Artifacts and Errors Flashcards
(47 cards)
CR PLATE ERASURE ERROR
GHOSTING ERROR
Identify artifact : Double image of equine tarsus. One image properly exposed.
GHOSTING ERROR
This artifact occurs because of malfunction
of roller in computed radiography reader,
causing defective scanning and resulting
in alteration in image contrast ( arrows) in upper
and lower half of the chest radiograph.
Roller Malfunction Error- CR Reader Error
Lower half of chest radiograph was exposed to
laser beam for longer time, which resulted in
brighter image output that rendered image
suboptimal.
Roller Malfunction Error- CR Reader Error
is plate reader
artifact resulting from dirt in light guide.
Radiopaque line (white arrow)
When using CR cassettes with grids a very
specific line spacing ( grid frequency) is required to avoid the Moire pattern, which is
a wave like artifact caused by the scanning
laser beam overlapping with the grid line structure.
CR GRID ERROR- MOIRE
can occur if the laser scan
of the CR runs parallel to the grid lines.
Moire artifacts
Most grid frequencies are between ____ the higher grid
frequency provides better image quality.
80 and
178 lines per inch;
A pattern of radiation exposure levels (ei, dose) being increased by clinicians in an attempt to achieve better image quality in diagnostic radiography.
DOSE CREEP
Although it is unlikely to result in immediate harm, it’s a problem that can have long-term consequences and that , over time , can affect many patients.
DOSE CREEP
both of which are intended to enhance the visual appearance of the image displayed for viewing on a monitor , in an effort to assist the radiologist.
Pre - processing and
Post - processing
includes all processing of raw data performed
to correct flaws in image acquisition
PRE-PROCESSING
includes manipulation of data that has been
pre-processed.
POST-PROCESSING
There are three types of pre-processing process used in CR units:
Exposure field Recognition
Histogram Analysis
Gratscale Analysis
is used to recognize the clinically useful area on the imaging
so it is the only data that will be manipulated, and it eliminates the
signals from outside the collimated field.
Exposure field recognition
exposure data recognition
Fuji
segmentation
Carestream
the information that are important on the histogram will be
determined by the values of interest, which will be different
for each body part.
Histogram analysis
The ___ also has LUT that has the appropriate contrast for each body part.
algorithm
which are unique to each manufacturer, process data once exposed are is determined and the signal histogram is established.
Algorithms
is completed by transforming input data values to
output values that will be displayed on a monitor.
Grayscale Analysis
This is
completed through the use of a grayscale look-up table has an
algebraic equation used for the conversion and results that are
stored in the computer, which saves processing time.
Grayscale Analysis
Under Post Processing
Annotation
Cropping
-writing on image
-time sequence studies
-upright/ supine notations
-artifact information
-portable identifier
-free text
Annotation
