Digital Artifacts - CTEToolbox.com

daughterduckUrban and Civil

Nov 15, 2013 (3 years and 11 months ago)

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QC/PACS Artifact

Identification

Artifact Causes


Image receptor/Hardware


Dirty


Foreign material


Failures


Software


Algorithm


Enhancements/manipulations


Operator/Patient


Collimation


Misused equipment


Incorrect patient data entry

Image Receptor/Hardware


Dirt


In the CR cassette or reader


Foreign material


Matter other than dirt within the CR cassette
or reader


Failures


Dead pixels


Mechanical failures with in the CR reader


Within the PACS network

CR Screen Artifacts


These are caused by

Dirt or other foreign

matter within the cassette/plate

apparatus

Dead Pixels


Calibration algorithms detect
individual pixels, clusters, and
lines of contiguous pixels that
fail to produce a usable output
value. Algorithms are applied
to the image to determine pixel
values for the ‘dead’ or missing
pixels.


CR Ghost Images


Ghost or memory artifacts occur when the radiation
remains trapped in the phosphor plate. Remember,
radiation can remain trapped for several minutes. CR
plates must be correctly erased to prevent ghost images.

Ghost Image



This artifact can also
occur with DR
systems; particularly
systems using
photodiodes.


The artifact occurs
when exposures are
made too rapidly and
the unit was unable to
clear its data
completely.

CR Reader Artifacts



Typically display as
lines across the
entire image


In contrast to dirt
within the cassette
or on the PSP
which are shorter
and/or curved lines.



Damaged laser beam

head


Transmission errors in

the network

Printer Distortion


Occurs when the image size and the
printed size are not equal.

Software Causes


Algorithms


Incorrect selection


Age related


Pathology induced


Post
-
processing


Edge enhancement, etc

Edge Enhancement


High contrast and edge definition


Lose fine detail on the edges of high contrast areas


For the pediatric chest an adult chest algorithm was selected.

Technologist error.

DR
-

RF Noise


Operator Errors


Collimation


Backscatter


Moire artifact


Quantum mottle


Insufficient mAs

Collimation


Too much or too little
collimation may effect
image quality. When
being reconstructed the
image histogram has
been programmed to
search for a particular
collimation pattern. If the
collimation is faulty it may
result in artifacts on the
final image.


Light bulb Artifact

Image A demonstrates backscatter on the image which produces a ‘light bulb’

effect within the image. Image B shows the same image with less kVp.

Moire Pattern


Grid lines run in the same direction as
the laser in the CR reader.

Quantum Mottle


Image A demonstrates quantum mottle resulting from too few photons striking the

imaging plate. Images B and C show increasing mAs values and decreasing

quantum mottle.

Conclusion


Digital artifacts can be caused by
numerous means.


It is the responsibility of the II/PACS
professional to be the final monitor of
image quality within the modern imaging
department.

Future Possibilities


Digital image monitoring