CT REGISTRY Exam Questions With
Correct Answers Already Passed 2025|
2026
What determines how much and what section of the collected raw data is used to create
an image CORRECT ANSWERS Display field of view
The "string of beads" artifact is most closely associated with which of the following?
CORRECT ANSWERS Maximum intensity projection images
A patient has a severe vagal reaction to iodinated contrast material that includes
bradycardia should be given a treatment of CORRECT ANSWERS *treatment includes
increasing blood pressure with IV fluids
*intravenous administration of atropine to block vagal stimulation of the heart
An MDCT image is reconstructed using a 512x512 matrix and a display field of view of
44 cm. If the detector collimation is set to a section width of 2.5 mm what is the volume
of each voxel CORRECT ANSWERS How to solve: The linear dimension of the pixel
must first be calculated by dividing the DFOV, in mm, by the matrix. This linear pixel
dimension is squared to yield the pixel area in mm^2. The volume of the voxel may be
calculated by multiplying the pixel area by the section width
step 1. 44 cm/ 512 =0.0859
step 2. 0.0859*2.5 mm = 0.2148
step 3. move the decimal point =2.15 mm^3
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?
CORRECT ANSWERS Equation (.21-.20/.21) × 1000= 50
A CT system measures the average linear attenuation coefficient of a voxel of tissue to
be 0.189. The linear coefficient of water for this scanner is 0.181. The CT number
assigned to the pixel representing this tissue is CORRECT ANSWERS 44 HU
use equation above
A CT scanner capable of producing an image that is a perfect reproduction of the actual
anatomic section is said to have an MTF modulator transfer function of CORRECT
ANSWERS 1
For an increase from 200 mA to 400 mA in a CT exam, the result would be to
CORRECT ANSWERS increase low contrast resolution
The major controlling factor of exam quality for coronary CTA is CORRECT ANSWERS
patients heart rate... 65-70 beats per minute yield the best results
, What is the atomic number of xenon gas? CORRECT ANSWERS 54
The exaggeration of displayed calcification within the coronary arteries during cardiac
MDCT study is referred to as CORRECT ANSWERS blooming
- the potential overestimation of vessel calcification due to partial volume artifact
a wide window setting (1500) or improving spatial resolution could help mitigate this
effect
Which of the following section widths would cause the greatest amount of partial volume
averaging
A. 1 mm
B. 3 mm
C. 5 mm
D. 10 mm CORRECT ANSWERS D. 10 mm
- Large section widths result in long voxel lengths with possibly several tissue types
accounted for within the voxel. When a CT number is assigned to the representative
pixel, the density of all the tissue types is averaged, yielding one attenuation coefficient.
Narrow section widths tend to reduce partial volume effect
What reduces partial volume effect? CORRECT ANSWERS narrow section widths
Patient is having a severe vagal reaction to contrast including brachycardia and
hypotension.. what should be done? CORRECT ANSWERS Iv fluids to raise blood
pressure
atrophine administration to block vagal stimulation of the heart.
What type of reconstruction technique was used in the first CT scanners? CORRECT
ANSWERS Iterative form of reconstruction
Sampling frequency CORRECT ANSWERS The number of views obtained by the CT
system during the data acquisition of the image.
How many samples of information comprising the raw data are there for a third-
generation, 64-row detector scanner with 850 detectors and 1700 projections acquired
during a 360 rotation CORRECT ANSWERS Solution: 850 x 1700 x 64 = 92,480,000
samples comprising raw data for this scan
What is the purpose of convolution? CORRECT ANSWERS To enhance the important
characteristics of the image before back projection is performed
In order to minimize partial volume artifacts___________ slices should be selected
CORRECT ANSWERS thinner
Correct Answers Already Passed 2025|
2026
What determines how much and what section of the collected raw data is used to create
an image CORRECT ANSWERS Display field of view
The "string of beads" artifact is most closely associated with which of the following?
CORRECT ANSWERS Maximum intensity projection images
A patient has a severe vagal reaction to iodinated contrast material that includes
bradycardia should be given a treatment of CORRECT ANSWERS *treatment includes
increasing blood pressure with IV fluids
*intravenous administration of atropine to block vagal stimulation of the heart
An MDCT image is reconstructed using a 512x512 matrix and a display field of view of
44 cm. If the detector collimation is set to a section width of 2.5 mm what is the volume
of each voxel CORRECT ANSWERS How to solve: The linear dimension of the pixel
must first be calculated by dividing the DFOV, in mm, by the matrix. This linear pixel
dimension is squared to yield the pixel area in mm^2. The volume of the voxel may be
calculated by multiplying the pixel area by the section width
step 1. 44 cm/ 512 =0.0859
step 2. 0.0859*2.5 mm = 0.2148
step 3. move the decimal point =2.15 mm^3
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?
CORRECT ANSWERS Equation (.21-.20/.21) × 1000= 50
A CT system measures the average linear attenuation coefficient of a voxel of tissue to
be 0.189. The linear coefficient of water for this scanner is 0.181. The CT number
assigned to the pixel representing this tissue is CORRECT ANSWERS 44 HU
use equation above
A CT scanner capable of producing an image that is a perfect reproduction of the actual
anatomic section is said to have an MTF modulator transfer function of CORRECT
ANSWERS 1
For an increase from 200 mA to 400 mA in a CT exam, the result would be to
CORRECT ANSWERS increase low contrast resolution
The major controlling factor of exam quality for coronary CTA is CORRECT ANSWERS
patients heart rate... 65-70 beats per minute yield the best results
, What is the atomic number of xenon gas? CORRECT ANSWERS 54
The exaggeration of displayed calcification within the coronary arteries during cardiac
MDCT study is referred to as CORRECT ANSWERS blooming
- the potential overestimation of vessel calcification due to partial volume artifact
a wide window setting (1500) or improving spatial resolution could help mitigate this
effect
Which of the following section widths would cause the greatest amount of partial volume
averaging
A. 1 mm
B. 3 mm
C. 5 mm
D. 10 mm CORRECT ANSWERS D. 10 mm
- Large section widths result in long voxel lengths with possibly several tissue types
accounted for within the voxel. When a CT number is assigned to the representative
pixel, the density of all the tissue types is averaged, yielding one attenuation coefficient.
Narrow section widths tend to reduce partial volume effect
What reduces partial volume effect? CORRECT ANSWERS narrow section widths
Patient is having a severe vagal reaction to contrast including brachycardia and
hypotension.. what should be done? CORRECT ANSWERS Iv fluids to raise blood
pressure
atrophine administration to block vagal stimulation of the heart.
What type of reconstruction technique was used in the first CT scanners? CORRECT
ANSWERS Iterative form of reconstruction
Sampling frequency CORRECT ANSWERS The number of views obtained by the CT
system during the data acquisition of the image.
How many samples of information comprising the raw data are there for a third-
generation, 64-row detector scanner with 850 detectors and 1700 projections acquired
during a 360 rotation CORRECT ANSWERS Solution: 850 x 1700 x 64 = 92,480,000
samples comprising raw data for this scan
What is the purpose of convolution? CORRECT ANSWERS To enhance the important
characteristics of the image before back projection is performed
In order to minimize partial volume artifacts___________ slices should be selected
CORRECT ANSWERS thinner
