an extraoral radiographic technique that is used to examin the upper and lower jaws on a single film
panoramic radiography
the panoramic film provides the dental radiographer with an overall image of the _____ and _____ and is often used to supplement _____ and selected ______ films.
maxilla
mandible
bite-wing
periapical
what purposes is the panoramic radiograph used for?
evaluate impacted teeth
evaluate eruption patterns, growth and development
detect disease, lesions and conditions of jaw
examin extent of large lesions
evaluate trauma
why can't the pano be used to evaluate and diagnose caries, perio or periapical lesions
not as defined or sharp as intraoral
t/f a pano should not be used as a substitute for intraoral films
true (unless intraoral is impossible)
what does the term tomo mean?
section
radiographic technique that allows the imaging of one layer or section of the body while blurring images from structures in other planes
tomography
the movement of the film and the tubehead produces an image through the process known as..?
tomography
the pivotal point or axis around which the cassette carrier and xray tubehead rotate is?
rotation center
what are the three types of rotation centers?
double center rotation
triple center rotation
moving center rotation
which rotation center involves one right and one left rotational centers?
double center rotation
which rotation has three centers of ration and create a uninterrupted radiographic image of the jaws?
triple center rotation
which rotation has a continuously moving center that is similar to the arches, creating an uninterrupted image of the jaws?
moving center rotation
a three-dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph
focal trough
the structures positioned outside the ____ _____ appear blurred or indistinct and are not readily visible on the pano
focal trough
the structures located ____ the focal trough appear reasonable well defined on the resulting pano
within
who controls the size and shape of the focal trough?
manufacturer
the ____ the rotation center is to the teeth, the narrower the focal trough
closer
in most pano machines the focal trough is _____ in anterior region and ____ in posterior regions
narrow
wide
panoramic units may differ in ____ of rotation centers, the ___ and ____ of the focal trough, and the type of____ transport mechanism used.
number
size
shape
film
what are the three main components of the pano unit
xray tubehead
head positioner
exposure controls
the pano xray _____ is similar to the intraoral xray _____
tubehead
tubehead
the _____ used in the panoramic xray machine is a lead plate with an opening in the shap of a narrow ____ _____
collimator
vertical slit
the beam passes throught the patient and exposes the film through another___ ____ in the cassette carrier
vertical slit
the tubehead of the pano unit is ____ in position so the xray beam is directed slightly ____
fixed
upward
the tubehead of the pano unit always rotates where?
behind the patients head
the film in the pano unit rotates where?
in front of the patient
what does a typical head positioner consist of?
chin rest
notched bite-block
forehead rest
lateral head supports or guides
who determines the exposure factors for the pano unit
manufacturer
the _____ and _____ settings are adjustable and can be vaired to accommodate patients of different sizes
milliamperage
kilovoltage
what exposure factor is fixed and cannot change?
exposure time
film that is sensitive to the light emitted from intensifying screens
screen film
the ___ ___ is placed between the two intensifying screens in a cassette holder
screen film
when the cassette holder is exposed to xray what happens with the screens?
the screens convert the xray energy into light
what are the two types of light used for screen films?
green light
blue light
what are the two sizes available for panos?
5 X 12 inch
6 X 12 inch
what are the two basic types of intensifying screens?
calcium tungstate
rare earth
what kind of light does the calcium tungstate screens emit
blue light
what color of light does the rare earth screens emit?
green
which intensifying screen requires less xray exposure?
rare earth
what intensifying screen is considered faster?
rare earth
why are rare earth screens recommended?
less radiation
device that is used to hold the extraoral film and intensifying screens?
cassette
a cassette may be ___ or ____, ____ or _____ depending on pano unit
rigid or flexible
curved or straight
all cassettes must be ___ ___ to protect the film from exposure
light tight
where are the intensifying screens placed?
each side of the film
t/f a lead apron and a thyroid collar are used on the patient when taking a pano?
false-no thyroid collar
what is the midsagittal plane?
imaginary line that divides the patients face into right and left sides
how should the midsagittal plane be positioned?
perpendicular to the floor
what is the frankfort plane
imaginary plane that passes throught the top of the ear canal and the bottom of the eye socket
how should the frankfort plane be positioned?
parallel with the floor
what is a radiopaque artifact seen on pano?
ghost image
what results in a ghost image?
radiodense object is penetrated twice by the xray beam
what appears on pano if patients lips are not closed?
radiolucent shadow over anterior teeth
what appears on pano if the tongue is not in contact with the palate?
dark radiolucent shadow over apices of maxillary teeth
what plane is wrong if the patients chin is positioned too high
frankfort plane
what four things are seen on the pano when the frankfort plane is angled upward
hard plate and floor of nasal cavity superimposed over roots of max teeth
loss of detal in max incisors
max incisors appear blurred and magnified
reverse smile line
what happens if the frankfort plane is angled downward? (4)
mandibular incisors appear blurred
loss of detail in anterior apical region
mandibular condyles not visible
exaggerated smile line
what happens if the patients teeth are anterior to focal trough
anterior teeth appear skinny and blurred
what happens if patients teeth are posterior to focal trough
anterior teeth appear fat and blurred
what happens if the midsagittal plane is not centered?
ramus and post teeth unequally magnified
what if the patient is not standing or sitting with a straight spine?
cervical spine appears in center of film
what are the four advantages to the panoramic radiograph
