This document provides an overview of panoramic radiography. It defines panoramic radiography as a body section imaging technique that results in a wide, curved image layer depicting the maxillary and mandibular dental arches and their supporting structures. The document discusses the principles, indications, disadvantages, centers of rotation, focal troughs, images, patient positioning, zones, receptors, cassettes, films, and interpretation of panoramic radiographs. The overall document serves as a comprehensive guide to panoramic radiography.

1. PANORAMIC
RADIOGRAPHY
Submitted by
Sooraj Suresh
Part 1

2. • CONTENTS
1. INTRODUCTION
2. DEFINITION
3. INDICATIONS
4. DISADVANTAGES
5. PRINCIPLES OF PANORAMIC RADIOGRAPHY
6. CENTRE OF ROTATION OF PANORAMIC RADIOGRAPHY
7. FOCAL TROUGH
8. IMAGES IN PANORAMIC RADIOGRAPHY
9. PATIENT POSITIONING IN PANORAMIC RADIOGRAPHY
10. CONCEPTS IN PANORAMIC RADIOGRAPHY
11. ZONES IN PANORAMIC RADIOGRAPHY
12. IMAGE RECEPTOR IN PANORAMIC RADIOGRAPHY
13. CASSETTES IN PANORAMIC RADIOGRAPHY
14. PANORAMIC SCREENS
15. INTENSIFYING SCREENS
16. INTERPRETATION IN PANORAMIC RADIOGRAPHY
17. REFERENCE

3. • INTRODUCTION
Panoramic images are most useful clinically for diagnostic
challenges requiring broad coverage of the jaws.
Panoramic imaging is often used in initial patient evaluation
that can provide the required insight or assist in determining
the need for other projections.
Common clinical applications include evaluation of trauma
including jaw fractures, location of third molars, extensive
dental or osseous disease, known or suspected large lesions,
tooth development and eruption (especially in the mixed
dentition), impacted or unerupted teeth and root remnants
(in edentulous patients), temporomandibular joint (TMJ)
pain, and developmental anomalies

4. • DEFINITION
 Panoramic radiography (also called pantomography) is a body
section imaging technique that results in a wide, curved image
layer depicting the maxillary and mandibular dental arches and
their supporting structures.

5. • INDICATIONS
 Overall evaluation of dentition.
 Examine for intraosseous pathology, such as cysts, tumors, or infections.
 Gross evaluation of temporomandibular joints.
 Evaluation of position of impacted teeth.
 Evaluation of eruption of permanent dentition.
 Dentomaxillofacial trauma.
 Developmental disturbances of maxillofacial skeleton.

6. • DISADVANTAGES
 Lower-resolution images that do not provide the fine details provided by
intraoral radiographs
 Magnification across image is unequal, making linear measurements
unreliable
 Image is superimposition of real, double, and ghost images and requires
careful visualization to decipher anatomic and pathologic details
 Requires accurate patient positioning to avoid positioning errors and artifacts
 Difficult to image both jaws when patient has severe maxillomandibular
discrepancy

7. • PRINCIPLE OF PANORAMIC RADIOGRAPHY
 The principles of panoramic radiography were first described by
Paatero and Numata independently in 1948 and 1933, respectively.
 Assembly containing a disk with upright physical objects (represented
by letters) and an image receptor.

8.  The receptor travels upward through the beam at the same speed as objects A
through C rotate through the beam.
 A lead collimator in the shape of a slit located at the x-ray source limits the
x-rays to a narrow vertical beam.
 Another collimator between the objects and the image receptor reduces
scattered radiation from the objects to the image receptor.
 Consider first radiopaque objects A through C. As the disk rotates, their
radiographic images are recorded sharply on the receptor that also moves
through the beam at the same direction and speed.
 The source-receptor distance is constant and the object-receptor distance is
the same for each object, all objects are magnified equally. Now consider
objects D through F.
 They are located on the opposite side of the disk, between the x-ray source
and the center of rotation of the disk. These objects move in the opposite
direction of the receptor, so their shadows are reversed on the receptor.
 Because these objects are much closer to the x-ray source, their images are
greatly magnified.

9.  The fig shows that the same relationship between the rotating receptor and
objects can be achieved if the disk is held stationary but the x-ray source and
the receptor are rotated around the center of rotation in the disk.
 The x-ray beam still passes through the center of the disk and sequentially
through objects A through C. Similarly, the receptor is still moved through the
beam and at the same rate as the beam passes through A through C. In this
situation, as before, objects A through C move through the x-ray beam in the
same direction and at the same rate as the receptor.

10.  The illustration demonstrates the positions of the x-ray source and the
receptor early in an exposure cycle.
 The center of rotation is located off to the side of the arch, away from the
objects being imaged.
 The rate of movement of the receptor is regulated to be the same as that of
the x-ray beam sweeping through the dentoalveolar structures on the side of
the patient nearest the receptor.
 Structures on the opposite side of the patient (near the x-ray tube) are
distorted and appear out of focus because the x-ray beam sweeps through
them in the direction opposite that in which the image receptor is moving.

11.  In addition, structures near the x-ray source are so magnified (and their
borders so blurred) that they are not seen as discrete images on the resultant
image. These structures appear only as diffuse phantom or ghost images.
Because of both of these circumstances, only structures near the receptor are
usefully captured on the resultant image.

12. • CENTER OF ROTATION OF PANORAMIC
RADIOGRAPHY
 Contemporary panoramic machines use a continuously moving center of
rotation rather than multiple fixed locations.
 This feature optimizes the shape of the focal trough to image best the teeth
and supporting bone.
 This center of rotation is initially near the lingual surface of the right body of
the mandible when the left TMJ region is being imaged.
 The rotational center moves anteriorly along an arc that ends just lingual to
the symphysis of the mandible when the midline is imaged.

13.  The arc is reversed as the opposite side of the jaws is imaged.

14. • FOCAL TROUGH
 The focal trough or image layer is a wide, three-
dimensional curved zone, where the structures
positioned within this zone are reasonably well
defined on the panoramic image.
 The anatomic structures seen on a panoramic image
are primarily those positioned within the focal
trough during imaging.
 Structures positioned in the center of the focal
trough are the clearest and those that are
progressively farther from the center of the focal
trough become progressively less clear.
 Objects outside the focal trough are blurred,
magnified, or reduced in size and are sometimes
distorted to the extent of not being recognizable.

15. • IMAGES IN PANORAMIC RADIOGRAPHY
 REAL IMAGE
 Objects that lie between the
center of rotation and the receptor
form a real image.
 Within this zone, objects that lie
within the focal trough cast
relatively sharp images, whereas
images of objects located outside
the focal trough are blurred.

16.  DOUBLE IMAGE
 Objects that lie posterior to the
center of rotation and that are
intercepted twice by the x-ray beam
form double images.
 This region includes the hyoid bone,
epiglottis, and cervical spine, all of
which cast images on both the right
and left side of the image.

17.  GHOST IMAGE
 Some objects are located between the x-
ray source and the center of rotation.
These objects cast ghost images.
 On the panoramic image, ghost images
appear on the opposite side of its true
anatomic location and at a higher level
because of the upward inclination of the
x-ray beam.
 As the object is located outside of the focal
plane and close to the xray source, the
ghost image is blurred and significantly
magnified.

18. • PATIENT POSITION AND HEAD ALIGNMENT
 Proper patient preparation and positioning within the focal
trough are essential to obtaining diagnostic panoramic
radiographs.
 The anteroposterior head position is achieved typically by
having patients place the incisal edges of their maxillary and
mandibular incisors into a notched positioning device (bite-
stick).
 Patient's midsagittal plane must be centered within the focal
trough without any lateral shift in the mandible when making
this protrusive movement.
 Most panoramic units have laser beams to facilitate alignment
of the patient's midsagittal plane, Frankfort plane, and
anteroposterior position within the focal trough.
 Tongue must be positioned on roof of mouth.

19.  Placement of the patient either too far anterior or too far
posterior relative to the focal trough results in significant
dimensional aberrations in the images.
 Too far posterior positioning results in magnified mesiodistal
dimensions (“fat” teeth) through the anterior sextants .
 Too far anterior positioning results in reduced mesiodistal
dimensions (“thin” teeth) through the anterior sextants.
 Poor midline positioning is a common error, causing
horizontal distortion in the posterior regions; excessive tooth
overlap in the premolar regions; and occasionally,
nondiagnostic, clinically unacceptable images.
 3 anatomical line – mid sagittal , canthomeatal line, and
canine line should be matched by patient.

20. • CONCEPTS OF PANORAMIC RADIOGRAPHY
 CONCEPT 1: Structures are flattened and spread out
 The radiographic image is laid out as the film in the cassette passes the slit
opening, in the same way paint is applied toa wall this results in flattened
image of a curved surface.

21. • CONCEPT 2: Midline structures may project as single images or double images
 Single image is formed when anatomical structures is located between the
rotation centre of beam and the film.
 Double image is formed when the object are intercepted twice by the beam.

22. • CONCEPT 3: Ghost images are formed
 A ghost image is formed when the image is located the x-ray source and the
centre of rotation.

23. • CONCEPT 4: Soft tissue shadows are seen.
 One of the unique advantages of the panoramic radiograph is that some of the
soft tissue structures attenuate the beam of radiation to a sufficient degree
to become visible in the radiograph.

24. • CONCEPT 5: Air spaces are seen.
 Because areas containing air do not attenuate the x-ray beam as much as soft
and hard tissues, air spaces usually appear black.

25. • CONCEPT 6: Relative radiolucencies and radioopacities are seen.
 In any image, it is important to separate shadows originating from parts of the
machine from those coming from the patient.

26. • CONCEPT 7: Panoramic radiograph are unique.
 The scope of assessment and interpretive
potential from panoramic radiograph in many
ways exceed that of the full mouth intraoral
survey. The uniqueness of the panoramic
technique is that it results in an excellent
projection of a variety of structures on a
single film, which no other imaging system
can achieve.

27. • ZONES OF PANORAMIC RADIOGRAPHY
 ZONE 1: DENTITION
 The should be arranged with a smile-like upward curve posteriorly and be
separated from each other. This separation produces an interocclusal space in the
radiograph.

28.  ZONE 2: NOSE-SINUS
 The images of the inferior turbinates and their surrounding air space should be
contained within the nasal cavity. The soft tissues of the nose cartilage should not
be seen.

29.  ZONE 3: MANDIBULAR BODY
 The inferior cortex of the mandible should be smooth and continuous. The double
image, or ghost image of the body of the hyoid, should be absent in this area. The
midline area should not be overly enlarged superiorly – inferiorly.

30.  ZONE 4 & 6 : FOUR CORNERS; CONDYLES AND HYOID
 Zone 4 contains the condyles bilaterally. The condyles should be equal in size and
on the same horizontal plane.
 Zone 6 contains the body of hyoid bone sometimes the greater horn. It should
appear as a double image equal in size bilaterally.

31.  ZONE 5: RAMUS – SPINE
 The ramus of mandible should be the same width bilaterally. The spine, although
usually not seen, may be present so long as it does not superimpose on the ramus.

32. • IMAGE RECEPTORS IN PANORAMIC RADIOGRAPHY
 The use of digital image receptors in panoramic imaging has
become very common. Both PSP and solid-state detectors (CCD or
complementary metal oxide semiconductor [CMOS] device) are
used in panoramic imaging .
 In indirect digital acquisition with the film-sized PSP plate, the
image is processed by reading the latent image off of the PSP
plate, yielding a digital image.
 Alternatively, direct digital acquisition panoramic machines use an
array of solid-state detectors that transmit an electronic signal to
the controlling computer, which is transmitted to the display
screen, as it is being acquired.
 The American Dental Association endorses the use of DICOM as the
standard for exchange of all dental digital images and recommends
that all new digital xray units be DICOM compliant.

33. • CASETTE IN PANORAMIC RADIOGRAPHY
 Device used to hold extra oral film and
intensifying screen.
 Two types
1. Rigid
2. Flexible
 Rigid cassettes – intensifying screens are
attached to inside cover and base of a rigid
cassette. A & B are rigid
 Flexible – panoramic film is placed between to
flexible intensifying screen. C is flexible

34. • PANORAMIC FILM
 Screen film used available in two sizes
 5x12 inch
 6x12 inch
 Placed between two intensifying screens in a cassette holder.
 Sensitive to light emitted by intensifying screens.
 When exposed to x-ray, screen convert x-ray energy into light.

35. • INTENSIFYING SCREEN
 Two types
 Calcium tungstate – emit blue light
 Rare earth – emit green light

36. • INTERPRETING PANORAMIC FILMS

37. • MANDIBLE

38. • MID FACIAL REGION

39. • SOFT TISSUES

40. • CONCLUSION
 An OPG has several advantages in the field of dentistry
and its inevitable role in a diagnosis every dentist should
know about. Compared with the conventional
radiographic technique involving atleast 16 intraoral
exposures OPG has several advantages it takes fairly
takes one minute and shows the entire oral cavity in one
minute however resulting image produces less detail
than IOPA.

41. • REFERENCE
 White SC , Pharoah MJ. Oral radiology: Principles and interpretation. 6th
edition. Missouri Mosby Elsevier; 2015
 Whaites E ,Drage N . Essentials of dental radiography and radiology. 5th ed.
Edinburgh: Churchill Livingstone Elsevier; 2015
 Olaf E. Langland , Robert P. Langlais . Principles of dental imaging. 2th ed.
Balitmore : Williams & Wilkins; 1997