Panoramic Radiographs: Technique & Anatomy Review
Course Number: 533
Course Contents
Causes and Appearance of Errors in Technique
It is important for the clinician to be able to understand errors when they occur and how to correct them. Table 5 lists various errors that can occur with panoramic imaging. It also addresses the radiographic appearance of the errors and solutions for correcting the problem.
Table 5. Patient Positioning Errors.1
| # | Error | Appearance on Image | Correction |
|---|---|---|---|
| 1 | Ghost images |
Ghost image resembles real image Projected on opposite side of film and is higher | Have patient remove all radiodense objects before exposure |
| 2 | Lead apron artifact | Radiopaque, cone-shaped artifact in center of image | Use lead apron without thyroid collar |
| 3 | Patient lips not closed | Dark radiolucent shadow around anterior teeth | Remind patient to close lips around bite block |
| 4 | Patient chin too high |
Condyles may not be visible Maxillary incisors appear blurred and magnified Reverse smile line (frown) | Keep Frankfort plane parallel with floor |
| 5 | Patient chin too low |
Exaggerated smile line (Joker) Condyles higher on image Mandibular incisors appear blurred; roots appear short | Keep Frankfort plane parallel with floor |
| 6 | Patient too far forward (anterior to focal trough) (Figure 9) |
Anterior teeth are narrowed Spine is visible on film | Make sure patient’s teeth are in bite block notches |
| 7 | Patient too far back (posterior to focal trough) |
Anterior teeth appear magnified Ramus isn’t entirely visible | Make sure patient’s teeth are in bite block notches |
| 8 | Patient head not centered (Figure 10) |
Ramus and posterior teeth appear unequally magnified Side farthest from receptor appears magnified Side closest to receptor appears smaller Example: Patient turned to right will produce image with magnification on left side and overlapping of contacts | Keep midsagittal plane perpendicular to floor & ensure indicating light is located at center of patient’s nose (between the maxillary central incisors) |
| 9 | Patient spine isn’t straight | Cervical spine appears as radiopacity in center of image | Have patient stand as tall as possible. Seat patient if necessary |
Figure 9. Incorrect positioning.
The patient is positioned too far forward, because the canine indicator light is posterior to the canine.
Figure 10. Incorrect positioning.
The patient's midsagittal plane is not centered along the midline of the face. The indicator light is over tooth #9, rather than between the maxillary central incisors.
As mentioned previously, the most common error is the failure to position the tongue directly against the hard palate.2,5,10 In Figure 11, the maxillary roots of the anterior teeth are not visible, due to the fact that the tongue was not flat against the hard palate. The radiolucent area between the dorsum of the tongue and the hard palate is the palatoglossal air space, which is more pronounced.
Another error that is visible in Figure 11 is that the chin position is too low causing the spine to be more pronounced on the image. In addition, the mandibular incisors appear blurry with short roots.1,10
Figure 11. Patient Positioning.
Figure 11. Patient Positioning.
Image source: Dr. Iwata
Most patients are able to tolerate the panoramic procedure with ease. However, certain patients will have challenges with the imaging process due to difficulty maintaining the proper position. For example, elderly patients may be unable to stand for the duration of the image, but some panoramic imaging units allow for the patient to sit. 11 If the patient is seated during the procedure, they must be reminded to sit as upright as possible in order to prevent slumping, which can cause superimposition of the spine over the anterior teeth. 5