This document provides information about panoramic radiography (OPG). It discusses the components and operation of panoramic units, patient positioning, common errors, and limitations. The key points are: - Panoramic radiography shows the entire dentition and related structures on a single film by rotating the x-ray tube and film around the patient. - Proper patient positioning within the focal trough is important for image quality, with errors including the chin being too high or low or the head being twisted. - Common errors involve patient preparation like ghost images from jewelry or lead apron placement, as well as positioning errors where the teeth are outside the focal trough. - Panoramic radiography

1. Panoramic Radiography
OPG = ( Orthopantomagraphy ) ‫د‬. ‫ضيف‬
‫طالب‬
‫عناد‬

2. Introduction
▪ Extraoral radiographs (outside the mouth) are taken when large
areas of the skull or jaw must be examined or when patients are
unable to open their mouths for film placement .
▪ Extraoral radiographs do not show the details as well as intraoral
films.
▪ Extraoral radiographs are very useful for evaluating large areas of
the skull and jaws but are not adequate for detection of subtle
changes such as the early stages of dental caries or periodontal
disease.
▪ There are many type of extraoral radiographs. Some types are used
to view the entire skull, whereas other types focus on the maxilla
and mandible.

3. Panoramic Radiography
▪ Panoramic radiographs show the entire dentition and related
structures on a single film.
▪ Some types of panoramic units operate with the patient in a seated
position, and other types require the patient to be in a standing
position.
▪ Regardless of the type of machine, you must follow the
manufacturer’s instructions carefully.
▪ Because the images on a panoramic film are not as clear or as well
defined as the images on intraoral films, bite-wing films are used to
supplement a panoramic film to detect dental caries or periapical
lesions.

4. Indications
The main indication for panoramic radiography is attaining a larger field size
Than is possible with periapical and bitewing radiography. Clinical situations
In which a panoramic unit is useful and helpful include :
▪ Detecting large areas Of pathologic conditions .
▪ Disualizing impacted teeth .
▪ Jaw fractures .
▪ Patients Who cannot or will not open their mouths .
▪ Evaluating tooth development And eruption patterns .
▪ TMJ problems; foreign bodies; and implant evaluation .

5. Advantages
▪ Size of the Field
▪ Quality Control
▪ Simplicity
▪ Patient Cooperation
▪ Time
▪ Dose

6. Disadvantages
▪ Image Quality
▪ Focal Trough (Image Layer)
▪ Overlap
▪ Superimposition
▪ Distortion
▪ Overuse
▪ Cost

7. Basic Concepts
▪ In panoramic radiography the film and tubehead rotate
around the patient, and it produces a series of individual
images .
▪ The term panorama means “an unobstructed view of a
region in any direction.” When the series of images are
combined onto a single film, an overall view (panorama)
of the maxilla and mandible is created .

8. The film and x-ray tubehead move around the patient
in opposite directions in panoramic radiography.

9. Focal Trough
▪ An imaginary, three-dimensional curved area that is
horseshoe shaped.
▪ This is a very important concept because many
technique errors are caused by improper positioning of
the patient’s jaws within the focal trough.
▪ When the jaws are positioned within this area, the
radiograph will be clear.
▪ When the jaws are positioned outside of this area, the
images on the radiograph will appear blurred or
indistinct.

10. An example of an image layer, or “ focal trough ”

11. An example of an image layer, or “ focal trough ”

12. Components of the Panoramic Unit
▪ Panoramic x-ray tubehead
▪ Head positioner
▪ Exposure controls

13. Components of the Panoramic Unit
▪ Panoramic x-ray tubehead
▪ Head positioner
▪ Exposure controls

14. Components of the Panoramic Unit
▪ Panoramic x-ray tubehead
▪ Head positioner
▪ Exposure controls

15. The main components of a panoramic unit .

16. The Head Positioner
▪ Each panoramic unit has a head positioner used
to align the patient’s teeth as accurately as
possible.
▪ Each head positioner consists of a chin rest,
notched bite-block, forehead rest, and lateral
head supports or guides.
▪ Each panoramic unit is different, and the
operator must follow the manufacturer’s
instructions on how to position the patient in
the focal trough.

17. The head positioner is used to align the patient’s teeth in the focal trough.

18. Exposure controls or Control panel

19. Cassette with Film

20. Steps in Taking a Panoramic image
▪ Unit (equipment) Preparation
▪ Patient Preparation
▪ Patient Positioning
▪ Pre-exposure Instructions
▪ Exposure and patient dismissal

21. Unit ( equipment ) preparation
▪ The cassette containing the phosphor plate or film should be inserted into
carriage assembly (if appropriate).
▪ The exposure control panel should be covered in cling film
▪ The operator should put on suitable protective gloves (e.g.latex or nitrile)
▪ The collimation should be set to the size of field required.
▪ The appropriate exposure factors should be selected according to the size
of the patient – typically in the range of 70–90 kV and 4–12 mA.

22. Unit (equipment) preparation
▪ Set the program mode on the panoramic unit
▪ Set the exposure – For most panoramic units, patient exposure
is adjusted by alteration of the kilovoltage (kVp) and
milliamperage (mA).
▪ Assemble and insert bite block
▪ Position machine slightly higher than patient’s chin
▪ Have the patient shuffle forward

23. Patient preparation
▪ Patients should be asked to remove any earrings, jewellery, hair
pins, spectacles and dentures or orthodontic appliances.
▪ The procedure and equipment movements should be explained,
to reassure patients and if necessary a test exposure should be
used to show them the machine’s movements.
▪ Place the lead apron on the patient .
▪ Do not use a THYROID COLLAR . The use of a thyroid collar
or improper lead apron placement will block the x-ray beam and
prevent imaging of structures at or near the midline.

24. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

25. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

26. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

27. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

28. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

29. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

30. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

31. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

32. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

33. Patient positioning
▪ Midsagittal plane
▪ Frankfort Plane
▪ Anteroposterior Plane
▪ Bite block position:
▪ Chin position:
▪ Head position:
▪ Patient stabilization:
▪ Tongue position
▪ Posture:

34. Pre-exposure Instructions
Directly before exposure ask the patient to:
▪ Swallow
▪ Close the mouth
▪ Put the tongue against the hard palate
▪ Breath normally during the exposure
▪ Not move for the duration of the exposure

35. Ideal or Optimal Radiographic Image

36. Ideal or Optimal Radiographic Image

37. Panoramic Errors
▪ Equipment or machine preparation errors
▪ Patient preparation errors
▪ Patient positioning errors

38. Common Errors
▪ Patient preparation errors
– Ghost images: A ghost image looks like the real object
except that it appears on the opposite side of the film.
– Lead apron artifact: If the lead apron is placed too
high, or if a lead apron with a thyroid collar is used, a
cone-shaped radiopaque artifact results.
▪ Patient seating errors
– Chin too high
– Chin too low
– Head Twisting , Rotated or Turned .
– Head Tilting or Canted .

39. Large hoop earrings (A) and ghost images (B). The ghost image of
the earring appears on the opposite side of the film .

40. On a panoramic radiograph, a lead apron artifact appears as
a large cone-shaped radiopacity obscuring the mandible .

41. Examples of thyroid collar artifact

42. The patient’s head is tipped too far upward.

43. The patient’s head is incorrectly positioned; the chin is tipped downward.

44. Positioning of the Teeth
▪ Posterior to focal trough
– If the patient’s anterior teeth are not positioned in
the groove on the bite-block and are either too far
back on the bite-block or posterior to the focal
trough, the anterior teeth appear “fat” and out of
focus on the radiograph.
▪ Anterior to focal trough
– If the patient’s anterior teeth are not positioned in
the groove on the bite-block and are either too far
forward or anterior to the focal trough, the teeth will
appear “skinny” and out of focus.

45. The patient is biting too far back on the bite-block.

46. The anterior teeth appear widened and blurred on a panoramic film when the
patient is positioned too far back on the bite-block.

47. The anterior teeth appear narrowed and blurred on a panoramic film when the
patient is positioned too far forward on the bite-block.

48. If the tongue is not placed on the roof of the mouth, a radiolucent shadow will be
superimposed over the apices of the maxillary teeth.

49. Positioning of the Spine
▪ If the patient’s spine is not straight, the cervical
spine will appear as a radiopaque artifact in the
center of the film and obscure diagnostic
information .

50. If the patient is not standing erect, superimposition of the cervical spine
(arrows) may be seen on the center of the panoramic film.

52. Limitations and Difficulties in OPG
▪ Errors and artefacts may occur at every stage of taking a panoramic radiograph .
▪ Panoramic radiography cannot be taken in neonates, unconscious patients and
individuals who cannot maintain erect position of cervical spine even when sitting .
▪ Lack of cooperation in a child. Although sometimes age limitations for panoramic
radiography are set by legal provisions (e.g. 5 years), in many countries there is no strict
age limit ٫depends on ability to follow the instructions of staff and then to maintain
motionless position during the exposure .
▪ Involuntary movements (tics, jerks, myoclonic seizures, tremors) may result in inferior-
quality radiographs or giving up the exposure altogether . It is advocated to examine
patients with diseases such as Parkinson’s disease in panoramic machines allowing
compensation for smaller movements.

53. Limitations and Difficulties in OPG
▪ In patients with advanced Class II or Class III malocclusion it may be impossible to
place upper and lower incisors in groove on bite piece.
▪ Large facial skeleton asymmetry makes positioning of right and left side of the face
within the focal trough challenging. The resultant radiograph will present one side more
clearly than the other.
▪ Advanced periodontal bone disease with tooth mobility affects patient ability to bite the
groove on the bite piece as during closing the mouth mobile teeth tend to tilt. In such
case using a chin support for edentulous patients and separating upper and lower
incisors with a cotton roll may be considered.
▪ Some patients following trauma presenting with swelling, lockjaw and/or injuries of lips
or tongue may require use of chin support for edentulous patients, too, supplemented
with a cotton roll.
▪ Taking a panoramic in a mentally disabled patient or a senile one with dementia can be
very challenging, too, and sometimes impossible.

54. Than you