4. • The value of any diagnostic procedure depends on the
amount and validity of the information that can be
derived from it.
• The importance of intra oral radiograph in dental
diagnosis is well documented. However, the intra oral
radiograph is some what limited in the structures it
covers.
• Panoramic radiographs do not replace the conventional
dental film but when used as a supplemental
diagnostic technique, it gives a good outcome due to
its increased overall coverage of the dental arches and
associated structures, reduced radiation dosage to the
patient and simplicity of operation
Introduction
Panorama – “an unobstructed wide angle view of a region” 3/60
5. Historical background
The first attempts to image the whole jaw was made with
intraoral radiation sources at the beginning of 19th century in
1922.
Dr Host Beger of Germany
Uses a small x-ray tube that
can be introduced into the
patient’s mouth-patient, source &
film are stationary.
Koch and Sterzel of Essen Germany (panoramix).
Siemens corp. Erlangen, Germany (staters-x)
Philips Medical systems, Inc, Holland (shot oralix)
4/60
6. 1933 - Dr. H. Numata of Japan was the first to propose extraoral
technique - He used intraoral curved films with the source rotating.
1948 - Dr. Yrjoveli Paotero used a long curved film inserted
lingual to the teeth with the patient rotating -
PARABOLOGRAPHY
1949 - Film extra orally – film and patient moved while source
was stationary - PANTOMOGRAPHY
1950 – Robert J Nelson used Paotero’s parabolographic technique,
used an intraoral film,with the source moving for posterior projections
and patient+film stationary and vise versa for anteriors
1959 – Patero modified this technique with
extraoral films – called it as Orthopantomography
and the first orthopantomograph of clinical
importance approved in 1960
First Orthopantomograph machine became available
in 1961
Comercially available Orthopantomograph machines
are manufactured by Palomex ( Siemens Corp.
Germany).
Orthopantomo N-70 (Hilda Electric co) and
Panoramax (Asahi Roentgen Co.)
5/60
7. Working principle
• Employs scanography (slit beam) & tomography
• Tomography: A term derived from greek words tomos meaning “slice or
section” and graphia meaning “picture”
6/60
9. Practical application of the working principle
ABCD move past the film with the same velocity in
opposite direction – hence are sharply recorded on the
film.
8/60
10. To obtain optimal image definition, it is crucial that the speed of
the film passing the collimator slit is maintained equal to the
speed at which the xray beam sweeps through the objects of
interest.
9/60
11. • Stationary rotation centre
Centers of Rotation
• Single rotation centre
• Double rotation centre
10/60
12. 3. Triple center of rotation – Panoram ; Panora
4. Multiple centers of rotation – Ellipso pantomograph
11/60
16. Focal trough
• It is an imaginary three- dimensional curved zone in which structures
are clearly demonstrated on a panoramic radiograph
12/60
17. Form And Thickness Of Image Layer
• A constant film speed in relation to the beam places
the center of the image layer at a defined distance
from the rotation center.
• The distance from the rotation center of the beam to
the center of the image layer may be called the
effective projection radius. The thickness of the image
layer is dependent on the length of this radius.
• The longer the radius thicker the image layer, and is
inversely proportional to the width of the beam.
13/60
20. Number of OPG units available which vary depending on
• Number of rotation centers
• Size and shape of the focal trough
• Type of films used
Equipment
14/60
21. • Units that follow the principle
of stationary x ray source with
rotating object and receptor.
• Eg : Tomax panaromic unit
Koch and Sterzel of Essen
Germany (panoramix).
Siemens corp. Erlangen, Germany
(staters-x)
Philips Medical systems, Inc,
Holland (shot oralix)
15/60
22. • Orthopantomograph 10 E
unit
• Patient in the sitting position.
• Panellipse unit
• Patient in the standing
position.
16/60
24. EQUIPMENT
• Panoramic x-ray tube head
• Head positioner
• Cephalometric component
• Exposure controls
• Cassettes
• Films
Planmecca pro EC
18/60
25. • The panoramic x-ray tube head is very similar to an intra
oral x-ray tube head each has a filament used to produce
electrons and a target used to produce x-rays.
• Collimator used in the panoramic tube head differs from
the collimator used in intra oral x-ray tube head. Collimator
used in panoramic x-ray machine is a lead plate with an
opening in the shape of a narrow vertical slit through which
x-ray beam emerges as a narrow band. Beam passes
through the patients and then exposes the film through
another vertical slit in the cassette carrier. Narrow x-ray
beam emerging from the collimater minimizes patient
exposure to x-radiation.
19/60
27. • Each head positioner consists of a chin rest,
notched bite-block, forehead rest, and lateral
head supports or guides.
20/60
28. Patient positioning
• Patient should remove jackets or any bulky clothing and
metallic items from the head and neck region.
• Patient should sit or stand erect with back straight.
• The mid sagittal plane should be aligned with the vertical
centerline of chin rest.
• The frankfort’s horizontal plane should be perpendicular to
the floor
21/60
29. • The patient is asked to bite on the bite block with the upper
and lower incisors.
• The red guide light determines whether the jaws are in the
image layer – it should fall on the mesial aspect of the canine
tooth
• Explain to the patient how the machine works.
• Have patient close the lips and place the tongue against the
roof of the mouth.
22/60
31. Exposure parameters
• Kvp - 72 ; mA - 8 ; Exposure time 18 sec
Dose to the patient - 0.103mR
• Kvp - 80 ; mA 15 ; Exposure time 15 sec
Dose to the patient - 0.116mR
• In case of full mouth examination with 14
intraoral films
Dose to the patient 0.712mR
24/60
32. Intensifying screens and films
• Intensifying screen is a
device that transfers X-
ray energy into visible
light; visible light in turn
exposes screen film.
• Consists of base,
phosphor layer,
protective layer
25/60
33. • Base – Polyster plastic, measuring about 0.25mm.
• Reflecting coat - Titanium dioxide or magnesium oxide,
measuring about 0.0254 mm.
• Phosphor layer – calcium tungstate, or rare earth
materials. ( 40-100 mm)
» Terbium activated gadolinium oxy-sulphide
» Thalium activated lanthanum oxybromide
» Niobium activated Yttrium tantalate
• Protective coat – Polymer coat made up of cellulose (15-
25 µm thick )
26/60
34. • Film screen combinations :
• S
Emulsions sensitive to blue light – standard silver halide
emulsions
Sensitive to green light – Orthochromatic emulsions
Sensitive to red light – panchromatic emusions
Sensitive to UV light – modified silver halide emulsions
27/60
35. • Cassettes :
– Cassette is a device that is used to hold the extra oral film and
intensifying screens.
– Cassettes may be rigid or flexible curved or straight.
– All the cassettes must be light tight to avoid film from
exposure
30/60
40. Image
Real
Ghost
Single Double
Ghost Image : Objects with high attenuations
may in certain instances be observed in two
positions in panoramic radiograph only one of
these images is intended and the other is usually
rejected to as a ghost image.
31/60
42. Ghost image in recognized by:
Unsharpness which is in horizontal dimension;
Always projected at a higher position in the radiograph than
its real counterpart (because beam is directed from below)
Image is always reversed.
Ghost images are formed of more radiodense objects because
it is formed by objects that are out of focus and are usually
obscured , hence more radiolucent objects fail to project in the
radiograph as images.
32/60
43. Normal Anatomy
• Real Or Actual Shadows:
These include:
– Teeth
– Mandible
– Maxilla, including floor, anterior and posterior walls of the antrum
– Hard palate
– Zygomatic arches and zygoma
– Styloid processes
– Hyoid bone
– Nasal septum and conchae
– Orbital rim
– Base of skull
31/60
44. • Important Soft Tissue Shadows:
1. Tongue
2. Soft Palate and uvula
3. Lip Line
4. Ear lobes
Nose
Nasolabial folds
• Air Shadows:
1. Palatoglossal air space
2. Nasopharyngeal
3. Glossopharyngeal
• Ghost or Artefactual Shadows:
– Cervical vertebrae
– Body, angle and ramus of the contra lateral side of the mandible
– Palate.
32/60
52. Improper positioning of the patient
When the lips are not closed - lip shadow is seen.
When the chin is tipped too high - the maxillary teeth roots are superimposed,
- the maxillary incisors appear blurred,
- flattening of occlusal plane ( reverse smile line)
39/60
53. When chin is placed downward
When the chin is tipped too high - the mandibular incisors appear blurred,
- the apices of the lower incisors are out of focus
and blurred
- one/both condyles may cut off from the radiograph
- increased curvature of the occlusal plane
(exaggerated smile line)
40/60
54. When patient is positioned too far forward –
anterior to the focal trough
-The anterior teeth appear blurred, narrower and out of focus.
- Spine is superimposed on the ramus area
41/60
55. When patient is positioned too far backward –
posterior to the focal trough
-The anterior teeth appear blurred, broader and out of focus.
- Ghost image of the mandibular spine is more prominent.
42/60
56. When patient’s head is tilted
-One side condyle appears larger than the other side.
- The side tilted towards the xray tube is enlarged.
43/60
57. When the patient’s spine is not straight
It appears as a radio-opaque artifact in the centre of the film
superimposed on the anterior region
44/60
72. Interpretation
Zone 1 : The teeth and the surrounding bone
Zone 2 : Nose&sinus
Zone 3: The inferior cortex of the mandibular body.
- Principles and practice of panoramic radiology by langland langlais & Morris
47/60
73. Zone 4: The condyles are centered in this zone.
Zone 5: Ramus and Spine
Zone 6: The hyoid bone.
- Principles and practice of panoramic radiology by langland langlais & Morris
48/60
74. • The Orthopantomograph should be viewed as if
looking at the patient i.e. with the image of the
patient’s left side on the operators right.
• Should be viewed on a view box with sufficient
light.
• A thorough knowledge of the normal anatomical
landmarks and the superimposed structures is
mandatory.
• The potential artifacts associated with the patient
and machine movement, patient positioning and
unusual patient anatomy have to be identified
and understood.
- Oral Radiology, Principles and interpretation; White & Pharoah (6th Edition)
49/60
75. INTERPRETATION
• Assess the periphery and corners of the image
• Examine the outer cortices of the mandible
• Examine the cortices of the maxilla
• Examine the zygomatic bones and arches
• Assess the internal density of the maxillary sinuses
• Assess the structures of the nasal cavity and the palates
• Examine bone the pattern of the maxilla and mandible
• Alveolar processes and teeth
/60
S Perschbacher. Interpretation of panoramic radiographs.
Australian Dental Journal 2012; 57:(1 Suppl): 40–45
76. Condylar process and temporomandibular
joint
Coronoid process Ramus
Body and angle followed by mandibular
dentition and supporting alveolus
Mandible
51/60
77. Midfacial region
Cortical boundary of the maxilla including the
posterior border
Pterygomaxillary fissure – maxillary sinuses
Zygomatic complex (inferior and lateral borders of
orbit, zygomatic process, anterior portion of arch)
Nasal cavity --- conchae – Maxillary dentition and
supporting alveolus
54/60
78. 56/60
Cortical boundary of the maxilla including the posterior border
Pterygomaxillary fissure – maxillary sinuses
Zygomatic complex (inferior and lateral borders of orbit, zygomatic process,
anterior portion of arch)
Nasal cavity --- conchae – Maxillary dentition and supporting alveolus
79. Advancements
A new panoramic radiography system, in which a large
number of vertical strip images can be acquired with a
semiconductor detector used to reconstruct high-quality
images using the concept of tomosynthesis.
It uses SCAN-300FPC detector
with 20 frames/degree of
rotation.
Development of a new dental panoramic radiographic
system based on a tomosynthesis method .
Dentomaxillofacial Radiology (2010)
Cone beam computed tomography
57/60
80. Conclusion
• Panoramic radiographs have proved to be good adjuvant
radiographs to conventional intraoral radiographs mainly because
they produce a single tomographic image of facial structures that
include both maxilla and mandible and their supporting structures..
• The diagnostic value of these films is increased considerably if
clinicians are aware of their limitations and apply a systematic
approach to its interpretation.
58/60
81. References
• Principles of dental imaging –
Langland Langlais & Morris
• Oral radiology , Principles and Interpretation –
White & Pharoah ( 4th , 5th & 6th edition)
• Essentials if Dental Radiology –
Eric Whaites (3rd Edition )
• Textbook of Oral Radiology – Anil Govindrao Ghom.
• Textbook of Dental and Maxillofacial Radiology –
Freny R Karjodhkar ( 2nd edition )
59/60
Editor's Notes
The panoramic radiograph is unique in that the foci of the projection in the vertical and horizontal dimensions are not the same, in the horizontal dimension it is the rotation center of the beam that constitutes, the functional focus, whereas in the vertical dimension it is the x-ray source.
1. The image layer is directly related to the distance from the center of rotation to the central plane of the image, which is called the "effective projection radius." The width of the layer depends on the length of the radius (Fig. 9.5). The longer the radius, the thicker the layer.
2. The layer thickness is inversely proportional to the width of the long, narrow slit beam. The narrower the x-ray beam, the wider the image layer. The image layer is directly related to the distance from the center of rotation to the central plane of the image, which is called the "effective projection radius." The width of the layer depends on the length of the radius. The longer the radius, the thicker the layer.
Deceleration shifts the position of the layer successively towards the rotation center.
Acceleration shifts the position of the image layer successively away from the rotation center of the beam.
0.013 msv;
Lead apron artifact, use poncho style apron
Fixer and developer stains
Over exposure, under exposure
Film not starting in house; resulting in panoramic cone cut
Linear defect on intensifying screen. Distinguished from scratches…
Multiple Tiny defects on screen and crimp marks
Static electricity: dry air, improper handling,
Scratch marks
Damaged Plastic intensifying screen resulting in light leak
Reversed film
Double exposure and unexposed film.
Pt movement, wavy outline of mandible
The following steps are an example of an approach to analysing the complex projection of the anatomic structures on a panoramic radiograph:
