MOSBY'S CT STUDY GUIDE 2026 QUESTIONS AND
SOLUTIONS RATED A+
✔✔absorbed dose - ✔✔the amount of x-ray energy absorbed in a unit of mass. It is
measured in grays. (Gy)
✔✔360-degree linear interpolation (360 LI) - ✔✔type of algorithm used for MSCT image
reconstruction in which two sets of projection data acquired 360 degress apart are used
to form an image at a precise z-axis location.
✔✔absorptopm efficiency - ✔✔the ability of an individual CT detector to absorb and
measure the transmitted x-ray intensity incident upon it. primarilly controlled by the
characteristics and physical makeup of the detector material.
✔✔adaptive array - ✔✔the type of MSCT detector array configured with the thinnest
detectors at the center, surrounded by detectors of incrementally increasing widths
along the z-axis.
✔✔advanced single-slice rebinning (ASSR) algorithm - ✔✔cone beam correction
algorithm used to overcome potential attenuation calculation errors from the divergent
beam of MSCT systems.
✔✔afterglow - ✔✔the tendency of a scintillation-type CT detector to continue to glow in
response to x-radiation after the exposure source has been terminated.
✔✔Agatston score - ✔✔quantification of the volume and density of calcium within the
coronary arteries. as calculated a CT coronary artery calcification (CAC) examination,
the Agatston score is used to indicate a patient's risk of suffering a cardiac event.
✔✔ALARA - ✔✔acronym for "as low as reasonably achievable," the cardinal principle of
radiation dose reduction for all radiologic procedures, including CT.
✔✔algorithm - ✔✔mathematical filter applied to raw data during image reconstruction to
remove blurring artifact inherent to back-projection. may also be referred to as kernel.
✔✔aliasing - ✔✔a form of streak artifact caused by an isufficient number of views (data
samples) obtained during data acquisition.
✔✔analog-to-digital converter - ✔✔component of the data acquisition system (DAS)
responsible for converting the electronic signal emitted by the CT detectors into digital
form.
✔✔archival - ✔✔the storage of CT data in either hard (film) or soft (digital) form.
, ✔✔array processor - ✔✔component of the CT computer system responsible for
receiving raw scan data, performing all of the major processing of the CT image, and
returning the reconstructed image to the storage memory of the host computer.
✔✔arterial phase - ✔✔period of peak arterial enhancement following the bolus IV
administration of iodinated contrast materia. for example, the hepatic arterial phase
occurs approximately 25-35 seconds after the initiation of contrast agent administration.
✔✔Artifact - ✔✔a form of noise on the CT image resulting from errors during the
measurement of transmitted radiation by the detectors.
✔✔attenuation - ✔✔the reduction in intensity of a radiation beam as it passes through a
substance.
✔✔attenuation coefficient - ✔✔the value assigned to an object quantifying its ability to
attenuate an x-ray beam
✔✔back-projection - ✔✔the mathematical process of CT image reconstruction whereby
ray sum data are projected back onto a matrix.
✔✔automatic tube current modulation (ATCM) - ✔✔CT system software used to adjust
mA throughout an acquisition to reduce patient radiation dose to a minimum.
✔✔beam hardening - ✔✔the phenomenom whereby low-energy photons are absorbed
as the x-ray beam passes through an object, resulting in an increase in the average
photon energy of the x-ray beam.
✔✔beam pitch - ✔✔the ratio of table feed per gantry rotation to the total collimation
used during acquisition with a multi-slice (MSCT) system.
✔✔beam width - ✔✔the dimension of the primary beam in the longitudinal z-axis of
controlled by the pre-patient collimator.
✔✔binning - ✔✔the process of electronically combining signal from adjacent detector
elements to produce a reconstructed CT image that is thicker than the individual
detector width
✔✔bit depth - ✔✔the number of information bits contained within each pixel
✔✔blood urea nitrogen (BUN) - ✔✔a measurement of renal function, determined as the
amount of nitrogen in the blood in the form of waste product urea. the normal range of
BUN in adults is 7 to 25 mg/dL.
SOLUTIONS RATED A+
✔✔absorbed dose - ✔✔the amount of x-ray energy absorbed in a unit of mass. It is
measured in grays. (Gy)
✔✔360-degree linear interpolation (360 LI) - ✔✔type of algorithm used for MSCT image
reconstruction in which two sets of projection data acquired 360 degress apart are used
to form an image at a precise z-axis location.
✔✔absorptopm efficiency - ✔✔the ability of an individual CT detector to absorb and
measure the transmitted x-ray intensity incident upon it. primarilly controlled by the
characteristics and physical makeup of the detector material.
✔✔adaptive array - ✔✔the type of MSCT detector array configured with the thinnest
detectors at the center, surrounded by detectors of incrementally increasing widths
along the z-axis.
✔✔advanced single-slice rebinning (ASSR) algorithm - ✔✔cone beam correction
algorithm used to overcome potential attenuation calculation errors from the divergent
beam of MSCT systems.
✔✔afterglow - ✔✔the tendency of a scintillation-type CT detector to continue to glow in
response to x-radiation after the exposure source has been terminated.
✔✔Agatston score - ✔✔quantification of the volume and density of calcium within the
coronary arteries. as calculated a CT coronary artery calcification (CAC) examination,
the Agatston score is used to indicate a patient's risk of suffering a cardiac event.
✔✔ALARA - ✔✔acronym for "as low as reasonably achievable," the cardinal principle of
radiation dose reduction for all radiologic procedures, including CT.
✔✔algorithm - ✔✔mathematical filter applied to raw data during image reconstruction to
remove blurring artifact inherent to back-projection. may also be referred to as kernel.
✔✔aliasing - ✔✔a form of streak artifact caused by an isufficient number of views (data
samples) obtained during data acquisition.
✔✔analog-to-digital converter - ✔✔component of the data acquisition system (DAS)
responsible for converting the electronic signal emitted by the CT detectors into digital
form.
✔✔archival - ✔✔the storage of CT data in either hard (film) or soft (digital) form.
, ✔✔array processor - ✔✔component of the CT computer system responsible for
receiving raw scan data, performing all of the major processing of the CT image, and
returning the reconstructed image to the storage memory of the host computer.
✔✔arterial phase - ✔✔period of peak arterial enhancement following the bolus IV
administration of iodinated contrast materia. for example, the hepatic arterial phase
occurs approximately 25-35 seconds after the initiation of contrast agent administration.
✔✔Artifact - ✔✔a form of noise on the CT image resulting from errors during the
measurement of transmitted radiation by the detectors.
✔✔attenuation - ✔✔the reduction in intensity of a radiation beam as it passes through a
substance.
✔✔attenuation coefficient - ✔✔the value assigned to an object quantifying its ability to
attenuate an x-ray beam
✔✔back-projection - ✔✔the mathematical process of CT image reconstruction whereby
ray sum data are projected back onto a matrix.
✔✔automatic tube current modulation (ATCM) - ✔✔CT system software used to adjust
mA throughout an acquisition to reduce patient radiation dose to a minimum.
✔✔beam hardening - ✔✔the phenomenom whereby low-energy photons are absorbed
as the x-ray beam passes through an object, resulting in an increase in the average
photon energy of the x-ray beam.
✔✔beam pitch - ✔✔the ratio of table feed per gantry rotation to the total collimation
used during acquisition with a multi-slice (MSCT) system.
✔✔beam width - ✔✔the dimension of the primary beam in the longitudinal z-axis of
controlled by the pre-patient collimator.
✔✔binning - ✔✔the process of electronically combining signal from adjacent detector
elements to produce a reconstructed CT image that is thicker than the individual
detector width
✔✔bit depth - ✔✔the number of information bits contained within each pixel
✔✔blood urea nitrogen (BUN) - ✔✔a measurement of renal function, determined as the
amount of nitrogen in the blood in the form of waste product urea. the normal range of
BUN in adults is 7 to 25 mg/dL.
