANSWER✔✔-*spatial resolution
*sensitivity
Which of the following factors have an affect on contrast resolution - VERIFIED ANSWER✔✔-*patient size
*slice thickness
*pixel size
*mAs/dose
As mAs/dose increases contrast resolution decreases - VERIFIED ANSWER✔✔-FALSE
As mAs/dose increases contrast resolution INCREASES - VERIFIED ANSWER✔✔-TRUE
The ability of a CT scanner to accurately image objects with similar densities is termed - VERIFIED
ANSWER✔✔-*contrast resolution
*sensitivity
Which of the following has a direct relationship on increasing contrast resolution - VERIFIED ANSWER✔✔-
*mAs/dose increase
*Slice thickness
For a particular CT scanner's beam quality, the linear attenuation coefficient for water is 0.20 cm-1 and for a
certain tumor is 0.21 cm-1. What is the CT number of the tumor? - VERIFIED ANSWER✔✔-50. Equation
(.21-.20/.21) × 1000= 50
A CT scanner with poor contrast resolution or low sensitivity has difficulty separating - VERIFIED
ANSWER✔✔-tissues whose linear attenuation coefficients are nearly equal
What is the basic physical quantity being measured by a CT system - VERIFIED ANSWER✔✔-Linear
attenuation coefficient
Assume the linear attenuation coefficient is 0.20 cm-1 for water and 0.40 cm-1 for tissue within a given voxel.
What is the CT number in Hounsfield units for the pixel representing this voxel? - VERIFIED ANSWER✔✔-
+1,000....Equation { (.4-.2) /.2} x 1000
What fraction of monoenergetic x-rays will be absorbed by a 20-cm thick material having a linear attenuation
coefficient of 0.05 cm-1? - VERIFIED ANSWER✔✔-0.63
The contrast resolution of CT is approximately ? % - VERIFIED ANSWER✔✔-0.3 to 0.6
,This term describes the ability CT scanner to differentiate objects with MINIMAL differences in attenuation
coefficients - VERIFIED ANSWER✔✔-contrast resolution
What is the term for resolution of a CT scanner referred to as the system's ability to differentiate objects with
SIMILAR densities. - VERIFIED ANSWER✔✔-contrast resolution
In order to pass ACR CT accreditation, the CT scanner's adult head protocol must be within - VERIFIED
ANSWER✔✔-1.0
The QC test for the average CT number for water should be done - VERIFIED ANSWER✔✔-Daily
The following are all basic tenets of a QC program for computed tomography scanner - VERIFIED
ANSWER✔✔-*QC test must be conducted regularly
*Accurate record keeping
*all test results must be interpreted promptly
Using the ACR CT accreditation phantom, module 3 is used to measure which of the following - VERIFIED
ANSWER✔✔-CT number uniformity
The following QC test should be done on a monthly basis - VERIFIED ANSWER✔✔-high contrast resolution
The CT number at the center of a uniformly filled water phantom should ideally be - VERIFIED ANSWER✔✔-0
The ACR CT accreditation phantom is designed to perform QC measurements of - VERIFIED ANSWER✔✔-
*positioning accuracy and light accuracy alignment only
*CT number accuracy and slice thickness only
*low contrast resolution, CT number uniformity, and high contrast resolution
The ACR tolerance limit for the CT number accuracy for water is - VERIFIED ANSWER✔✔-+-7HU or +-5
preferred
The test for the average CT number of water should be tested at - VERIFIED ANSWER✔✔-*acceptance
*daily
The ACR tolerance limit for the CT number uniformity is which of the following - VERIFIED ANSWER✔✔-
The center CT number must be between plus or minus 7HU plus the abdomen protocol must be used
To evaluate low contrast resolution, phantoms are scanned using different ? settings - VERIFIED ANSWER✔✔-
mAs
For an increase from 200 mA to 400 mA in a CT exam, the result would be to - VERIFIED ANSWER✔✔-
Increase low contrast resolution
This ability is also commonly referred to as the low contrast resolution or the sensitivity of the CT scanner -
VERIFIED ANSWER✔✔-contrast resolution
The major advantage of a CT scanner over a screen-film radiography system is - VERIFIED ANSWER✔✔-
Better low contrast discrimination
For CT images, all of the following factors improve the visibility of large, low-contrast lesions except? -
VERIFIED ANSWER✔✔-Smaller pixel sizes
As the iodine concentration ? the viscosity of the substance will ? - VERIFIED ANSWER✔✔-increase, increase
A fluid with a high viscosity is relatively - VERIFIED ANSWER✔✔-thick and flows slowly
The viscosity of a solution may be changed by regulating - VERIFIED ANSWER✔✔-temperature
A patient with a temperature over ______ is considered to have a fever.
, 98.6.
96.8.
99.8.
100. - VERIFIED ANSWER✔✔-Correct Answer:
99.8
www.examedge.com
The body temperature fluctuates, and the normal range is between - VERIFIED ANSWER✔✔-96.8 and 99.8.
www.examedge.com
A patient has a fever once the temperature rises above ?. Temperatures are likely to be higher as it grows later. -
VERIFIED ANSWER✔✔-99.8
www.examedge.com
Which of these describes a liver window setting?
Approximate width of 275 and window level 90.
Approximate width of 150 and window level 70.
Approximate width of 305 and window level 50.
Approximate width of 80 and window level 90. - VERIFIED ANSWER✔✔-Approximate width of 150 and
window level 70.
www.examedge.com
The use of the liver window makes it easier to view subtle - VERIFIED ANSWER✔✔-liver lesions
www.examedge.com
Although it may be a bit more difficult to see subtle liver lesions, a ? can also be used. - VERIFIED
ANSWER✔✔-routine soft-tissue window setting
www.examedge.com
Contrast enhancement phases of the liver include which of the following - VERIFIED ANSWER✔✔-*arterial
*portal venous
*equilibrium phase
*early arterial
*delayed phases
Malignant neoplasms of the liver include which of the following - VERIFIED ANSWER✔✔-*hepatocellular
carcinoma HCC
Malignant neoplasms of the liver include which of the following - VERIFIED ANSWER✔✔-*hepatocellular
carcinoma HCC
What is the most common malignant neoplasms of the liver - VERIFIED ANSWER✔✔-hepatocellular carcinoma
HCC and metastases
IMAGE IS metastases
Hemanglomas and focal nodular hyperplasia FNH are both examples of what types of tumors - VERIFIED
Complete Solutions
What is the smallest component of a digital image - VERIFIED ANSWER✔✔-pixel
How many CT numbers are assigned to each pixel in the image matrix? - VERIFIED ANSWER✔✔-One
In a CT image, the CT number - VERIFIED 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 - VERIFIED ANSWER✔✔-pixel
What is an element of the digital image - VERIFIED ANSWER✔✔-pixel
Which of the following influences the spatial resolution in cardiac CT imaging - VERIFIED ANSWER✔✔-
*detector size
*reconstruction interval
*pitch
As patient motion increases spatial resolution decreases - VERIFIED ANSWER✔✔-TRUE
Which is an advantage of using a small focal spot - VERIFIED ANSWER✔✔-increased spatial resolution
Increasing the CT image matrix from 256x256 to 512x512 will likely improve? - VERIFIED 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? -
VERIFIED ANSWER✔✔-1.4 mm
Use of a bone filter, as opposed to a soft tissue filter, to reconstruct CT images would likely improve? -
VERIFIED ANSWER✔✔-Spatial resolution
The spatial resolution of a typical CT scanner is on the order of? - VERIFIED 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? - VERIFIED ANSWER✔✔-8.5
When comparing a 512x512 matrix to a 1024x1024 matrix, the 1024x1024 matrix? - VERIFIED 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 -
VERIFIED ANSWER✔✔-Biannually
To improve the high contrast spatial resolution of a CT study, one would increase _____ while keeping all other
factors the same. - VERIFIED 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 - VERIFIED 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? - VERIFIED 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? - VERIFIED ANSWER✔✔-0
,How many pixels are contained in a 1,024 matrix image? - VERIFIED ANSWER✔✔-D. 1,048,576
MATH 1024 X1024
It is located in a matrix and is a two dimensional representation of a voxel - VERIFIED ANSWER✔✔-pixel
When CT numbers are calculated for voxels (volume elements) of tissue what is assigned the calculated number
and a subsequent shade of gray - VERIFIED ANSWER✔✔-pixel
What is defined as a picture element or the smallest component of the digital image - VERIFIED 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. - VERIFIED 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? - VERIFIED
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 - VERIFIED ANSWER✔✔-*spatial resolution
*sensitivity
Which of the following factors have an affect on contrast resolution - VERIFIED ANSWER✔✔-*patient size
*slice thickness
*pixel size
*mAs/dose
As mAs/dose increases contrast resolution decreases - VERIFIED ANSWER✔✔-FALSE
As mAs/dose increases contrast resolution INCREASES - VERIFIED ANSWER✔✔-TRUE
The ability of a CT scanner to accurately image objects with similar densities is termed - VERIFIED
ANSWER✔✔-*contrast resolution
*sensitivity
Which of the following has a direct relationship on increasing contrast resolution - VERIFIED ANSWER✔✔-
*mAs/dose increase
*Slice thickness
For a particular CT scanner's beam quality, the linear attenuation coefficient for water is 0.20 cm-1 and for a
certain tumor is 0.21 cm-1. What is the CT number of the tumor? - VERIFIED ANSWER✔✔-50. Equation
(.21-.20/.21) × 1000= 50
A CT scanner with poor contrast resolution or low sensitivity has difficulty separating - VERIFIED
ANSWER✔✔-tissues whose linear attenuation coefficients are nearly equal
What is the basic physical quantity being measured by a CT system - VERIFIED ANSWER✔✔-Linear
attenuation coefficient
Assume the linear attenuation coefficient is 0.20 cm-1 for water and 0.40 cm-1 for tissue within a given voxel.
What is the CT number in Hounsfield units for the pixel representing this voxel? - VERIFIED ANSWER✔✔-
+1,000....Equation { (.4-.2) /.2} x 1000
What fraction of monoenergetic x-rays will be absorbed by a 20-cm thick material having a linear attenuation
coefficient of 0.05 cm-1? - VERIFIED ANSWER✔✔-0.63
The contrast resolution of CT is approximately ? % - VERIFIED ANSWER✔✔-0.3 to 0.6
,This term describes the ability CT scanner to differentiate objects with MINIMAL differences in attenuation
coefficients - VERIFIED ANSWER✔✔-contrast resolution
What is the term for resolution of a CT scanner referred to as the system's ability to differentiate objects with
SIMILAR densities. - VERIFIED ANSWER✔✔-contrast resolution
In order to pass ACR CT accreditation, the CT scanner's adult head protocol must be within - VERIFIED
ANSWER✔✔-1.0
The QC test for the average CT number for water should be done - VERIFIED ANSWER✔✔-Daily
The following are all basic tenets of a QC program for computed tomography scanner - VERIFIED
ANSWER✔✔-*QC test must be conducted regularly
*Accurate record keeping
*all test results must be interpreted promptly
Using the ACR CT accreditation phantom, module 3 is used to measure which of the following - VERIFIED
ANSWER✔✔-CT number uniformity
The following QC test should be done on a monthly basis - VERIFIED ANSWER✔✔-high contrast resolution
The CT number at the center of a uniformly filled water phantom should ideally be - VERIFIED ANSWER✔✔-0
The ACR CT accreditation phantom is designed to perform QC measurements of - VERIFIED ANSWER✔✔-
*positioning accuracy and light accuracy alignment only
*CT number accuracy and slice thickness only
*low contrast resolution, CT number uniformity, and high contrast resolution
The ACR tolerance limit for the CT number accuracy for water is - VERIFIED ANSWER✔✔-+-7HU or +-5
preferred
The test for the average CT number of water should be tested at - VERIFIED ANSWER✔✔-*acceptance
*daily
The ACR tolerance limit for the CT number uniformity is which of the following - VERIFIED ANSWER✔✔-
The center CT number must be between plus or minus 7HU plus the abdomen protocol must be used
To evaluate low contrast resolution, phantoms are scanned using different ? settings - VERIFIED ANSWER✔✔-
mAs
For an increase from 200 mA to 400 mA in a CT exam, the result would be to - VERIFIED ANSWER✔✔-
Increase low contrast resolution
This ability is also commonly referred to as the low contrast resolution or the sensitivity of the CT scanner -
VERIFIED ANSWER✔✔-contrast resolution
The major advantage of a CT scanner over a screen-film radiography system is - VERIFIED ANSWER✔✔-
Better low contrast discrimination
For CT images, all of the following factors improve the visibility of large, low-contrast lesions except? -
VERIFIED ANSWER✔✔-Smaller pixel sizes
As the iodine concentration ? the viscosity of the substance will ? - VERIFIED ANSWER✔✔-increase, increase
A fluid with a high viscosity is relatively - VERIFIED ANSWER✔✔-thick and flows slowly
The viscosity of a solution may be changed by regulating - VERIFIED ANSWER✔✔-temperature
A patient with a temperature over ______ is considered to have a fever.
, 98.6.
96.8.
99.8.
100. - VERIFIED ANSWER✔✔-Correct Answer:
99.8
www.examedge.com
The body temperature fluctuates, and the normal range is between - VERIFIED ANSWER✔✔-96.8 and 99.8.
www.examedge.com
A patient has a fever once the temperature rises above ?. Temperatures are likely to be higher as it grows later. -
VERIFIED ANSWER✔✔-99.8
www.examedge.com
Which of these describes a liver window setting?
Approximate width of 275 and window level 90.
Approximate width of 150 and window level 70.
Approximate width of 305 and window level 50.
Approximate width of 80 and window level 90. - VERIFIED ANSWER✔✔-Approximate width of 150 and
window level 70.
www.examedge.com
The use of the liver window makes it easier to view subtle - VERIFIED ANSWER✔✔-liver lesions
www.examedge.com
Although it may be a bit more difficult to see subtle liver lesions, a ? can also be used. - VERIFIED
ANSWER✔✔-routine soft-tissue window setting
www.examedge.com
Contrast enhancement phases of the liver include which of the following - VERIFIED ANSWER✔✔-*arterial
*portal venous
*equilibrium phase
*early arterial
*delayed phases
Malignant neoplasms of the liver include which of the following - VERIFIED ANSWER✔✔-*hepatocellular
carcinoma HCC
Malignant neoplasms of the liver include which of the following - VERIFIED ANSWER✔✔-*hepatocellular
carcinoma HCC
What is the most common malignant neoplasms of the liver - VERIFIED ANSWER✔✔-hepatocellular carcinoma
HCC and metastases
IMAGE IS metastases
Hemanglomas and focal nodular hyperplasia FNH are both examples of what types of tumors - VERIFIED
