Computed Tomography Test CT Image Quality and Reconstruction

Question 1

In CT, spatial resolution is most commonly measured using which parameter?

Accepted Answer

Modulation Transfer Function (MTF) or line pairs per centimeter (lp/cm)

Answer

Spatial resolution in CT is quantified by the MTF or high-contrast resolution measured in line pairs per centimeter, describing the system's ability to resolve fine detail.

Question 2

What is the Hounsfield Unit (HU) value of water on a CT scan?

Accepted Answer

0 HU

Answer

Water is defined as 0 HU in the Hounsfield scale, which serves as the reference point with air at −1000 HU and dense cortical bone at +1000 HU or greater.

Question 3

Which reconstruction algorithm provides the sharpest images but also the most noise in CT?

Accepted Answer

High-frequency (bone/edge) kernel

Answer

High-frequency (bone/detail) kernels sharpen edges and fine structures but amplify image noise, making them ideal for bone but not soft tissue evaluation.

Question 4

What does the term 'partial volume effect' describe in CT imaging?

Accepted Answer

Averaging of attenuation from different tissues within a single voxel

Answer

Partial volume averaging occurs when a voxel contains multiple tissue types, and the assigned HU is an average of all tissues present, potentially obscuring small lesions.

Question 5

In CT, increasing the field of view (FOV) while keeping matrix size constant will have what effect on voxel size?

Accepted Answer

Voxel size increases, reducing spatial resolution

Answer

Voxel size = FOV / matrix size; a larger FOV with the same matrix produces larger voxels, lowering spatial resolution.

Computed Tomography Test Practice Test

Computed Tomography Test Practice Test

Computed Tomography Test CT Image Quality and Reconstruction