Computed Tomography Test CT Image Quality and Reconstruction 3

Question 1

What type of CT post-processing technique is most useful for evaluating complex vascular anatomy by removing bone from CT angiography data?

Accepted Answer

Maximum Intensity Projection (MIP) after bone subtraction

Answer

MIP displays the brightest voxels along each ray, ideal for showing enhanced vessels; subtracting bone first prevents it from obscuring vascular structures.

Question 2

Which CT post-processing technique is specifically used to evaluate low-attenuation structures like the airways and lung parenchyma?

Accepted Answer

Minimum Intensity Projection (MinIP)

Answer

MinIP projects the lowest attenuation voxel along each ray, making it ideal for visualizing air-filled structures like bronchi and emphysematous lung.

Question 3

What is the primary advantage of dual-energy CT (DECT) over single-energy CT?

Accepted Answer

Material decomposition allowing tissue characterization (e.g., uric acid vs. calcium)

Answer

DECT acquires data at two kVp levels and uses material decomposition algorithms to distinguish substances by their different attenuation characteristics at different energies.

Question 4

Quantum noise (mottle) in CT images is primarily caused by:

Accepted Answer

Insufficient number of X-ray photons reaching the detectors

Answer

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.

Question 5

Which CT reconstruction parameter controls the trade-off between image noise and spatial resolution?

Accepted Answer

Reconstruction kernel (filter)

Answer

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.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test CT Image Quality and Reconstruction 3