Quality Assurance and Fault Analysis Flashcards
What is the purpose of quality assurance in dental radiology?
The purpose of quality assurance in dental radiology is to ensure consistently adequate diagnostic information, whilst radiation doses to patients (and other persons) are kept ALARP, taking into account the relevant requirements of IRMER 17 and IRR17
Where ia a quality assurance programme necessary in?
- Necessary in every dental practice/hospital
A quality assurance programme should cover all aspects of using radiographs. What are these? (7)
- Procedures (e.g. risk assessment, local rules, contingency plans etc.)
- Staff training
- X-ray equipment
- Patient dose
- Image processing
- Display equipment
- Image quality
Who puts input into the creation of a quality assurance programme?
- A medical physics expert (role defined in IRMER 17)
- This is a physicist who is appropriately qualified to give advice on medical matters
Why do we need to do quality assessment of digital image receptors?
- Digital receptors are reusable therefore wear and tear (and mishandling) will eventually impact image quality & necessitate replacement
When should digital image receptors be checked?
- Should be formally checked on a regular basis e.g. every 3 months (or sooner if issue is suspected)
When checking image receptros, what should we check? (3)
- The receptor itself
- Image uniformity
- Image quality
When checking image receptors what are we looking at when we are checking the receptor itself? (2)
- Check for visible damage to casing/wiring
- Check if clean (e.g. no congealed disinfectant/saliva)
When checking image receptors what are we looking at when we are checking the image uniformity? (1)
- Expose receptor to an unattenuated x-ray beam & check if resulting image is uniform (e.g. should show a constant shade of grey across the whole image)
When checking image receptors what are we looking at when we are checking the image quality? (2)
- Take a radiograph of a test object & assess the resulting image against a baseline
What kind of receptor damage can we get on phosphor plate receptors? (3)
- Scratches
- Cracking (from flexing)
- Delamination i.e. separation of phosphor layer from base plate
What kind of receptor damage can we get on solid-state sensors?
- sensor damage
- Don’t tend to have as many problems because all of the sensitive parts are encased in a fairly sturdy plastic covering
What can receptor damage cause the film image to look like? (2)
- Damage often appears as black marks due to sensitisation of radiographic emulsion
- However, may appear white if emulsion is scraped off
- Marks may represent nail marks, bite marks, fingerprints etc
One way in which we can do a quality assessment of the receptor image quality is by using a step wedge. What is this?
- A step wedge is one type of test object used to check image quality/contrast (self-made or provided by manufacturer)
- Exposed to a normal clinical exposure (e.g. adult mandibular molar periapical)
- Must be able to differentiate all the steps
- Carried out regularly (e.g. every morning)
What is the aim of the quality assessment of the clinical image quality?
- Aims to ensure that radiographs are consistently adequate for diagnostic purposes
The quality assessment of the clinical image quality consists of 3 parts. What are these parts?
- Image quality rating
- Grading each image - Image quality analysis
- Reviewing images to calculate ‘success rate’ & identify any trends for suboptimal images
- Carried out periodically (e.g. every 4 months you review last 150 images) - Reject analysis
- Recording & analysing each unacceptable image
- Action MUST be taken if non-diagnostic images are occurring too requently or if same issue keeps arising
What are the quality ratings we can give an image?
- Diagnostically acceptable
- Diagnostically unacceptablr
When could you call an imagine ‘diagnostically acceptable’?
- No errors or minimal errors in either patient preparation, exposure, positioning, image (receptor) processing or image reconstruction and of sufficient image quality to answer the clinical question
When could you call an image ‘diagnostically unacceptable’?
- Eroors in either patient preparation, exposure, positioning, image (receptor) processing or image reconstruction which render the image diagnostically unacceptable
To determine whether or not an image is ‘diagnostically acceptable’, you must know what the image is supposed to show. What is this? (4)
- Which tooth/teeth?
- What parts of the tooth/teeth?
- What other structures?
- What extent of the pathology?
To determine whether or not an image is ‘diagnostically acceptable’, you must know what the image is supposed to show. What do there vary depening on? (2)
- The type of radiograph being taken
- The clinical justification for taking it
When determining if a bitewing radiograph is diagnostically acceptable, What should it contain in it? (4)
- Show entire crowns of upper and lower teeth
- Include distal aspect of the fore-standing posterior tooth & mesial aspect of the last standing tooth (may require >1 radiograph)
- Every approximal surface shown at least once without overlap (where possible - may be impossible if crowding)
- Must also have adequate contrast, sharpness & resolution, as well as minimal distortion
When determining if a periapical radiograph is diagnostically acceptable, What should it contain in it? (4)
- Shows entire root
- Shows periapical bone
- Shows crown
- Must also have adequate contrast, sharpness & resultion, as well as minimal distortion
What is fault analysis?
- Identifying & explaining faults so that they can be remedied
What are potential faults that can be visible on an image? (6)
- Too dark or pale (N.B may be possible to correct if digital)
- Inadequate contrast
- Unsharp
- Distorted
- Over-collimated
- Receptor marks/damage
One potential fault is a collimation error ‘cone cutting’. What causes this? (3)
- Incorrect assembly of receptor holder
- Incorrect alignment between x-ray tube & receptor holder
- Incorrect orientation of the rectangular collimator (attached to x-ray unit)
One potential fault is incorrect image radiodentisy. What does this mean?
- Image is too dark or too light
One potential fault is incorrect image radiodensity. What are the potential causes of this? (3)
- Exposure factors (incorrect exposure settings, patient’s tissues too thick, faulty timer on x-ray unit)
- Developing factors (film)
(Incorrect duration, incorrect temperature, incorrect concentration) - Viewing factors (inappropriate light source (film), inappropriate display screen (digital), excessive environmental light
Look at slide on the control panel
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Look at slides with pictures on them
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