Mosby's Exam Review for CT
Questions with Accurate Answers
180-dgree linear interpolation (180 LI) correct answer Type of algorith used for
MSCT image reconstruction in which data acquired from a shorter distance (180
degrees) away from the reconstructed slice location are interpolated.
360-degree linear interpolation (360 LI) correct answer 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.
absorbed dose correct answer the amount of x-ray energy absorbed in a unit of
mass. It is measured in grays. (Gy)
absorptopm efficiency correct answer 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 correct answer 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 correct answer cone beam
correction algorithm used to overcome potential attenuation calculation errors
from the divergent beam of MSCT systems.
afterglow correct answer 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 correct answer 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 correct answer acronym for "as low as reasonably achievable," the
cardinal principle of radiation dose reduction for all radiologic procedures,
including CT.
algorithm correct answer 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 correct answer a form of streak artifact caused by an isufficient number of
views (data samples) obtained during data acquisition.
analog-to-digital converter correct answer component of the data acquisition
system (DAS) responsible for converting the electronic signal emitted by the CT
detectors into digital form.
archival correct answer the storage of CT data in either hard (film) or soft (digital)
form.
array processor correct answer 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 correct answer 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 correct answer a form of noise on the CT image resulting from errors
during the measurement of transmitted radiation by the detectors.
attenuation coefficient correct answer the value assigned to an object quantifying
its ability to attenuate an x-ray beam
attenuation correct answer the reduction in intensity of a radiation beam as it
passes through a substance.
automatic tube current modulation (ATCM) correct answer CT system software
used to adjust mA throughout an acquisition to reduce patient radiation dose to a
minimum.
back-projection correct answer the mathematical process of CT image
reconstruction whereby ray sum data are projected back onto a matrix.
beam hardening correct answer 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 correct answer the ratio of table feed per gantry rotation to the total
collimation used during acquisition with a multi-slice (MSCT) system.
Questions with Accurate Answers
180-dgree linear interpolation (180 LI) correct answer Type of algorith used for
MSCT image reconstruction in which data acquired from a shorter distance (180
degrees) away from the reconstructed slice location are interpolated.
360-degree linear interpolation (360 LI) correct answer 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.
absorbed dose correct answer the amount of x-ray energy absorbed in a unit of
mass. It is measured in grays. (Gy)
absorptopm efficiency correct answer 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 correct answer 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 correct answer cone beam
correction algorithm used to overcome potential attenuation calculation errors
from the divergent beam of MSCT systems.
afterglow correct answer 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 correct answer 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 correct answer acronym for "as low as reasonably achievable," the
cardinal principle of radiation dose reduction for all radiologic procedures,
including CT.
algorithm correct answer 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 correct answer a form of streak artifact caused by an isufficient number of
views (data samples) obtained during data acquisition.
analog-to-digital converter correct answer component of the data acquisition
system (DAS) responsible for converting the electronic signal emitted by the CT
detectors into digital form.
archival correct answer the storage of CT data in either hard (film) or soft (digital)
form.
array processor correct answer 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 correct answer 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 correct answer a form of noise on the CT image resulting from errors
during the measurement of transmitted radiation by the detectors.
attenuation coefficient correct answer the value assigned to an object quantifying
its ability to attenuate an x-ray beam
attenuation correct answer the reduction in intensity of a radiation beam as it
passes through a substance.
automatic tube current modulation (ATCM) correct answer CT system software
used to adjust mA throughout an acquisition to reduce patient radiation dose to a
minimum.
back-projection correct answer the mathematical process of CT image
reconstruction whereby ray sum data are projected back onto a matrix.
beam hardening correct answer 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 correct answer the ratio of table feed per gantry rotation to the total
collimation used during acquisition with a multi-slice (MSCT) system.
