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) 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 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
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 6.

Image of incorrect patient positioning, because the midsagittal plane is not centered along the midline of the face.
Example of incorrect patient positioning, because the midsagittal plane is not centered along the midline of the face.

Figure 7. Incorrect positioning.

Image of incorrect positioning.
The patient is positioned too far forward, because the canine indicator light is posterior to the canine.

Figure 8. Patient Positioning.

Image of patient positioning.

As mentioned previously, the most common error is the failure to position the tongue directly against the hard palate.2,5,10 As is noted in Figure 8, 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 8 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

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. Thankfully, 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