dental panoramic tomography. what we will cover… indications indications advantages/disadvantages...
TRANSCRIPT
Dental Panoramic Dental Panoramic TomographyTomography
What we will cover…What we will cover… IndicationsIndications
Advantages/disadvantagesAdvantages/disadvantages
Technical principlesTechnical principles
EquipmentEquipment
TechniqueTechnique
Film critique and common mistakesFilm critique and common mistakes
IndicationsIndications Large pathologies/un-erupted teeth too big for intra-oral filmLarge pathologies/un-erupted teeth too big for intra-oral film
Intra-orals not possibleIntra-orals not possible
Assessment in:Assessment in:• advanced periodontitisadvanced periodontitis• Extraction of wisdom teethExtraction of wisdom teeth• OrthodonticsOrthodontics• Growth and developmentGrowth and development• ImplantsImplants
Grossly neglected mouthGrossly neglected mouth
TraumaTrauma
TMJ dysfunctionTMJ dysfunction
AdvantagesAdvantages Large area of coverageLarge area of coverage
Bilateral view for comparisonBilateral view for comparison
Low doseLow dose
Relatively simple to performRelatively simple to perform
Easy to explain resultant image to patientEasy to explain resultant image to patient
Patient movement effects only one sectionPatient movement effects only one section
Rapid assessment methodRapid assessment method
DisadvantagesDisadvantages Less sharp than intra-oralLess sharp than intra-oral
• Subtle pathology may be missedSubtle pathology may be missed
MagnificationMagnification
DistortionDistortion
SectionalSectional
More complicated to interpretMore complicated to interpret
Ghost images producedGhost images produced
Intensifying screens result in reduced resolutionIntensifying screens result in reduced resolution
Different shaped dental archesDifferent shaped dental arches
TomographyTomography
Focal TroughFocal Trough
‘Narrow zone of sharp focus’
The technical bit..The technical bit.. Linear tomographyLinear tomography
• Flat focal troughFlat focal trough• E.g. Gas removal from kidneyE.g. Gas removal from kidney
Rotational tomographyRotational tomography• Arc shaped focal troughArc shaped focal trough
1 centre of rotation1 centre of rotation
Dental panoramic tomographyDental panoramic tomography• How do we achieve a horseshoe shape?How do we achieve a horseshoe shape?
2+ centres of rotation2+ centres of rotation
RotationalTomography
Centres of rotationCentres of rotation
DentalPanoramic
Tomography
How does tomography work…How does tomography work…
X-ray tube orbits back of headX-ray tube orbits back of head
Cassette holder moves around front of Cassette holder moves around front of faceface
X-ray tube and cassette holder move in X-ray tube and cassette holder move in opposite directionsopposite directions
Cassette moves in same direction as X-ray Cassette moves in same direction as X-ray tubetube
Focal Corridorf=height of filmd=focal trough to film distancex=height of XR beam
Explain…Explain…
Why do we need a moving X-ray Why do we need a moving X-ray source?source?
Why does the cassette carriage Why does the cassette carriage move?move?
Why does the cassette move?Why does the cassette move?
Equipment FeaturesEquipment Features
TubeheadTubehead
Control panelControl panel
Positioning apparatusPositioning apparatus• Chin supportChin support• Bite rodBite rod• Light beam markersLight beam markers• Head clampsHead clamps• mirrormirror
Image receptorImage receptor
The Control PanelThe Control Panel
What do we need?What do we need?• kV, mA settingskV, mA settings• Patient size selectionPatient size selection• Height adjustmentHeight adjustment• AP bite rod adjustment (canine light)AP bite rod adjustment (canine light)• Field limitation optionsField limitation options• Range of dental arch shapesRange of dental arch shapes
Light Beam MarkersLight Beam Markers
Mid-sagittal plane - Mid-sagittal plane - verticalvertical
Frankfort plane – Frankfort plane – horizontalhorizontal
Canine lightCanine light• Position between Position between
upper lateral incisor upper lateral incisor and canineand canine
The Image receptorThe Image receptor
Intensifying screensIntensifying screens
Intensifying screens convert X-ray Intensifying screens convert X-ray photons to light (UV and visible) to photons to light (UV and visible) to amplify blackening effectamplify blackening effect
Uses light emitted from photoelectric Uses light emitted from photoelectric effecteffect
Less radiation needed to expose filmLess radiation needed to expose film
Technique: PreparationTechnique: Preparation
Load cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriage
Set carriage to start position
Load cassette and place in carriage
Remove artefacts
Insert bite rod/cover
Set exposure factors
Load cassette and place in carriage
Technique: PositioningTechnique: Positioning
Load cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriageLoad cassette and place in carriage
Place chin on support
Patient holds handles
Guide patient into unit
Bite upper and lower teeth into groove on bite rod
Patient stands up straight and steps forward slightly
Technique: PositioningTechnique: Positioning
Patient swallows and places tongue in roof of mouth
Ask patient to keep still
Explain movements to patient
Use light beam markers to check position
Expose
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Anatomy
Normal AnatomyNormal Anatomy
1.Mandibular condyle1.Mandibular condyle
2.Angle of mandible2.Angle of mandible
3.Body of mandible3.Body of mandible
4.Ramus of mandible4.Ramus of mandible
5.Right Orbit5.Right Orbit
6.Symphysis of mandible6.Symphysis of mandible
7.Left maxillary sinus7.Left maxillary sinus
8.Zygomatic arch8.Zygomatic arch
9.Mandibular 39.Mandibular 3rdrd molar molar
10.Ear lobe10.Ear lobe
11.Cervical spine11.Cervical spine
12.(Root of) mandibular12.(Root of) mandibular 22ndnd premolar premolar
Film EvaluationFilm Evaluation
1. Identification1. Identification
2. Anatomical marker2. Anatomical marker
3. Collimation3. Collimation
3. Area of interest 3. Area of interest
4. Correct positioning4. Correct positioning
5. Artefacts5. Artefacts
6. Adequate exposure factors6. Adequate exposure factors
Film EvaluationFilm Evaluation
Common ProblemsCommon Problems
Patient movementPatient movement GhostingGhosting
• of artefactsof artefacts• of Cervical spineof Cervical spine
Incorrect positioningIncorrect positioning• AP positioningAP positioning• RotationRotation• Chin tiltChin tilt• TiltingTilting
Standing up straightStanding up straight
Digital
Conventional
3d3d