CT OPERATORS LICENSE CERTIFICATION
MASTERY 2026 AND 2027 COMPLETE
QUESTIONS AND ANSWERS 100% ACCURATE
EDITION.
◎ image quality. ANSWER:- measured by examining contrast resolution, linearity, the
noise found in the image, the uniformity of the image, as well as the spatial and
temporal resolution
◎ contrast resolution. ANSWER:- -ability to image adjacent tissues that have similar
mass density and effective atomic density.
-the ability to distinguish between similar tissues.
-can be improved by using a smaller field of view, thicker slices, a smaller matrix size,
larger pixel size, a higher milliampere seconds (mAs) or a low-pass filter.
◎ linearity. ANSWER:- o assigning the correct Hounsfield unit to a specific material
being scanned. CT mean values are calculated for a particular reference material as
measured using a phantom. After the phantom is scanned, the resulting CT numbers
are compared to linear attenuation coefficients for the object. These phantom tests
determine the CT numbers for water and other known materials.
◎ Water CT number. ANSWER:- 0
◎ bone CT number. ANSWER:- 1000
◎ noise. ANSWER:- -occurs because an insufficient number of photons reach the
detectors. Increased noise degrades the contrast resolution ©2017 ASRT. All rights
reserved. CT Basics Module 6 - Image Quality of the image. Reconstruction filters and
selectable technical factors can affect the amount of noise in the image.
-reduced by increasing the mAs, slice thickness or pixel size. Each of these parameters
affects the total amount of photons that reach the detectors. If more photons are
detected, the _______ is less apparent
◎ Uniformity. ANSWER:- -ability of the CT scanner to assign the same Hounsfield
number to the same tissue each time.
-standardizes the appearance of a CT scan for a large patient and the appearance of
the same scan for a small patient.
◎ Spatial Resolution. ANSWER:- -degree of blurring in an image. It represents the
ability to discriminate objects of varying density, a small distance apart, against a
uniform background.
, -measure of how small an object can be imaged using CT. CT is a superior imaging
modality for
-------- ---------- because it is able to differentiate tissue with density differences of less
than 0.5%. In comparison, conventional radiography cannot differentiate densities less
than 10%.
◎ point spread function (PSF). ANSWER:- lack of sharpness that occurs when a point
in the object being scanned is not represented as a true point on the image
◎ Line Spread Function (LSF). ANSWER:- "unsharpness" of an imaging system in
terms of breaking down an object into its frequency components
◎ spatial resolution. ANSWER:- _______ _______ can be improved by using thin slice
thicknesses, an image matrix with a small pixel size, reconstruction filters such as a
high-frequency convolution filter and a small detector size.
◎ temporal resolution. ANSWER:- -ability of the scanner to image moving objects
effectively.
-often associated with cardiac imaging, where the goal is to image a beating heart
effectively
◎ focal spot. ANSWER:- area on the anode that electrons hit during x-ray production
◎ smaller. ANSWER:- the ________ the focal spot the better the spatial resolution, but
this can increase tube heating on the anode
◎ anode angle. ANSWER:- 8-17 degrees
◎ beam geometry. ANSWER:- path the xray beam takes once it leaves the xray tube,
passes through patient and strikes the detectors;
more detector rows = wider _____ ________ and more scatter
◎ subject contrast. ANSWER:- -determined by the body habitus of the patient and the
anatomy of interest.
-Large patients produce more scatter radiation and require increased technical factors
to penetrate anatomy, which also increases scatter and degrades the image.
◎ SFOV. ANSWER:- -establishes which detectors are activated during the scan and
the size of the resulting pixels.
-Anatomy should always be within the scan field of view because, otherwise, out-of-field
artifacts will occur (really fat people)
◎ less. ANSWER:- -displaying a larger field of view results in _______ noticeable noise
in the image.
MASTERY 2026 AND 2027 COMPLETE
QUESTIONS AND ANSWERS 100% ACCURATE
EDITION.
◎ image quality. ANSWER:- measured by examining contrast resolution, linearity, the
noise found in the image, the uniformity of the image, as well as the spatial and
temporal resolution
◎ contrast resolution. ANSWER:- -ability to image adjacent tissues that have similar
mass density and effective atomic density.
-the ability to distinguish between similar tissues.
-can be improved by using a smaller field of view, thicker slices, a smaller matrix size,
larger pixel size, a higher milliampere seconds (mAs) or a low-pass filter.
◎ linearity. ANSWER:- o assigning the correct Hounsfield unit to a specific material
being scanned. CT mean values are calculated for a particular reference material as
measured using a phantom. After the phantom is scanned, the resulting CT numbers
are compared to linear attenuation coefficients for the object. These phantom tests
determine the CT numbers for water and other known materials.
◎ Water CT number. ANSWER:- 0
◎ bone CT number. ANSWER:- 1000
◎ noise. ANSWER:- -occurs because an insufficient number of photons reach the
detectors. Increased noise degrades the contrast resolution ©2017 ASRT. All rights
reserved. CT Basics Module 6 - Image Quality of the image. Reconstruction filters and
selectable technical factors can affect the amount of noise in the image.
-reduced by increasing the mAs, slice thickness or pixel size. Each of these parameters
affects the total amount of photons that reach the detectors. If more photons are
detected, the _______ is less apparent
◎ Uniformity. ANSWER:- -ability of the CT scanner to assign the same Hounsfield
number to the same tissue each time.
-standardizes the appearance of a CT scan for a large patient and the appearance of
the same scan for a small patient.
◎ Spatial Resolution. ANSWER:- -degree of blurring in an image. It represents the
ability to discriminate objects of varying density, a small distance apart, against a
uniform background.
, -measure of how small an object can be imaged using CT. CT is a superior imaging
modality for
-------- ---------- because it is able to differentiate tissue with density differences of less
than 0.5%. In comparison, conventional radiography cannot differentiate densities less
than 10%.
◎ point spread function (PSF). ANSWER:- lack of sharpness that occurs when a point
in the object being scanned is not represented as a true point on the image
◎ Line Spread Function (LSF). ANSWER:- "unsharpness" of an imaging system in
terms of breaking down an object into its frequency components
◎ spatial resolution. ANSWER:- _______ _______ can be improved by using thin slice
thicknesses, an image matrix with a small pixel size, reconstruction filters such as a
high-frequency convolution filter and a small detector size.
◎ temporal resolution. ANSWER:- -ability of the scanner to image moving objects
effectively.
-often associated with cardiac imaging, where the goal is to image a beating heart
effectively
◎ focal spot. ANSWER:- area on the anode that electrons hit during x-ray production
◎ smaller. ANSWER:- the ________ the focal spot the better the spatial resolution, but
this can increase tube heating on the anode
◎ anode angle. ANSWER:- 8-17 degrees
◎ beam geometry. ANSWER:- path the xray beam takes once it leaves the xray tube,
passes through patient and strikes the detectors;
more detector rows = wider _____ ________ and more scatter
◎ subject contrast. ANSWER:- -determined by the body habitus of the patient and the
anatomy of interest.
-Large patients produce more scatter radiation and require increased technical factors
to penetrate anatomy, which also increases scatter and degrades the image.
◎ SFOV. ANSWER:- -establishes which detectors are activated during the scan and
the size of the resulting pixels.
-Anatomy should always be within the scan field of view because, otherwise, out-of-field
artifacts will occur (really fat people)
◎ less. ANSWER:- -displaying a larger field of view results in _______ noticeable noise
in the image.
