牙科放射線學 (1) 陳玉昆副教授 : 高雄醫學大學口腔病理科 07-3121101~2755...

牙科放射線學 (1)

陳玉昆副教授 : 高雄醫學大學口腔病理科 07-3121101~2755 [email protected]

Panoramic Radiography (1) (2)

環口放射線攝影術 (1) (2)

Historical Aspect

Theory of Tomographic Movement

Concept of Rotation Center & Focal Trough

Kinds of Image on Panorex

Role of Dentist to Detect Carotid Atherosclerosis on PanorexNormal Structures on Panorex

Common & Position Errors on Panorex

學習目標學習目標

1. Eric Whaites: Essentials of dental radiography & radiology 3rd edition, Chapter 14-15, p. 153-76.2. White & Pharoah: Oral radiology: principle & interpretation, 5th edition, Chapter 10, p. 191-209

參考資料 (1)

3. Kaugars GE et al. Panoramic ghosts. Oral Surg Oral Med Oral Pathol 1987;63:103-84. Mason RA. Sydney Blackman 1898 – 1971 A pioneer of panoramic radiography. Dent Maxillofac Radiol 1998;27:371-55. Monsour PA. et al. Panoramic ghost images as an aid in the localization of soft tissue calcifications. Oral Surg Oral Med Oral Pathol 1990;69:748-56 6. Brown RS et al. Synthetic hair braid extension artifacts in panoramic radiographs. JADA 1998;129:601-47. Aydin U. Tuberculous lymph node calcification detected on routine panoramic radiography: a case report. Dent Maxillofac Radiol 2003;32:252-4

8. Reuter I et al. Triple images on panoramic radiographs Dent Maxillofac Radiol 1999;28:316-9 9. Kaohsiung Medical University Oral Pathology

10. McDavid W et al. Real, double, and ghost images in rotational panoramic radiography. Dentomaxillofac Radiol 1983;12:122-811. Scheifele C. Hair artefacts in the head and neck region. Dentomaxillofac Radiol 2003;32:255-7

參考資料 (2)

12. Farman AF et al. The role of the dentist in detection of carotid atherosclerosis. S Afr Dent J 2001;56:549-5313. Eric Whaites: Essentials of dental radiography & radiology 4th edition, 2007, p. 198-9. 14. João César Guimarães Henriques et al. Panoramic radiography in the diagnosis of carotid artery atheromas and the associated risk factors. The Open Dentistry Journal, 2011, 5, 79-83

15. Sansare K et al. Oral tuberculosis: unusual radiographic findings. Dentomaxillofac Radiol 2011;40:251-6

Historical AspectSydney Blackman 1898-1971

A pioneer of panoramic radiography

Sydney Blackman 1898-1971A pioneer of panoramic radiography

Ref. 4

Examples of Panorex Obtained With The Rotograph

Multiple unerupted teeth in an 8-yr old childMultiple unerupted teeth in an 8-yr old child

Developing dentition in a 13-yr old childDeveloping dentition in a 13-yr old child

Ref. 4


Types of Tomographic Movement1. Linear: Thin x-ray beam Broad x-ray beam2. Circular3. Ellipical4. Spiral5. Hypocycloidal

Linear: thin x-ray beam

Direction of movement of the film

Direction of movement of x-ray tubehead

Points A-F all appear on different parts of the film and are blurred out

Point O, centre of rotation, appears in the same placeon the film throughout the exposure and is sharply defined

Linear: broad x-ray beam

X-ray tube-head

Film

Multiple center of rotations

Zone within the focal plane(section of the patient):sharply defined on film

Start

Start

Start

Start

Finish

Finish

Finish

FinishRef. 1

Width of Focal Plane: Amount of movement (angle of swing)

Large movement

Thin focal plane

Small movement

Thick focal plane

Ref. 1

Film plane and direction of film travel

Direction of X-ray tube travel

Object plane

Rotation center

BlurredSection in focusBlurred

Linear Tomographic Principle –Section in Focus

Ref. 10

Hypocycloidal

Circular / Elliptical

Spiral

Different Types of Tomography

Ref. 1

【數學】圓內旋輪線，內擺線【數學】圓內旋輪線，內擺線

Start

Finish

Tubehead orbitsbehind the head

Tubehead orbitsbehind the head

Cassette carrierorbits in front ofthe face

Cassette carrierorbits in front ofthe face

Film movesinside thecassette carrier

Rotation Center

Refs. 1, 3

X-ray source

Cassettecarrier

Beam

Film insidecassettecarrier self orbit

Various Types of Rotation Center

2 stationary 3 stationary

Continuallymoving

3 stationary &moving

Continuous mode

Continuous modeContinuous mode

Split mode

Ref. 1

X-raysource

Shifting center

X-raysource

Shifting center

Shifting Rotation Centers

Film

Film

Ref. 2


Ref. 1

Cassette carrierorbits around the front of the face

The filmalso starts

to move

Start

Shi

ftin

g ce

nter

s

The entire filmhas been exposed

Finish

Shifting centers

Continuous mode

Split modeThe entire film

has been exposed

Finish

Shifting centers

Cassette carrierorbits around the front of the face

The filmalso starts

to move

Start

Shi

ftin

g ce

nter

sR L

Ref. 1


3D focal trough

x = Height of x-ray beam (collimation)f = Height of filmd = Distance between focal trough & film

Upward angulationFinal image is slightlymagnified

Collimation

3D focal trough

Focal Trough

Film

Refs. 1, 2, 3

X-ray source Rotation center Film

In focus 的區域 (focal trough)

In front of focal trough

Behindfocal trough

Patient is placedasymmetrically to the machine

Impaction canbe seen

Impactioncannotbe seen

Vertical wall of focal trough in incisor region

Class I Class II Class III

Shaded area outside focal trough is out of focus and will be blurred

Different shapes of focal trough

Refs. 1, 3

Different Shapes of Focal Trough

X-ray source

cassette

Cassettecarrier

Orbit

Orbitbehindpatient

Orbitbeforepatient

Cassettewith filminside

Cassettecarrier

Refs. 10, catalogue of manufacturer

Example of Panorex Machine

Control panel

X-raysource

3D focal trough

F-H plane

AnteriorBite block

Refs. 10, catalogue of manufacturer

Example of Panorex Machine

Kinds of Image Real (primary) imageDouble real (lateral) imageGhost (secondary) imageTriple image

Real (Primary) image:When the object is located between the rotation center and the film(within the focal troughwith minimal unsharpness& distortion)

Object

X-raysource

Realimage

Rotationcenter

Film

Ref. 10

Split movement patternContinuous movement pattern

Real image zoneReal image zone

Midline object

Always blurred becausecorresponding to a region between rotation center &central plane of layer

May not be blurred sincecorresponding to a region include the sharply depictedplane in anterior region

Double image

Ref. 10

Real (Primary) Image

Double image of nasal gastric tube

Refs. 9, 10

Double (Real) Lateral Image

Ghostimage

X-raysource

Object

Rotationcenter

Film Ghost (Secondary) image:When the object is located between the rotation center & the x-ray source(outside the focal troughwith unsharpness anddistortion; the closer therotation center, the moredistortion of the image)

Ref. 10

Ghost (Secondary) Image

Continuous movement pattern

Ghost envelope Composite

Split movement pattern

Ghost envelope Composite

Orthopantomograph-5 Panelipse

3 D ghost envelope

Panorex

3 D ghost envelope

Split movement pattern

3 D ghost envelope

Refs. 3, 5, 10

Ghost Envelope

Half dry skull

Real image

R

Ghost image

Curved x-ray film

Ghostimage

X-raysource

Rotationcenter

Refs. 1, 10

Ghost Image (1)

Midlinechain

Refs. 9, 10

Ghost Image (2)

Cervical spine

Cervical spine

Bilateral double real

Central ghost

Bilateral double real + Central ghost = Triple images

Film

Film

Rotation center Position 1

Position 2

X-raysource

G

R

G

R

G

R

X-raysource

R: In the real image zone moves in the same direction as the film

G: In the ghost image zone moves in the opposite direction as the film

Image is extremely blurred

Blurring of Ghost Image

Ref. 10

Distance from the x-ray source (mm)

x-ray sourceRotation

centerCentral planeof the layer

Film

0 100 200 300 400 500

1

0

2

3

4

5

Ghostimage

Realimage

Verticalmagnification

Horizontalmagnification

Horizontalmagnification

Vertical magnification= Horizontal magnificationM

agn

ific

atio

n f

acto

r

Magnification of Panorex

Refs. 3, 10

Summaries of Ghost Image1. The object is dense enough to block radiation2. It is located outside focal trough3. It is located inside ghost envelope

Ref. 3

1. It will always be distorted, especially the horizontal component.2. In most cases, it will be seen

radiographically at a higher location than the primary object.

3. It may not been seen on a clinical radiograph if superimposed over areas of dense anatomy.

4. It may appear even if the primary object is not seen on the radiograph.

5. It will always have some degree of radiopacity.

Characteristics of a Ghost Image:

6. Pronounced horizontal blurring indicates that the primary object was at or close to

center of rotation.7. It is reversed when compared with the

primary image.8. It can be caused by physical objects such

as earrings, a napkin chain, a necklace, a zipper on a pullover sweater, amalgam restorations or crowns, and radon or radium implants.

9. It can be caused by anatomic structures, such as the body & ramus of the mandible or cervical vertebrae.

10. It can be caused by parts of panoramic machine such as the chin rest or the letters R & L on the head positioner.

11. It can be pathologic (e.g. a sialolith or an impacted third molar).

Ref. 13

Cervicalvertebrae

Cervicalvertebrae

RamusRamus

PalatePalate

Summaries of Ghost Image

Ref. 13

Ramus(real image)

Ramus(real image)

Ramus(ghost image)

Ramus(ghost image)

RR LL

Summaries of Ghost Image

Basic Principle:Location and appearance of ghost images shown on thepanoramic radiograph can provideinformation of the soft tissuecalcifications or predict thelocations of the soft tissuecalcifications

Ghost Images as an Aid to Localize Soft Tissue Calcifications

Ghost Images as an Aid to Localize Soft Tissue Calcifications

Location of lead sphere Ghost imageOcclusal view Lateral view

Central ghost

g

Object is along the median plane

Ref. 5

No ghost image

No ghost image

No ghost image

Object is buccal or lingual to mandibular body

Ghost image appearance

Occlusal view

Location of lead sphere

Lateral view

Ref. 5

No ghost image

No ghost image

No ghost image

Location of lead sphere Ghost image

Occlusal view Lateral view

Object is inferior to ramus

Ghost image

Ref. 5

No ghost image

No ghost image

Location of lead sphere Ghost imageLateral viewOcclusal view

Object is posterior to condyle

Ghost image

Ghost image

Ref. 5

Object is lateral or medial of ramus Ghost image Location of lead sphere

Occlusal view Lateral view

Ghost image

Ghost image

Ghost image

Double primaryimage

Ref. 5

Triple Image

Ref. 8

Retained foreign body(shrapnel)

Ghost imageGhost image

Real imageReal image

Position of primary object did not change; creation of a triple image is due to slight differences in patient positioning

Triple image

Real imageReal imageGhost imageGhost image

2 Ghost images2 Ghost imagesReal imageReal image

Positions of Object ShowingTriple Image

Position 1 Position 2



Triple image

Triple imageTriple imagea: X-ray beamb (yellow arrows): direction of tube movementc: path of rotation centerd: center of image layer

a: X-ray beamb (yellow arrows): direction of tube movementc: path of rotation centerd: center of image layer

Ref. 8Ref. 8

Triple image

Positions of Objects Showing I, II & III Images

Ref. 8

Center of rotation

Left Right

Diagram showing the areas where the test object is portrayed once (IA, IB), twice (II) and thrice (III). The solid white line indicates the path of rotation center & the dotted line the center of image layers

I A

I B

II

III

II

I A

II

IB

III

R

R

RL

L

L

LR

Diagram showing the location of the 1, 2 & 3 images & the extent of distortion of the test object in relation to regions IA, B, II & III. The path of rotation center is shown as a solid white line. Note how triple images are generated in region III

Positions of Object is Related to the Formationof Single, Double and Triple Images

Triple image:

One real & two ghostimages (diamond-shaped area immediatelydistal to path ofrotation of center)Two lateral real andone central ghostimages(cervical spine)

a b c

1 x2 x3 x

Ref. 8

(a) X-ray beam moves from its starting point to the anterior rotation center creates a single (1x) & an initial double (2x) image

(b) Moves around the anterior center creates single (1x) & double images (2x) of objects in the central region

(c) Moves from the anterior rotation center to the end of tube movement completes the formation of lateral images (2x) & also portrays the central region for a third time (3x)

(a) X-ray beam moves from its starting point to the anterior rotation center creates a single (1x) & an initial double (2x) image

(b) Moves around the anterior center creates single (1x) & double images (2x) of objects in the central region

(c) Moves from the anterior rotation center to the end of tube movement completes the formation of lateral images (2x) & also portrays the central region for a third time (3x)

Role of Dentist to Detect Carotid Atherosclerosis

Atheroma ： Calcified plaques especially composed of lipids and fibrous tissue deposited on the walls of blood vessels trigger atherosclerosis.

Atherosclerosis ： A chronic inflammatory disease of an immunological nature, characterized by thickening and loss of elasticity of the arterial walls, associated with the presence of atheromas.

Atheroma ： Calcified plaques especially composed of lipids and fibrous tissue deposited on the walls of blood vessels trigger atherosclerosis.

Atherosclerosis ： A chronic inflammatory disease of an immunological nature, characterized by thickening and loss of elasticity of the arterial walls, associated with the presence of atheromas.

Development of Atherosclerosis

Development of atherosclerosis:(A) Cross sectional cut of the artery when it was still whole(B) Initial injury of the endothelium(C) The atheromatous plaque formed(D) A thrombus associated with the plaque, completely obstructing the hollow passage of the vessel

Ref. 14

(A) (B)

(C) (D)

Effect of Carotid Atherosclerosis

*When affect the carotids (supply the brain) strokes *When affect the coronary (supply the heart) myocardial infarction*Result in the death of thousands of people all over the world

Ref. 14

Blood clot

Fattydeposits

Internalcarotidartery

Commoncarotidartery

Cerebralarteries

Blood supply from the heart

Diagrammatic Illustration of Panorexof Cartoid Atherosclerosis (1)

Ref. 14

A

C1 C1

C2 C2

C3 C3

C4 C4

Why is PANOREX?1. Low radiation doses, low cost and has technical simplicity2. Normally deposited along the ascendant trajectory of the common carotid artery that bifurcates into internal and external carotid arteries comprised within the area of coverage of panoramic radiography

Carotid atherosclerosis

Atheroscleroticcalcifiesthat can be seen on panorex

angle ofmandible

externalcarotidartery

hyoid

internalcarotidartery

atheroma

commoncarotidartery

bifurcation

Ref. 12

Diagrammatic Illustration of Panorexof Cartoid Atherosclerosis (2)

Ref. 14

Some Examples (1)

BB

Ref. 14

Some Examples (2)

C

Some Examples (3)

Ref. 12

Calcified carotid atheroma (arrow)

Calcified atheromas of carotid artery bifurcation (arrows)

More Example (1)

Ref. 12

Bilateral carotid atherosclerosis Upper arrow on the right shows a calcified triticeous cartilage

Calcified atheromatous plaque (arrow)

More Example (2)

Ref. 7

A carotid plaque (arrows) visible in the left neck inferior & posterior to the angle of the mandible

More Example (3)

Ref. 7

Small carotid plaque (arrows) visible in the right & left neck, inferior & posterior to the angle of the mandible

Refs. 12, 14

Differentiate with Structures in Vicinity

Triticeous (triticeal) cartilageHomogeneous RO when calcified- Regular oval shapes - ~2-4mm wide, 7-9mm long - Superimposed on the airspace of pharynx - Close to superior portion of C4

Care needs to be taken to differentiate between calcified atheroma & other structures in vicinity that can also calcify (thyroid cartilage, thyroid gland, triticeous cartilage, epiglottis)

Refs. 12, 14

Differentiate with Structures in Vicinity

The best way to differentiate: PA radiograph taken by means of Modified Towne techniqueAtheromas dispose laterally to the vertebrae, whereas the triticeal cartilages (a more medial localization) will not be observed (superimposed on the spinal column)

Phleboliths in patientswith sclerosing hemangioma

The calcifications are notcarotid calcifications &should be differentiatefrom carotid calcification

Ref. 12

Differentiate with Venous Calcification

Ref. 9

More Example for Phlebolith

Calcified Lymph NodeShown on Panorex

Ref. 7

R

L

Carotid atheroma

Ghost imageCalcifiedlymph node

Organ Systems Frequently Affected in Extrapulmonary Tuberculosis

Ref. 7

Site Lymph nodes (13 - a85%)Pleura (9-77%)Genitourinary system (a2 - 74%)Central nervous system (1 - b36%)Bones and joints (a2 - 17%)Gastrointestinal system (a9 - 16%)Disseminated tuberculosis (7, 12%)Pericardium (1 - 6%)Peritoneum (4%)

aIn surgical specimensbIncluding spinal/vertebral tuberculosis

Extrapulmonary Tuberculosis -Jaw Bones & TMJ

Ref. 15

Resorption of condylar process

Extrapulmonary Tuberculosis -Jaw Bones & TMJ

Ref. 15

Resorption of angle of mandible

Diffuse area of rarefaction in the mandible near the extraction socket

Ref. 7

Differential Diagnosis ofProjected Radiopacities

1. Lymph node calcification2. Sialolith3. Radiopaque lesions of the bone (when

superimposed to mandible)4. Superimposed myositis ossificans5. Idiopathic calcification6. Ghost images7. Foreign bodies8. Carotid atheromas9. Calcified stylohyoid ligament complex10. Tonsillithiasis11. Phleboliths

Normal Structures (1)

Ref. 2


Zygmatic arch

HyoidboneRef. 2


Dorsum of tongue Soft palateEarlobe

Ref. 2

Various Landmarks on Panorex (1)

Ref. 2

Various Landmarks on Panorex (2)

Ref. 2

Earring

Earring

Common Errors

Necklace

Metal plates

Denture

Orthodontic appliance

Lead apron

Ref. 1

Hair Artifact

Ref. 11

Hair Braid Artifact

Ref. 6

A: synthetic hair braid extension artifactsB: Nose ring artifact

Hair Braid Artifact

Ref. 6

A: synthetic hair braid extension artifacts

Metal Artifact

Ref. 9

Position Error

Ref. 1

Positioning error Film fault

Patient too far from the film

Patient too close to the film

Patient positionedasymmetrically (headturned to the right or left)

Patient‘ s chin positioned too high or too low

Anterior teeth magnifiedin width & out of focus

Anterior teeth narrowed& out of focus

Posterior teeth enlarged onone side & reduced onthe other

Distortion in the shape ofthe mandible & the anterior teeth out of focus

Refs. 1, 9

Positioning error Film fault

Patient positionedasymmetrically (headturned to the right or left

Patient still wearing earrings,jewellery, dentures or orthodontic appliances

Failure to instruct the patientto keep still throughout thecycle

Posterior teeth enlarged onone side and reduced onthe other

Artefactual shadow(s) ofthe offending object

Vertical or horizontaldistortion of the part of theimage being produced atthe time of the movement

Position Error

Historical Aspect


Concept of Rotation Center & Focal Trough

Kinds of Image on Panorex

Normal Structures on Panorex

Common & Position Errors on Panorex

Knowing:Knowing:

Role of Dentist to Detect Carotid Atherosclerosis on Panorex

謝謝

牙科放射線學 (1) 陳玉昆副教授 : 高雄醫學大學 口腔病理科 07-3121101~2755...

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牙科放射線學 (1) 陳玉昆副教授 : 高雄醫學大學口腔病理科 07-3121101~2755...