panoramic-techique errors


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panoramic-techique errors

  1. 1. Panoramic Technique ErrorsThe following slides identify common panoramictechnique errors.
  2. 2. Teeth Too AnteriorIf the teeth are positioned in front of the notches in thebitestick (see diagram below left), the anterior teethwill appear narrower and will be blurred (less sharpthan normal). If the teeth are in front of the notches,they are closer to the film, resulting in lessmagnification horizontally (narrowing). Being out ofthe focal trough makes the images less sharp.
  3. 3. Teeth Too AnteriorThis film shows the blurring and narrowing ofthe anterior teeth. R L
  4. 4. Teeth Too AnteriorR LR L
  5. 5. Teeth Too PosteriorIf the teeth are positioned behind the notches in thebitestick (see diagram below left), the anterior teethwill appear wider and will be blurred (less sharp thannormal). If the teeth are behind the notches, they arefarther from the film, resulting in more magnificationhorizontally (widening). Being out of the focal troughmakes the images less sharp.
  6. 6. Teeth Too PosteriorR L
  7. 7. Teeth Too PosteriorR L
  8. 8. Head TurnedIf the head is turned slightly to the side (notcentered on the bitestick), the structures onone side will be closer to the film and thestructures on the other side will be fartherfrom the film. In the diagram below, the headwas turned to the right and the teeth arecloser to the film on that side.
  9. 9. Head TurnedThe teeth are smaller on the side to which thehead is turned. (When the teeth are closer to thefilm, there is less magnification horizontally).The teeth that are farther from the film are widerbecause there is increased magnificationhorizontally.
  10. 10. Head TurnedIn this patient, the molars on the patient’s right sideare noticeably wider than the molars on thepatient’s left. Which way was the head turned?To the left. Left side closer to film, less magnification. R L
  11. 11. Head TurnedOn this film, not only are the teeth wider on one side,but the ramus is also wider on that side. (The blackarrows are the same length on both sides). Which sidewas farthest from the film? The patient’s right side; farther from the film, more magnification. R L
  12. 12. Head TurnedIn this film, the patient’s head was turned to theright, resulting in a widening of the teeth andramus on the patient’s left side. R
  13. 13. Head Tipped DownIf the head is positioned so that the Frankfort Planeis inclined downward (see diagram below left), themandibular incisors will appear shortened and themandible will be V-shaped (Exaggerated smile).
  14. 14. Head Tipped DownNotice how short the mandibular incisors appear.The rest of the teeth are relatively normal. R L
  15. 15. Head Tipped DownAgain we see shortened mandibular incisors, V-shaped mandible. R
  16. 16. Head Tipped UpIf the Frankfort Plane is angled upward, the mandiblewill be “squared-off” (angle of the mandibleapproximately 90 degrees) and the hard palate will besuperimposed over the roots of the maxillary teeth.May have the appearance of a “reverse” smile.
  17. 17. Head Tipped UpIn the film below, the hard palate (red arrows) iscovering the roots of the maxillary teeth. Notethe reverse smile. R L
  18. 18. Head Tipped UpThis film shows the reverse smile and it isdifficult to see the root areas of the maxillaryteeth.
  19. 19. Lead ApronIf the lead apron is improperly positioned so that itis located high on the back of the patient’s neck, itmay block part of the beam and result in a clear(appears white on the viewbox) area on the film. Lead apron shadow
  20. 20. Lead ApronThe two completely radiopaque areas on the filmbelow were caused by the lead apron. You can’tsee any anatomy in these areas due to completeblockage of the x-ray beam by the apron. R L
  21. 21. Lead ApronThe film below shows an extensive white areacaused by the lead apron. Note the black dots(arrows) that represent the stitching on theapron. The thyroid collar should never be usedfor panoramic radiography since it wouldroutinely cause this same problem. R L
  22. 22. Cervical Vertebrae (Spine)If the patient is not standing straight, the cervicalvertebrae may block the x-ray beam as the tubeheadtravels behind the patient at an upward angle. Thisresults in a radiopaque area that extends up throughthe middle of the film (arrows below). The teeth/boneare faintly visible in the radiopaque area (notcompletely blocked out as with the lead apron).
  23. 23. Cervical Vertebrae (Spine)This film shows the radiopaque “shadow” caused bythe cervical vertebrae in a patient that is not standingstraight. Note that the edges of this radiopaque areaare not as sharp as those produced by the lead apron;here the radiopacity blends in with the surroundingbone.
  24. 24. Palatoglossal Air SpaceThe Palatoglossal Air Space (black area below) iscaused by failure to keep the tongue against the palateduring exposure. This makes it difficult to diagnoseperiapical pathology, which also is dark, in the maxillaryarea. Many patients have difficulty complying with theinstructions to keep the tongue against the palateduring exposure and this space is often seen. As longas you instruct the patient, this would not be consideredan error.
  25. 25. Palatoglossal Air Space The arrows in the film below identify the palatoglossal air space.R
  26. 26. Static ElectricityStatic electricity appears as black lines or dots onthe film, often having a tree-branch appearance. It iscaused by removing the film from the box orcassette too quickly, creating static discharge.
  27. 27. Static ElectricityThis film shows two major errors, one of which is theinteresting aliigator-like static electricity at the top ofthe film. The small black circles at the bottom of thefilm are also caused by static. What is the other errorseen on this film?The film is extremely underexposed. This wasprobably caused by placing the film outside theintensifying screens (not between them) in a flexiblecassette. R L
  28. 28. Failure to Remove AppliancesAs part of patient preparation, appliances should beremoved from the mouth. In this patient, the completeupper denture was left in the mouth. This would notrequire a retake, since the acrylic of the denture baseallows x-rays to pass through and the bone is clearlyvisible. R L
  29. 29. Failure to Remove AppliancesIn this patient, both upper and lower removable partialdentures were left in the mouth. In this case the metalframeworks obscure large areas of the teeth and thefilm should be retaken. R L
  30. 30. Failure to Remove Tongue RingAnything removable in the mouth should be taken outbefore exposing a panoramic film. In this patient, atongue “ring” was left in place and blocks a couple ofteeth. Does the tongue ring need to be removed forperiapical films?No. The tongue ring would be behind the film and wouldnot cause a problem, assuming normal film placement. R L
  31. 31. GlassesGlasses should routinely be removed for panoramicexposures. The bottom part of the frame/lenses mayobscure the periapical area of the maxillary anteriorteeth. What other error is evident on this film?The head is tipped up too much. Notice the reversesmile and the proximity of the hard palate to the rootsof the maxillary teeth. R L
  32. 32. Patient MovementIt is important for the patient to remain still duringa panoramic exposure. This film shows excessivepatient movement (unknown cause) and must beretaken. R L
  33. 33. Patient MovementThis film shows much more subtle movement(arrow), resulting in an uneven inferior border ofthe mandible. This might be misinterpreted asbeing the result of a fracture. R
  34. 34. Double ExposureIt is preferable to process films immediately afterexposure. If cassettes are laid aside for laterprocessing, the operator may inadvertently pick up acassette that has already been exposed and use itagain. This results in a double exposure as seen below.What other error is evident on this film? Static electricity at the bottom of the film. R
  35. 35. Incorrect Exposure SettingsIf incorrect exposure factors are selected for apatient (kVp, mA), a film that is too light(underexposed) or too dark (over-exposed) mayresult. The film would normally be retaken. overexposure underexposure