review final Flashcards
cephalostat
special device to position the head for extraoral films
computed tomography
a radiographic technique that produces two dimensional images or slices of specific area
cone beam computed tomography
a three dimensional digital imaging method that uses a cone shaped beam of radiation that rotates around the patient
digital panoramic unit
filmless method of recording a panoramic image and displays it by using an electronic sensor and computer to process the image
exposure controls
a feature that allows the operator to adjust the milliamperage and kilovoltage settings
extraoral imagin
methods used to attain diagnostic images take outside the mouth of a specific area of the skull or jaw
field of view
an area of interest to be shown when performing imaging procedures
focal trough
imaginary three dimensional horseshoe shaped zone used to focus panoramic radiographs
frankfort plane
an imaginary plane that passes through the top of the ear canal and the bottom of the eye socket
midsagittal plane
an imaginary line that divides the patients face into right and left sides
temporomandibular joint
joint on each side of the head that allows movement of the mandible
three-dimensional digital imaging
an image that demonstrates the anatomy in three dimensions
what are the panoramic imaging equipment and accessories
- tubehead
- head positioner
- chin rest
- notched bite blocl
- forehead rest
- lateral head supports
- exposure controls
- film and intensifying screens ( has an image receptor)
- direct digital imaging (sensors)
CBCT
- arm
- head and neck stabilizers
- and other things in same pan
fundamentals of all extraoral projections
lateral cephalometric projection
- used to evaluate facial growth and development, trauma, disease and developmental abnormalities
- shows bone of face and skull, and soft tissue
posterioranterior projection
- used to evaluate facial growth and development, trauma, disease and developmental abnormalities
- shows the frontal and ethmoid sinuses, orbitis and nasal cavity
temporomandibular joint projection
- shows the bone and relationship of the jaw joint
- articular disc and other soft tissues of tmj cannot be examined
patient positioning for all exposures
- patient should sit or stand as tall as possible with a straight spine
- both max and mand teeth should be positioned in the grooves of the bite block
- midsagittal plane should be perpendicular to the floor and frankfort plane must be parallel to the floor
- tongue on roof of mouth, swallow, and lips closed
- patient remains still
procedural steps for preparing the equipment for panoramic imaging
- load pan cassette in the darkroom under safelight
- place infection control barrier and container
- cover bite block
- cover or disinfect parts of the machine that comes in contact with the patient
- set exposure
- adjust machine to accommodate height
- load cassette into carrier
procedural steps for preparing the patient for panoramic imaging
- explain procedure to patient
- ask patient to remove all metal objects
- place lead apron
procedural steps to positioning the patient for panoramic imaging
- instruct patient to site and stand as tall as possible
- instruct patient to bite on the plastic bite block and place teeth in notch
- position midsagittal plan perpendicular to the floor
- position frankfort plane parallel to the floor
- instruct patient to position tongue on roof of mouth
- instruct patient to remain still
- expose film and process
- document
what are error images that can occur
time and temp - underdeveloped (light), overdeveloped (dark), reticulation of emulsion (cracks)
chemical - black spots (developer spots), white spots (fixer spots), yellow-brown stains (old developer or fixer)
film handling - straight white border (developer cutoff), straight black border (fixer cutoff), white or dark areas (film overlapping), white circles (water or air bubbles), black crescent (fingernail artifact), black fingerprint (fingerprint artifact), thin branches (static electricity), white lines (scratched film)
lighting - black (exposed to light), gray (fogged film)
bent film
poor pid alignment
patient movement
film is placed backwards in mouth
ghost images
lead apron artifact
lips and tongue
chin too high to too low
teeth are posterior or anterior to focal trough
spine not straight
what are some tips to success when exposing panoramic images
- use plastic barriers on bite block
- explain procedure to patient
- place proper type of lead apron
- ask patient to remove radiopaque objects
- ask patient to stand or sit as straight as possible
- ensure teeth are in grooves
- midsagittal plane must be perpendicular to the floor
- frankfort plane must be parallel to floor
- lips must be closed, swallow, tongue on roof of mouth
what are advantages and disadvantages of cbct
advantages
- lower radiation dose
- brief scanning time
- anatomically accurate images
- ability to save and easily transport images
disadvantages
- patient movement causes artifacts
- size of field of view
- cost of equipment
- training
what are uses for cone beam computed tomography
- surgical planning for impacted teeth
- diagnosing tmj disorders
- accurate placement for dental implants
- evaluation of jaw, sinuses, nerve canals and nasal cavity
- tumours of jaw
- determining bone structure and tooth orientation
- pain or patho
- reconstructive surgery
what are advantages and disadvantages of pano imaging
advantages- field size, ease of use, patient acceptance, less radiation exposure
disadvantages
- image sharpness
- focal trough limitations
- distortion
- cost of equipment
what are the most common skull radiographs
lateral cephalometric projection
- evaluates facial growth, trauma, disease
- bones of face, skull and soft tissues
posterioranterior projection
- evaluates facial growth, trauma, disease
- shows frontal, ethmoid, orbitis and nasal cavities
temporomandibular joint projection
- shows the projection of tmj, bone and its relationship
what is the additional uses for xrays
trauma - injury produced by external force
intrusion - displacement of a tooth into the bone
extrusion - displacement of a tooth from the bone
avulsed tooth - tooth completely displaced from alveolar bone
