ARRT Image Quality 3

Question 1

Which window setting is most appropriate for evaluating pulmonary nodules in the lung parenchyma?

Accepted Answer

Window width ~1500 HU, window level ~-600 HU

Answer

Lung windows use a wide width (~1500 HU) and negative level (~-600 HU) to display the full range of lung attenuation from air to soft tissue.

Question 2

Partial volume averaging artifact in CT is BEST minimized by:

Accepted Answer

Using thinner slice collimation

Answer

Thinner slices reduce the z-axis extent of each voxel, decreasing the chance that multiple tissue types are averaged into a single voxel.

Question 3

Adaptive statistical iterative reconstruction (ASIR) improves CT image quality primarily by:

Accepted Answer

Reducing image noise while maintaining resolution

Answer

ASIR uses statistical modeling to reduce noise, allowing diagnostic images at lower dose without proportional loss of spatial resolution.

Question 4

The pitch value in helical CT is defined as:

Accepted Answer

Table travel per rotation divided by total beam collimation width

Answer

Pitch = table distance traveled per 360° rotation ÷ total collimated beam width, and values >1 indicate gaps in data coverage.

Question 5

A CT image shows ring artifacts. The MOST likely cause is:

Accepted Answer

A malfunctioning or miscalibrated detector element

Answer

Ring artifacts appear as circular bands centered on the isocenter and are caused by a single detector element producing consistently incorrect readings.

(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test

(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test

ARRT Image Quality 3