Lecture 6 panoramic radiograph

Al Azhar University Gaza
Dr. lama khaled El Banna
Faculty of Oral and Dental Medicine

1. Oral Radilogy
Dr. Rawand Samy Mohamed Abu Nahla
Oral Medicine, periodontology& oral Radiology Department.
Dr. Haydar. A. Shafy Faculty Of Dentistry.Dr. Haydar. A. Shafy Faculty Of Dentistry.
El Azhar University.El Azhar University.

2. Lecture 6:
PANORAMIC RADIOGRAPHY

3. Dental Radiography
•Questions
•What equipment is used in panoramic
radiography?
•What is the focal trough?
•What are the advantages and
disadvantages of panoramic radiography?

4. 1-Introduction
•Purpose
•To present basic concepts of panoramic
radiography
•To describe the patient preparation, equipment
preparation, and patient positioning procedures
needed to perform this procedure

5. A-Basic Concepts
•Purpose and Use
•Fundamentals
•Rotation center
•Focal trough
•Equipment
•Basic Concepts

6. Basic Concepts
•Panoramic film
•Shows a wide view of the upper and lower jaws
•Panoramic radiography
•Used to examine the upper and lower jaws on a single
film

7.   A, Panoramic radiograph. B, Panoramic anatomy

8. B-Purpose and Use
•An overall image of the maxilla and mandible
•Often used to supplement bite-wing and selected
periapical films
•Images seen on a panoramic film are not as defined
or sharp as the images seen on intraoral films

9. C-Fundamentals
•In panoramic radiography, the film and x-ray
tubehead move around the patient
•The x-ray tube rotates around the patient’s head in one
direction while the film rotates in the opposite direction
•The patient may stand or sit in a stationary position

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

11. Fundamentals
•The movement of the film and the tubehead
produces an image through the process known as
tomography
•Tomography
•A radiographic technique that allows the imaging of one
layer or section of the body while blurring images from
structures in other planes

12. Rotation Center
•The pivotal point, or axis, around which the cassette
carrier and x-ray tubehead rotate
•There are three basic rotation centers depending on the
manufacturer
•Double-center rotation
•Triple-center rotation
•Moving-center rotation

13. Types of panoramic x-
ray machines. A,
Double-center rotation
machines have two
rotational centers, one
for the right and one for
the left side of the jaws.
B, Triple-center rotation
machines have three
centers of rotation and
create an uninterrupted
radiographic image of
the jaws. C, Moving-
center rotation machines
rotate around a
continuously moving
center that is similar to
the arches, creating an
uninterrupted image of
the jaws

14. Focal Trough
•Can be defined as a three-dimensional curved zone
in which structures are clearly demonstrated on a
panoramic radiograph

15. Example of an “image layer” or “focal trough

16. D-Equipment
•Panoramic x-ray units
•Film
•Intensifying screens
•Cassette

17. 1-Panoramic X-ray Units
•There are a number of different
panoramic x-ray units
•All have similar components
•X-ray tubehead
•Head positioner
•Exposure controls

18. A, Orthophos XG Plus extraoral x-ray machine. B,
Orthoralix 8500 extraoral x-ray machine. C, Example of a
digital panoramic system

19. Main components of the Orthophos XG 5: A, x-ray tubehead;
B, head positioner; C, exposure controls

20. Panoramic X-ray Units
•X-ray Tubehead
•Similar to an intraoral x-ray tubehead
•Collimator
•Differs from the collimator used in the intraoral x-ray
tube head, the collimator used in the panoramic x-ray
machine is a lead plate with an opening in the shape
of a narrow vertical slit

21. Panoramic X-ray Units
•The x-ray beam emerges from the panoramic
tubehead through the collimator as a narrow band
•It passes through the patient and exposes the film
through another vertical slit in the cassette carrier
•The vertical angulation is fixed so that the x-ray beam is
directed slightly upward

22. Head Positioner
•A chin rest, notched bite-block, forehead rest, and
lateral head supports or guides
•Used to align the patient’s teeth as accurately as possible

23. The head positioner (notched bite-block, forehead rest, and
lateral head supports) is used to align the patients teeth in the
focal trough

24. Exposure Controls
•Suggested exposure factors for milliamperage and
kilovoltage are provided by the manufacturer and
can be varied to accommodate patients of different
sizes
•Exposure time is fixed

25.    Exposure controls on the Orthophos XG 5
can be used to adjust exposure factors

26. 2-Film
•Screen film is used in panoramic radiography
•It is sensitive to the light from an intensifying screen
•It is placed between two intensifying screens in a
cassette holder

27. 3-Intensifying Screens
•Calcium tungstate
•Emit blue light
•Rare earth
•Emit green light
•Require less x-ray exposure than calcium tungstate
screens

28. 3-Cassette
•A device used to hold the extraoral film and
intensifying screens
•May be rigid or flexible, curved or straight
•Must be light-tight
•Must be marked to orient the finished radiograph

29. •Film cassettes. A and B, Rigid
cassettes. Intensifying screens
are attached to the inside cover
and base of a rigid cassette.
When the panoramic film is
placed in the cassette, it lies
between the screens. C,
Flexible cassette has an
opening at one end, creating a
pouch. The panoramic film is
placed between two
removable, flexible
intensifying screens, which are
then slid into the pouch

30. This panoramic film is labeled with two metal letters
indicating the patients right (R) and left (L) sides

31. Step-by-Step Procedures
•Equipment Preparation
•Patient Preparation
•Patient Positioning

32. 1-Equipment Preparation
•Load the panoramic cassette in the darkroom under
safelight conditions
•Cover the bite-block with a disposable plastic
coverslip or sterilize between patients
•Set the exposure factors

33. 2-Patient Preparation
•Explain the radiographic procedures
•Place a lead apron without a thyroid collar on the
patient and secure it
•A double-sided lead apron is recommended
•Remove all objects from the head and neck area that
may interfere with film exposure

34. A double-sided lead apron is recommended for use during
exposure of a panoramic film

35. Patient Positioning
•Instruct the patient to sit or stand “as tall as
possible” with the back straight and erect
•Instruct the patient to bite on the plastic bite-block
•Position the midsagittal plane perpendicular to the
floor

36. The patients teeth must be positioned in the grooves
on the bite-block

37. Frankfort and midsagittal planes. The Frankfort plane passes through the
floor of the orbit and the external auditory meatus. The midsagittal plane
divides the body in half into right and left sides

38. The patients Frankfort plane must be positioned
so that it is parallel to the floor

39. Patient Positioning
•Position the Frankfort plane parallel with the floor
•Instruct the patient to position the tongue on the roof
of the mouth and keep the tongue in that position
during exposure of the film
•Instruct the patient to close the lips around the bite-
block
•Instruct the patient to remain still while the machine
is rotating during exposure
•Expose the film and proceed with film processing

40. Common Errors
•Patient Preparation Errors
•Patient Positioning Errors

41. 1-Patient Preparation Errors
•Ghost Images
•Lead Apron Artifact

42. 1-Ghost Images
•A radiographic artifact seen on a panoramic film
that is produced when a radiodense object is
penetrated twice by the x-ray beam
•It is found on the opposite side of the film
•It appears indistinct, larger, and higher than its actual
counterpart

43. Large hoop earrings (1) and ghost images (2). The ghost image
of the earring appears on the opposite side of the film and is
enlarged and laterally distorted

44. Ghost Images
•Problem
•If all metallic or radiodense objects are not removed
before exposure, a ghost image results that obscures
diagnostic information
•Solution
•The dental radiographer must instruct the patient to
remove all radiodense objects in the head and neck
region prior to positioning the patient

45. 2-Lead Apron Artifact
•Problem
•A radiopaque cone-shaped artifact that obscures
diagnostic information results if the lead apron is
incorrectly placed, or if a lead apron with a thyroid collar
is used
•Solution
•The dental radiographer must always use a lead apron
without a thyroid collar when exposing a panoramic film

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

47. 2-Patient Positioning Errors
•Positioning of the lips and tongue
•Positioning of the Frankfort Plane – Upward
•Positioning of the Frankfort Plane – Downward
•Positioning of the Teeth – Anterior to the Focal
Trough
•Positioning of the Teeth – Posterior to the Focal
Trough
•Positioning of the Midsagittal Plane
•Positioning of the Spine

48. 1-Positioning of the Lips and
Tongue
•Problem
•If the patient’s lips are not closed on the bite-block during the
exposure of a panoramic film, a dark radiolucent shadow results that
obscures the anterior teeth
•If the tongue is not in contact with the palate during exposure of a
panoramic film, a dark radiolucent shadow results that obscures the
apices of the maxillary teeth
•Solution
•Instruct the patient to close the lips around the bite-block and swallow
and raise the tongue up to the palate during the exposure of the film

49. 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

50. 3-Positioning of the
Frankfort Plane Upward
•Problem
•If the patient’s chin is positioned too high a “reverse
smile line” is apparent on the radiograph
•Solution
•Position the patient so the Frankfort plane is parallel
with the floor

51. The patients head is incorrectly positioned; the
chin is tipped up

52. A “reverse smile line” is seen on a panoramic film when the
patients chin is tipped up

53. 4-Positioning of the
Frankfort Plane Downward
•Problem
•If the patient’s chin is positioned too low or is tipped
down an “exaggerated smile line” is apparent on the
radiograph
•Solution
•Position the patient so that the Frankfort plane is
parallel with the floor

54. The patients head is incorrectly positioned; the
chin is tipped down

55. An “exaggerated smile line” is seen on a panoramic film when
the patients chin is tipped down

56. 5-Positioning of the Teeth –
Anterior to the Focal Trough
•Problem
•If the patient’s teeth are positioned too far forward on
the bite-block or anterior to the focal trough, the
anterior teeth appear “skinny” and out of focus
•Solution
•Position the patient so that the anterior teeth are placed
in an end-to-end position in the groove on the bite-block

57. The patient is incorrectly positioned; the teeth are too far
forward on the bite-block

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

59. 6-Positioning of the Teeth –
Posterior to the Focal Trough
•Problem
•If the patient’s teeth are positioned too far back on the bite-
block or posterior to the focal trough, the anterior teeth
appear “fat” and out of focus
•Solution
•Position the patient so that the anterior teeth are placed in an
end-to-end position in the groove on the bite-block

60. The patient is incorrectly positioned; the teeth are too far back
and not on the bite-block

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

62. 7-Positioning of the Midsagittal
Plane
•Problem
•If the patient’s head is not centered the ramus and posterior teeth
appear unequally magnified on the panoramic radiograph
•The side farthest from the film appears magnified
•Solution
•Position the patient’s head so that the midsagittal plane is
perpendicular to the floor while the midline is centered on the bite-
block

63. The patient is incorrectly positioned; the head
is not centered

64. The patients posterior teeth and ramus appear to be magnified
on a panoramic film when the head is not centered

65. 8-Positioning of the Spine
•Problem
•If the patient is not standing or sitting with a straight
spine, the cervical spine appears as a radiopacity in the
center of the film and obscures diagnostic information
•Solution
•Instruct the patient to stand or sit “as tall as possible”
with a straight back

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

67. Advantages of Panoramic Radiography
•Field size
•Simplicity
•Patient cooperation
•Minimal exposure

68. Panoramic radiograph of a pediatric
patient

69. Disadvantages of Panoramic
Radiography
•Image quality
•Focal trough limitations
•Distortion
•Equipment cost

70. Thank you