CAMRT Computed Tomography and Advanced Imaging Questions and Answers 1

Question 1

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

Accepted Answer

The attenuation value of tissue relative to water

Answer

Hounsfield units quantify the x-ray attenuation of a tissue relative to water (0 HU), with air at −1000 HU and dense bone at +1000 HU.

Question 2

Which CT windowing setting would best display pulmonary parenchyma?

Accepted Answer

Window width 1500, level −600 (lung window)

Answer

A wide window width (~1500 HU) centered at a low level (~−600 HU) is used for lung windows to display the air-filled parenchyma with adequate contrast.

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

Helical CT acquires a continuous volume of data during one breath-hold, enabling multiplanar reconstructions and reducing motion artifacts.

Question 4

In CT, pitch is defined as:

Accepted Answer

Table distance traveled per gantry rotation divided by beam collimation

Answer

Pitch = table feed per rotation ÷ total beam collimation; a pitch >1 means faster coverage but can reduce dose and slice overlap.

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

Metal implants absorb x-rays so strongly that insufficient photons reach the detector, causing beam-hardening and photon starvation, producing characteristic streak artifacts.

CAMRT - Canadian Association of Medical Radiation Technologists Practice Test

CAMRT - Canadian Association of Medical Radiation Technologists Practice Test

CAMRT Computed Tomography and Advanced Imaging Questions and Answers 1