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CT Test Review Questions and Answers
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CT Test Review Questions and Answers
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CT Test reviewWhich is NOT a synonym for the preliminary/localizer image taken at the start of a CT examination?
A. Topogram
B. Scout
C. Scanogram
D. Spiral - Answer-D. Spiral
The ability of a system to differentiate, on the image, objects with similar densities is known as:
A. High contrast resolution
B. Low contrast resolution
C. Spatial resolution
D. Temporal resolution - Answer-B. Low contrast resolution
Each two dimensional square of data that make up the CT image is called a:
A. Pixel
B. Voxel
C. Matrix
D. Fragment - Answer-A. Pixel
,How many pixels are contained in a 1,024 matrix image? A. 1,024
B. 2,048
C. 262,144
D. 1,048,576 - Answer-D. 1,048,576
Beam attenuation can be defined as:
A. The phenomenon by which artifacts result when lower energy photons are preferentially absorbed,
leaving only higher-intensity photons to strike the detector array.
B. Xray energy that is produced from bombarding a substance with fast moving electrons.
C. The ability of the detector to capture transmitted photons and change them to electronic signals.
D. The phenomenon by which an xray beam passing through a structure is decreased in intensity or
amount because of absorption and interaction with matter. - Answer-D. The phenomenon by which an
xray beam passing through a structure is decreased in intensity or amount because of absorption and
interaction with matter.
Which of the following is a low attenuation structure:
A. Iodine filled aorta
B. Rib
C. Trachea
D. Calcified arteries - Answer-C. Trachea
An object is slightly less dense than water. What is the expected hounsfield measurement?
A. -940
B. -10
C. 50
D. 850 - Answer-B. -10
,Why does the administration of iodinated contrast media result in an enhanced image?
A. Iodinated contrast material increases the ability of the enhanced structure to attenuate the xray
beam.
B. Iodinated contrast material decreases the average photon energy of the xray beam; therefore more
photons are absorbed by the patient.
C. The administration of contrast material results in a smaller pixel, thereby increasing spatial resolution,
which results in an enhanced image.
D. - Answer-A. Iodinated contrast material increases the ability of the enhanced structure to attenuate
the xray beam.
The xray beam sources for CT produce xray energy that is polychromatic. This means:
A. When viewed by the naked eye, the beam exhibits many different colors.
B. It produce, as a byproduct, a substance known as polychlorinated biphenyl.
C. Photons contained in the beam are all of the same wavelength.
D. The beam comprises photons with varying energies. - Answer-D. The beam comprises photons with
varying energies.
An object that appears on the image but is not present in the object scanned is called a/n:
A. Artifact
B. Anomaly
C. Shadow
D. Ghost - Answer-A. Artifact
Which is an advantage of filtering the xray beam?
A. Filtering reduces the anode heat load
B. A filtered beam produces images with substantially less quantum mottle
C. Filtering the beam prevents energy from being converted to heat, therefore 100% of the energy is
converted to xrays.
, D. Filtering reduces the radiation dose to the patient. - Answer-D. Filtering reduces the radiation dose to
the patient
Scan thickness is primarily important for the part it plays in:
A. Noise reduction
B. The contrast scale
C. Detector aperture opening
D. Volume averaging - Answer-D. Volume averaging
You are working with the radiologist to establish examination protocols for your department. Which of
the following is a logical consideration when determining an appropriate slice thickness for studies of
the internal auditory canal?
A. Because the auditory ossicles are quite small, a thin slice will be necessary to reduce the chance that
volume averaging will obscure their appearance on the image.
B. The appropriate slice thickness will vary considerably from patient to patient. Therefore, each
technologist should be free to adjust the slice thickness as he or she deems necessary for the particular
patient.
C. A slice thickness of 5 to 7mm is adequate because the structures of interest are not particularly small
and the examination is most often ordered as a screening study for asymptomatic patients.
D. The thickest slice available should be used to reduce the radiation dose to the corneas. - Answer-A.
Because the auditory ossicles are quite small, a thin slice will be necessary to reduce the chance that
volume averaging will obscure their appearance on the image.
How many CT numbers are assigned to each pixel in the image matrix?
A. One half the number of all values recorded from the detector array
B. One
C. The number of HU per pixel is one tenth the display field of view
D. Two values for a 256 matrix; 4 values for a 512 matrix - Answer-B. One
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