MOSBY'S CT FINAL EXAM 2026 QUESTIONS AND
SOLUTIONS RATED A+
✔✔detector collimation - ✔✔the process of determining section width in the MSCT
system as determined by the defined beam width and the number and thickness of
detectors utilized for image reconstruction.
✔✔detector configuration - ✔✔the number, length, and organization of the individual
detector elements in an MSCT system
✔✔detector pitch - ✔✔the ratio of table feed per gantry rotation to the acquired section
width. this definition of pitch is used for helical single-slice CT (SSCT)
✔✔diastole - ✔✔portion of the cardiac cycle when the heart muscle is relaxed. it is the
bottom number provided during the assessment of blood pressure.
✔✔DICOM - ✔✔acronym for the "digital imaging and communications in
medicine."standard for the process of recording, storing, printing, and transmitting
medical image data.
✔✔display field of view (DFOV) - ✔✔the diameter of the acquired attenuation data
displayed across the image matrix. may also be referred to as the zoom factor or target
view.
✔✔dose length product (DLP) - ✔✔the measurement of dose for the entire series of CT
images. equal to the calculated dose per section mulitplied by the length of a CT
acquisition along the z-axis.
✔✔dose profile - ✔✔the section of the patient exsposed to radiation at the gantry
isocenter.
✔✔dual-energy CT - ✔✔simultaneous acquisition, by and MSCT system, of attenuation
data for a single anatomic section with two x-ray beams, each having a different energy
spectrum. these CT systems rapidly switch between or alternate kVp settings during
data acquisition, allowing for improved contrast between substances of differing
densities.
✔✔dual-source CT - ✔✔CT system that consists of two seperate x-ray tubes and
detector arrays mounted 90 degrees from each other within the gantry, allowing for
dual-energy CT aquisition.
✔✔edge gradient - ✔✔streak artifact that occurs at the interface between a high-density
object and the lower-attenuation material surrounding it.
,✔✔effective dose - ✔✔approximation of the relative risk from exposure to ionizing
radiation; is calculated by assigning weighting factors to different tissues on the basis of
their individual radiosensitivities. measured in Sieverts (Sv)
✔✔effective mAs - ✔✔the calculated mAs per acquired slice with a multislice CT
(MSCT) system.
✔✔effective section width - ✔✔the slice sensitivity profile (SSP) of the reconstructed CT
section. it is measured at the full width at half maximum (FWHM) of the SSP for a given
CT acquisition.
✔✔electrocardiogram (ECG) - ✔✔a graphical representation of the electrical activity of
the heart recorded over time through electrodes placed on the patient's skin.
✔✔electrom beam CT - ✔✔specialized CT design devoid of moving parts. utilizes a
beam of electrons bombarding a tungsten target to produce x-radiation. these systems
are capable of extremely short exposure times and have their greatest application in
cardiac imaging.
✔✔equilibrium phase - ✔✔contrast phase of the liver when hepatic parenchymal
ehancement dissipates and there is minimal attenuation differenes between the
intravascular and extravascualr spaces. usually occurs at 2 to 3 minutes after the
initiation of contrast agent administration.
✔✔excretory phase - ✔✔a delayed imaging renal enhancement that begins
approximately 3 minutes after the initiation of contrast agent administration. contrast
material has been excreted into the renal calyces, opacifying the renal pelvis and the
remainder of the urinary collecting system (ureters, bladder)
✔✔exposure - ✔✔the ability of x-rays to ionize a volume of air. it is measured in
Roentgens (R)
✔✔extravasatipn - ✔✔the escape of contrast material outside the blood vessel into the
surrounding tissue.
✔✔fan angle - ✔✔angle of coverage by the x-ray beam as it emerges from the tube
housing and exposes the detector array within the scan plane (x-y axis)
✔✔Feldkamp-Davis-Kress (FDK) algorithm - ✔✔cone beam correction algorithm utilized
to overcome potential attenuation calculation erros from the divergent beam of MSCT
systems.
✔✔filtered back-projection - ✔✔the mathematical process of CT image reconstruction
that involves convolution of the raw data prior to their projection back onto a matrix.
, ✔✔filtration - ✔✔removal of the low-energy x-ray photons emitted from the x-ray tube to
improve beam quality and reduce patient radiation dose.
✔✔flat-panel detector - ✔✔large-area detector consisting of a film of scintillating crystals
bonded to a matrix of silicon photosensors. may be used in place of the segmented
detector rows found in MDCT systems.
✔✔flying focal spot - ✔✔electronic switching technique whereby the electron beam is
electromagnetically steered toward two separate locations on the rotating anode. results
in the emission of two sources of x-radiation from the CT x-ray tube and a doubling of
the data samples acquired from each gantry rotation.
✔✔full width at half maximum (FWHM) - ✔✔the midpoint of a slice sensitivity profile
(SSP), where the effective section width for a CT acquisition is determined.
✔✔gantry - ✔✔the assembly that house the x-ray tube, detectors, and additional data
acquisition components of a CT system, where the patient is positioned.
✔✔geometric efficiency - ✔✔the ability of a detector array to absorb and measure the
transmitted x-ray intensity incident upon it. primarily controlled by the physical
arrangement of detectors within the array and the amount of interspace material
required between adjacent detectors.
✔✔glomerular filtration rate (GFR) - ✔✔an approximation of creatinine clearance or the
rate by which creatinine is filtered from the bloodstream. utilized as a measure of renal
function.
✔✔helical - ✔✔the type of CT acquisition whereby the x-ray tube and patient
continuously move during scanning, yielding a data set in the form of a helix. may also
be commonly refered to as spiral.
✔✔Hounsfield bar - ✔✔specific type of streaking beam-hardening artifact that occurs in
the posterior fossa of the brain.
✔✔Hounsfield unit - ✔✔the unit of the CT number scale assigned to each pixel to
quantify relative attenuation.
✔✔hybrid-array - ✔✔the type of MSCT detector array with narrower detectors
positioned midline, flanked by the wider detectors.
✔✔hyperdense - ✔✔possessing CT attenuation values greater than the values of the
surrounding tissue.
SOLUTIONS RATED A+
✔✔detector collimation - ✔✔the process of determining section width in the MSCT
system as determined by the defined beam width and the number and thickness of
detectors utilized for image reconstruction.
✔✔detector configuration - ✔✔the number, length, and organization of the individual
detector elements in an MSCT system
✔✔detector pitch - ✔✔the ratio of table feed per gantry rotation to the acquired section
width. this definition of pitch is used for helical single-slice CT (SSCT)
✔✔diastole - ✔✔portion of the cardiac cycle when the heart muscle is relaxed. it is the
bottom number provided during the assessment of blood pressure.
✔✔DICOM - ✔✔acronym for the "digital imaging and communications in
medicine."standard for the process of recording, storing, printing, and transmitting
medical image data.
✔✔display field of view (DFOV) - ✔✔the diameter of the acquired attenuation data
displayed across the image matrix. may also be referred to as the zoom factor or target
view.
✔✔dose length product (DLP) - ✔✔the measurement of dose for the entire series of CT
images. equal to the calculated dose per section mulitplied by the length of a CT
acquisition along the z-axis.
✔✔dose profile - ✔✔the section of the patient exsposed to radiation at the gantry
isocenter.
✔✔dual-energy CT - ✔✔simultaneous acquisition, by and MSCT system, of attenuation
data for a single anatomic section with two x-ray beams, each having a different energy
spectrum. these CT systems rapidly switch between or alternate kVp settings during
data acquisition, allowing for improved contrast between substances of differing
densities.
✔✔dual-source CT - ✔✔CT system that consists of two seperate x-ray tubes and
detector arrays mounted 90 degrees from each other within the gantry, allowing for
dual-energy CT aquisition.
✔✔edge gradient - ✔✔streak artifact that occurs at the interface between a high-density
object and the lower-attenuation material surrounding it.
,✔✔effective dose - ✔✔approximation of the relative risk from exposure to ionizing
radiation; is calculated by assigning weighting factors to different tissues on the basis of
their individual radiosensitivities. measured in Sieverts (Sv)
✔✔effective mAs - ✔✔the calculated mAs per acquired slice with a multislice CT
(MSCT) system.
✔✔effective section width - ✔✔the slice sensitivity profile (SSP) of the reconstructed CT
section. it is measured at the full width at half maximum (FWHM) of the SSP for a given
CT acquisition.
✔✔electrocardiogram (ECG) - ✔✔a graphical representation of the electrical activity of
the heart recorded over time through electrodes placed on the patient's skin.
✔✔electrom beam CT - ✔✔specialized CT design devoid of moving parts. utilizes a
beam of electrons bombarding a tungsten target to produce x-radiation. these systems
are capable of extremely short exposure times and have their greatest application in
cardiac imaging.
✔✔equilibrium phase - ✔✔contrast phase of the liver when hepatic parenchymal
ehancement dissipates and there is minimal attenuation differenes between the
intravascular and extravascualr spaces. usually occurs at 2 to 3 minutes after the
initiation of contrast agent administration.
✔✔excretory phase - ✔✔a delayed imaging renal enhancement that begins
approximately 3 minutes after the initiation of contrast agent administration. contrast
material has been excreted into the renal calyces, opacifying the renal pelvis and the
remainder of the urinary collecting system (ureters, bladder)
✔✔exposure - ✔✔the ability of x-rays to ionize a volume of air. it is measured in
Roentgens (R)
✔✔extravasatipn - ✔✔the escape of contrast material outside the blood vessel into the
surrounding tissue.
✔✔fan angle - ✔✔angle of coverage by the x-ray beam as it emerges from the tube
housing and exposes the detector array within the scan plane (x-y axis)
✔✔Feldkamp-Davis-Kress (FDK) algorithm - ✔✔cone beam correction algorithm utilized
to overcome potential attenuation calculation erros from the divergent beam of MSCT
systems.
✔✔filtered back-projection - ✔✔the mathematical process of CT image reconstruction
that involves convolution of the raw data prior to their projection back onto a matrix.
, ✔✔filtration - ✔✔removal of the low-energy x-ray photons emitted from the x-ray tube to
improve beam quality and reduce patient radiation dose.
✔✔flat-panel detector - ✔✔large-area detector consisting of a film of scintillating crystals
bonded to a matrix of silicon photosensors. may be used in place of the segmented
detector rows found in MDCT systems.
✔✔flying focal spot - ✔✔electronic switching technique whereby the electron beam is
electromagnetically steered toward two separate locations on the rotating anode. results
in the emission of two sources of x-radiation from the CT x-ray tube and a doubling of
the data samples acquired from each gantry rotation.
✔✔full width at half maximum (FWHM) - ✔✔the midpoint of a slice sensitivity profile
(SSP), where the effective section width for a CT acquisition is determined.
✔✔gantry - ✔✔the assembly that house the x-ray tube, detectors, and additional data
acquisition components of a CT system, where the patient is positioned.
✔✔geometric efficiency - ✔✔the ability of a detector array to absorb and measure the
transmitted x-ray intensity incident upon it. primarily controlled by the physical
arrangement of detectors within the array and the amount of interspace material
required between adjacent detectors.
✔✔glomerular filtration rate (GFR) - ✔✔an approximation of creatinine clearance or the
rate by which creatinine is filtered from the bloodstream. utilized as a measure of renal
function.
✔✔helical - ✔✔the type of CT acquisition whereby the x-ray tube and patient
continuously move during scanning, yielding a data set in the form of a helix. may also
be commonly refered to as spiral.
✔✔Hounsfield bar - ✔✔specific type of streaking beam-hardening artifact that occurs in
the posterior fossa of the brain.
✔✔Hounsfield unit - ✔✔the unit of the CT number scale assigned to each pixel to
quantify relative attenuation.
✔✔hybrid-array - ✔✔the type of MSCT detector array with narrower detectors
positioned midline, flanked by the wider detectors.
✔✔hyperdense - ✔✔possessing CT attenuation values greater than the values of the
surrounding tissue.
