Quality Assurance and Fault Analysis Flashcards
what is the purpose of quality assurance
ensure consistently adequate diagnostic information while radiation doses are kept ALARP
how often should digital receptors be checked
every 3 months or sooner (on a regular basis)
what do you check with digital receptor checks
receptor itself
image uniformity
image qualify
what do you look for on the receptor when checking it
visible damage
if clean
how do you check for image uniformity
expose receptor to an unattenuated x-ray beam and check if resulting image is uniform
how do you check image quality
take radiograph of a test object and assess resulting image against a baseline
what do scratches appear as on phosphor plates
white lines
what does cracking appear as on a phosphor plate
network of white lines
what does delamination appear as on phosphor plates
white areas around edge
on solid state sensors, what does sensor damage look like
white squares/straight lines
what does damage on film appear as
black marks due to sensitisation of radiographic emulsion
when would damage on film appear as white
if emulsion is scraped off
what is a step wedge
one type of test object used to check image quality/contrast
how do you use a step wedge
it is exposed to normal clinical exposure and resulting image is compared to a baseline
what are the 3 parts of quality assurance of clinical image quality
image quality rating
image quality analysis
reject analysis
what are the grades for quality assurance
diagnostically acceptable
diagnostically not acceptable
what are the potential faults visible on image
too dark or pale
inadequate contrast
unsharp
distorted
over collimated
receptor marks/damage
what can cause a collimation error
incorrect assembly of receptor folder
incorrect alignment between x-ray tube and receptor holder
incorrect orientation of the rectangular collimator
what is the cause of incorrect image radiodensity
exposure factors - tissues too thick
developing factors
viewing factors
