review 8-9 Flashcards
system for assessing radiographs
A or N
diagnostically Acceptable or Non-acceptiable
film and phosphor plate damage appearance
similar damage effects as similar physically
- But different chemical reactions so can appear different
- Film - white (completely scraped off) or black (sensitisation)
- Phosphor plate - white
solid state sensor damage appearance
complete encased in hard plastic – won’t get scratches, bending, delamination as components that make image are encased in hard plastic
But electronic components can fail – so get dead pixels
parallax effect is
The apparent movement of an object viewed from different positions
The object itself isn’t moving – the viewpoint has
what do you need to do parallax
- more than one image of the object of interest
- need movement of viewpoint
- need 2 but not necessariliy of different types
- images need to be taken from different angles/positions
- a shared reference point on hte images
- e.g. root of erupted tooth
ideally taken at same time (one after the other) – time delay risk physical move in mouth due to eruption not parallax effect
what radiographs can you combine for parallax?
any 2 images with sufficient ‘tube shift’ between them
vertically and/or horizontally
which 2 views are unrelaible pair for parallax?
- 2 periapicals at different angles
- 2 bitewings at different angles
- 2 maxillary occlusals at different angles
- periapical and panoramic
- periapical and maxillary occlusal
- panoramic and maxillary occlusal
- bitewing and lateral maxillary occlusal
periapical and panoramic
- Shift is limited and unpredictable between peri and pano*
- Avoid using*
tricks to help using parallax (3)
- fingers
- further away move with use
- SLOB mnemonis
- same lingual opposite buccal
- PAL mnemonic
- my PAL goes with me - palatal moves with you/tube
position of unerupted left maxillary canine
buccal,palatal or same plane
Palatal
Point of view to pt left from midline
- Initially in line with root cancel of central
- Second one is central, lateral
- Canine is no longer superimposing middle of root closer to distal
- Moved more to the pt left on view
Maxillary canine in relation to root right central incisor
Buccal, palatal/lingual, same plane?
PALATAL
Move towards pt left – right lat to left lat in middle
- Cusp canine superimposing root canal right central incisor (next to suture)
- Now cusp touching left central incisor
- Moved with so PALATAL
maxillary occlusals - where is unerupted canine
- first right sided max occlusal – viewing pt from right*
- midline – move towards left of pt*
cusp no longer superimposing lateral incisor
- so as we move left canine moved left in relation to lateral incisors
- Palatal
where are unerupted canines often found in maxilla
palatal
Where are 2 canines in relation to incisors?
Buccal, palatal/lingual, same plane
vertical parallax
Palatal
Pano to max occlusal – point of view up
- Large chunk of roots above in panoramic
- Crown superimposed over majority of root in max occlusal – only apices
- View up and canine up so palatal
why not just use CBCT instead of trying to do parallax
CBCT – all angles
- But follow ALARP
- CBCT 50 times radiation as amount of 2 periapicals
and
- Save money
- Time and effort, qualifications, access to machine
Impractical and expensive to use all the time
Unnecessary radiation
diagnostically acceptable
A
no errors or minimal errors
in either pt prep, exposure, position, image (receptor) processing or image reconstruction and of sufficinet image quality to answer the clinical question
image quality rating
to assess periodonta bone levels around tooth 38
N
Collimation error so cannot assess distal bone levels
Fault analysis – collimation error
image quality rating
to assess bone level arount tooth 26
A
Apices bit unclear – but can be anatomh issue – dense bone in area potentially
See from other contrast is good
image quality rating
to assess auto-transplanted 14 in 23 space
Small, resorbed B next to it
- Major issue – distortion at top
- Trabeculae - stretched up the way
- fault analysis – receptor bent
- anatomy at edge bent
- causes:
- shallow palate
- receptor to close to teeth – bent backwards
not a large effect on transplanted – probably some around apex
either way
