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29 Cards in this Set

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What is the purpose of extraoral imaging?

  • Examine large areas of the dental arches and skull
  • Study growth and development of the bone and teeth
  • Detect fractures and evaluate trauma
  • Detect pathological lesions and diseases of the jaw
  • Deteck and evaluate impacted teeth
  • Evaluate TMJ disorders
  • Plan treatment for dental implants and prosthetic appliances

What are other reasons for extraoral radiography?

  • Limited opening
  • Lack of patient compliance for intraoral films
  • Disabled patient who cannot cooperate or are physically incapable of managing intraoral films
  • Patients with trismus or TMJ disorder
  • Specialty needs

What do orthodontists use extraoral radographs for?

  • comparison and measurement of growth and development

What do Prosthodotists use extraoral radographs for?

  • facial profiles are recorded to assist with reproducing contours of the face and the relationship of the teeth

What do oral surgeons use extraoral radographs for?

  • evaluation of trauma, fractures, impacted teeth, lesions and TMJ disorders

What are the types of Extraoral Radiographs of the Maxillofacial Region?

  • Lateral Jaw
  • Lateral Cephalometric
  • Posterioanterior Cephalometric
  • Waters
  • Reverse towne
  • Submentovertex
  • Transcranial
Which EO Radiograph is this?
What does it examine?

Which EO Radiograph is this?


What does it examine?

  • Lateral Jaw
  • The posterior region of the mandible

- Body and ramus


- Coronoid process


- Condyle

Which EO Radiograph is this?
What does it examine?

Which EO Radiograph is this?


What does it examine?

  • Lateral Cephalometric
  • Facial growth and development, trauma, disease, and developmental abnormalities
  • Posterioanterior Projection
  • facial growth and development, disease, trauma, developmental abnormalities
  • Waters Projection
  • the maxillary, frontal and ethmoid sinuses
  • Reverse Towne Projection
  • Fractures of the condylar neck and ramus area
  • Submentovertex
  • the position of the condyles, demonstrate the base of the scull, and evaluate fractures of the zygomatic arch
  • Transcranial
  • The superior surface/head of the condyle and the articular eminence, malignancies, fractures, and tissue changes of the TMJ

Why is a screen film used in conjunction with intensifying screens?

to maintain low dosage

How must extra oral films be handled?

carefully, without plastic or latex gloves (cause static), on the edges (cause finger prints), in appropriate lighting because (not packaged separately so will ruin all films exposed to light)

What is the intensifying screen? what does it do?

  • A screen that transfers X-ray energy into visible light
  • Visible light then exposes the film
  • Image produced results from exposure to fluorescent light instead of directly from x-rays
  • Intensifying screens allow the amount of radiation required to be reduced.

What are the characteristics of the intensifying screens?

  • Work in mairs
  • Coated with fluorescent crystals which fluoresce and emit energy in the form of light when they absorb x-rays
  • Each crystal (phosphor) gives off blue or green light
  • Film is in between two screens
  • X-rays cause the crystals to fluoresce and return the light to the film emulsion to produce the image

What does sensitivity and image sharpness depend on?

  • The type of screen being used
  • size of crystals being used

- large crystals produce a less sharp image


  • thickness of the emulsion

-Thicker emulsion = faster speed screen = less radiation but also less sharp image


  • type of phosphor used

How is the correct side of the film identified?

  • DO NOT HAVE AN EMBOSSED DOTS!
  • R and L are placed on the cassette or in the cassette by the manufacturer

What should be checked for when inspecting the cassettes and screens?

  • for light tightness and hinge function
  • that the cassette closes properly and tightly
  • examine the screens for cleanliness and scratches

What are grids? How are they used? What do they require?

  • Mechanical devices composed of thin strips of lead alternating with radiolucent material
  • Placed between the patient and the film to absorb scatter radiation and reduce film fogging for better image contrast
  • Requires increased radiation

What are exposure factors based on?

  • Equipment used and type of exposure
  • Patient's size and tissue density
  • Manufacturer's recommendations

What are three types of new techonolgy?

Tomography - Simultaneous movement of the x-ray source and the image receptor to image structures within a selected plane of tissue


Computed tomography (CT scan) - Patient lies on a table with head in scanner


x-ray beam rotates 360 degrees around the head


Cone beam computed tomography - Patient seated or standing upright while machine rotates around head

How many exposures does the Cone Beam Computed Tomography expose within the 360 degrees?


What does the computer created from the images?


What are the images for?

  • over 500 individual images
  • image volumes called voxels
  • the software can reassemble into sagittal, coronal and axial images of the patients head

What is the Cone beam computed tomography?


What does it acquire and how?

x-rays taken with a cone-shaped x-ray beam


acquires 3-D information by the source of radiation rotating around the head of the patient

What are the various sizes of Field of view?

Large medium and small

What are the three planes of the body that the CBCT images?

  • Axail plane - Horizontal plane dividing the body into superior and inferior sides
  • Coronal plane- vertical plane running perpendicular to the ground dividing the body into anterior and posterior
  • Sagittal plane- vertical plane running prependicular to the ground dividing the body into right and left sides

What are advantages of the CBCT?

  • Less radiation than CT scan

- 42 mSv for maxilla and 75 mSv for mandible


- pandoramic exposure is 7 mSv


  • Can provide accurate multiple layer images with no superimposed blurring
  • Allows for more accurate diagnosis of bone support for implants and assists in orientation of the implant and placement

What are disadvantages of CBCT digital radiography?

  • Patient movement and artifacts
  • size of the field of view
  • cost of equipment
  • lack of training for interpretation of image on data on areas outside the maxilla and mandible