IR Artifacts
Artifacts on digital IRs can be caused by these 3 things.
Rough handling, scratches, dust
A _________ is a graph of the frequency of each pixel value in a digital image.
Histogram
Object artifacts come from ________ errors.
Technologist
Digital IRs suffer artifact errors when ______ (or other debris) accumulates on the IR.
Dust
Applying the wrong histogram selection to an image will cause _________ errors.
Reconstruction
Exposure field recognition errors may occur if the x-ray exposure field is not properly _________, _______, and _________.
collimated, sized, positioned
______ residue from marker placement may also cause image artifacts.
Tape
Digital imaging relies on the image histogram to make the "________" image appear like a normal radiograph.
Exposure field recognition errors lead to ________ errors b/c the signal outside the exposure field is included in the histogram.
histogram analysis
Dust, dirt, & debris must be carefully removed using _________ cleaners.
Manufacturer-specific
Most digital imaging systems store the last ___ of each type of image and average the values of each frequency interval.
50
An image with histogram analysis errors can be very ______, very ______, or very ________.
dark, light, noisy
A damaged PSP IP from rough handling will result in pixel _______ on the image. The PSP IP must be ________.
malfunction, replaced
"Processing" an image under the wrong body part means the ______ is labeled incorrectly and the incorrect ________ alters the image.
Header, histogram
_________ distinct, parallel collimated margins are best.
4
Incomplete erasure of the PSP IP will result in _______ images.
Ghost
The digital imaging system will manipulate the output of the ______ to correct for potential artifacts (______, _______).
IR, dead pixels, dead rows/columns of pixels
In film/screen, _________ was important for reducing pt exposure and improving img contrast.
Collimation
T/F: A ghost image is a s/i or double-exposed image.
False, think residual or lag image
Digital images are obtained as raw data sets which are ready "__________". "__________" images are then manipulated into "For presentation" images.
"For processing"
In _________, collimation has the added role of defining the image histogram.
Digital imaging
PSP IPs must be erased every _____ hrs if not used to remove scatter and background radiation.
24
Calibrating digital equipment allows the software to recognize dead pixels and “_______” the areas.
"Auto-fill"
When using _____, it is important to select the appropriate cell and to be mindful of ________ in relation to the cell.
AEC, collimation
Digital IRs are (MORE/LESS) sensitive to scatter than film.
More
Preprocessing happens when the dead pixel areas are repaired using ___________ techniques to assign digital values to each dead pixel, row, or column.
Interpolation
If any patient shielding covers any portion of the AEC, pt dose will ________.
Increase
Name the 3 types of IR Artifacts:
- Dust, dirt, scratches
- Pixel malfunction
- Ghost images
Flatfielding
Digital Irs can easily adapt to _______ numbers of exposures, when they are centered and collimated.
Even
Because digital images can be huge, these 2 data compression techniques are used.
Lossless, Lossy
This allows 2 or more images on a single CR IR.WE must ensure proper image separation and collimation on each projection to avoid histogram errors.
Partitioning
This data compression technique reconstructs the images to the same size as the original by reducing the data file from 10-50%. Best for digital images.
Lossless
IP, IR, Alignment
This data compression technique reduces the digital image data by 100% or more, but exact measurement/fine detail is lost. Ok for video.
Lossy
1. These artifacts are associated with the manner in which the R/g conducts the examination.
2. (T/F) Foreign bodies are considered exposure artifacts.
1. Exposure Artifacts
2. False, Are not
Average # of images per exam for:
1. MR
2. CT
3. CR, DR, Mammo
1. 570
2. 680
3. 3-4
Name the 4 Exposure Artifacts:
1. Foreign Objects
2. S/i images
3. Motion blur
4. Grid cutoff
Name the 3 Software Artifacts:
- Histograms
- Range/scaling
- Image Compression
Name the 3 types of Object Artifacts:
- Pt positioning
- Collimator/partition
- Backscatter