Artifacts in Computed Tomography Flashcards
What is an artifact?
Any discrepancy between the CT numbers represented in the image and the expected CT number based on the linear attenuation coefficient
What are the appearances of artifacts?
-Streaks
-Shading
-Bands
-Rings
What are sources of artifacts?
-Patient
-Imaging process and equipment
What ae patient induced artifacts?
-Motion
-Metal Artifact
-Out of field Artifact
What is motion artifacts caused by?
-Voluntary Motion
-Involuntary Motion
What does motion artifact produce?
Ghosting
What is the remedy for voluntary motion? Involuntary Motion?
Voluntary Motion: Explanation of the procedure and good communication with a patient
Involuntary Motion: Short Scan time
How does metal artifacts manifest themsleves?
As “Star Streaking”
What causes Star Streaking?
By the presence of metallic objects inside or outside the patient.
What are the remedies for metal artifacts?
-Removal of external metallic objects
-Mar Software
-Gantry Angulation
What is out of field artifact?
When the patient is not entirely enclosed in the scanning field of view
What can happen in out of field artifact?
The patient’s ody can obsrtuct detectors and patient tissue outside the SFOV will further harden the x-ray beam
How does out of field artifact appear?
As streaks and shading
What are the remedies for out of field artifacts?
-Selection of larger SFOV
-Taping patient tissue
-Raising patient’s arms above their head on the scan of chest and abdomen
What are equipment imaging process artifacts?
-Ring
-Line in Tomogram
-Staircase
