MOSBY'S CT LATEST 2026 EXAM QUESTIONS AND
SOLUTIONS RATED A+
✔✔noise - ✔✔grainy appearance on the CT image due primarilly to an insufficient x-ray
photon flux per voxel. may also be described as any portion of the signal that contains
no useful information, as evident in certain CT image artifacts.
✔✔Nyquist theorem - ✔✔a sampling law dictating that the data sampling frequency
must be at least twice the object's spatial frequency in order for the oject to be resolved
by the CT system.
✔✔O-arm - ✔✔portable CT-fluoroscopy unit with a telescoping gantry used to acquire
3D CT images and standard fluoroscopy during invasive or surgical procedures.
✔✔opacification - ✔✔the increase in CT density of a structure due to filling with positive
contrast material.
✔✔operating system (OS) - ✔✔the main software of the CT computer, controlling the
utilization of the hardware resources including the available memory, CPU time, disk
space, and so on.
✔✔orthogonal - ✔✔imaging planes that are perpendicular to each other.
✔✔orthographic volume rendering - ✔✔technique yielding a 3D model with the
persepctive of externally viewing the reconstructed object.
✔✔osmolality - ✔✔the propensity of an iodinated contrast medium to cause fluid from
outside the blood vessel to move into the bloodstream.
✔✔out-of-field artifact - ✔✔hyperdense streaking that occurs when a portion of a patient
has been positioned outside the scan field of view (SFOV)
✔✔overbeaming - ✔✔expansion of the primary beam in an MSCT system to ensure that
all detectors of the array are exposed to x-rays of equal intensity.
✔✔overlapping images - ✔✔CT images produced with a reconstruction interval that is
less than the section width.
✔✔ovverranging - ✔✔the process of applying radiation dose before and after the
acquisition volume to ensure sufficient data collection for the interpolation algorithms of
helical CT reconstruction.
✔✔PACS - ✔✔acronym for a picture archival and communication system. responsible
for storing, retrieving, distributing, and displaying CT and other digital images.
, ✔✔pancreatic phase - ✔✔a delayed arterial enhancement phase occuring
approximately 35 to 45 seconds after the start of contrast agent administration, if an
adequate volume has been injected at a rate of 3mL/sec or greater.
✔✔parallel processing - ✔✔the ability of a computer to perfrom multiple functions
simultaneously.
✔✔partial volume artifact - ✔✔an error that occurs when a structure is only partially
positioned within a voxel and the attenuation for the object is not accurately represented
by a pixel value.
✔✔partial volume averaging - ✔✔inaccuracy in pixel values that occurs when the
associated voxels contain attenuation coefficients for multiple tissue types. the values
are averaged together to yield a single pixel value that attempts to represent an
assortment of different materials.
✔✔perspective volume rendering - ✔✔technique yielding a 3D model with the
perspective of being within the lumen of the object, similar to an endoscopic view. may
also be referred to as immersive rendering.
✔✔phantom - ✔✔a quality control device typically composed of a radiolucent plastic
material containing specialized inserts that is used to measure specific image quality
criteria.
✔✔photodiode - ✔✔device used by a solid-state CT detector to convert the light emitted
by a scintillation crystal into a proportional eletronic signal.
✔✔photon fluence - ✔✔quantity of x-ray photons passing through a specifies area.
✔✔ohoton flux - ✔✔the rate at which a quantity of x-ray photons (fluence) passes
through a unit area over a unit time.
✔✔pipelining - ✔✔a form of parallel processing used by a computer to improve
computation speed.
✔✔pitch - ✔✔the relationship between collimation and table movement per gantry
rotation.
✔✔pixel - ✔✔abbreviating of picture element. refers to the individual boxes arranged in
the matrix used to display the CT image.
SOLUTIONS RATED A+
✔✔noise - ✔✔grainy appearance on the CT image due primarilly to an insufficient x-ray
photon flux per voxel. may also be described as any portion of the signal that contains
no useful information, as evident in certain CT image artifacts.
✔✔Nyquist theorem - ✔✔a sampling law dictating that the data sampling frequency
must be at least twice the object's spatial frequency in order for the oject to be resolved
by the CT system.
✔✔O-arm - ✔✔portable CT-fluoroscopy unit with a telescoping gantry used to acquire
3D CT images and standard fluoroscopy during invasive or surgical procedures.
✔✔opacification - ✔✔the increase in CT density of a structure due to filling with positive
contrast material.
✔✔operating system (OS) - ✔✔the main software of the CT computer, controlling the
utilization of the hardware resources including the available memory, CPU time, disk
space, and so on.
✔✔orthogonal - ✔✔imaging planes that are perpendicular to each other.
✔✔orthographic volume rendering - ✔✔technique yielding a 3D model with the
persepctive of externally viewing the reconstructed object.
✔✔osmolality - ✔✔the propensity of an iodinated contrast medium to cause fluid from
outside the blood vessel to move into the bloodstream.
✔✔out-of-field artifact - ✔✔hyperdense streaking that occurs when a portion of a patient
has been positioned outside the scan field of view (SFOV)
✔✔overbeaming - ✔✔expansion of the primary beam in an MSCT system to ensure that
all detectors of the array are exposed to x-rays of equal intensity.
✔✔overlapping images - ✔✔CT images produced with a reconstruction interval that is
less than the section width.
✔✔ovverranging - ✔✔the process of applying radiation dose before and after the
acquisition volume to ensure sufficient data collection for the interpolation algorithms of
helical CT reconstruction.
✔✔PACS - ✔✔acronym for a picture archival and communication system. responsible
for storing, retrieving, distributing, and displaying CT and other digital images.
, ✔✔pancreatic phase - ✔✔a delayed arterial enhancement phase occuring
approximately 35 to 45 seconds after the start of contrast agent administration, if an
adequate volume has been injected at a rate of 3mL/sec or greater.
✔✔parallel processing - ✔✔the ability of a computer to perfrom multiple functions
simultaneously.
✔✔partial volume artifact - ✔✔an error that occurs when a structure is only partially
positioned within a voxel and the attenuation for the object is not accurately represented
by a pixel value.
✔✔partial volume averaging - ✔✔inaccuracy in pixel values that occurs when the
associated voxels contain attenuation coefficients for multiple tissue types. the values
are averaged together to yield a single pixel value that attempts to represent an
assortment of different materials.
✔✔perspective volume rendering - ✔✔technique yielding a 3D model with the
perspective of being within the lumen of the object, similar to an endoscopic view. may
also be referred to as immersive rendering.
✔✔phantom - ✔✔a quality control device typically composed of a radiolucent plastic
material containing specialized inserts that is used to measure specific image quality
criteria.
✔✔photodiode - ✔✔device used by a solid-state CT detector to convert the light emitted
by a scintillation crystal into a proportional eletronic signal.
✔✔photon fluence - ✔✔quantity of x-ray photons passing through a specifies area.
✔✔ohoton flux - ✔✔the rate at which a quantity of x-ray photons (fluence) passes
through a unit area over a unit time.
✔✔pipelining - ✔✔a form of parallel processing used by a computer to improve
computation speed.
✔✔pitch - ✔✔the relationship between collimation and table movement per gantry
rotation.
✔✔pixel - ✔✔abbreviating of picture element. refers to the individual boxes arranged in
the matrix used to display the CT image.
