panoramic radiography
Used to examine the upper and lower jaws on a single film
panoramic film
Shows a wide view of the upper and lower jaws
supplement bite-wing and selected periapical films
purpose and use of panoramic radiography
opposite
do the x-ray tube and the film rotate in the same or opposite directions?
tomography
movement of the film and the tubehead produces an image through what process?
tomography
A radiographic technique that allows the imaging of one layer or section of the body while blurring images from structures in other planes
rotation center
The pivotal point, or axis, around which the cassette carrier and x-ray tubehead rotate
double-center, triple-center, moving-center
3 types of rotation centers
focal trough
as a three-dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph
focal trough
what is this?
tubehead, head positioner, exposure controls
panoramic x-ray unit components
collimator
a lead plate with an opening in the shape of a narrow vertical slit
from the tubehead through the collimator
how does the x-ray beam emerge for panoramic x-ray units?
vertical
Which angulation is fixed so that the x-ray beam is directed slightly upward?
head positioner
A chin rest, notched bite-block, forehead rest, and lateral head supports or guides
head positioner
Used to align the patient's teeth as accurately as possible
milliamperage and kilovoltage
units for exposure
patients of different sizes
how are exposure controls varied?
screen
what type of film is used in panoramic radiography?
between two intensifying screens in a cassette holder
where is the screen film placed?
calcium tungstate, rare earth
2 types of intensifying screens
blue
what color light does calcium tungstate emit?
green
what color light does rare earth emit?
rare earth
which intensifying screen requires less x-ray exposure?
rare earth
which intensifying screen is recommended in panoramic radiography?
cassette
A device used to hold the extraoral film and intensifying screens
rigid, flexible, curved, straight
cassette shapes
static electricity
what can be created when the film is removed from the box too quickly?
equipment prep, patient prep, patient positioning
step-by-step procedures for panos
equipment preparation
Load the panoramic cassette in the darkroom under safelight conditions
Cover the bite-block with a disposable plastic coverslip or sterilize between patients
Set the exposure factors
patient preparation
Explain the radiographic procedures
Place a lead apron without a thyroid collar on the patient and secure it
Remove all objects from the head and neck area that may interfere with film exposure
thyroid collar
what about the lead apron needs to be left off?
patient positioning
Instruct the patient to sit or stand "as tall as possible" with the back straight and erect
Instruct the patient to bite on the plastic bite-block
Position the midsagittal plane perpendicular to the floor
perpendicular
How should the midsagittal plane be positioned with the floor?
frankfort plane
the line below the eye socket
midsagittal
the line dividing the face in half
on roof of mouth
where should the tongue be during exposure?
closed around biteblock
where should the lips be during exposure?
patient prep
what category error are ghost images in?
patient prep
what category error is a lead apron artifact in?
ghost images
A radiographic artifact seen on a panoramic film that is produced when a radiodense object is penetrated twice by the x-ray beam
lead apron artifact
A radiographic artifact seen on a panoramic film that is produced when a radiodense object is penetrated twice by the x-ray beam
lips not closed on biteblock
what problem creates a dark radiolucent shadow that obscures the anterior teeth
tongue not on roof of mouth
what problem results in a dark radiolucent shadow that obscures the apices of the maxillary teeth
frankfort plane upward
what problem results in a "reverse smile line" on the radiograph
frankfort plane downward
what problem results in an "exaggerated smile line" on the radiograph
teeth anterior to the focal trough
what problem results in teeth appearing "skinny
teeth posterior to focal trough
what problem results in teeth appearing "fat
patient's head not centered
what problem results in the ramus and posterior teeth appearing unequally magnified
patient not standing or sitting with a straight spine
what results in the cervical spine appearing as a radiopacity in the center of the film
field size, simplicity, cooperation, minimal exposure
4 advantages of panoramic radiographs
image quality, focal trough limitations, distortion, equipment cost
4 disadvantages of panoramic radiographs
bisecting technique
another method that can be used to expose periapical films
lingual
what surface of the tooth is the film placed for bisecting technique
long axis and film
what two line angles form an angle at the point where the film contacts the tooth?
imaginary bisector
what bisects the angle formed by the film and long axis?
perpendicular to the imaginary bisector
where is the central ray directed?
right triangles and congruent
what are the two triangles that result from the central ray and imaginary bisector being perpendicular?
film holder
A device used to position an intraoral film
Recommended because they eliminate the need for the patient to stabilize the film
finger-holding method
Patient's finger or thumb is used to stabilize the periapical film
2
what size film is traditionally used for bisecting?
perpendicular to the curvature of the arch and through the contacts
correct horizontal angulation in bisecting?
film placement, film position, vertical and horizontal angulation
rules for bisecting technique
mx anterior (R-L), mn anterior (L-R), mx R Q, mn R Q, mx L Q, mn L Q
bisecting exposure sequence
no film holder
Bisecting technique advantages
image distortion, angulation problems, unnecessary exposure
bisecting technique disadvantages
mx molar
which film is most likely to elicit the gag reflex?
sliding the film along the palate
For gagging patients, what should be avoided?
topical anesthetic
what should you not use with a gagging patient?
bisecting
which technique is preferred for children with a primary or transitional dentition?
endodontics
The branch of dentistry concerned with the diagnosis and treatment of diseases of the dental pulp within the tooth
EndoRay film holder
what can be used to aid in positioning the film during a root canal procedure
paralleling
what technique is recommended for endodontic patients?