OPG Errors Flashcards
Ghost images
How do they appear & how to correct?
Appearance on Image
- Ghost image resembles real images
- Projected on opposite side of film and is higher
- More blurry + more magnified
Correction
- Have patient remove all radiodense objects before exposure
Lead apron artefact
How does this appear & how to correct?
Appearance on Image
Radiopaque cone-shaped artefact in centre of image
Correction
Use lead apron without thyroid collar
Patient lips not closed
How does this appear & how to correct?
Appearance on Image
Dark radiolucent shadow around anterior teeth
Correction
Remind patient to close lips around bite block
Patient chin too high
How does this appear & how to correct?
Appearance on Image
Condyles may not be visible
Maxillary incisors appear blurred and magnified
Reverse smile line (frown) or flat occlusal plane
Correction
Keep Frankfort plane parallel with floor
Patient chin to low
How does this appear & how to correct?
Appearance on Image
Exaggerated smile line (joker)
Condyles a higher on image
Mandibular incisors appear blurred, roots appear short
Correction
Keep Frankfort plane parallel with floor
Patient too far forward (in front of focal trough)
How does this appear & how to correct?
Appearance on Image
Anterior teeth appear narrow
Spine is visible on film
Correction
Make sure patients teeth are in bite block notches& focal trough line is at the tip of the Mx canines
Patient too far back (posterior to focal trough)
How does this appear & how to correct?
Appearance on Image
Anterior teeth appear magnified
Ramus isn’t entirely visible
Correction
Make sure patients teeth are in bite block notches & focal trough line is at the tip of the mx canines
Patient head not centred (head rotation to right/left)
How does this appear & how to correct?
Appearance on Image
Ramus and posterior teeth appear unequally magnified
Side furthest from receptor appears magnified
Side closest to receptor appears smaller
Example: patient turned to right will produce image with magnification on right side and overlapping of contacts
Correction
Keep midsagittal plane perpendicular to floor & ensure indicating light is located at centre of patients nose
Head tilt
How does this appear & how to correct?
Appearance on Image
Asymmetry of the face on OPG
E.g. head tile to the right - the right side of the face is more inferiorly positioned than the LHS
Correction
Ensure the patients midline & the Frankfort plane are perpendicular to each other
Tongue not touching the palate
How does this appear & how to correct?
Appearance on Image
Glossopalatal airspace is superimposed over the maxillary tooth roots
Correction
Make sure the patients tongue is touching the palate during the scan (without swallowing)
Patient spine isn’t straight / neck extension
How does this appear & how to correct?
_Appearance on Image_ Cervical spine (ghost image) appears as linear radiopacity in centre of image
Correction
Have patient stand as tall as possible
Seat patient if necessary
Swallowing
How does this appear & how to correct?
Appearance on Image
Soft palate is lifted to the nasopharynx (blocking the airway) + hyoid bone is lifted
Correction
Make sure the patient does not swallow during the scan
