DPT's Flashcards
what is a panoramic?
film/tubehead move in opp directions
only structures within certian slice = focal trough are sharp on image
objects further from trough = blurred
what shape is the focal trough?
horseshoe shaped, corresponds to shape of dental arch
patients with non standard arch shape may not conform and image quality may suffer
how does a panoramic work?
film and cassette
film is sensitive to light - intensifying screen in cassette
screen absorbs xray and produces light
light interacts with film and produces an image
dose reduced but so is clarity
disadvantages of intensifying screens?
light goes in all directions
light affects larger area of film than a single photon = image quality not as good as direct film
in digital film what is the indirect action film and intensifying screen replaced with?
phosphor plates and solid state sensors
advantages of dpt’s?
images teeth and facial bones comfortably in one image
assess fully/partially/unerupted teeth
both sides on one image
assess tumours, cycts
vertical height of mandible/inf dental canal can be seen
shows max sinus walls
reduced dose and less time to take
when to take a dpt?
where lesion/burried tooth not vis on intra oral
gross disease
symptomatic 3rd molars
ortho assessment
mandibular fractures
degenerate TMJ disease
assess vertical bone height in implant planning
DPT taken with sympotms/reason and not for screening
problems with dpt’s?
no fine detail
superimposition of soft tissues, hard tissues and air
exposure time over 14 seconds
pt must be positioned correctly
distance from object to fim = magnification
beam details?
beam is fan shaped and angled up at approximately 8 degrees to horizontal
diff part of film exposed to beam at any time
exposure values? dpt? periapical? chest? bckground yearly radiation
3.85-30microSV
1-8.3microSV
0.02mSv
2.5mSv/year
what hard tissues can be seen on a dpt?
teeth, mandible, maxilla, hard palate, zygoma, zygomatic arch, styloid process, hyoid bone, nasal septum and conchae, orbital rim
soft tissues on a dpt?
ear, nasal cartilage, soft palate, tongue, lips
what air shadows can be seen on a dpt?
between lips
oral cavity
oropharynx
nasopharynx
what features of the mandible can be seen?
condyle coronoid process ramus angle body mandibular foramen mental foramen inferior dental canal hyoid bone
what are ghost images?
images of a structure on one side which are projected onto the other side
