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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 [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
Theory of Tomographic Movement
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
Shifting Rotation Centers
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
Shifting Rotation Centers
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 ¢ral 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
Position 3 Position 4
Position 5 Position 6
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
Normal Structures (2)
Zygmatic arch
HyoidboneRef. 2
Normal Structures (3)
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
Theory of Tomographic Movement
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
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