CT Image Quality and Reconstruction Flashcards
6 cards from real Computed Tomography Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CT Image Quality and Reconstruction flashcards as text
What type of CT post-processing technique is most useful for evaluating complex vascular anatomy by removing bone from CT angiography data?
Answer: Maximum Intensity Projection (MIP) after bone subtraction
MIP displays the brightest voxels along each ray, ideal for showing enhanced vessels; subtracting bone first prevents it from obscuring vascular structures.
Which CT post-processing technique is specifically used to evaluate low-attenuation structures like the airways and lung parenchyma?
Answer: Minimum Intensity Projection (MinIP)
MinIP projects the lowest attenuation voxel along each ray, making it ideal for visualizing air-filled structures like bronchi and emphysematous lung.
What is the primary advantage of dual-energy CT (DECT) over single-energy CT?
Answer: Material decomposition allowing tissue characterization (e.g., uric acid vs. calcium)
DECT acquires data at two kVp levels and uses material decomposition algorithms to distinguish substances by their different attenuation characteristics at different energies.
Quantum noise (mottle) in CT images is primarily caused by:
Answer: Insufficient number of X-ray photons reaching the detectors
Quantum noise results from statistical fluctuations in photon detection; when too few photons reach the detector (low mAs or large patient), random variations appear as image noise.
Which CT reconstruction parameter controls the trade-off between image noise and spatial resolution?
Answer: Reconstruction kernel (filter)
The reconstruction kernel (convolution filter) determines whether the image is optimized for smoothness (low noise) or edge sharpness (high resolution), with a fundamental trade-off between the two.
What artifact appears in cardiac CT when the heart rate is irregular or too fast for the gantry rotation time?
Answer: Motion artifact causing blurring of cardiac structures
Cardiac motion during acquisition causes blurring and misregistration of cardiac structures; ECG gating and fast gantry rotation times mitigate but cannot eliminate this when heart rate is high or irregular.