Radiology #5

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?