RADIOLOGY: Recent Episodes
Dr.Mayakha Mariam
RADIATION PHYSICS
Cathode
Both made of tungsten *
Anode
Xray produced at anode by an effect called BRHAMSTALUNG effect or CHRACTERISTIC EFFECT (interaction of high speed with tungsten nuclei)
FLITER
Filters away the low energy x-rays
Made of Aluminium
From x-ray cone
COLLIMATOR
Absorbs X-rays in unwanted direction
Made of lead
Circular tube
Rectangular collimator is best due to less patient exposure = 7mm diameter QN
LESS EXPOSURE FACTOR FOR PATIENT
Decrease current decrease Time
Increase KVP (potential) (kilovolt potential)
If Kvp increased – speed of e increses and more energy photons are formed, thus penetrate the body creating images
INTENSIFYING SCREENS
Decreases patient exposure , but decreases film contrast
∴ contraindicated intraorally (IOPA)
- made of rare earth material QN
FACTORS DECREASING XRAY EXPOSURE TO TRACHEA
Lead apron
Thyroid collar
Position — distance rule
6 feet away position (5 ft for cephalometry)
How to increase the image quality – increase the distance between object & the cone
90° - 130° angle
ALARA – As Low As Reasonably Achievable
C/F SEEN INTRA ORALLY — AS AFTER EFFECT OF RADIATION
1. Mucositis – inflammation of mucosa
2. Radiation caries – mainly due to radiation injury to parotid gland, causing smooth surface caries due to xerostomia
3. c/f –
— blackish discolouration of crown
--- affects labial + lingual surface of all teeth +cervical third
— patient also gives h/s of cancer – suspect radiation therapy
Rx – 1% NaF every day QN
Preventive method done soon after radiation
TYPES OF RADIOGRAPHY
IOPA
Intra – oral periapical radiograph
Function – to determine
o Working length
o Periapical pathosis QN
o External root resorption
Commonly used size – size 2
In anterior teeth – proximal caries – IOPA is used QN
If improper horizontal angulation – OVERLAPPING PROXIMAL SURFACES
BISECTING ANGLE
The film is placed as close as possible to the surface.
Central ray is directed perpendicular to the imaginary bisector.
Advantage – shorter exposure time, more patient acceptance cos we don’t need a beam aligner ring.
Disadvatage – image distortion/ magnification is possible. Angulation problems maybe, coz beam aligner right.
PARALELLING BEAM
It is easy to place using a film holder.
Central ray is perpendicular to both recptor & long axis of the tooth.
To maintain the parallelism between the object & the film, - INCREASE TARGET TO OBJECT DISTANCE *
Advantage – more accurate & Simplicity (no extra calculations required)
Disadvantages – patient discomfort.
BITE WING
Function – proximal caries best detected by bitwing – post (whereas anterior proximal caries best – IOPA) *
Vertical angulation for a bitewing radiograph is: 10 degree downward.
Determination of 2° caries
Crest of interdental bone
Incorrect horizontal angulation will lead to overlapping of proximal surface of teeth
OCCLUSAL
Commonly used in right angled technique
Function to determine
o Mesiodense
o Mandibular tori
o Sialolithiasis in Submandibular duct
o (other sialolithiasis best detected by – radiography)
It is the only radiograph can be done intraorally in TRISMUS cases QN
OPG
ORTHOPANTAMOGRAM
Most commonly used for dental implants QN ( BEST is CBCT )
ANATOMICAL LANDMARKS
o Mental foramen – radiolucency at the apex of premolar
o Zygoma – J shaped radio opacity at 1st or 2nd max molar
o Sinus lining
o Mandibular canal
o Vertebrae – cervical
o Styloid process
o Ear lobe
o Hyoid
ERRORS IN OPG
HEAD placed ———— ———— APPEARANCE
a) Anterior to focal trough ** Blur and narrow
b) Posterior to focal trough Blur and Magnified
HEAD tilted ————————— APPEARANCES
a) Downward smiling appearance to OPG Rx – tilt chin up
b) Upward reverse curve / flat curve in OPG Rx – tilt chin DOWN
TONGUE –
a) OBSCURES THE APICES OF MAX TEETH – SO MUST BE PLACED ON THE PALATE TO AVOID THIS !**
SIALOGRAPHY
Assessment of salivary and lacrimal gland
Dye used iodine
Appearances :
o Normal sialographic — tree limb
o Sjogren’s syndrome — cherry blossom or fruit laiden tree
It is the best investigation done for sialolithiasis Except in submand duct.
Anatomical assessment of salivary – sialography
Functional assessment of salivary gland — scintigraphy
ULTRA SONOGRAPH / USH (non – radiation)
To dislinguish between cystic and solid lesion
No radiation here CYST
Barium Meal test known as schilling test for malabsorption disorder.
MRI (non – radiation)
Indication – soft tissues in dental and bony outlines (disk position)
o Investigation for TMJ outline morphology of TMJ (metal component)
o No radiation
o MRI + prosthesis – results in prosthetic failure and image failure except in dental
implants ( no influence) due to titanium content
ARTHROGRAPHY
Indication –
o POSITION & FUNCTION OF DISC
o PERFORATIONS OF DISC & RETRODISCAL TISSUE
o ACCURATE IN demonstrating articular DISC DISPLACEMENT
o TMJ MOVEMENT/DYNAMICS
CT after injection of a high contrast fluid
Highest radiation – transcranial
Not used for TMJ outline
TMJ DIAGNOSIS
For TMJ Movement (Transcranial cannot be used)
o Computerized tomography
o Conventional tomography
o Arthrography
For disc displacement / position - MRI scan
For morphology of TMJ Bone - MRI scan
For disc perforation - ARTHROGRAPHY
For best imaging of TMJ Disc - CBCT
For single / bilateral condylar fracture (# at neck of mandible), condyle shift - REVERSE TOWN
To see condylar head orientation - REVERSE TOWN
Radiograph show condylar head orientation & facial symmetry - REVERSE TOWN.
The image show disk position & morphology of TMJ bone - MRI.
In case of fracture of the ramus of the mandible, to evaluate if fracture favorable or unfavourable - 30 DEGREE OBLIQUE RADIOGRAPH.
RADIOGRAPHIC PROJECTIONS:-
MAXILLA
A. Max sinus
B. Zygoma
C. Zygomatic arch
D. Nasal bone – lateral image or lateral projection
WATER’S PROJECTION / OCCIPITO- MENTAL PROJECTION
o Area visualized — all sinus especially MAXILLARY SINUS
o Radiolucent seen — zygoma (zygoma is not zygomatic arch)
o Zygoma fracture best viewed in waters projection
o If fracture of anterior wall of maxillary sinus — fluid in sinus filled appearance QN
o Maxilla fracture.
o Projection — from occipital bone to nasal meatus.
SUBMENTO VERTEX PROJECTION
o Fracture of cranial base / base of the skull
o Inferior border of mandible
o zygomatic arch fracture
o Zygomatico maxillar complex fracture visualisable- when done at normal time exposure.
o 1/3rd the normal exposure time ie. underexposed — zygomatic arch as jug handle view
MANDIBLE
1. Condyle
2. Condylar Neck
3. Ramus
4. Body
REVERSE TOWN
MOST RADIOGRAPHS ARE ANTERIO-POSTERIOR PROJECTIONS – TOWN’S PROJECTION.
However REVERSE TOWN MEAN POSTER-ANTERIOR PROJECTION!
o HIGHcondylar neck fracture
o SUBCONDYLAR PART FRACTURE
o displacement of condylar
o CONDYLAR HYPERPLASIA & HYPOPLASIA
o INTRACAPSULAR FRACTURE*
TRANSORBITAL PROJECTION
o Anterioir view of the joint
o condylar neck fracture
o medial displacement of fractured condyle
TRANSCRANIAL VIEW
o condylar movement and gross anatomical change
TRANSPHARYNGEAL/IINFRACCRANIAL
- BEST TO VIEW TMJ PER SAY !
TRANSPHARYNGEAL/IINFRACCRANIAL
- BEST TO VIEW TMJ PER SAY !
OPG
o GROSS VIEW OF BODY AND RAMUS FRACTURE
Lateral oblique (30°)
o Unfavourable # of body and ramus.
RADIOGRAPHIC FINDINGS :-
NORMAL VARIENTS
1. MENTAL FORMAEN – Well defined unilocular radiolucent are between normal / vital mandibular bicuspids
2. U- shaped radiopaque at max. 1st molar area is ZYGOMATIC PROCESS ,
3. While radiolucency in the same area is MAXILLARY ANTRUM.
ABNORMAL VARIENTS
1. Attrition cases – in xray you’ll see hypercementosis
2. HYPERCEMENTOSIS IS SEEEN AS – radiopacity attached to root of a tooth
3. If intrusion case after trauma – youl see inflammatory type of root serorption / progressive root resorption in xray
4. INVERTED PEAR SHAPE – GLOBULLOMAXILLARY CYST
5. SUNRAY APPEARANCE – OSTEOSARCOMMA
6. SCALLOPED BORDER – TRAUMATIC / HEMEORRHAGIC BONE CYST
OSTEOPOROSIS
Seen in females after menopause
Bone becomes brittle
MAJOR FINDING IN MAnDIBLE SEEN ON OPG IS – THIN CORTICAL PLATES
OSTEORADIONECROSIS**
Cause – reduced blood supply to the radiation site QN
Factors – surgery at radiation site – infection by staphylococcus
C/F – sequestrum – deadbone (3H hypocellular, hypovascular, hypoxic tissue and Bone) - invulcrum – living bone
Prevention – surgical procedure before 6 weeks is best (1 and ½ month)
Other methods – surgical procedure 4 months after stoppage of radiation therapy
RCT is not contra- indicated
Management :-
o hyperbaric O2 therapy --> 100% O2(also used in diffusion hypoxia) [best management]
o sequestrctomy
o resection , Hemimandibulectomy } also done
Prevention – surgical procedure before 6 weeks is best (1 and ½ month)
Other methods – surgical procedure 4 months after stoppage of radiation therapy
RCT is not contra- indicated
Management :-
o hyperbaric O2 therapy --> 100% O2(also used in diffusion hypoxia) [best management]
o sequestrctomy
o resection , Hemimandibulectomy } also done
Management :-
o hyperbaric O2 therapy --> 100% O2(also used in diffusion hypoxia) [best management]
o sequestrctomy
o resection , Hemimandibulectomy } also done
OSTEOMYLITIS
streptococci , staph aureus, -ve rods
commonly seen in mandible – due to reduced blood supply compared to maxilla
suppurative osteomyelitis – parasthesia of lip
o ACUTE S O
Swelling
Radiographic change
o CHRONIC S O
No swelling
Moth eaten appearance in radiograph QN
Rx FOR BOTH ACUTE AND CHRONIC
Hyperbaric O2 therapy
Sequestromy
Resection etc
Seen more in mandible due to reduced blood supply
It begins in the medullary bone involving the cancellous bone
GARRE’S OSTEOMYLITIS:
Non suppurative O M – seen in children QN
Proliferative
Onion peel appearance or concentric periosteal ring – RADIOGRAPHIC
Xray Technician Radiation limit = 100m REM/
Dentigerous cyst
Seen as radiolucency surrounding an unerupted tooth
Qn comes as missing tooth, xray shows some radiolucency around the impacted canine.
SLOB RULE – TUBE SHIFT TQ
Same side lingual, opposite side buccal
Know the tube shift — than can known the side