ARRT ARRT CT Post-Processing and Reconstruction 1

Question 1

Which CT post-processing technique displays only voxels above a selected threshold, making it useful for 3D visualization of bones and vascular structures?

Accepted Answer

Maximum intensity projection (MIP)

Answer

Maximum intensity projection (MIP) selects and displays the highest attenuation voxel along each ray through the dataset, ideal for visualizing contrast-enhanced vessels or calcifications.

Question 2

Multiplanar reformation (MPR) in CT refers to:

Accepted Answer

Reconstructing axial images into coronal, sagittal, or oblique planes

Answer

MPR uses the volumetric CT dataset to create reformatted images in any anatomical plane without additional radiation exposure to the patient.

Question 3

In CT, the filtered back projection (FBP) reconstruction algorithm applies a mathematical filter primarily to:

Accepted Answer

Correct for star artifacts inherent in simple back projection

Answer

FBP applies a ramp or other convolution filter to projection data before back-projecting to eliminate the blurring ('star artifact') produced by simple back projection.

Question 4

Iterative reconstruction (IR) techniques in CT offer which primary advantage over filtered back projection?

Accepted Answer

Reduced image noise at the same or lower radiation dose

Answer

IR algorithms use repeated mathematical modeling of the imaging process to suppress noise, allowing diagnostic image quality to be maintained at reduced mAs and dose.

Question 5

Curved planar reformation (CPR) in CT is most useful for:

Accepted Answer

Straightening and displaying tortuous structures such as vessels or the spine along their entire length

Answer

CPR follows a user-defined curved path through the volume dataset to display a tortuous structure in a single unfolded plane, useful for coronary arteries or the aorta.

(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test

(ARRT) American Registry of Radiologic Technologists Computed Tomography Certification Practice Test

ARRT ARRT CT Post-Processing and Reconstruction 1