40 Questions
What is the axial plane spatial resolution achievable with modern CT scanners?
0.6-0.9 mm
How does the number of detector rows affect scan volume and scan time?
More detector rows decrease scan time
What is the advantage of iterative reconstruction over filtered backprojection?
Improved image quality
What is the advantage of using 64 active detector rows in a CT scanner?
Improved longitudinal spatial resolution
What is the maximum scan volume covered by a 320 detector row CT scanner?
160 mm
What is the purpose of algebraic reconstruction in CT imaging?
To improve image quality
What is the effect of using multiple rotations in a helical acquisition?
Improved longitudinal spatial resolution
What is the advantage of fast simple backprojection over iterative reconstruction?
Faster reconstruction time
What is the primary limitation of spatial resolution in CT scanners?
All of the above
What is the unit of measurement for temporal resolution in CT scanners?
Seconds
What is the primary factor that affects low-contrast resolution in CT scanners?
Image noise
What is the purpose of the Catphan 500 phantom in CT quality control tests?
To measure all of the above
What is the range of spatial resolution in 64-slice CT scanners, expressed as the full-width half-maximum of the point spread function?
0.6-0.9 mm
What is the term used to describe the graphical representation of system performance in spatial resolution tests?
Modulation Transfer Function (MTF)
What is the purpose of the sensitometry module in CT quality control tests?
To measure CT linearity
What is the term used to describe the in-plane x-y direction and longitudinal in z-direction of spatial resolution in CT scanners?
Spatial resolution
What is the purpose of scanning a patient in a specific position during radiotherapy treatment planning?
To ensure accurate radiation dosage
What is the primary application of dual energy CT imaging?
Discriminating certain tissues and pathology
What is the purpose of the CatPhan phantom in CT imaging?
To evaluate the numerical value of Hounsfield units
What is the primary goal of daily quality control tests for CT?
To ensure optimal image quality
What is the purpose of the air calibration test in CT quality control?
To calibrate the zero value of the detector
What is the purpose of the standard test from safety code 35 in CT quality control?
To check CT number accuracy and cross-field uniformity
What is the purpose of the noise test in CT quality control?
To measure the standard deviation in the phantom
What is the primary application of 4D CT imaging?
Visualizing the movement of joints
What is the purpose of ECG dose modulation in cardiac CT scanning?
To reduce the radiation dose in the phases that are not of interest
What is the benefit of using prospective ECG-triggered reconstructions in cardiac CT?
Reduced patient dose
What is the term used to describe the ratio of table translation per 360° tube rotation relative to the nominal beam width in helical CT?
Pitch factor
What is the advantage of using multislice CT scanners over single slice CT scanners?
Increased number of transmission profiles measured simultaneously
What is the purpose of cardiac motion minimization in cardiac CT scanning?
To freeze the cardiac motion during scanning
What is the benefit of retrospective ECG-gated reconstructions in cardiac CT?
Ability to select cardiac phase retrospectively
What is the purpose of helical scanning in CT acquisition?
To enable the measurement of a large number of transmission profiles simultaneously
What is the advantage of using 16 or 64 adjacent active arrays of detectors in multislice CT scanners?
Increased number of transmission profiles measured simultaneously
What is the unit of measurement for CTDIvol?
mGy
What is the formula to calculate DLP from CTDIvol?
DLP = CTDIvol * Scan Length
What is the CT pitch factor, θp, equal to?
l / (N * T)
What is the formula to calculate the weighted CT Kerma Index, Cw?
Cw = 1/3 (CPMMA,100,c + 2 * CPMMA,100,p)
What is the unit of measurement for DLP?
mGy*cm
What is the scan length of the patient in the example scenario?
16 cm
What is the value of CTDIvol in the example scenario?
10 mGy
What is the value of DLP in the example scenario?
160 mGy*cm
This quiz tests knowledge of quality control tests for CT scanners, including linearity and spatial resolution tests using phantoms and modulation transfer function analysis.
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