Week 12 Ch. 25/26 - Panoramic & Extraoral Imaging

dental caries, periodontal disease, periapical lesions

what should panoramic images not be used to diagnose?

tomography

imaging technique that allows the imaging of one layer or section of the body while blurring images from structures in other planes

rotation center

pivotal point, or axis, around which the cassette carrier and xray tubehead rotate

focal trough

3-D curved zone in which structures are clearly demonstrated on a pan image; pt jaw must be positioned in this zone to obtain a reasonably clear and well-defined image

real image

results when a structure lies between the receptor and moving rotation center; structures found within the focal trough appear sharp on the resultant image while the structures outisde of the focal trough appear blurred

double image

results when an anatomic structure that is located behind the moving rotation center is penetrated twice by the xray beam

ghost image

results when an anatomic structure or object is located outside of the focal plane and close to the xray source

collimator

lead plate with an opening in the shape of a narrow verticle slit

head positioner

chin rest, notched bite-block, forehead rest and lateral head supports or guides - used to align the patient’s teeth as accurately as possible

area 1: dentition

teeth are arranged in a smile-like curve; crowns and apices of all teeth visible

area 2: ramus and spine

ramus should be the same width on each side; cervical spine may be present along edges, but should not overlap ramus

area 3: nasal cavity and max sinus

hard palate double image appears above the apices of the max teeth

area 4: body of mandible

inferior border of mandible appears smooth and continuous

area 5: condyle

condyle is centered, is of equal size on each side, and is one the same horizontal plane

area 6: hyoid bone

hyoid bone double image appears, may slightly overlap mandible

ghost image

imaging artifact seen on a panoramic image that is produced when a metallic or dense object is penetrated twice by the xray beam; found on opposite side of the receptor

lead apron artifact

radiopaque cone-shaped artifact obscures diagnostic information results if the lead apron is incorrectly placed or if thyroid collar is used

positioning of the lips and tongue

radiolucent shadow results that obscures the anterior teeth if lips are not closed; radiolucent shadow results that obscures the apices of the max teeth if tongue is not in contact with palate

chin tipped up

reverse smile line apparent on the image

chin tipped down

exaggerated smile line is apparent on the image

teeth anterior to focal trough

pt teeth is positioned too far forward on the bite-block; teeth appear narrow/skinny and out of focus

tooth posterior to focal trough

pt teeth positioned too far back on bite-block; anterior teeth appear broad/widened and out of focus

head turned

ramus and posterior teeth appear unequally magnified on the panoramic image; the side farther from the receptor appears magnified

slumped posture

pt not standing or sitting with a straight spine; cervical spine appears as radiopacity in the center of the receptor and obscures diagnostic information

field size, simplicity, pt cooperation, minimal exposure

what are some adv of panos?

image quality, focal trough limitations, distortion, equipment cost

what are some disadv of pano?

grid

device used to reduce amount of scatter radiation that reaches an extraoral film during exposure; placed between pt head and film

lateral jaw imaging

used to examine the posterior region of the mandible; includes body and ramus of mandible

lateral jaw - body of mandible

evaluate impacted teeth, fractures and lesions in the body of the mandible region

lateral jaw - ramus of mandible

evaluate impacted third molars, large lesions and fractures that extend into the ramus of mandible

skull imaging

used to examine the bones of the face and the skull - used most often in oral sx and orthodontics

lateral cephalometric

to evaluate facial growth and development, trauma, disease and developmental abnormalities; shows soft tissue profile

posteroanterior

to evaluate facial growth and development, trauma disease and developmental abnormalities; shows sinuses, nasal cavity and orbits

waters

to evaluate the max sinus area; shows sinuses, nasal cavity and orbits

submentovertex

to identify the position of the condyles, demonstrates the base of the skull and evaluate fractures of the zygomatic arch

reverse towne

to identify fractures of the condylar neck and ramus

tmj joint

to evaluate tmj area

transcranial

evaluate the superior surface of the condyle and articular eminence; can also be used to evaluate movement of the condyle when the mouth is opened and to compare joint spaces

extraoral bw

provide diagnostic information about max and mand teeth, interproximal regions, periapical bone and surrounding structures; similar to bw but with larger view of anatomic structure