panoramic radiography abeer a almashraqi ass
DESCRIPTION
Definition It is an extra-oral radiographic technique for producing a single image of both the maxillary & mandibular dental arches & their supporting structures.TRANSCRIPT
Panoramic Radiography Abeer A Almashraqi Ass
Panoramic RadiographyAbeer A Almashraqi Ass. Professor of Oral and
Maxillofacial Radiology Definition It is an extra-oral radiographic
technique for producing a single image of both the maxillary &
mandibular dental arches & their supporting structures.
Principles Scanography (slit beam).
Tomography (curved surface rotation). Panoramic Imaging : General
Principles
Tomography: allows radiographing in one plane of an object while
blurring or eliminating images from structures in other planes.
Tomo is Greek for section View sections or radiographic slices
Panoramic Imaging : General Principles
Tomogram Patient remains stationary while x-ray source & film
move in opposite directions in a fixed relationship through one or
a series of rotation points. Rotation points can be inside or
outside of the focal trough Panoramic Imaging : General
Principles
Focal trough in tomogram Or plane of acceptable detail, or image
layer, is the plane that is not blurred on the radiograph Panoramic
Imaging : General Principles
Focal trough in pantogram Width & thickness governed by many
factors Objects lying within the focal spot are shown clearly;
objects outside are blurred Panoramic Imaging : General
Principles
Curved surface A panoramic radiographor pantomogram is produced
using curved-surface tomography. Flat surface Panoramic Imaging :
General Principles
Rotational panoramic radiography: It is accomplished by rotating a
narrow beam of radiation in the horizontal plane around an
invisible pivot point/axis positioned intraorally. Cassette &
tube travel in opposite directions around the patient Panoramic
Imaging : General Principles
Patient remains stationary as x-ray tube and film cassette-holder
(which are connected) both rotate around the client Panoramic
Imaging : General Principles
A vertical, narrow beam (scanography) is used compared with the
larger, circular or rectangular beam used in conventional intraoral
radiography Panoramic Imaging: Principles of Image Layer
Formation
Film placed on circular drum or a moving flat cassette Horizontal
magnification is reduced to match vertical magnification by
adjusting speed of film in respect to projection of beam Panoramic
Imaging: Principles of Image Layer Formation
The image layer is called the focal trough Panoramic Imaging: Image
Layer/Focal Trough Defined
A three-dimensionalzone in which structures are reasonably
well-defined. A zone in an object defined as containing those
object points depicted with sufficient detail to be distinguished.
Determines where dental arches must be positioned to achieve
clearest image Panoramic Imaging: Principles of Image Layer
Formation
Objects outside this sharply depicted plane will appear distorted,
fuzzy, or may not be visible Indications Assessment of impacted
teeth.
Assessment of both jaws before implant placement. Assessment of
both jaws before planning for dentures. Indications: Demonstrating
fractures of the mandible. Indications: 5- Demonstrating cysts,
tumors & other pathological conditions affecting both jaws.
Indications: Demonstrating periodontal disease in overall view
(allowing intra-oral films to be kept minimal). Indications:
Demonstrating an anterior view of the sinuses & thefloor of the
nasal cavity. Orthodontic assessment & evaluation of the
eruption patterns, growth & development. Advantages It allows
examination of both jaws in one radiograph.
Its procedures are relatively simple to perform & require
minimal time. It requires minimal patient cooperation. It can be
used with patient unable to open their mouth.
It delivers radiation dose less than full mouth survey. It is
useful in case presentation & patient education. Limitations 1.
Image quality: - Magnification and distortion
- Poor definition compared to intraoral - Overlap - Superimposition
& ghost images Limitations: 1- image quality
- Certain amount of magnification ( film object distance) &
overlapping is present even with proper technique. Limitations:
image quality
- Poor definition (lack of details) compared to intraoral due to:
1- The use of intensifying screen & fast films. 2- Tomographic
process. 3- Increased object-film distance. Panoramic Periapical
Periapical & Bitewing radiographs are preferred over Panoramic
radiograph for:
Caries Periodontal involvement Early or limited periapical
pathology Endo. treatment Limitations: 2- Focal Trough (Image
Layer) limitation:
- Areas outside are not visible - Size & shape limits to those
structures which fit into the image layer - Size & shape not
adjustable so not all patients arches image equally well 3- The
high cost of the equipment. Components of Panoramic Units
All machines share main components: -X-ray tube head & slit
collimator. -Cassette & cassette-carriage assembly. -Head
positioning apparatus. -Exposure controls. -Standing or sitting
patient position. - Pan / Ceph or Pan only X-ray tube head and slit
collimator Intraoral Collimation Panoramic Curved /Rigid Straight
/Rigid Flexible/ Soft Head Positioner/Cassette Holder Exposure
control Sitting / Standing Pan/Ceph Panoramic Technique 1- Patient
Preparation
2-Machine Preparation ( Setting Exposure Parameters) 3-Patient
Positioning Patient preparation: Explain the procedure to the
patient & ask him to remain still without motion. Ask the
patient to remove any dental appliance, earrings, hair pins,
necklace, eyeglass & any other metallic object in the head
& neck region. Ask the patient to wear a lead apron without a
thyroid collar. The apron must be placed low Equipment
Preparation:
Loading the panoramic cassette. Sterilize bite block between
patients or cover it with a disposable plastic cover. Set the
exposure factors according to manufacturers recommendations to
accommodate patients height & age. Patient positioning: Ask the
patient to sit/stand with the back straight & erect. Position
the mid sagittal planeperpendicular to the floor. Patient
positioning: Instruct the patient to bite on the plastic
bite-block. N.B. Upper & lower anterior teeth must be placed in
the groove found in the bite block (in an edge to edge position).
Patient positioning: :
Position the Frankfort plane (plane passing from the floor of the
orbit to the external auditory meatus) parallel to the floor. Ask
the patient to close his lips & to place the tongue against the
hard palate.