CAMRT Computed Tomography and Advanced Imaging Questions and Answers

Question 1

In CT imaging, what does the term 'Hounsfield unit (HU)' measure?

Accepted Answer

The attenuation value of tissue relative to water

Answer

Radiation dose to the patient

Answer

The speed of image reconstruction

Answer

The collimator aperture width

Question 2

Which CT windowing setting would best display pulmonary parenchyma?

Accepted Answer

Window width 1500, level −600 (lung window)

Answer

Window width 400, level 40 (soft tissue)

Answer

Window width 80, level 35 (brain window)

Answer

Window width 2000, level 500 (bone window)

Question 3

What is the primary advantage of helical (spiral) CT over conventional axial CT?

Accepted Answer

Continuous data acquisition allowing volume imaging and multiplanar reconstruction

Answer

Lower radiation dose per slice

Answer

Better spatial resolution

Answer

Elimination of beam-hardening artifacts

Question 4

In CT, pitch is defined as:

Accepted Answer

Table distance traveled per gantry rotation divided by beam collimation

Answer

The thickness of a single CT slice

Answer

The number of detector rows

Answer

The tube current in milliamperes

Question 5

Which artifact in CT is caused by very dense structures (such as metal implants) and appears as dark and light streaks radiating from the object?

Accepted Answer

Beam-hardening/metal artifact

Answer

Partial volume artifact

Answer

Ring artifact

Answer

Motion artifact

Question 6

What does CTDI (CT Dose Index) measure?

Accepted Answer

Radiation dose profile along the z-axis for a single CT scan rotation

Answer

Total effective dose to the patient

Answer

Image noise level

Answer

Detector efficiency