Week 11: Artifacts

Question 1

Upside Down Cassette Artifact

Answer 1

Cassette is placed upside down and you can see the inside cassette material not he image.

Question 2

Phantom or Ghost Image Artifact

Answer 2

These occur during incomplete erasure of the IP when using a CR system. Data from a previous exposure is adding information to the current exposure that should not be there.

Question 3

Moire Artifact

Answer 3

Can occur when stationary grid lines are parallel to the IRD scan lines. Usually the IRD scan direction is along the short axis of the IP while the grid lines run parallel to the long axis which should typically prevent this artifact. Sometimes IRD will remove the lines caused by this artifact having poor contrast and image brightness but without the line which can be confusing.

Question 4

Back Scatter Artifact

Answer 4

Occurs when portions of the bucket under the IR are plotted on the image because radiation has scattered back up to the IR after passing through the first time. This can occur due to lack of lead at the detector or because of open collimation and heavy exposure.

Question 5

Dropout Artifact

Answer 5

Occurs because of a DR pixel array failure. White lines appear on an image because no signal was collected.

Question 6

Scratched IP

Answer 6

Part of the IP have no PSP due to scratching or damage so they appear as bright white lines on the image.

Question 7

Tube Filter Failure

Answer 7

Filters in the assembly of the x-ray tube could become loose and mispositioned in the x-ray beam. The filters then attenuate the x-ray beam non-uniformly and result in an unwanted attenuation pattern.

Question 8

Data Drop

Answer 8

Data elements receive so much exposure they cannot process the information. When the image is reconstructed for display these elements are ‘‘dropped’’ and display no information (often black) which can mimic pathology.

Question 9

Halo Artifact

Answer 9

Dark bands at a structure interface where vast different material meet which gives an appearance of a loose prosthesis.

Question 10

Excessive Equalization Error

Answer 10

When a tech collimates tighter than the anatomical algorithm expects. The computer sensed the collimated border and creates a histogram from inside that border and the LUT only has a small filed to work with which results in an undiagnostic image. EI will show underexposed but the image will look very dark,

Question 11

Collimation Detection Error

Answer 11

Images that are off centre the IR cause the computer to get confused and it includes all the information on the whole IP, averaging the underexposed area into the histogram causing an incorrect contrast/brightness to be displayed.

Question 12

IP Fogging

Answer 12

IPs that are not used for weeks and the digital receptors have absorbed scatter and background radiation.

Question 13

Heat Blur

Answer 13

IP that is inappropriately stored near heat source, blurry image.