Computed Tomography Test Computed Tomography Science 3

Question 1

In CT scanner design, the gantry aperture refers to:

Accepted Answer

The opening through which the patient passes

Answer

The gantry aperture is the circular opening (typically 70–90 cm in diameter) through which the patient or object is positioned for scanning.

Question 2

What is the primary purpose of the bow-tie (wedge) filter in a CT system?

Accepted Answer

To equalize photon flux across the detector array

Answer

The bow-tie filter attenuates the peripheral portion of the beam more than the center, equalizing photon fluence across the detector and reducing patient dose.

Question 3

During a CT scan, tube current modulation (TCM) adjusts the mA based on:

Accepted Answer

Patient attenuation in real time

Answer

TCM reduces mA in less-attenuating regions (e.g., lungs) and increases it in denser regions (e.g., shoulders), optimizing dose while maintaining image quality.

Question 4

The 'reconstruction kernel' (convolution filter) in CT primarily affects:

Accepted Answer

Spatial resolution and noise

Answer

Sharp kernels enhance spatial resolution but increase noise, while smooth kernels reduce noise at the cost of spatial resolution.

Question 5

Which measure quantifies the overall radiation output of a CT scanner independent of scan length?

Accepted Answer

CTDI (CT Dose Index)

Answer

CTDI quantifies the radiation output of the CT scanner per rotation, independent of scan length, and is measured in mGy.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test Computed Tomography Science 3