The document provides an overview of panoramic imaging (orthopantomography). It discusses the principles of panoramic image formation using a single rotation of the x-ray source and image receptor around the patient's head. It describes patient positioning and head alignment to obtain diagnostic images and outlines how to interpret panoramic images, including evaluating the dentition, mandible, maxilla and soft tissues. The document also reviews the advantages and disadvantages of panoramic imaging and different panoramic machine models.

1. PANORAMIC
IMAGINING;
ORTHOPANTOMOGRAP
HY
Anamika Mishra (BDS final year)

2. CONTENTS:
Introduction
Principles of Panoramic image formation
Panoramic Machines
Patient positioning & Head Alignment
Panoramic Film Dark room Technique
Interpreting Panoramic Images
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3. INTRODUCTION
• Panoramic radiography is a body section imaging technique that
results in wide, curved image layer depicting the maxillary &
mandibular dental arches & their supporting structures.
• This is achieved by using single rotation of x-ray source & image
receptor around patient’s head.
• Clinical applications include: evaluation of trauma including jaw
fractures ,location of 3rd molars ,extensive dental or osseous
disease, impacted or unerupted teeth & root remnants , TMJ pain &
developmental anomalies.
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Schematic view of relationships between x-ray source, the patient ,the secondary
collimator,& image receptor

6. PANORAMIC IMAGING
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Overall evaluation of dentition
Examine for intraosseous
pathology such as cysts,
tumors ,or infections.
Gross evaluation of
temporomandibular joints
Evaluation of position of
impacted tooth
Evaluation of eruption of
permanent dentition
Dentomaxillofacial trauma
Developmental disturbances of
maxillofacial skeleton
Indications

7. Advantage
s
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 Broad coverage of facial bone & teeth.
 Low radiation dose.
 Ease of panoramic radiographic technique.
 Can be used in patients with trismus or in patient who can’t
tolerate intraoral radiography.
 Quick and convenient radiographic technique.
 Useful visual aids in patient education & case presentstion.

8. Disadvantage
s
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 Lower resolution images that d’nt provide the fine details
provided by intraoral radiographs.
 Magnification across images is unequal ,making linear
measurements unreliable.
 Image is superimposition of real,doubleand ghost images &
requires careful visualisation to decipher anatomic & pathologic
details.
 Requires accurate patient positioning to avoid errors & artifacts.
 Difficult to image both jaws when patient has severe
maxillomandibular discrepancy.

9. PRINCIPLE OF PANORAMIC IMAGE FORMATION
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 it was first described by Paatero and Numata independently in 1948 & 1933 respectively.
 It explain the formation of focal through in a panoramic machine . Imagine an assembly
containing a disk with upright physical objects and a image receptor .
 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 objects and the image receptor .
 As disk rotates ,their radiographic images are recorded sharply on receptor that also moves
through the beam at the same direction and speed .
 The spatial relationship of the shadows of these objects correctly represents the relationship
of the actual objects.
 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.

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The x-ray source and collimator are held stationary .the receptor moves through the beam ,and the rotating
disk also carries objects A-F through beam. objects A-C move through the beam at the same rate and
direction as the image receptor and are imaged well. Objects D-F move through the beam at the same rate
as the receptor but in opposite direction, and so their image are blurred

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Intially, the x-ray beam rotates on the end of dotted arc on the tube side of patient. As
the x-ray source moves behind the patient, the centre of rotation moves forward along
the arc. the drawing shows the directions of the x-ray beam at various intervals for the
first half of the exposure cycle. The x-ray source then continues to move around the
patient to image the opposite side

12. FOCAL TROUGH(IMAGE LAYER)
 It is wide 3-D curved zone,where the structures positioned within this
zone are reasonably well defined on the panoramic image.
 Structures positioned in the centre of focal trough are the clearest
and those that are progressively farther from the centre of focal
trough are blurred , magnified, or reduced in size or sometimes
distorted to the extent of not recognisable.
 The shape of focal trough varies with the brand of equipment used ,
as well as with the imaging protocol selected within each unit .
 The shape and width of focal through is determined by the path and
velocity of the receptor and x-ray tube head,alignment of x-ray beam,
collimator width.
 The location of the focal trough can change with extensive machine
use ,so recalibration may be necessary if consistently suboptimal
images are being produced.
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 In some panoramic machines, the shape and size of the focal trough can
be adjusted to conform better to the patients maxillomandibular anatomy
allowing better imaging of children , patients with atypical jaw morphology
or specific anatomic sites such as TMJ or maxillary sinuses.
 This modification achieved by decreasing the rotational arc of the x-ray
source-receptor movement to reduce the focal trough size to better adapt
to pediatric jaws.

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Focal trough:the moving source and receptor generate a zone of sharpness
known as focal trough or image layer

15. REAL ,DOUBLE, AND GHOST IMAGES
Because of rotational nature of x-ray source and receptor, the x-ray beam
intercepts some anatomic structures twice during the single exposure
cycle
Depending on their location ,objects cast three different types of images:
1. Real images:
 Objects that lie between the center of rotation and receptor form real
image.Within this zone,objects that lie within focal trough cast
relatively sharp images ,whereas images of object located outside the
focal trough are blurred
2. Double image:
 Objects that lie posterior to the centre of rotation and that are
intercepted twice by the x-ray beam form double images
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3. Ghost image
 Some objects are located between the x-ray source and centre of rotation
,these objects cast ghost images .
 Ghost images appear on the opposite side of its true anatomic location and
at higher level because of upward inclination of the x-ray beam
 As the object is located outside of the focal plane and close to the x-ray
source ,the ghost image is blurred and magnified

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IMAGE DISTORTION
 the image distortion is influenced by several factors, including x-
ray beam angulation,x-ray source to object distance ,path of
rotational center,and position of object within focal trough.
 These parameters very among panoramic units and among
different regions of the jaws for the same unit.They are also
strongly dependent on patient anatomy and positioning of the
patient unit.
 The magnitude of horizontal distortion depends on the distance of
the object from the center of focal trough and thus strongly
influenced positioning
 Thus as a general rule ,when the structure of interest is displaced
to the lingual side of its optimal position in focal trough ,towards
the x-ray source ,the beam passes more slowly through it than the
speed of receptor moves.Consequently,the image structure in this
region are elongated horizontally,and they appear wide.

19.  When mandible is displaced towards buccal aspect of focal trough,the
beam passes at a rate faster than normal through structures,the image
compressed horizontally and they appear thinner.
 The same principle applies in midsagittal plane being rotated in focal
trough .the posterior structures on the side which the patient’s head is
rotated are magnified in horizontal dimension because the posterior
structures are positioned away from receptor.
 Vertical magnification is determined by distance between the x-ray source
and the object, this distance is maintained constant throughout the
exposure cycle ,resulting in relatively constant vertical magnification in
different areas of the image.
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23. PANORAMIC MACHINES
A no.of manufacturers produce high quality film based and digital
panoramic machines.
Most of these units have versatility to allow for adjustment of focal trough
shape based on patient size(adult v/s child) for panoramic image and
produce tomographic cross sectional images of selected areas of facial
skeleton.
In addition to producing standard panoramic images of the jaws,some of
these units have capability of adjusting to patients of various sizes and
making frontal and lateral images of TMJ.
These views are acquired by having special x-ray source and receptor
movements programmed into the machine.
Extraoral bitewing view are also offered by few panoramic units
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25. PATIENT POSITIONING AND HEAD
ALIGNMENT
• Proper patient positioning within focal trough are essential to obtaining
diagnostic panoramic radiographs.
• Dental appliances,earrings ,nrcklaces,hairpins and any other metallic
objects in the head and neck region should be removed.
• The anteroposterior head position is achieved typically by having patients
place the incisal edges of their maxillary and mandibular incisor into a
notched positioning device (bite stick).patient midsagittal plane must be
centered within the focal trough without any lateral shift in the mandible
when making this protrusive movement.
• Placement of the patient either too far anterior or too far posterior relative to
the focal trough result in significant dimensional aberrations in the images
• The patient’s chin and occlusal plane must be properly positioned to avoid
distortion.
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26. • The occlusal plane is aligned so that it is slightly lower anteriorly. A general
guide for chin positioning is to position the patient so that a line from the
tragus of the ear to the outer canthus of the eye parallel with the floor.
• If the chin tipped too high ,the occlusal plane on radiograph appears flat or
inverted, and resultant image of mandible is distorted. In addition ,the
radiopaque shadow of the hard palate is superimposed on the roots of the
maxillary teeth.
• If chin tipped too low ,the occlusal plane shows an exaggerated smile line
,the teeth becomes severely overlapped ,the symphyseal region of mandible
may be cut off the film ,and both mandible condyles may be projected off the
superior edge of the film.
• Patients are positioned with their backs and spines as erect as possible and
their neck extended
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Chin is too low
Chin is too high

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Improper neck positioning:large
radiopaque region in the middle
because the patient has the
neck angled forward. the ghost
image of cervical spine formed
Improper tongue positioning
,where dorsum of tongue was
not positioned flat against the
palate ,resulting in airspace
below the hard palate hindering
visualistion of the apices of the
maxillary teeth

29. PANORAMIC FILM DARKROOM TECHNIQUES
o Special darkroom procedures are needed when panoramic film is being
processed.
o The films are more sensitive than intraoral films , especially after they
have been exposed.
o A kodak GBX-2 filter can be installed with 15 –watt bulb at least 4 feet
from the working surface.
o Panoramic film should be developed either manually or in automatic film
processor according to manufacturers recommendations
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30. INTERPRETING PANORAMIC IMAGES
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It is important to recognise the planes of the patient that are represented in
different parts of panoramic images.
The panoramic image represents the curved jaw that is unfolded onto a flat
plane.
In posterior regions,the panoramic images depicts a sagittal (lateral) views of
the jaws, whereas in the anterior sextant ,it represents a coronal
(anterioposterior) view.
1. Dentition :
 panoramic image demonstrate the complete dentition
 Interpretation must always include identification of all erupted and developing
teeth .
 Teeth should be examined for abnormalities of number,position and anatomy
 Excessively wide or narrow anterior teeth suggest malposition of the patient in
the focal trough

31. Gross caries and periapical and periodontal diseases may be evident .
It is particularly important to examine impacted third molar, the orientation
of the molars; number and configuration of the roots
 the relationship of the tooth components to critical anatomic structures
,such as mandibular canal ,floor and posterior wall of the maxillary sinus,
maxillary tuberosity.
Presence of the abnormalities in the Pericoronal and periradicular bone
must be carefully studied
2. Midfacial region:
 The midface a complex mixture of bones ,air cavities ,and soft tissues all
of which appear in panoramic images.
 Individual bones that may appear on the panoramic image
include,zygoma, mandible ,frontal, maxilla , sphenoid , ethmoid ,vomar
,nasal conchae and palate
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33. 3. Mandible:
 Assessment of mandible can be compartmentalized into the major
anatomic areas, as follows
condylar process of TMJ
coronoid process
ramus
body and angle
anterior sextant
mandible dentition and supporting alveolus
 The clinician should be able to follow a cortical border around the entire
bone, the border should be smooth and have symmetric thicknesss in
complete anatomic areas
 The condyle is generally positioned slightly anteroinferior to its normal
closed position
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34.  TMJ can be assessed for gross anatomic changes of the condylar head
and glenoid fossa;the soft tissues such as articular disc and posterior
ligamentous attachment cannot be evaluated.
 Shadows of other structures that can be superimposed over mandibular
ramal area include following :
oropharyngeal and nasopharyngeal airway shadows when patient
unable to expel the air and place tongue in the palate during
exposure.
posterior wall of nasopharynx
cervical vertebrae
earlobe
nasal cartilage
soft palate and uvula
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From the angle of mandible ,viewing should be continued anteriorly towards the
symphyseal region.
A fracture often manifests as discontinuity(step deformity) in inferior border.
A sharp changes in the level of the occlusal plane indicates that the fracture
passes through the tooth bearing area.
The width of the cortical bones at the inferior border of mandible of the mandible
should be at least 3mm in adults and uniform density.
There may be localised or generalised bone thinning indicating an expansile
lesion such as cyst or systemic disease such as hyperparathyroidism and
osteoporosis.
An expansion of mandibular canal suggest neurovascular pathology .
Th midline is more opaque because of mental protuberance and attenuation of
beam passing through cervical spine


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4. Soft tissues:
 Numerous opaque soft tissue structure may be identified on panoramic
radiographs, including tongue arching across the image under the hard
palate ,lip markings, the posterior wall of oral and nasal pharynx, nasal
septum ,nose ,nasolabial folds

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42. TIMELINE
Q1
Q2
Q3
Q4
Synergize scalable e-commerce
Coordinate e-business applications
Deploy strategic networks with compelling e-business
needs
Disseminate standardized metrics
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43. THANK YOU
Mirjam Nilsson
mirjam@contoso.com
www.contoso.com
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