Fault Analysis and Quality Insurance Flashcards
what is the purpose of quality assurance in dental radiology
- ensure consistently adequate diagnostic information
what aspects of radiography does QA programmes cover
- procedures
- staff training
- x-ray equipment
- patient dose
- image processing
- display equipment
- image quality
why are digital receptors so often damaged
- because they are reusable and are used so often
how often should Digital receptors be checked
- every 3 months
what needs to be checked for digital receptors
- receptor itself
- image uniformly
- image quality
how is the receptor of the digital receptor checked
- check for visible damage to casing/wiring
- check if clean = no congealed disinfectant/saliva
how is image uniformity of digital receptors checked
- expose receptor to an unattenuated x-ray beam and check if resulting image is uniform
- should show a consistent shade of grey across whole image
how is image quality of digital receptor checked
- take a radiograph of a test object and assess the resulting image against a baseline
how does scratches show up on phosphor plate
- white lines across image
- can be very thin and fine or large
how does cracking (from flexing) show up on phosphor plates
- network of fine lines
- start to get creases if been bent, and cracks can start to form along it
- like spider webbing
how does delamination show up on phosphor plates
- white areas around the edge
- separation of phosphor layer from base plate
- only around edge of image
- starts to arise from peeling away of phosphor layer either from saliva of being damaged
how does damage often appear as on solid-state sensors
- white squares/striaght lines
- don’t get many scratches as encased in strong plastic
how does damage often appear as on film receptor
- black marks due to sensitisation of radiographic emulsion
- however, may appear white if emulsion is scraped off
- appears black because when damage image the silver halide crystals in emulsion get sensitised (by heat and pressure)
what often causes marks on receptors
- nail marks, bite marks, fingerprints
how can delamination occur
- from image being wet and then drying causing phosphor layer to peel away
what is step wedge technique of QA receptor image quality
- self-made or provided by manufacturer
- small wooden spatula and wrap lead foil round it in different thicknesses
- when expose to radiograph = put receptor underneath
- should get image down below
what should the baseline step wedge show
- 6 differentiated steps
how often should step wedge be carried out
- regularly = every morning
why do we need to be more careful doing film radiographs
- more potential sources of error as need to process them
what does QA of clinical image quality include
- image quality rating
- image quality analysis
- reject analysis
what is image quality rating
- grading each image
what does image quality analysis involve
- reviewing images to calculate;ate ‘success rate’ and identify any trends for suboptimal images
- carried out periodically = every 4 months you review the last 150 images
what does reject analysis involve
- recording and analysing each unacceptable image
what does diagnostically acceptable mean
- no errors or minimal erros
- sufficient image quality to answer the clinical question
- in digital imaging = not less than 95%
- film imaging = no less than 90%
