ARRT ARRT CT Artifacts and Troubleshooting 2

Question 1

Which technique is most commonly used to reduce metal artifact in CT imaging of patients with hip prostheses?

Accepted Answer

Metal artifact reduction (MAR) software

Answer

Metal artifact reduction (MAR) algorithms replace corrupted projection data near metal with interpolated data, significantly reducing streaking artifacts.

Question 2

A starburst pattern of streaks emanating from the edge of the patient's shoulders during a neck CT is most likely caused by:

Accepted Answer

Beam hardening from bone and soft tissue interfaces

Answer

Dense cortical bone at the shoulder causes beam hardening, producing characteristic streak artifacts that radiate into adjacent soft tissues.

Question 3

Quantum (photon) noise in CT images is most visible under which conditions?

Accepted Answer

Low mAs or large patient size

Answer

Quantum noise increases when fewer photons reach the detectors, which occurs with low mAs settings or when X-rays are attenuated by a large patient.

Question 4

The windmill artifact seen in helical CT is most commonly associated with which acquisition parameter?

Accepted Answer

High pitch values

Answer

Windmill artifacts appear as alternating dark and bright streaks rotating around structures and are caused by the under-sampling that occurs at high pitch values.

Question 5

Which of the following best describes an out-of-field artifact in CT?

Accepted Answer

Streaking caused by anatomy extending beyond the scan FOV

Answer

Out-of-field artifacts occur when part of the patient's anatomy lies outside the calibrated scan FOV, causing truncation of projection data and bright peripheral streaks.

(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 Artifacts and Troubleshooting 2