Computed Tomography

The bow tie filter used in CT scanners reduces the patient dose but also the image quality.

• True

• False

The tube current modulation (TCM) resulted in 15% to 50% dose reduction, depending on anatomical region in the x-y plane

• True

• False

For the ramp in filtered backprojection, low frequency values are amplified and high frequency values attenuated

• True

• False

Metal streak artifacts are caused by the following:

• Beam Hardening

• Poisson noise

• Scattering

• All of above

This is the typical reconstruction method for CT images

• Backpropagation

• Backprojection

• Filtered Backprojection

• Iterative reconstruction

What is the highest resolution for clinical CT scanners?

• 1 mm

• 75 um

• 500 um

• 10 um

This image shows an example of this artifact:

• Aliaising

• Poisson noise

• Scattering

• Beam Hardening

Image smearing is a side effect of the backprojection algorithm due to oversampling of the centre of the image frequency plane

• True

• False

This is the ratio between gantry speed and the table speed in a CT system

• Table pitch

• Feed speed

• Image velocity

• Feed ratio

The Fourier slice theorem explains the equivalency of spatial frequency in a line projection

• True

• False