ARRT CT Registry Exam
(2024/2025) Questions with Correct
Detailed Answers || Already Graded
A+
<RECENT VERSION>
What is most likely to have the highest osmolality - ANSWER ✔ An ionic IV
contrast agent
Ionic agents dissociate into - ANSWER ✔ ions in solution
What types of contrast would be administered for a CT study of the lumbosacral
spine? - ANSWER ✔ Contrast agents are generally not administered unless there is
a suspected mass.
To evaluate a mass, iodinated IV contrast is typically administered.
If post-pyelogram, intrathecal contrast would have been previously administered.
Which studies might cranial nerve XI be visualized? - ANSWER ✔ soft tissue
neck
In order to generate a diagnostic 3D reconstruction of the hips, the reconstruction
software utilizes - ANSWER ✔ the axial image data
,What is the appropriate range of coverage for a coronal sinus study? - ANSWER
✔ From the dorsum sella to the anterior aspect of the frontal sinus
What is a reason for using thinner slices in the posterior fossa compared with the
more superior regions of the brain? - ANSWER ✔ To reduce beam hardening
artifacts
to improve spatial resolution
A localizer image of what orientations should be used to set up axial slices so that
they can be angled parallel to the plane of a specific lumbar disk? - ANSWER ✔
Lateral
Intravenous contrast is not administered to rule out - ANSWER ✔ a herniated disk
Axial slices are not generally acquired through the entire thoracic spine, but rather
through - ANSWER ✔ a few specified disk spaces.
It is impossible to position an adult in such a way that one could directly obtain -
ANSWER ✔ sagittal or coronal images. These are reformatted from the axial
images.
What is a location where one would expect to find cerebral spinal fluid? -
ANSWER ✔ Subarachnoid space
Fourth ventricle of the brain
What is the expected result of a CT number calibration test performed on a water
phantom? - ANSWER ✔ 0 +/-3
,If the system fails the CT number standard deviation test, what is most likely? -
ANSWER ✔ Detector noise has increased
mA is a measurement of? - ANSWER ✔ The electron current from cathode to
anode
What determines slice thickness? - ANSWER ✔ Pre-patient collimation
If the patient table of a spiral, or helical, scanner is moved at a rate of 0.6cm per
gantry rotation, and a pitch of 1.5 is selected what will be the slice thickness? -
ANSWER ✔ 4mm
6mm/1.5=4mm
Slice thickness is equal to? - ANSWER ✔ the table incrementation rate divided by
the pitch
What may be the cause of two parallel black lines seen on a localizer image of a
third- or fourth-generation scanner? - ANSWER ✔ Two faulty detector elements
How would we expect metal to affect the appearance of a localizer image? -
ANSWER ✔ Any metal within the scan field-of-view may create an artifact.
Streaks caused by a combo of beam hardening, the edge gradient effect, the partial
volume effect , and motion.
Why must we choose a scan field-of-view which is larger than the anatomy to be
scanned? - ANSWER ✔ to avoid out-of-field artifcacts
, One of the most common equipment induced artifacts is the result of - ANSWER
✔ a faulty or miscalibrated detector element.
On a third-generation scanner, if there is a problem with a single detector, it will
be represented as a - ANSWER ✔ ring on the CT images
Ring artifacts are rarely seen on which generation of scanners? - ANSWER ✔
Fourth-generation, and when apparent the cause is usually an error in the back
projection of the reconstruction process
Beam hardening refers to - ANSWER ✔ the increase in the mean energy of the
photons that reach the detectors
What might increase the possibility of motion artifacts occurring? - ANSWER ✔
using no straps or pads so that the patient feels comfortable and unrestricted.
What is the cause of aliasing artifacts - ANSWER ✔ Collecting too few data
samples
what would reduce the partial volume effect? - ANSWER ✔ decreased slice
thickness
What would increase the severity of the edge gradient effect? - ANSWER ✔ a
scanner with a low data sampling rate
what affects the severity of metal artifacts? - ANSWER ✔ the quality,
composition and shape of the metal
the slice thickness
(2024/2025) Questions with Correct
Detailed Answers || Already Graded
A+
<RECENT VERSION>
What is most likely to have the highest osmolality - ANSWER ✔ An ionic IV
contrast agent
Ionic agents dissociate into - ANSWER ✔ ions in solution
What types of contrast would be administered for a CT study of the lumbosacral
spine? - ANSWER ✔ Contrast agents are generally not administered unless there is
a suspected mass.
To evaluate a mass, iodinated IV contrast is typically administered.
If post-pyelogram, intrathecal contrast would have been previously administered.
Which studies might cranial nerve XI be visualized? - ANSWER ✔ soft tissue
neck
In order to generate a diagnostic 3D reconstruction of the hips, the reconstruction
software utilizes - ANSWER ✔ the axial image data
,What is the appropriate range of coverage for a coronal sinus study? - ANSWER
✔ From the dorsum sella to the anterior aspect of the frontal sinus
What is a reason for using thinner slices in the posterior fossa compared with the
more superior regions of the brain? - ANSWER ✔ To reduce beam hardening
artifacts
to improve spatial resolution
A localizer image of what orientations should be used to set up axial slices so that
they can be angled parallel to the plane of a specific lumbar disk? - ANSWER ✔
Lateral
Intravenous contrast is not administered to rule out - ANSWER ✔ a herniated disk
Axial slices are not generally acquired through the entire thoracic spine, but rather
through - ANSWER ✔ a few specified disk spaces.
It is impossible to position an adult in such a way that one could directly obtain -
ANSWER ✔ sagittal or coronal images. These are reformatted from the axial
images.
What is a location where one would expect to find cerebral spinal fluid? -
ANSWER ✔ Subarachnoid space
Fourth ventricle of the brain
What is the expected result of a CT number calibration test performed on a water
phantom? - ANSWER ✔ 0 +/-3
,If the system fails the CT number standard deviation test, what is most likely? -
ANSWER ✔ Detector noise has increased
mA is a measurement of? - ANSWER ✔ The electron current from cathode to
anode
What determines slice thickness? - ANSWER ✔ Pre-patient collimation
If the patient table of a spiral, or helical, scanner is moved at a rate of 0.6cm per
gantry rotation, and a pitch of 1.5 is selected what will be the slice thickness? -
ANSWER ✔ 4mm
6mm/1.5=4mm
Slice thickness is equal to? - ANSWER ✔ the table incrementation rate divided by
the pitch
What may be the cause of two parallel black lines seen on a localizer image of a
third- or fourth-generation scanner? - ANSWER ✔ Two faulty detector elements
How would we expect metal to affect the appearance of a localizer image? -
ANSWER ✔ Any metal within the scan field-of-view may create an artifact.
Streaks caused by a combo of beam hardening, the edge gradient effect, the partial
volume effect , and motion.
Why must we choose a scan field-of-view which is larger than the anatomy to be
scanned? - ANSWER ✔ to avoid out-of-field artifcacts
, One of the most common equipment induced artifacts is the result of - ANSWER
✔ a faulty or miscalibrated detector element.
On a third-generation scanner, if there is a problem with a single detector, it will
be represented as a - ANSWER ✔ ring on the CT images
Ring artifacts are rarely seen on which generation of scanners? - ANSWER ✔
Fourth-generation, and when apparent the cause is usually an error in the back
projection of the reconstruction process
Beam hardening refers to - ANSWER ✔ the increase in the mean energy of the
photons that reach the detectors
What might increase the possibility of motion artifacts occurring? - ANSWER ✔
using no straps or pads so that the patient feels comfortable and unrestricted.
What is the cause of aliasing artifacts - ANSWER ✔ Collecting too few data
samples
what would reduce the partial volume effect? - ANSWER ✔ decreased slice
thickness
What would increase the severity of the edge gradient effect? - ANSWER ✔ a
scanner with a low data sampling rate
what affects the severity of metal artifacts? - ANSWER ✔ the quality,
composition and shape of the metal
the slice thickness
