Imaging Systems

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19.10.0619.10.06

IMAGING SYSTEMSIMAGING SYSTEMS

ININ

DENTISTRYDENTISTRY

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UNDER THE VALUABLE SUPPORT AND UNDER THE VALUABLE SUPPORT AND GUIDANCE OF:GUIDANCE OF:

Prof. Dr. Srinivasa Raju.Prof. Dr. Srinivasa Raju.Prof. Dr. Satish Reddy.Prof. Dr. Satish Reddy.Dr. Ravi Prakash SM.Dr. Ravi Prakash SM.Dr. Raghunath.Dr. Raghunath.

By:By: Dr. RUCHI Dr. RUCHI DHIRDHIR MDS- Iyr.MDS- Iyr. Deptt. Conservative Deptt. Conservative Dentistry Dentistry && Endodontics.Endodontics.

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CONTENTSCONTENTS Introduction.Introduction. Classification of dental imaging system.Classification of dental imaging system. Conventional Radiography:Conventional Radiography: Intra-oral.Intra-oral. Extra-oral.Extra-oral. Temporomandibular Joint ProjectionsTemporomandibular Joint Projections Panoramic Radiography.Panoramic Radiography.

Specialized Techniques:Specialized Techniques: Electric Thermography.Electric Thermography.

Tomography.Tomography.

Stereography.Stereography.

Scanography.Scanography.

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Digital Radiography. Digital Radiography. Magnetic Resonance Imaging.Magnetic Resonance Imaging.

Nuclear MedicineNuclear Medicine

Ultrasonography.Ultrasonography.

Xeroradiography.Xeroradiography.

Arthrography.Arthrography.

Sialography.Sialography.

Conclusion.Conclusion.

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INTRODUCTIONINTRODUCTION

The history of dental imaging system began with the discovery of

X-rays that revolutionized the practicing medicine and dentistry by making it possible to visualize the internal body structures.

The X-rays were discovered by ‘Prof. Willehm Conrad Roentgen’ accidently while working with cathode tube, in November 1895, in a darkened room.

But as Neil Armstrong stated for his mission to moon applies equally well to the discovery of X-rays:

“ One step forward for man and a giant leap for mankind ! ”

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Roentgen called the discovered rays as X-rays, since their nature

was then unknown.

They are actually a form of high energy electromagnetic radiations and are part of electromagnetic spectrum.

They consist of ‘wave packets’ of energy.Each packet is called a ‘photon’ and is equivalent to one

‘quantum’ of energy.

The X-ray beam, as used in diagnostic radiology, is made up of

million of individual photons.

X-rays are produced when high speed electrons bombard a target

material and are brought suddenly to rest, thereby, producing an image on the ‘film’.

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‘Radiographic Imaging’ forms the backbone of dental science. Conventional radiography ( intra-oral and extra-oral ) began the era of diagnostic aids in dentistry in the beginning of nineteenth century.

But, today, increasing awareness of the importance of risks associated with exposure to ionizing radiation and infection control; there is introduction of faster films, improved film/ screen combinations; improved technology for complex motion tomography; rapid developments in new imaging modalities such as Digital Radiography, Computed Tomography [CT], Magnetic Resonance Imaging [MRI] etc.

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CLASSIFICATION OF DENTAL CLASSIFICATION OF DENTAL IMAGING SYSTEM IMAGING SYSTEM

CONVENTIONAL SPECIALIZED CONVENTIONAL SPECIALIZED RADIOGRAPHY RADIOGRAPHY

RADIOGRAPHYRADIOGRAPHY

Intra-Oral Radiography:Intra-Oral Radiography:

Intra-oral Periapical Intra-oral Periapical Radography.Radography. Bitewing Radiography.Bitewing Radiography. Occlusal .Radiography.Occlusal .Radiography. SLOB / Clark’s SLOB / Clark’s technique.technique.

Electronic ThermographyElectronic Thermography Tomography.Tomography. Stereoscopy.Stereoscopy. Scanography.Scanography. Computed Tomography Computed Tomography ( CT Scans).( CT Scans). Magnetic ResonanceMagnetic Resonance Imaging ( MRI ).Imaging ( MRI ). Ultrasonography ( USG ).Ultrasonography ( USG ).

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Extra-Oral RadiographyExtra-Oral Radiography

Skull Projections.Skull Projections. Lateral MandibularLateral Mandibular Oblique Projections.Oblique Projections. Oral Pantamogram.Oral Pantamogram. Temporomandibular Temporomandibular JointJoint Projections.Projections.

Nuclear MedicineNuclear Medicine (Scintigraphy)(Scintigraphy) Digital Imaging:Digital Imaging:

- Direct Digital - Direct Digital Imaging.Imaging. - Indirect Digital - Indirect Digital Imaging.Imaging. -Digital Subtraction-Digital Subtraction RadiographyRadiography -Digitised Image-Digitised Image Interpretation.Interpretation.

Xeroradiography.Xeroradiography. Sialography.Sialography. Arthrology.Arthrology. Radio Visuo Graphy Radio Visuo Graphy ( RVG).( RVG).

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1. INTRA-ORAL RADIOGRAPHY1. INTRA-ORAL RADIOGRAPHYIt includes the radiographic techniques that involve It includes the radiographic techniques that involve

placement ofplacement of X-ray films inside the mouth.X-ray films inside the mouth.

Intra-oral radiographs can be divided into four categories:Intra-oral radiographs can be divided into four categories:

1.1. Peri-apical Projections.Peri-apical Projections.

2.2. Bitewing Projections.Bitewing Projections.

3.3. Occlusal Projections.Occlusal Projections.

4.4. SLOB / Clark’s Technique.SLOB / Clark’s Technique.

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I.I. PERI-APICAL PROJECTIONSPERI-APICAL PROJECTIONS

Main indications:Main indications:

Detection of apical infection or inflammation.Detection of apical infection or inflammation.

Assessing the periodontal status.Assessing the periodontal status.

After trauma to teeth and associated alveolar bone.After trauma to teeth and associated alveolar bone.

Assessment of presence and position of unerupted Assessment of presence and position of unerupted teeth.teeth.

During endodontic procedures.During endodontic procedures.

Pre-operative assessment and post-operative Pre-operative assessment and post-operative appraisal of apical surgery.appraisal of apical surgery.

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Detailed evaluation of apical cysts and other lesions Detailed evaluation of apical cysts and other lesions within within

the alveolar bone.the alveolar bone.

Evaluation of ‘Implants’ post-operatively.Evaluation of ‘Implants’ post-operatively.

It includes: It includes:

a.) Paralleling Technique. b.) Bisecting Angle a.) Paralleling Technique. b.) Bisecting Angle Technique.Technique.

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A.) PARALLELING TECHNIQUE: RIGHT ANGLE TECHNIQUE LONG CONE TECHNIQUE.

PrinciplePrinciple:: The X-ray film isThe X-ray film is supported parallel to supported parallel to

thethe long axis of the teethlong axis of the teeth and the central ray ofand the central ray of the X-ray beam isthe X-ray beam is directed at right directed at right

angles angles to the teeth and film.to the teeth and film.

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Advantages:Advantages:

Minimum geometric distortion of the image.Minimum geometric distortion of the image.

Use of long source to object distance reduces the size Use of long source to object distance reduces the size of the of the

apparent focal spot.apparent focal spot.

The image is sharp and defined.The image is sharp and defined.

The shadow of the zygomatic buttress appears above The shadow of the zygomatic buttress appears above thethe

apices of the molars.apices of the molars.

The periapical tissues are clearly shown with minimalThe periapical tissues are clearly shown with minimal distortion.distortion.

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The crowns of teeth are well defined to detect proximalThe crowns of teeth are well defined to detect proximal caries.caries.

The horizontal and vertical angulations of the X-ray tubeThe horizontal and vertical angulations of the X-ray tube head are automatically determined by the positioninghead are automatically determined by the positioning devices, if correctly positioned.devices, if correctly positioned.

The X-ray beam is aimed accurately at the centre of theThe X-ray beam is aimed accurately at the centre of the film- all areas of film are irradiated and there is no film- all areas of film are irradiated and there is no coningconing off or cone cutting.off or cone cutting.

The relative positions of the film packet, teeth and X-rayThe relative positions of the film packet, teeth and X-ray beam are maintained irrespective of the patient’s headbeam are maintained irrespective of the patient’s head position.position.

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Disadvantages:Disadvantages:

Film positioning can be uncomfortable to the patient Film positioning can be uncomfortable to the patient specially the posterior teeth.specially the posterior teeth.

Positioning the holders is difficult for inexperiencedPositioning the holders is difficult for inexperienced operators.operators.

Anatomy of mouth makes the technique difficult Anatomy of mouth makes the technique difficult eg. shallow, flat palate. eg. shallow, flat palate.

Root apices may appear very near to the edge of the Root apices may appear very near to the edge of the film.film.

Positioning the holder in lower third molar region is Positioning the holder in lower third molar region is difficult.difficult.

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The technique cannot be performed satisfactorily by The technique cannot be performed satisfactorily by using ausing a

short focal spot to skin distance due to resultant short focal spot to skin distance due to resultant magnification.magnification.

The holders need to be autoclavable or disposable. The holders need to be autoclavable or disposable.

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B.) BISECTING ANGLE TECHNIQUE B.) BISECTING ANGLE TECHNIQUE Principle:Principle:

It is based on a simpleIt is based on a simple geometric theorem,geometric theorem, Cieszynski’s rule ofCieszynski’s rule of isometry:isometry:

Two triangles are Two triangles are equal when they equal when they

share share one complete side one complete side

and and have two equal have two equal

angles.angles.

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Comfortable positioning of film packet in all areas of Comfortable positioning of film packet in all areas of thethe

mouth.mouth.

Quick and simple positioning.Quick and simple positioning.

Tooth image is same as the tooth itself.Tooth image is same as the tooth itself.


Distorted image due to use of many variables.Distorted image due to use of many variables.

Incorrect vertical angulation results in foreshortening Incorrect vertical angulation results in foreshortening oror

elongation of the image.elongation of the image.

Periodontal bone levels are poorly defined.Periodontal bone levels are poorly defined.

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Shadow of zygomatic buttress overlies the roots of theShadow of zygomatic buttress overlies the roots of the upper molars.upper molars.

Coning off or cone cut Coning off or cone cut may result if the central ray is not may result if the central ray is not aimed at the centre of the film.aimed at the centre of the film.

Incorrect horizontal angulation results in the overlapping Incorrect horizontal angulation results in the overlapping ofof

the crowns and roots.the crowns and roots.

The crowns of the teeth are often distorted, thereby,The crowns of the teeth are often distorted, thereby, preventing the detection of proximal caries.preventing the detection of proximal caries.

The buccal roots of the maxillary premolars and molars The buccal roots of the maxillary premolars and molars areare

often foreshortened.often foreshortened.

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Hence, Paralleling technique is the technique of Hence, Paralleling technique is the technique of choice forchoice for

peri-apical radiography. peri-apical radiography.

But due to lack of required armamentarium and But due to lack of required armamentarium and tedioustedious

procedure, procedure, Bisecting Angle Technique is still Bisecting Angle Technique is still followedfollowed

in the routine practice.in the routine practice.

Its use is recommended by the NRPB/ RCR in theirIts use is recommended by the NRPB/ RCR in their document ‘Guidelines on Radiology Standards in document ‘Guidelines on Radiology Standards in

PrimaryPrimary Dental Care and in the new 2001 Guidance Notes.Dental Care and in the new 2001 Guidance Notes.

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CLARK’S TECHNIQUECLARK’S TECHNIQUE

SAME LINGUAL OPPOSITE BUCCAL SAME LINGUAL OPPOSITE BUCCAL ( SLOB )( SLOB )

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II. BITEWING PROJECTIONS:INTERPROXIMAL II. BITEWING PROJECTIONS:INTERPROXIMAL They are named so on the basis of original technique They are named so on the basis of original technique where the patient is required to where the patient is required to bite bite on a small on a small wing wing attached to an intra-oral film packet.attached to an intra-oral film packet.

TYPESTYPES Horizontal VerticalHorizontal Vertical

The films are positioned either with the help of The films are positioned either with the help of tabs tabs or or film holding device .film holding device .

Indications:Indications: Detection of incipient, proximal carious lesions.Detection of incipient, proximal carious lesions. Detection of secondary caries.Detection of secondary caries. Assessment of the inter-dental alveolar bone height Assessment of the inter-dental alveolar bone height

using the vertical bitewing radiographs.using the vertical bitewing radiographs. Detection of inter-dental calculus deposits.Detection of inter-dental calculus deposits.

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FILM HOLDING DEVICE BITEWING LOOP TABFILM HOLDING DEVICE BITEWING LOOP TAB

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Advantages:Advantages: The device is simple.The device is simple.

The ‘tabs’ are inexpensive and disposable, so no The ‘tabs’ are inexpensive and disposable, so no cross-infection.cross-infection.

Tabs can be used easily in children also.Tabs can be used easily in children also.

If film packet holders are used then film packet If film packet holders are used then film packet cannot be displaced by tongue.cannot be displaced by tongue.

If film holders are used, it avoids If film holders are used, it avoids coning-off or cone coning-off or cone cuttingcutting of anterior part of film by approximating the of anterior part of film by approximating the external localizing ring.external localizing ring.

Holders are autoclavable and disposable.Holders are autoclavable and disposable.

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Radiographs are not accurately reproducible, so not Radiographs are not accurately reproducible, so not ideal for monitoring the progression of caries.ideal for monitoring the progression of caries.

Coning off or cone cutConing off or cone cut of anterior part of film is of anterior part of film is common if tabs are used.common if tabs are used.

Some film holders are expensive.Some film holders are expensive.

Holders are not comfortable for children.Holders are not comfortable for children.

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III.III. OCCLUSAL TECHNIQUEOCCLUSAL TECHNIQUE It is the intra-oral radiographic technique where X-It is the intra-oral radiographic technique where X-

ray film is placed on the occlusal plane.ray film is placed on the occlusal plane.The film size is: 5.7 X 7.6 cm.The film size is: 5.7 X 7.6 cm.

Indications: Indications:

Peri-apical assessment of the upper anterior teeth.Peri-apical assessment of the upper anterior teeth.

Detecting the presence of unerupted canines, Detecting the presence of unerupted canines, impacted teeth, supernumeraries and odontomes.impacted teeth, supernumeraries and odontomes.

To evaluate the integrity of anterior, medial, and To evaluate the integrity of anterior, medial, and lateral outlines of the maxillary sinus.lateral outlines of the maxillary sinus.

Evaluating the size and extent of lesions such as Evaluating the size and extent of lesions such as cysts or tumors in the anterior maxilla.cysts or tumors in the anterior maxilla.

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Assessment of fractures of the anterior teeth and alveolar bone.

To localize foreign bodies in the jaws and stones in the ducts of sublingual and submandibular salivary glands.

To examine the patients with restricted mouth opening.

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Various Occlusal Radiographic techniques include:Various Occlusal Radiographic techniques include:

Maxillary Occlusal Projections:Maxillary Occlusal Projections:

Anterior Maxillary Occlusal Projection Anterior Maxillary Occlusal Projection ( Topographical )( Topographical )

Cross-sectional Maxillary Occlusal Projection.Cross-sectional Maxillary Occlusal Projection. Lateral Maxillary Occlusal Projection.Lateral Maxillary Occlusal Projection.

Mandibular Occlusal Projections:Mandibular Occlusal Projections:

Anterior Mandibular Occlusal Projection.Anterior Mandibular Occlusal Projection. Cross-sectional Mandibular Cross-sectional Mandibular Occlusal Projection.Occlusal Projection. Lateral Mandibular Occlusal Projection.Lateral Mandibular Occlusal Projection.

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ANTERIOR MAXILLARY OCCLUSAL ANTERIOR MAXILLARY OCCLUSAL PROJECTIONPROJECTION

Image fieldImage field

Anterior maxilla.Anterior maxilla.Anterior floor of nasal fossa.Anterior floor of nasal fossa.Teeth from canine to canine.Teeth from canine to canine.

Projection of Central Ray:Projection of Central Ray:vertical angulation: +45vertical angulation: +450 0

horizontal angulation: 0horizontal angulation: 000

Point of entry: Point of entry: tip of nose.tip of nose.

p. 154 wpp. 154 wp

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CROSS-SECTIONAL MAXILLARY OCCLUSAL CROSS-SECTIONAL MAXILLARY OCCLUSAL PROJECTION PROJECTION

Location:Location:The palate, zygomatic processes of The palate, zygomatic processes of the maxilla, antero-inferior aspects the maxilla, antero-inferior aspects of antra, teeth from second molar of antra, teeth from second molar to second molar, and nasal septum.to second molar, and nasal septum.

Projection of Central Ray:Projection of Central Ray:Vertical angulation: + 65Vertical angulation: + 650 0

Horizontal angulation: 0Horizontal angulation: 000

Point of entry; Point of entry; bridge of nose.bridge of nose.

p155 wpp155 wp

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LATERAL MAXILLARY OCCLUSAL LATERAL MAXILLARY OCCLUSAL PROJECTIONPROJECTION

Image field: Image field: Quadrant of Quadrant of alveolar ridge of maxilla,alveolar ridge of maxilla,inferolateral aspect of inferolateral aspect of antrum,antrum,teeth from lateral incisor teeth from lateral incisor to contralateral third to contralateral third molar.molar.

Projection; Projection; +60+600.0.

Point of entry; Point of entry; 2cm. 2cm. below the lateral canthus below the lateral canthus of eye, toward the centre of eye, toward the centre of film.of film.

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ANTERIOR MANDIBULAR ANTERIOR MANDIBULAR OCCLUSAL PROJECTIONOCCLUSAL PROJECTION

Image field: Image field: Anterior Anterior portion of mandible, portion of mandible, dentition from canine dentition from canine to canine,to canine,inferior cortical border inferior cortical border of the mandible.of the mandible.

Projection of central Projection of central ray:ray:-10-100.0.

Point of entry; Through Point of entry; Through chin. chin.

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CROSS-SECTIONAL MANDIBULAR CROSS-SECTIONAL MANDIBULAR OCCLUSAL PROJECTIONOCCLUSAL PROJECTION

Image field:Image field: Soft tissue of Soft tissue of the floor of mouth, the floor of mouth, lingual and buccal plate of lingual and buccal plate of mandible from second mandible from second molar to molar.molar to molar.

Projection of central ray:Projection of central ray:90900 0 to the centre of film. to the centre of film.

Point of entry: Point of entry: Midline Midline through the floor of mouth, through the floor of mouth, 3cm. below the chin.3cm. below the chin.

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LATERAL MANDIBULAR LATERAL MANDIBULAR OCCLUSAL PROJECTIONOCCLUSAL PROJECTION

Image field:Image field:Soft tissue of half the Soft tissue of half the floor of mouth, buccal floor of mouth, buccal and lingual cortical and lingual cortical plates of half of plates of half of mandible from lateral mandible from lateral incisor to third molar.incisor to third molar.

Projection of central Projection of central ray: ray: 90900.0.

Point of entry: Point of entry: Beneath Beneath the chin. 3cm. posterior the chin. 3cm. posterior to the chin and 3cm. to the chin and 3cm. lateral to midline.lateral to midline.

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2. EXTRA-ORAL RADIOGRAPHY2. EXTRA-ORAL RADIOGRAPHY

Extra-oral radiographic examinations include all the Extra-oral radiographic examinations include all the views made of the oro-facial region with the films views made of the oro-facial region with the films positioned extra-orally in conjunction with positioned extra-orally in conjunction with intensifying screens within a cassette.intensifying screens within a cassette.

Use of Intensifying Screens;Use of Intensifying Screens;

To decrease the patient radiation exposure.To decrease the patient radiation exposure.

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a.) Skull Projections. b.) Mandibular Obliquea.) Skull Projections. b.) Mandibular Oblique Lateral Lateral

Projections. Projections. 1. Postero-anterior Projection. 1. Mandibular Body Projection.1. Postero-anterior Projection. 1. Mandibular Body Projection.

2.2. Antero-posterior Projection. 2. Mandibular Ramus Projection.Antero-posterior Projection. 2. Mandibular Ramus Projection.

3. Lateral Skull Projection. 3. Lateral Skull Projection. (Lateral Cephalometric).(Lateral Cephalometric).

4. Water’s Projection.4. Water’s Projection.

5. Reverse Towne’s Projection.5. Reverse Towne’s Projection.

6. Submento-vertex Projection6. Submento-vertex Projection ( Jug Handle View/ Base or Full Axial Projection) ( Jug Handle View/ Base or Full Axial Projection)

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C. ORTHO PANTOMOGRAPHY ( OPG )C. ORTHO PANTOMOGRAPHY ( OPG )

D. TMJ PROJECTIONS:D. TMJ PROJECTIONS:

1.1. Trans-cranial View ( Open and Closed Mouth).Trans-cranial View ( Open and Closed Mouth).2.2. Trans- pharyngeal View.Trans- pharyngeal View.3.3. Trans-Orbital View.Trans-Orbital View.

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POSTERO-ANTERIOR PROJECTIONPOSTERO-ANTERIOR PROJECTIONIndication:Indication: Skull examination.Skull examination. Progressive changes in Progressive changes in

mesio-lingual mesio-lingual dimensions.dimensions.

Frontal or ethmoidal Frontal or ethmoidal sinuses,sinuses,

nasal fossae, orbits.nasal fossae, orbits.

Projection of central ray:Projection of central ray: 909000 to the image to the image

receptor and parallel to receptor and parallel to patient’s mid-sagittal patient’s mid-sagittal plane at the bridge of plane at the bridge of nose.nose.

Distance: 30-40”.Distance: 30-40”.

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For Cephalometric evaluation,For Cephalometric evaluation,

FHP is perpendicular to film.FHP is perpendicular to film. Cantho – meatal line is 10Cantho – meatal line is 1000 above horizontal. above horizontal.

Superior border of petrous temporal ridge in lower Superior border of petrous temporal ridge in lower third of the orbit.third of the orbit.

Occlusal plane is in horizontal position. Occlusal plane is in horizontal position.

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POSTERO-ANTERIOR CEPHALOMETRIC POSTERO-ANTERIOR CEPHALOMETRIC PROJECTIONPROJECTION

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LATERAL SKULL PROJECTIONLATERAL SKULL PROJECTIONIndications:Indications:

Skull survey.Skull survey. Naso-pharyngeal soft Naso-pharyngeal soft

tissue, PNS, hard palate.tissue, PNS, hard palate. Facial growth Facial growth

assessment.assessment. Soft tissue profile.Soft tissue profile.

Projection of Central Ray: The central beam makes

900 with patient’s mid-sagittal plane and is centered over external auditory meatus.

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LATERAL SKULL PROJECTIONLATERAL SKULL PROJECTION

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WATER’S PROJECTIONWATER’S PROJECTIONIndications;Indications;

PNS, zygomatic frontal PNS, zygomatic frontal suture.suture.

Position of coronoid Position of coronoid process between process between maxillary and maxillary and zygomatic arch.zygomatic arch.

Sphenoid sinus.Sphenoid sinus.

Projection of Central Ray:Projection of Central Ray: 909000 to the film and is to the film and is

centered at the level centered at the level of maxillary sinus.of maxillary sinus.

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WATER’S PROJECTIONWATER’S PROJECTION

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Reverse Towne’s projectionReverse Towne’s projection

Indications:Indications:

Condylar fracture of neck.Condylar fracture of neck.

Medially displaced Medially displaced condyle.condyle.

Postero- lateral wall of Postero- lateral wall of maxillary antrum.maxillary antrum.

Projection of Central Ray:Projection of Central Ray: 909000 to the cassette and to the cassette and

parallel to patient’s mid-parallel to patient’s mid-sagittal plane and sagittal plane and centered at level of centered at level of condyles.condyles.

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REVERSE- TOWNE PROJECTIONREVERSE- TOWNE PROJECTION

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SUBMENTO VERTEX PROJECTIONSUBMENTO VERTEX PROJECTIONIndication:Indication: Base of skull.Base of skull. Position and orientation of Position and orientation of

condyles.condyles. Sphenoid sinus.Sphenoid sinus. Curvature of mandible.Curvature of mandible. Lateral wall of maxillary sinus.Lateral wall of maxillary sinus. Fracture zygomaFracture zygoma ( Jug handle view).( Jug handle view). Medial/ lateral pterygoid Medial/ lateral pterygoid

plate.plate. Foramen f base of skullForamen f base of skull

Projection of Central Ray:Projection of Central Ray: Through vertex to the centre Through vertex to the centre

of film, 2cm. from a line of film, 2cm. from a line connecting the two condyles.connecting the two condyles.

..

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SUBMENTO VERTEX PROJECTIONSUBMENTO VERTEX PROJECTION

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B. MANDIBULAR LATERAL OBLIQUEB. MANDIBULAR LATERAL OBLIQUE PROJECTIONS PROJECTIONS

Mandibular Body Mandibular Body

ProjectionProjection

Indications:Indications: Image of teeth, alveolar Image of teeth, alveolar

ridge and body of mandible.ridge and body of mandible.

Projection of Central Ray;Projection of Central Ray; Towards the molar- premolar Towards the molar- premolar

region from a point 2cm. region from a point 2cm. below the angle of mandible below the angle of mandible of opposite side. p218 11.6of opposite side. p218 11.6

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MANDIBULAR BODY PROJECTIONMANDIBULAR BODY PROJECTION

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Indications:Indications: To view third molar- retro-To view third molar- retro-

molar areamolar area Angle of mandibleAngle of mandible Ramus, andRamus, and Condylar head.Condylar head.

Projection of central ray:Projection of central ray: Towards the centre of the Towards the centre of the

imaged ramus, 2cm. below imaged ramus, 2cm. below the inferior border of the the inferior border of the opposite side of the mandible opposite side of the mandible at the area of first molar.at the area of first molar.

Mandibular Ramus Mandibular Ramus ProjectionProjection

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MANDIBULAR RAMUS PROJECTIONMANDIBULAR RAMUS PROJECTION

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TMJ PROJECTIONSTMJ PROJECTIONS Transcranial Projection.Transcranial Projection.

Transpharyngeal Projection.Transpharyngeal Projection.

Transorbital Projection. Transorbital Projection.

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TRANSCRANIAL PROJECTIONTRANSCRANIAL PROJECTION

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Projection of X-ray beam:Projection of X-ray beam:

Downward from the opposite side , through the Downward from the opposite side , through the cranium and above the petrous ridge of the cranium and above the petrous ridge of the temporal bone, at a 25temporal bone, at a 2500 positive angle centered positive angle centered through the joint.through the joint.


Identification of gross osseous changes on the Identification of gross osseous changes on the lateral aspect of the joint only.lateral aspect of the joint only.

Displaced condylar fractures.Displaced condylar fractures.

Range of condylar motion.Range of condylar motion.

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TRANSPHARYNGEAL ( PARMA) PROJECTIONTRANSPHARYNGEAL ( PARMA) PROJECTION

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Projection of X-ray beam:Projection of X-ray beam:

5500 through the sigmoid notch and 7 – 8 through the sigmoid notch and 7 – 800 from the from the anterior.anterior.


Helps visualizing erosive changes of the condyles.Helps visualizing erosive changes of the condyles.

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3. TRANSORBITAL PROJECTION3. TRANSORBITAL PROJECTIONProjection of Central Ray:Projection of Central Ray:

Downward 10Downward 1000 and 30 and 3000 laterally through the laterally through the ipsilateralipsilateral

orbit, so that centered over the TMJ.orbit, so that centered over the TMJ.


Helps viewing condylar neck fractures.Helps viewing condylar neck fractures.

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3. PANORAMIC IMAGING: 3. PANORAMIC IMAGING: PANTOMOGRAPHY.PANTOMOGRAPHY.

: DENTAL PANORAMIC TOMOGRAPHY. : DENTAL PANORAMIC TOMOGRAPHY.

The radiologic technique The radiologic technique used for producing a used for producing a single image of the single image of the facial structures that facial structures that includes both the includes both the maxillary and maxillary and mandibular dental mandibular dental arches and their arches and their supporting supporting structures.structures.

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Principle:Principle: The dental arch, though curved, is not the The dental arch, though curved, is not the shape of an arc of a circle.shape of an arc of a circle.

To produce the required elliptical, horse-shoe shaped To produce the required elliptical, horse-shoe shaped focal trough, panoramic imaging employs the focal trough, panoramic imaging employs the principle ofprinciple of narrow-beam rotational tomography narrow-beam rotational tomography while using two or more centers of rotation.while using two or more centers of rotation.

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Two stationary centers of rotationTwo stationary centers of rotation

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One centre of rotationOne centre of rotation

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SHIFTING CENTER OF ROTATIONSHIFTING CENTER OF ROTATION

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INDICATIONSINDICATIONS

To evaluate the trauma, third molars, extensive or To evaluate the trauma, third molars, extensive or unique pathoses, and their associated surgical unique pathoses, and their associated surgical procedures.procedures.

To evaluation tooth development.To evaluation tooth development.

To evaluate developmental anomalies.To evaluate developmental anomalies.

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CONTRA- INDICATIONSCONTRA- INDICATIONS Not suitable for diagnostic examinations requiring Not suitable for diagnostic examinations requiring

high image resolution.high image resolution.

When a full mouth set of radiographs is available for When a full mouth set of radiographs is available for a patient receiving a general screening examination.a patient receiving a general screening examination.

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PATIENT POSITIONING AND HEAD PATIENT POSITIONING AND HEAD ALIGNMENT PARAMETERSALIGNMENT PARAMETERS

The dental arches are located in the centre of focal The dental arches are located in the centre of focal trough.trough.

Place the incisal edges on a bite block.Place the incisal edges on a bite block.

The MSP must be in the exact center of the focal The MSP must be in the exact center of the focal trough.trough.

Patient’s occlusal plane is angled 20-30Patient’s occlusal plane is angled 20-3000 below the below the horizontal, and FHP is parallel to the floor.horizontal, and FHP is parallel to the floor.

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Advantages:Advantages: Broad coverage of the facial bones and teeth.

Low patient radiation dose.

Can be used in patients who are unable to open their mouth.

Less time consuming.

The image is easy for patients to understand, and is, The image is easy for patients to understand, and is, therefore, a useful teaching aid.therefore, a useful teaching aid.

Positioning is relatively simple and minimal Positioning is relatively simple and minimal expertise is required.expertise is required.

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Images do not show fine anatomic display.Images do not show fine anatomic display.

Structures or abnormalities not in the focal trough Structures or abnormalities not in the focal trough may not be evident.may not be evident.

Soft tissue and air shadows can overlie the required Soft tissue and air shadows can overlie the required hard tissue structures.hard tissue structures.

The tomographic movement, together with the The tomographic movement, together with the distance between the focal trough and film produce distance between the focal trough and film produce distortion and magnification of the final image.distortion and magnification of the final image.

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Recent Development :Recent Development :

A recent development in panoramic tomography is the ability to A recent development in panoramic tomography is the ability to programme the equipment to only X-ray certain parts of programme the equipment to only X-ray certain parts of the jaws ( the jaws ( segmental panoramic image)segmental panoramic image) when only specific when only specific information is required. information is required.

This leads to the significant reduction in radiation dose.This leads to the significant reduction in radiation dose.

It is the It is the ‘Field Limitation Technique’. ‘Field Limitation Technique’.

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SPECIALIZED RADIOGRAPHIC SPECIALIZED RADIOGRAPHIC TECHNIQUESTECHNIQUES

i.i. Electronic ThermographyElectronic Thermography

ii.ii. TomographyTomography

iii.iii. StereoscopyStereoscopy

iv.iv. ScanographyScanography

v.v. Digital radiographyDigital radiography Direct Digital RadiographyDirect Digital Radiography Indirect Digital RadiographyIndirect Digital Radiography Digital Subtraction RadiographyDigital Subtraction Radiography Digitized Image InterpretationDigitized Image Interpretation

vi.vi. Computed Tomography (CT SCAN)Computed Tomography (CT SCAN)

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vi.vi. Magnetic Resonance Imaging (MRI)Magnetic Resonance Imaging (MRI)

vii.vii. Ultrasonography (USG)Ultrasonography (USG)

viii.viii. Nuclear medicine (Scintigraphy)Nuclear medicine (Scintigraphy)

ix.ix. XeroradiographyXeroradiography

x.x. SialographySialography

xi.xi. ArthrographyArthrography

xii.xii. RadioVisioGraphy (RVG)RadioVisioGraphy (RVG)

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ELECTRONIC THERMOGRAPHYELECTRONIC THERMOGRAPHY““THERMOGRAPHY”-Methods of temperature pattern THERMOGRAPHY”-Methods of temperature pattern

resolution and analysisresolution and analysis

ABNORMAL TEMPERATURE PATTERNSABNORMAL TEMPERATURE PATTERNS Alteration in blood supplyAlteration in blood supply Presence of inflammationPresence of inflammation

SENSORSSENSORS ThermistorsThermistors Liquid crystalsLiquid crystals Infrared scanners (small tv cameras)Infrared scanners (small tv cameras)

PROTOTYPE MIGHT BE A USEFUL METHOD INPROTOTYPE MIGHT BE A USEFUL METHOD IN• Tooth’s vitality.Tooth’s vitality.• Atypical odontalgia.Atypical odontalgia.• Internal derangement of TMJInternal derangement of TMJ

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TOMOGRAPHYTOMOGRAPHY

TECHNIQUES-TECHNIQUES-To image more clearly To image more clearly

objects lying within a objects lying within a plane of interest.plane of interest.

-Process of “Motion -Process of “Motion Unsharpness”.Unsharpness”.

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TYPES OF TYPES OF TOMOGRAPHIC TOMOGRAPHIC MOVEMENTS MOVEMENTS

DISADVANTAGES OFDISADVANTAGES OFLINEAR TOMOGRAPHYLINEAR TOMOGRAPHY

- Streaked/ ’Parasitic Lines Streaked/ ’Parasitic Lines ’.’.

- No optimal blurring.No optimal blurring.

- Inconsistent magnification.- Inconsistent magnification.

Indications of TomographyIndications of Tomography

High contrast anatomy.High contrast anatomy.

TMJ.TMJ.

Dental implants.Dental implants.

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TOMOGRAPHIC LAYER ∞ ____TOMOGRAPHIC LAYER ∞ ____ 1______________1______________ TOMOGRAPHIC ANGLETOMOGRAPHIC ANGLE

WIDE ANGLE TOMOGRAPHYWIDE ANGLE TOMOGRAPHY

Uses >10Uses >100 0 angulation. angulation.

Layers as thin as 1mm can be imaged.Layers as thin as 1mm can be imaged.

Best used for studying dense tissues.Best used for studying dense tissues.

NARROW ANGLE TOMOGRAPHY (ZONOGRAPHY)NARROW ANGLE TOMOGRAPHY (ZONOGRAPHY)

Uses < 1OUses < 1O0 0 angulation. angulation.

Tissue thickness up to 25mm. is sharply imaged.Tissue thickness up to 25mm. is sharply imaged.

Best used for studying soft tissues.Best used for studying soft tissues.

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LINEAR TOMOGRAM OF TMJ SPIRAL TOMOGRAM LINEAR TOMOGRAM OF TMJ SPIRAL TOMOGRAM OF TMJOF TMJ

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XERORADIOGRAPHYXERORADIOGRAPHYTWO TYPESTWO TYPES

1- MEDICAL XRG SYSTEM : Mammography.1- MEDICAL XRG SYSTEM : Mammography. Cephalography.Cephalography.

2- DENTAL XRG SYSTEMS: Dental pathologies.2- DENTAL XRG SYSTEMS: Dental pathologies.

ADVANTAGESADVANTAGES

Pronounced edge enhancement.Pronounced edge enhancement.

A choice of positive and negative display.A choice of positive and negative display.

Good details.Good details.

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Wide exposure latitude.Wide exposure latitude.

No need of x-ray films.No need of x-ray films.

Less radiation required than e-speed films.Less radiation required than e-speed films.

DISADVANTAGESDISADVANTAGES

High cost.High cost.

Only marginally better images than conventional Only marginally better images than conventional radiography.radiography.

RECORDING MEDIA:RECORDING MEDIA:

Selenium plate - retains charge on it.Selenium plate - retains charge on it. is semiconductor.is semiconductor.

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MECHANISM MECHANISM

X-ray Exposure.X-ray Exposure.

Charge pattern Charge pattern on selenium on selenium coated plate.coated plate.

Lines of force Lines of force produced as a produced as a result of result of difference in difference in charge densities charge densities on plate surface.on plate surface.

Toner distribution Toner distribution on plate. on plate.

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NUCLEAR MEDICINENUCLEAR MEDICINESCINTIGRAPHY / RADIONUCLIDE SCINTIGRAPHY / RADIONUCLIDE

SCANSSCANSRADIOPHARMACEUTICLES-RADIOPHARMACEUTICLES- Radioactive elements or compoundsRadioactive elements or compounds 1818FF-, 99m-, 99mTcOTcO4-4- , , 113M113M In+++ In+++

Non radioactive carrier compoundsNon radioactive carrier compounds Labelled with a radioactive isotopeLabelled with a radioactive isotope 6767 Ga – labelled citrate. Ga – labelled citrate. 99 M99 M Tc – labelled polyphosphate. Tc – labelled polyphosphate. 125125 I – labelled human albumin. I – labelled human albumin. Of all, Of all, 99 M 99 M Tc is the most frequently used isotope.Tc is the most frequently used isotope.

RADIOACTIVE DETECTORS –RADIOACTIVE DETECTORS – Gamma cameras.Gamma cameras. Rectilinear scanner.Rectilinear scanner.

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PROCEDURE OF RADIONULIDE PROCEDURE OF RADIONULIDE IMAGINGIMAGING

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SODIUM IODIDE CRYSTAL SODIUM IODIDE CRYSTAL

Converts photon energy into fluorescent emission / Converts photon energy into fluorescent emission / scintillation.scintillation.

PHOTOMULTIPLIER TUBE PHOTOMULTIPLIER TUBE

Detects and amplifies the scintillations.Detects and amplifies the scintillations. Relays it to console.Relays it to console.

OSCILLOSCOPEOSCILLOSCOPE

Displays the emission patternDisplays the emission pattern Allows precise patient positioningAllows precise patient positioning

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The images are displayed on:The images are displayed on:

Polaroid Film: Low resolution images.Polaroid Film: Low resolution images.

White dots on a black background.White dots on a black background.

X-ray film – High resolution Images.X-ray film – High resolution Images.

Black dots on a white background.Black dots on a white background.

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Salivary Gland Scanning:Salivary Gland Scanning:

Dynamic Study:Dynamic Study:

Nose faces imaging head.Nose faces imaging head. 30- 120 s. images are taken.30- 120 s. images are taken. Yields information regarding vascularity.Yields information regarding vascularity.

Static Study:Static Study: 30-40 min.30-40 min. Head turned laterally.Head turned laterally. Demonstrates anatomy of salivary Glands and ability Demonstrates anatomy of salivary Glands and ability

to produce and secrete saliva.to produce and secrete saliva. Finally, 1% Citric acid given.Finally, 1% Citric acid given.

Demonstrates: Stimulated secretory capability.Demonstrates: Stimulated secretory capability.

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Indications and Interpretations:Indications and Interpretations:

Acute, Chronic Inflammations.Acute, Chronic Inflammations.

Tumors.Tumors.

Auto- Immune Diseases. Auto- Immune Diseases.

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Bone Scans:Bone Scans:

10- 15 mci 10- 15 mci 99m99mTcOTcO4-4- labelled phosphate compound labelled phosphate compound given i.v.given i.v.

Uptake ∞ quantity and rate of bone deposition.Uptake ∞ quantity and rate of bone deposition.

Uses:Uses: Bone grafts.Bone grafts. Extent of lesions and infections in jaws.Extent of lesions and infections in jaws. Planning of surgical margins.Planning of surgical margins. TMJ Diseases.TMJ Diseases. As a research tool.As a research tool.

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Tumor Scans:Tumor Scans:

99m99mTcOTcO4-4- cannot differentiate between Inflammation cannot differentiate between Inflammation and ‘Hot Spots’.and ‘Hot Spots’.

Overcome by the use of Galium citrate scans.Overcome by the use of Galium citrate scans.

Overall Advantages of Scintigraphy;Overall Advantages of Scintigraphy;

More sensitive to early changes than conventional More sensitive to early changes than conventional radiographs.radiographs.

Overall Disadvantages:Overall Disadvantages:

Poor image.Poor image. Not economical.Not economical. Radiation exposure is high.Radiation exposure is high. Confusion between neoplasia and inflammation.Confusion between neoplasia and inflammation.

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INCREASED UPTAKE OF RADIOISOTOPE IN INCREASED UPTAKE OF RADIOISOTOPE IN INFLAMMATORY REGIONS IN MAXILLA AND INFLAMMATORY REGIONS IN MAXILLA AND

MANDIBLEMANDIBLE

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COMPUTERIZED TOMOGRAPHYCOMPUTERIZED TOMOGRAPHY(CT SCAN)(CT SCAN)

INTRODUCTION:INTRODUCTION:

By Godfrey Housefield, 1972.By Godfrey Housefield, 1972.

Three important factors made CT possibleThree important factors made CT possible::

Scintillation of certain crystals sodium iodide and Scintillation of certain crystals sodium iodide and cesium iodide.cesium iodide.

Advent of electronics.Advent of electronics.

Revolution in computer sciences.Revolution in computer sciences.

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ADVANTAGES:ADVANTAGES: X-ray beam is limited to tissue section under study.X-ray beam is limited to tissue section under study.

- No scattered radiation produced, therefore no image - No scattered radiation produced, therefore no image degradation.degradation.

- X-ray detectors used in CT are highly efficient X-ray detectors used in CT are highly efficient collecting 100% of incident photons.collecting 100% of incident photons.

- Inherent noise in CT systems is less than 0.5 %Inherent noise in CT systems is less than 0.5 %

- Since image is recorded electronically, it can be Since image is recorded electronically, it can be displayed with wide range of contrast settings displayed with wide range of contrast settings without the need to repeat the scan.without the need to repeat the scan.

- Combining consecutive CT scans, a 3-D image of the - Combining consecutive CT scans, a 3-D image of the object can be accurately reconstructed.object can be accurately reconstructed.

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LIMITATIONS OF CT :LIMITATIONS OF CT :

Costly, expensive to maintain.Costly, expensive to maintain.

Number of patients that can be scanned per standard Number of patients that can be scanned per standard work day is limited.work day is limited.

Scan times are relatively long.Scan times are relatively long.

Motion of the structures during scanning will degrade Motion of the structures during scanning will degrade the image.the image.

Special artefacts are produced to high contrast Special artefacts are produced to high contrast discontinuities and peculiar curvilinear anatomic areas.discontinuities and peculiar curvilinear anatomic areas.

CT Scan is available only in axial planeCT Scan is available only in axial plane

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Uses of CT in maxillofacial region:Uses of CT in maxillofacial region:

To see anatomically precise location of the lesion and To see anatomically precise location of the lesion and extension and extension.extension and extension.

It is of unique value in delineating those lesions that It is of unique value in delineating those lesions that have both osseous and soft tissue extension. have both osseous and soft tissue extension.

Involvement of Infra-temporal, parapharyngeal Involvement of Infra-temporal, parapharyngeal spaces, skull base can be easily determined.spaces, skull base can be easily determined.

To distinguish between benign and malignant lesions.To distinguish between benign and malignant lesions.

To assess the extent of infection in maxillary facial To assess the extent of infection in maxillary facial region.region.

Using i.v contrast materials, sinus diseases are Using i.v contrast materials, sinus diseases are diagnosed.diagnosed.

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Improves staging of malignant tumors.Improves staging of malignant tumors.

To documents the results of irradiation and To documents the results of irradiation and chemotherapy.chemotherapy.

To locate the fractures precisely.To locate the fractures precisely.

To diagnose TMJ pathologies.To diagnose TMJ pathologies.

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X-RAY TUBEX-RAY TUBE

PATIENTPATIENT

SCINTILLATIONSCINTILLATION DETECTORDETECTOR

9999

36036000 rotation of scanner. rotation of scanner.One projection made every One projection made every 1/3 of a degree= 1080 1/3 of a degree= 1080

projections that make projections that make

1image1image Image matrix.Image matrix.

InterpolarationInterpolaration

3-D CT Image3-D CT Image

100100

pic in three sectionspic in three sections

101101

ULTRASONOGRAPHY (USG)ULTRASONOGRAPHY (USG)

Audible frequency – 1,500-20,000 Hz.Audible frequency – 1,500-20,000 Hz.

Diagnostic USG – 1-20 MHz.Diagnostic USG – 1-20 MHz.

Scannner generate electrical impulse.Scannner generate electrical impulse.

TRANSDUCERTRANSDUCER

Ultra- high frequency sound waves.Ultra- high frequency sound waves.

102102

TRANSDUCER – TRANSDUCER –

Most important component is a thin Most important component is a thin piezo - electrical crystal which is made up of a piezo - electrical crystal which is made up of a

great number of dipoles arranged in a great number of dipoles arranged in a geometric patterngeometric pattern

(most widely used dipole is PZT ).(most widely used dipole is PZT ).

It serves as both a transmitter and a receiver.It serves as both a transmitter and a receiver.

ACOUSTIC IMPEDENCE OF TISSUES = ACOUSTIC IMPEDENCE OF TISSUES = DENSITY X Beam angle of DENSITY X Beam angle of

incidence.incidence.

REAL TIME IMAGING.REAL TIME IMAGING.

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picpic

104104

MAGNETIC RESONANCE IMAGING MAGNETIC RESONANCE IMAGING ( MRI )( MRI )MRI uses non-ionizing radiation from the radio frequency MRI uses non-ionizing radiation from the radio frequency

band of the electromagnetic spectrum.band of the electromagnetic spectrum.

Indications:Indications: Assessment of intra-cranial lesion involving particularly Assessment of intra-cranial lesion involving particularly

the posterior cranial fossa, the pituitary and the spinal the posterior cranial fossa, the pituitary and the spinal cord.cord.

Tumor- staging: Evaluation of the site, size and extent Tumor- staging: Evaluation of the site, size and extent of all soft tissue tumors including nodal involvement of all soft tissue tumors including nodal involvement involving all areas in particular:involving all areas in particular:

salivary glands.salivary glands. tongue and floor of mouth.tongue and floor of mouth. pharynx and larynx.pharynx and larynx. sinuses.sinuses. orbits.orbits.

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Investigation of the Temporo-mandibular Joint to Investigation of the Temporo-mandibular Joint to show both the bony and the soft tissue components show both the bony and the soft tissue components of the joint including the disc position. MRI may be of the joint including the disc position. MRI may be indicated :indicated :

When diagnosis of internal derangement is in When diagnosis of internal derangement is in doubt.doubt.

As a pre-operative assessment before disc As a pre-operative assessment before disc surgery.surgery.

Implant assessment.Implant assessment.

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Ionizing radiation is not used.Ionizing radiation is not used.

No adverse effects.No adverse effects.

Image manipulation available.Image manipulation available.

High- resolution images can be constructed in all High- resolution images can be constructed in all planes ( using three dimensional volume techniques).planes ( using three dimensional volume techniques).

Excellent differentiation between different soft tissues Excellent differentiation between different soft tissues is possible and between normal and abnormal tissues, is possible and between normal and abnormal tissues, thereby, between benign and malignant disease and thereby, between benign and malignant disease and between recurrence and post-operative effects.between recurrence and post-operative effects.

Useful in determining intra-medullary spread. Useful in determining intra-medullary spread.

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Disadvantages:Disadvantages: Bone does not give an MR signal, a signal is only Bone does not give an MR signal, a signal is only

obtainable from bone marrow.obtainable from bone marrow.

Scanning time can be long and is thus demanding on Scanning time can be long and is thus demanding on the patient.the patient.

It is contra-indicated in patients with certain types of It is contra-indicated in patients with certain types of surgical clips, cardiac pace makers, cochlear surgical clips, cardiac pace makers, cochlear implants and in the first trimester of pregnancy.implants and in the first trimester of pregnancy.

Equipment tends to be claustrophobic and noisy.Equipment tends to be claustrophobic and noisy.

Metallic objects, eg. endotracheal tubes need to be Metallic objects, eg. endotracheal tubes need to be replaced by non- ferromagnetic alternatives.replaced by non- ferromagnetic alternatives.

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Equipment is expensive.Equipment is expensive.

The very powerful magnets can pose problem with The very powerful magnets can pose problem with siting of equipment.siting of equipment.

Bone, teeth , air and metallic objects all appear Bone, teeth , air and metallic objects all appear black making differentiation difficult.black making differentiation difficult.

109109

MAGNETIC RESONANCE IMAGE OF TMJMAGNETIC RESONANCE IMAGE OF TMJ

110110

DIGITAL RADIOGRAPHYDIGITAL RADIOGRAPHY

It allows for –It allows for –

Image acquistion.Image acquistion.

Manipulation.Manipulation. Storage.Storage.

Retrieval.Retrieval.

Transmission.Transmission.

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COMPONENTSCOMPONENTS Electronic sensor / detector (CCD / CMOS).Electronic sensor / detector (CCD / CMOS). Analog to digital converter (digitizer).Analog to digital converter (digitizer). A computer.A computer. Monitor / printer.Monitor / printer.

TYPES OF DIGITAL RADIOGRAPHY :TYPES OF DIGITAL RADIOGRAPHY : Direct Digital Radiography (RVG).Direct Digital Radiography (RVG).

Indirect Digital Radiography.Indirect Digital Radiography.

Digital Subtraction Radiography.Digital Subtraction Radiography.

Digitized Image Interpretation.Digitized Image Interpretation.

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DIGITAL IMAGE ACQUISTION AND DISPLAYDIGITAL IMAGE ACQUISTION AND DISPLAYImage from radiographic film. Detector ( CCD) Image from radiographic film. Detector ( CCD)

captured captured Image.Image.

Analog Output Signal.Analog Output Signal.

Digitised in the Computer ( 256 shades of gray ).Digitised in the Computer ( 256 shades of gray ).

Storage. Printout. Transmission.Storage. Printout. Transmission.

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DIGITIZATIONDIGITIZATION Digitizer measures the voltage of the analog output Digitizer measures the voltage of the analog output

signal and assigns a number from 0 to 256 , signal and assigns a number from 0 to 256 , according to the intensity of voltageaccording to the intensity of voltage

The 256 voltage levels are displayed on the screen The 256 voltage levels are displayed on the screen as 256 shades of gray .as 256 shades of gray .

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DIRECT DIGITAL RADIOGRAPHY (RVG )DIRECT DIGITAL RADIOGRAPHY (RVG )

““Radio” : Radio” : X-ray unit and Image detector ( CCD ).X-ray unit and Image detector ( CCD ).

““Visio” : Visio” : Converts the output signal from CCD to a Converts the output signal from CCD to a digital system that is recognizable by the computer.digital system that is recognizable by the computer.

“ “ Graphy” : Graphy” : Data storage unit and a printer.Data storage unit and a printer.

Advantages:Advantages: Immediate image display.Immediate image display.

Ability to manage image contrast and density.Ability to manage image contrast and density.

Significant dose reduction as compared to direct Significant dose reduction as compared to direct exposure films.exposure films.

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Decreased image resolution and contrast as Decreased image resolution and contrast as compared to film radiology.compared to film radiology.

Expensive.Expensive.


Detection of periodontal bone loss.Detection of periodontal bone loss.

Detection of early or incipient caries.Detection of early or incipient caries.

During Root Canal Treatment.During Root Canal Treatment.

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INDIRECT DIGITAL RADIOGRAPHYINDIRECT DIGITAL RADIOGRAPHYScanner or photomultiplier tube or video Scanner or photomultiplier tube or video

camera.camera.

Advantages:Advantages: Ability to manipulate digitized image: Optimum Ability to manipulate digitized image: Optimum

contrast and density can be obtained.contrast and density can be obtained.

Allows for storage and transmission.Allows for storage and transmission.


May result in loss of information during processing May result in loss of information during processing (scanning).(scanning).

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DIGITAL SUBTRACTION RADIOGRAPHYDIGITAL SUBTRACTION RADIOGRAPHYApplications:Applications: Early diagnosis of minute periodontal defect and Early diagnosis of minute periodontal defect and

carious lesions.carious lesions.

Evaluation of early changes in mandibular condyle Evaluation of early changes in mandibular condyle position and integrity of articular surface.position and integrity of articular surface.

Assessment of osseous remodelling around implants.Assessment of osseous remodelling around implants.

Advantages:Advantages: Very sensitive to detect even minute change Very sensitive to detect even minute change

of .12mm.of .12mm.

Contrast can be further enhanced with colour.Contrast can be further enhanced with colour.

Disadvantages:Disadvantages: Demands for identical alignment of X-ray tube, film Demands for identical alignment of X-ray tube, film

and patient position for two exposures.and patient position for two exposures.

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STEREOSCOPYSTEREOSCOPY

Invented byInvented by J. Mackenzie Davidson in 1898.

Principle:Principle:

Uses stereoscope that uses mirrors or prisms to Uses stereoscope that uses mirrors or prisms to coordinate the accomodation and convergence of coordinate the accomodation and convergence of the viewer’s eyes so that brain can fuse the two the viewer’s eyes so that brain can fuse the two images. images.

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Evaluation of bony pockets.Evaluation of bony pockets.

Determination of root configurations of teeth that Determination of root configurations of teeth that require endodontic therapy.require endodontic therapy.

Assessment of the relationship of the mandibular Assessment of the relationship of the mandibular canal to the roots of unerupted mandibular third canal to the roots of unerupted mandibular third molars.molars.

Assessment of bone shape, when placement of Assessment of bone shape, when placement of dental implants is considered.dental implants is considered.

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Advantages:Advantages: Educational value.Educational value.

Understanding of normal anatomy is simplified.Understanding of normal anatomy is simplified.

Location of small intra-canal calcifications and multiple Location of small intra-canal calcifications and multiple foreign bodies in dense or thick body sections.foreign bodies in dense or thick body sections.

To evaluate the relationships margins of bony fractures.To evaluate the relationships margins of bony fractures.

Disadvantages:Disadvantages: High radiation exposure.High radiation exposure.

Long patient positioning. Long patient positioning.

More time consuming.More time consuming.

121121

SCANOGRAPHYSCANOGRAPHYPrinciple:Principle:Uses a narrow, collimated, fan- shaped beam of radiation Uses a narrow, collimated, fan- shaped beam of radiation

to scan an area of interest, sequentially producing to scan an area of interest, sequentially producing image data relative to this area on to moving film, image data relative to this area on to moving film, much the same as in panoramic radiography.much the same as in panoramic radiography.

Advantages:Advantages: Higher contrast with perception of greater detail Higher contrast with perception of greater detail

since collimation of beam reduces the amount of since collimation of beam reduces the amount of radiation scattered to the film during exposure.radiation scattered to the film during exposure.

eg. Soredex.eg. Soredex. Scanora.Scanora.

Perform both rotational and linear scanography.Perform both rotational and linear scanography.

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ROTATIONAL SCANOGRAPHY:ROTATIONAL SCANOGRAPHY: The beam of radiation rotates about a fixed axis that isThe beam of radiation rotates about a fixed axis that is pre-determined based on the area to be imaged.pre-determined based on the area to be imaged.

It produces two or four scanograms.It produces two or four scanograms. Multiple images are produced. Any two can be used as Multiple images are produced. Any two can be used as stereoscopic pairs.stereoscopic pairs.

LINEAR SCANOGRAPHY:LINEAR SCANOGRAPHY: The X-ray film and scanner move in a linear fashion, The X-ray film and scanner move in a linear fashion, thereby, scanning the area of interest.thereby, scanning the area of interest.

It is similar to ‘Straightened out’ OPG.It is similar to ‘Straightened out’ OPG.

Capable of both P-A and lateral linear scanning pf theCapable of both P-A and lateral linear scanning pf the maxillary facial complex.maxillary facial complex.

More optimal image contrast is produced.More optimal image contrast is produced.

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ARTHROGRAPHYARTHROGRAPHY PrinciPrincipple:le: Technique in which an Technique in which an

indirect image of indirect image of the disk is obtained the disk is obtained by injecting a by injecting a radiopaque radiopaque contrast agent into contrast agent into one or both joint one or both joint spaces under spaces under fluoroscopic fluoroscopic guidance during guidance during open and closing open and closing movements.movements.

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Indication:Indication:

To assess disk position, function and morphology To assess disk position, function and morphology and integrity of diskal attachments .and integrity of diskal attachments .


The procedure is invasive.The procedure is invasive.

There may be allergy to non-ionic iodine contrast There may be allergy to non-ionic iodine contrast agent and infection.agent and infection.

Post-operative discomfort. Post-operative discomfort.

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SIALOGRAPHYSIALOGRAPHYA radiographic technique wherein radiopaque A radiographic technique wherein radiopaque

conttrastagent is infused into the ductal system of a conttrastagent is infused into the ductal system of a salivary gland before imaging.salivary gland before imaging.

Armamentarium:Armamentarium: Lacrimal probe.Lacrimal probe. Canula.Canula. Disposable syringe.Disposable syringe.

Contrast Agents:Contrast Agents: Lipid soluble : eg. Ethoidal .Lipid soluble : eg. Ethoidal . Lipid- insoluble: eg. Sinografin. Lipid- insoluble: eg. Sinografin.

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To evaluate chronic inflammatory diseases of To evaluate chronic inflammatory diseases of salivary glands.salivary glands.

To evaluate any ductal pathoses.To evaluate any ductal pathoses.

To detect any tumor in salivary duct.To detect any tumor in salivary duct.

Contra- indications:Contra- indications:

Any Acute infection of salivary gland .Any Acute infection of salivary gland .

Any known sensitivity to iodine.Any known sensitivity to iodine.

Immediately anticipated thyroid function tests.Immediately anticipated thyroid function tests.

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If a patient has to undergo both ‘Sialography’ and If a patient has to undergo both ‘Sialography’ and ‘Scintigraphy’, he should first be imaged for ‘Scintigraphy’, he should first be imaged for ‘Scintigraphy’, since, intra-venous injection of ‘Scintigraphy’, since, intra-venous injection of dye may inflame the ducts and ductal dye may inflame the ducts and ductal epithelium is liable to rupture and spill the dye epithelium is liable to rupture and spill the dye to the salivary gland.to the salivary gland.

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CONCLUSIONCONCLUSION With the advent of science and technology, recent With the advent of science and technology, recent advances have been done in the field of dental advances have been done in the field of dental

radiology. But, due to lower socio-economy, radiology. But, due to lower socio-economy, conventional radiography that makes use of conventional radiography that makes use of radiographic films is used .radiographic films is used .

Hence, there is need to develop imaging systems Hence, there is need to develop imaging systems that combine simple technique and equipment while that combine simple technique and equipment while maintaining quality and infection control at maintaining quality and infection control at reasonable costs.reasonable costs.

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REFERENCESREFERENCES White and Pharoah, Oral Radiology: Principles and White and Pharoah, Oral Radiology: Principles and

Interpretation, 5Interpretation, 5thth. edn., Mosby Publications.. edn., Mosby Publications.

Eric Whaites, Essentials of Oral Radiology, 2Eric Whaites, Essentials of Oral Radiology, 2ndnd edn., edn., Mosby Publications.Mosby Publications.

Anil Govindrao Ghom, Text Book of Oral Medicine, 5Anil Govindrao Ghom, Text Book of Oral Medicine, 5thth edn., Jaypee Publishers.edn., Jaypee Publishers.

J. Oral Surg. Oral Med. Endodont. Radiol, 1999, Vol. J. Oral Surg. Oral Med. Endodont. Radiol, 1999, Vol. 88, 100-104.88, 100-104.

J. Oral Surg. Oral Med. Endodont. Radiol, 2002, Vol. J. Oral Surg. Oral Med. Endodont. Radiol, 2002, Vol. 94, 131-135.94, 131-135.

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J. Oral Surg. Oral Med. Endodont. Radiol.,2004, Vol. 33 3A, 408-412.

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Imaging Systems