Radiographic Localisation Flashcards
What is the need for radiographic localization
to determine the location of a structure or pathological lesion in relation to other structures
only needed where clinical examination is insufficient to provide an answer
What are clinical situations where we can use radiographic localization
position of unereupted teeth location of roots/root canals relationship of pathological lesiosn trauma soft tissue swellings
When we look at radiographs what do we do
observation
interpretation
management
What does observation consist of
look carefully at the radiograph and consider the technical acceptability, abnormalities and if there is a need for further radiography
If we want a view at right angles what are the options
panoramic and lower true occlusal
paralleling periapical and lower true occlusal
CBCT - each of the MPRs is at a right angle to the others
What are the methods of radiographic localization
normally 2 views required
views at right angles in their projection geometry
views with any different projection
provided the difference is known
with tea id of opaque objects e.g GP point
anatomical knowledge is crucial
For views that are not at a right angle what is important
that we use a known projection geometry
must both include item to be localized and a stable ref point
multiple combinations possible
utilise horizontal or vertical tube shift to aid interpretation
What is parallax
an apparent change in the position of an object caused by a real change in the position of the observer
Where are radiographs normally viewed from
buccal aspect of px
beam passing from buccal to lingual so buccal is closest
What is SLOB
same lingual opposite buccal
if an object moves int he same direct as x ray tube source then it is lingual and if it moves in opposite direction its buccal
What’s PAL
palatal object goes with me, the direction you have moved the tube
What is the sequence of events for radiographic localization
identify direction of tube movement
What do we need to know the location of
Choose a reference
Observe movement of it in the correct direction
What are the parallax options for horizontal tube shifts
equivalent views
2 PA
2 bite wings
2 oblique occlusals
What are the parallax options for vertical tube shift
different views
panoramic and oblique occlusal
panoramic and lower (bisecting angle) periapical
