Review: Panoramic Radiography

Author: Boban Fidanoski

  1. Is the panoramic radiography intraoral, extraoral or something else?
    Panoramic radiography is an extraoral radiographic technique that is used to examine maxilla and mandible.

  2. Which parts move and which are stationary when using panoramic technique?
    Both the tube head and the film rotate around the patient who is stationary. X-ray tube goes in one direction, while the film in the opposite.

  3. How do exposure times with panoramic technique compare with those such as periapical radiography using paralleling technique?
    Exposure time in panoramic radiographic units is fixed and cannot be changed, while in intraoral radiography it can be changed.

  4. List three uses for panoramic radiography?
    1. To evaluate impacted teeth
    2. To evaluate eruption patterns, growth and development
    3. To detect diseases, lesions and conditions of jaws

  5. How useful are panoramic radiographs for evaluation of caries?
    Now quite useful. Pan is not recommended for evaluation and diagnosis of caries.

  6. What does the word “tomo” mean?
    Tomo is a Greek word that means section.

  7. What term describes the three dimensional curved zone in which structures are clearly demonstrated on a panoramic radiograph?
    The focal through, also known as the image layer.

  8. How is panoramic tube head collimator different than ordinary intraoral collimator?
    The collimator used in the intraoral x-ray units is lead plate with a small round or rectangular opening in the middle, whereas the collimator used in the panoramic units is lead plate with an opening in the shape of a narrow vertical slit.

  9. Which kind of film is used in panoramic radiography?
    Screen film is used in panoramic radiography. It is available in two sizes: 5x12 inch and 5x12 inch.

  10. Why is a thyroid collar not recommended during panoramic radiography?
    Because it blocks part of the beam and obscures important diagnostic information.

  11. What is the imaginary plane that passes through the top of the ear canal through the bottom of the eye socket called?
    Frankfort plane.

  12. What special instructions are given the patient to be followed during actual exposure using the panoramic unit?
    - To elevate the tongue so it touches the palate and keep the tongue in that position during the exposure.
    - to close the lips around the bite-block

  13. What is a ghost image?
    A ghost image is radiopaque artifact seen on a panoramic film that is produced when a radiodense object is penetrated twice by the x-ray beam.

  14. What causes lead apron artifacts on panoramic images?
    Incorrectly placed lead apron, or lead apron with thyroid collar.

  15. What radiograph effect occurs when the patient’s chin is tipped up during panoramic radiography?
    - reverse smile line
    - hard palate is superimposed over the maxillary roots
    - maxillary incisors appear blurred and magnified

  16. What causes an “exaggerated smile” on panoramic radiographs?
    Positioning of Frankfort plane downward (chin tipped down).

  17. List some advantages of using panoramic radiography technique?
    1. Field size
    2. Simplicity
    3. Patient cooperation
    4. Minimal exposure

  18. List some disadvantages of using panoramic radiography technique?
    1. Image quality
    2. Focal trough limitations
    3. Distortion
    4. Equipment cost.




author: Boban Fidanoski

© February, 2007 Copyright - Text
by B.Fidanoski- Port Credit, ON - Canada