7: Panoramic Radiography: Errors Seen in Radiographs

Chapter 7 Panoramic Radiography: Errors Seen in Radiographs

Learning Objectives

1. Identify errors in taking the panoramic radiograph
2. Know how to correct errors in taking the panoramic radiograph
3. Identify film handling and processing errors
4. Know how to correct film handling and processing errors
5. Recognize multiple errors in the same radiograph

Goal

To know how to recognize and correct errors seen in panoramic radiographs

BASIC CONCEPTS

The panoramic errors are viewed by students to be more difficult to learn than the intraoral ones. So we will limit the questions to one type of error at a time. Also to help, a preliminary explanation is provided as background information to help identify the errors. The panoramic technique is much easier to learn than the intraoral technique, and it is much less trouble with regard to clean up and infection control. However, patient positioning must be very exact, because noticeable errors develop with very small mistakes.

THE NORMAL PANORAMIC RADIOGRAPH

Mind’s Eye View of the Panoramic Radiograph (Diagram 7-1)

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DIAGRAM 7-1

Notice the panoramic image is divided into 9 areas that make up the 6 zones that you must learn to picture each panoramic radiograph or image in your mind’s eye. These zones are as follows:

Zone 1: The dentition. Here the occlusal plane should be mildly curved upward to make a smile-like line. The roots of the anterior teeth are in the image, and the posterior teeth are the same size on each side with no more overlapping of the contacts on one side than the other.
Zone 2: The nose-sinus. The turbinates should remain in the nose, and the hard palate shadows should cross the sinus above the apices of the posterior maxillary teeth.
Zone 3: The mandible. Here the inferior cortex should be a smooth curve and the hyoid bone and ghost image of the spine should not be superimposed.
Zone 4: The TMJs. This is a bilateral zone. Both condyles should be in about the center of the zone. Neither condyle should be higher or bigger than the other. The condyles should not go off the top or sides of the image.
Zone 5: The spine-ramus. In many panoramic machines the double real images of the spine are not seen at the edges. If they are seen, the spine should not be superimposed on the ramus and should be at an equal distance from the ramus on both sides. The spine images should be vertical and not sloped. The ramus should be the same width on each side with no ghost images of the ramus on either side.
Zone 6: The hyoid. Here the double real images of body and greater horn(s) of the hyoid can be seen on both sides. They should be the mirror image of each other with neither of them bigger, higher, or more spread out than the other. The hyoid should not be spread out across the mandible. The distance from the body of the hyoid to the mandible should be equal on both sides.

Normal Panoramic Image (Diagram 7-2) Notice that structures have been left out. This is to emphasize that not many structures need to be identified to properly troubleshoot the image for technique errors. In this diagram, the nose and sinus as well as the maxilla are left out because nothing goes wrong here in the perfect image. There is no distinct image of the lips, nose, or ears, nor is there any undesirable air. The teeth, mandible body, ramus, TMJs, and spine are nicely imaged as just described.

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DIAGRAM 7-2

STEPS IN TAKING A PANORAMIC RADIOGRAPH

Step 1

Assess the patient:

Remove extraoral and intraoral items.

Load cassette into machine.

Adjust machine settings:

kVp

Step 1 Errors

Items left in or on the patient

Cassette problems

Improper kVp setting selected:

Image too dark
Image too light

Step 2

Bite in the groove in the bite-block.

Check canine positioning light: should be aligned in middle of lower canine (varies a little with different machines).

Step 2 Errors

Patient positioned too far forward (Diagram 7-3)

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DIAGRAM 7-3

Patient positioned too far back (Diagram 7-4)

image

DIAGRAM 7-4

Step 3

Position chin on chin rest, and adjust height of chin rest.

Make sure patient is standing upright with neck and back straight.

Tilt chin downward about 5 degrees.

Check Frankfort plane (ala of nose to tragus of ear) positioning light.

Check canine light to ensure it is still okay.

Step 3 Errors

Chin not on chin rest (Diagram 7-5)

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DIAGRAM 7-5

Patient slumped or stooped (Diagram 7-6)

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DIAGRAM 7-6

Chin tipped too low (Diagram 7-7)

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DIAGRAM 7-7

Chin tipped too high (Diagram 7-8)

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DIAGRAM 7-8

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Related posts:

  1. 9: Radiation Health
  2. 2: Materials and Foreign Objects
  3. 8: Panoramic Digital Imaging
  4. 1: Normal Anatomy
  5. 13: Radiographic Assessment and Interpretation
  6. 6: Panoramic Radiography: Clinical Technique

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Jan 12, 2015 | Posted by in Oral and Maxillofacial Radiology | Comments Off on 7: Panoramic Radiography: Errors Seen in Radiographs

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