CT REGISTRY STUDY GUIDE EXAM QUESTIONS AND
ANSWERS SURE A+
✔✔array processor (AP) - ✔✔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.
✔✔On a single row detector scanner, collimation:
1. controls the slice thickness
2. minimizes the x-ray dose to the patient
3. reduces the detection of scatter radiation
a. 1 only
b. 2 only
c. 3 only
d. 1, 2 & 3 - ✔✔controls all
✔✔CT Network Client - ✔✔CT scanner, viewing consoles, printer for images
✔✔MDCT - ✔✔size of the detector arrays along the z-direction may be different
the attenuation information from adjacent detector arrays may be added together to
generate thicker slices
all the detector arrays may or may not be used
✔✔THE CT XRAY TUBE ROTATES ARUND THE PATIENT TO - ✔✔2. GENERATE
PROJECTION VIEWS AT DIFFERENT ANGLES
✔✔CT collimation - ✔✔is accomplished by physically blocking xrays
✔✔Tungsten - ✔✔used as target material on the tubes anode because it has a high
atomic number and high melting point.
✔✔A CT image is formed in part by projecting back all of the attenuation values
recorded during data acquisition onto a: - ✔✔
✔✔spatial resolution - ✔✔measured in lp/cm
✔✔spatial resolution quality control phantom - ✔✔measures spatial resolution
✔✔The MTF of a CT system is an objective measurement of a system's in-plane spatial
resolution. By evaluating an MTF curve of a particular image, the operator can assess
the spatial resolution of a CT system and appraise changes in spatial resolution
because of adjustments in technical factors. - ✔✔
, ✔✔increase spatial resolution - ✔✔The sampling frequency, or views per rotation
(VPM), controls the volume of transmission data acquired for each gantry rotation. Very
small objects exhibit high spatial frequencies that only systems with high sampling rates
will be capable of resolving.
✔✔The broadening of the slice sensitivity profile inherent to helical CT acquisition is
said to negatively affect the: - ✔✔Longitudinal spatial resolution describes the degree to
which patient movement during volumetric acquisition can negatively affect image
detail.
✔✔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.
✔✔Modulation Transfer Function (MTF) - ✔✔The degree of CT section broadening that
occurs along the z-axis during volumetric data acquisition is represented graphically by
the:
✔✔what factors affect longitudinal spatial resolution - ✔✔The factors that affect
longitudinal spatial resolution and the SSP include the type of spiral interpolation
algorithm inherent to the system and the selected detector pitch
✔✔Which of the following technical factors exhibit an effect upon longitudinal spatial
resolution - ✔✔Detector collimation, Detector pitch and Interpolation algorithm
✔✔CT acquisition of a water-filled phantom is performed utilizing a standardized set of
technical factors. If a region-of-interest (ROI) measurement is made, the image noise
corresponds to which of the following data - ✔✔Noise is most commonly measured by
scanning a water-filled phantom with a standardized set of technical factors. The image
noise is equal to the standard deviation of pixel values within a region-of-interest (ROI)
measurement of the image
✔✔Each 1.0% in contrast between adjacent objects amounts to a difference in pixel
value of approximately - ✔✔Each 1.0% in contrast between adjacent objects amounts
to a difference in pixel value of approximately 10 HU. MDCT systems are typically
capable of differentiating adjacent objects with attenuation differences as small as 3 HU
✔✔Which of the following technical adjustments would result in a decrease in the
signal-to-noise ratio (SNR)? - ✔✔Reducing the section width
✔✔uniformity - ✔✔The ability of a CT system to maintain consistent Hounsfield values
across the entire image of a homogeneous object is termed
ANSWERS SURE A+
✔✔array processor (AP) - ✔✔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.
✔✔On a single row detector scanner, collimation:
1. controls the slice thickness
2. minimizes the x-ray dose to the patient
3. reduces the detection of scatter radiation
a. 1 only
b. 2 only
c. 3 only
d. 1, 2 & 3 - ✔✔controls all
✔✔CT Network Client - ✔✔CT scanner, viewing consoles, printer for images
✔✔MDCT - ✔✔size of the detector arrays along the z-direction may be different
the attenuation information from adjacent detector arrays may be added together to
generate thicker slices
all the detector arrays may or may not be used
✔✔THE CT XRAY TUBE ROTATES ARUND THE PATIENT TO - ✔✔2. GENERATE
PROJECTION VIEWS AT DIFFERENT ANGLES
✔✔CT collimation - ✔✔is accomplished by physically blocking xrays
✔✔Tungsten - ✔✔used as target material on the tubes anode because it has a high
atomic number and high melting point.
✔✔A CT image is formed in part by projecting back all of the attenuation values
recorded during data acquisition onto a: - ✔✔
✔✔spatial resolution - ✔✔measured in lp/cm
✔✔spatial resolution quality control phantom - ✔✔measures spatial resolution
✔✔The MTF of a CT system is an objective measurement of a system's in-plane spatial
resolution. By evaluating an MTF curve of a particular image, the operator can assess
the spatial resolution of a CT system and appraise changes in spatial resolution
because of adjustments in technical factors. - ✔✔
, ✔✔increase spatial resolution - ✔✔The sampling frequency, or views per rotation
(VPM), controls the volume of transmission data acquired for each gantry rotation. Very
small objects exhibit high spatial frequencies that only systems with high sampling rates
will be capable of resolving.
✔✔The broadening of the slice sensitivity profile inherent to helical CT acquisition is
said to negatively affect the: - ✔✔Longitudinal spatial resolution describes the degree to
which patient movement during volumetric acquisition can negatively affect image
detail.
✔✔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.
✔✔Modulation Transfer Function (MTF) - ✔✔The degree of CT section broadening that
occurs along the z-axis during volumetric data acquisition is represented graphically by
the:
✔✔what factors affect longitudinal spatial resolution - ✔✔The factors that affect
longitudinal spatial resolution and the SSP include the type of spiral interpolation
algorithm inherent to the system and the selected detector pitch
✔✔Which of the following technical factors exhibit an effect upon longitudinal spatial
resolution - ✔✔Detector collimation, Detector pitch and Interpolation algorithm
✔✔CT acquisition of a water-filled phantom is performed utilizing a standardized set of
technical factors. If a region-of-interest (ROI) measurement is made, the image noise
corresponds to which of the following data - ✔✔Noise is most commonly measured by
scanning a water-filled phantom with a standardized set of technical factors. The image
noise is equal to the standard deviation of pixel values within a region-of-interest (ROI)
measurement of the image
✔✔Each 1.0% in contrast between adjacent objects amounts to a difference in pixel
value of approximately - ✔✔Each 1.0% in contrast between adjacent objects amounts
to a difference in pixel value of approximately 10 HU. MDCT systems are typically
capable of differentiating adjacent objects with attenuation differences as small as 3 HU
✔✔Which of the following technical adjustments would result in a decrease in the
signal-to-noise ratio (SNR)? - ✔✔Reducing the section width
✔✔uniformity - ✔✔The ability of a CT system to maintain consistent Hounsfield values
across the entire image of a homogeneous object is termed
