Quality Assurance Flashcards
What is the purpose of quality assurance?
To ensure consistently adequate diagnostic info whilst radiation doses to its and other people are kept ALARP (takes into account IRMER17 and IRR17)
What does radiology quality assurance take into account?
Ionising Radiation Medical Exposure Regulations 17 (IREMR17) - pts
IRR17 - Ionising radiation regulations 17 - staff and others
What is a quality assurance programme?
This is found in every practice and covers the following:
- procedures for radiographs - risk assessments, rules, contingency plans
- staff training
- x-ray equipment
- pt dose
- image processing
- display equipment
- image quality
OUTLINES WHO CAN TAKE THEM, WHERE AND WHAT DO DO IF SOMETHING GOES WRONG
What are QAP created with?
Input from medical physics experts
What receptors do we reuse?
Digital
Since we reuse digital receptors what happens?
There will vie wear and tear and mishandling so this will impact on the image quality and eventually will need replacing
How often should digital image receptors be checked?
Formally checked on regular basis - 3 monthly unless issue suspected sooner
What are the 3 digital image receptor checks?
THE RECEPTOR
IMAGE UNIFORMITY
IMAGE QUALITY
What do we check Digital image receptor for? (2)
we check for any visible damage by looking at it - look for scratches, check if its bent or creased
also check if its clean - no congealed saliva or disinfectant which can affect images
How do we check for image uniformity?
We expose the receptor to an unattenuated x-ray beam by placing receptor on table and aim X-ray tube at it and exposing it to the normal radiation dose and check if the resulting image is uniform
How do we know if our image is uniform on testing?
Will be a uniform grey colour across whole image
if not then we may see diff shades of grey
How do we test image quality?
Take radiograph of a test object and compare to baseline ideal image
What damage can we see on phosphor plates?
scratches
cracking
delamination
What will scratches appear like on phosphor plates?
White lines - can be fine or large
What will cracking appear like on phosphor plates?
Its a result of flexing and will look like a network of white lines (spider webbing)
Why does cracking appear on phosphor plates?
Happens because over time receptor is bent or mishandled in pts mouth and we get creasing and cracking along the phosphor layer and receptor - appears usually around edge or corner
What is delamination?
This is when there are white areas around the edge
How does delamination occur?
occurs when we get peeling away of the phosphor layer at the edges from being mishandled or getting wet and then drying out
Why does less damage happen to solid state sensors?
All sensitive parts of receptor encased in sturdy plastic
What damage can occur to solid state sensors?
can have white squares
white straight line
What are the white squares in solid state sensors?
Dead pixels
What are white lines on solid state sensors?
They are damage to whole line of pixels
What does damage to film receptors appear like?
appears as black marks due to sensitisation of radiographic emulsion - when we mishandle the image or it is damaged then silver halide crystals in radiograph emulsion get sensitised
Why can damage to film appear as white?
If the emulsion has been scraped off - the scratch is so bad it has removed emulsion rather than sensitising it
What does a nail mark look like?
cresent shaped
well defined
superimposed on tooth
on digital its white but on film its black
What can an image uniformity check show?
Any damage to receptor such as scratches, cracking or delamination
How do we know an image has been over collimated?
the edge of the image has been cut of due to X-ray tube not being lined up properly with the receptor
How do we carry out quality analysis of receptor image quality?
step wedge test
What is the step wedge test?
this is where we use a test object to check image quality/contrast - it can be self made or bought
How do we make a step wedge tester?
Wooden spatula and lead foil
- 1 wrap of lead foil…2 wraps… 3 wraps like a step until 6 wraps (so all inc thicknesses)
How do we do step wedge test?
take step wedge and place receptor underneath and then expose it and we will get an image that is attenuated to different degrees
What radiation exposure is used for step wedge test?
Normal clinical exposure - adult mandibular molar PA AND RESULTING IMAGE IS COMPARED TO BASELINE
How do we analyse step wedge test results?
Compare it to baseline - we must be able to see 6 steps
there will be most attenuation –> least attenuation as only single layer of foil
How do we know the receptor is undamaged?
Very clear defined areas if there is damage then not good contrast to differentiate between area
How often do we do step wedge test?
Daily - every morning
What is the aim of allaying assurance of clinical image quality?
To ensure radiograph are consistently adequate for diagnostic purposes
What does QA of clinical image quality consist of ? (3)
IMAGE QUALITY RATING
IMAGE QUALITY ANALYSIS
REJECT ANALYSIS
What is image quality rating?
This is where we grade the image
What is image quality analysis?
This is where we review images to calculate the success rate and identify any trends for suboptimal images (is it the dentist, does It occur in the morning?)
How often is image quality analysis carried out?
Periodically - every 4 months review last 150 images
What is reject analysis?
This is where we record and analyse each unacceptable image - what caused it to be suboptimal and non diagnostic? we need to then adress this and prevent from happening again
What is the new recommended QA system for clinical image quality?
DIGANOSTICALLY ACCEPTABLE (A)
DIAGNOSTICALLY NOT ACCEPTABLE (N)
What does diagnostically acceptable mean?
no errors or minimal errors in either pt prep, exposure, positioning, image receptor processing or image reconstruction and of a sufficient image quality to answer the clinical q
MINIMAL ERRORS IN ALL COMPONENTS THAT IS SUFFICENT IN ANSWERING OUR CLINICAL Q
What does diagnostically not acceptable mean?
errors in pt perp, exposure, positioning, image receptor processing or image reconstructing making the image diagnostically unacceptable
