RadiologyRadiology

An IntroductionAn Introduction

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Learning ObjectivesLearning Objectives

List the Properties of X-raysList the Properties of X-rays

Understand the need for radiologyUnderstand the need for radiology

Explain Radiation ProtectionExplain Radiation Protection

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IntroductionIntroduction

Discovery of the x-rayDiscovery of the x-ray

X-ray picture/ roentgenograph/radiographX-ray picture/ roentgenograph/radiograph

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Radiation, Radiology and Radiation, Radiology and RadiographyRadiography

RadiationRadiation = = Emission of energy in the Emission of energy in the form of EMR or particulate radiation.form of EMR or particulate radiation.

RadiographyRadiography = the techniques involved = the techniques involved in producing radiographs.in producing radiographs.

Radiology Radiology = = interpretation of radiographs interpretation of radiographs and other images.and other images.

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Dental RadiologyDental Radiology

Dental exams one of most commonDental exams one of most common

1997-8 survey in UK found:1997-8 survey in UK found: 19 million intra-oral radiographs taken19 million intra-oral radiographs taken 2.9 million panoramic radiographs taken2.9 million panoramic radiographs taken

In Sweden 15 millions/yIn Sweden 15 millions/y

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Properties of x-raysProperties of x-rays InvisibleInvisible

Have no chargeHave no charge

Travel at speed of lightTravel at speed of light

Have no mass or weight Have no mass or weight

Travel in straight linesTravel in straight lines

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Properties of x-raysProperties of x-rays

Can cause ionizationCan cause ionization

Can affect photographic film emulsionCan affect photographic film emulsion

Can affect living tissueCan affect living tissue

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Properties of x-raysProperties of x-rays

Can penetrate opaque tissues and Can penetrate opaque tissues and structuresstructures

Radiopaque(light)

Radiolucent(dark)

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Conventional Conventional Radiography and Digital Radiography and Digital ImagingImaging

Conventional radiographyConventional radiography uses uses radiographic film as the image radiographic film as the image detector/sensor.detector/sensor.

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Conventional Conventional Radiography and Digital Radiography and Digital ImagingImaging

Digital imagingDigital imaging uses a charged coupled uses a charged coupled device (CCD) as the image device (CCD) as the image detector/sensor.detector/sensor.

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Advantages of digital imagingAdvantages of digital imaging

No use of films, intensifying screens, cassettes No use of films, intensifying screens, cassettes etc.etc.

Computer hardware and software allows you to Computer hardware and software allows you to view and store images.view and store images.

Multiple images are obtained without changing Multiple images are obtained without changing film holder or using new film.film holder or using new film.

Less exposure to radiationLess exposure to radiation

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Why do we take Why do we take radiographs?radiographs?

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Role of radiographsRole of radiographs

Clinical examination phaseClinical examination phase Diagnosis (confirm / exclude)Diagnosis (confirm / exclude) Treatment planningTreatment planning During treatment During treatment Follow up after various treatment Follow up after various treatment

proceduresprocedures

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Are all radiographs Are all radiographs necessary?necessary?

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Must justify taking any radiographs; not a Must justify taking any radiographs; not a blanket screening for all patients.blanket screening for all patients.

Radiographs do have limitations and should Radiographs do have limitations and should never replace a thorough clinical examination.never replace a thorough clinical examination.

There are disadvantages and risks - must There are disadvantages and risks - must weigh up benefits against risks.weigh up benefits against risks.

Radiographs can indicate the need for further Radiographs can indicate the need for further investigation.investigation.

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The uses of radiographsThe uses of radiographs

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General dentistry:General dentistry:

Loss of tooth structureLoss of tooth structure

Carious (occlusal, proximal)Carious (occlusal, proximal)

Non - carious (attrition, abrasion, erosion, fracture)Non - carious (attrition, abrasion, erosion, fracture)

Periodontal diseasePeriodontal disease

Endodontic diseaseEndodontic disease

Impacted teethImpacted teeth

Trauma (root and alveolar fractures, foreign bodies)Trauma (root and alveolar fractures, foreign bodies)

Other pathology affecting boneOther pathology affecting bone

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Periodontics:Periodontics:

Alveolar bone heightAlveolar bone height Alveolar bone healthAlveolar bone health Generalised vs Generalised vs

localised localised

alveolar bone lossalveolar bone loss Peri-radicular Peri-radicular

infectioninfection

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Orthodontics:Orthodontics:

General growth and developmentGeneral growth and development Delayed eruptionDelayed eruption Ectopic teethEctopic teeth Eruption pathsEruption paths Impacted teethImpacted teeth Supernumerary teethSupernumerary teeth

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Oral medicine and oral Oral medicine and oral surgery:surgery:

ExtractionsExtractions Jaw fracturesJaw fractures TumoursTumours InfectionsInfections Foreign bodiesForeign bodies

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Endodontics:Endodontics: Anatomy of the pulp chamber and canal (s)Anatomy of the pulp chamber and canal (s)

Presence of peri-radicular and peri-apical Presence of peri-radicular and peri-apical pathologypathology

Resorption of rootsResorption of roots

Dental traumaDental trauma

Canal length determinationCanal length determination

Root fillingRoot filling

Follow-up/monitor healing (periapical, Follow-up/monitor healing (periapical, fracture, resorption)fracture, resorption)

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RadiologyRadiology

3 common dental X-rays:3 common dental X-rays:

BitewingsBitewings PeriapicalPeriapical PanoramicPanoramic

(Univ. Manitoba, 2005)(Univ. Manitoba, 2005)

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Types of RadiographsTypes of Radiographs

Intra-oralIntra-oral

Extra-oralExtra-oral

Other technologies/imaging modalitiesOther technologies/imaging modalities

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Intra-oral radiographyIntra-oral radiography

Radiographic film/detector is exposed Radiographic film/detector is exposed whilst inside the patient’s mouthwhilst inside the patient’s mouth

Image of a small area - a few teeth and Image of a small area - a few teeth and adjacent supporting structuresadjacent supporting structures

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Bitewing:Bitewing:

Indications:Indications: baseline examinationbaseline examination detection of:detection of:

- - dental caries dental caries

- non-carious tooth loss- non-carious tooth loss- monitoring the progress - monitoring the progress of any loss of tooth structureof any loss of tooth structure- assessing existing restorations - assessing existing restorations (defects, contacts)(defects, contacts)- assessment of periodontal status.- assessment of periodontal status.

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Periapical:Periapical:

Indications:Indications: detection of apical infection/inflammationdetection of apical infection/inflammation dental trauma (to the tooth and associated dental trauma (to the tooth and associated

alveolar bone)alveolar bone) assessment of root morphologyassessment of root morphology endodontic diagnosis, planning,endodontic diagnosis, planning,

treatment and monitoringtreatment and monitoring

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Occlusal:Occlusal:

Indications:Indications: presence/absence of developing teethpresence/absence of developing teeth supernumerary teethsupernumerary teeth impacted teethimpacted teeth pathology not fully demonstrated in an intraoral viewpathology not fully demonstrated in an intraoral view contour of buccal and lingual cortical platecontour of buccal and lingual cortical plate localisation technique (used with another film) localisation technique (used with another film) when unable to take intra-oral radiographswhen unable to take intra-oral radiographs

- limited opening of mouth- limited opening of mouth- uncooperative child.- uncooperative child.

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Occlusal:Occlusal:

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Extra-oral radiographyExtra-oral radiography

Radiographic film/detector positioned Radiographic film/detector positioned outside the patient’s mouth.outside the patient’s mouth.

Can image larger areas of the mandible Can image larger areas of the mandible and maxilla, face, skull.and maxilla, face, skull.

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Extra-oral radiographyExtra-oral radiography

Skull radiographs: Skull radiographs: lateral headlateral head

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Extra-oral radiographyExtra-oral radiography

anterio-posterior viewanterio-posterior view

lateral oblique jawlateral oblique jaw

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Extra-oral radiographyExtra-oral radiography

TMJTMJ

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Extra-oral radiographyExtra-oral radiography

TomographyTomography Panoramic radiographPanoramic radiograph

orthopantomograph (OPG)orthopantomograph (OPG) TMJTMJ maxillary sinus viewsmaxillary sinus views

Modern OPG machines can do a range of skull Modern OPG machines can do a range of skull views by altering the extent of the tomographic views by altering the extent of the tomographic layer used and by altering the shape of the layer used and by altering the shape of the tomographic layer usedtomographic layer used

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Indications for traditional Indications for traditional OPGOPG

Assessment of Assessment of

-- wisdom teethwisdom teeth

-- TMJ pathologyTMJ pathology

-- maxillary sinusmaxillary sinus

-- jaw bone jaw bone pathologiespathologies

-- orthodontic orthodontic diagnosisdiagnosis

-- jaw bone jaw bone fractures.fractures.

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Other Technologies and Other Technologies and Imaging ModalitiesImaging Modalities

Computerised tomography (CT)Computerised tomography (CT)

Magnetic resonance imaging (MRI)Magnetic resonance imaging (MRI)

UltrasoundUltrasound

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Computerised Computerised tomography (CT)tomography (CT)

Radiographic cutting of a region/structure Radiographic cutting of a region/structure into thin slicesinto thin slices

Fairly high dosesFairly high doses Good diagnostic informationGood diagnostic information Used in oral maxillofacial surgery Used in oral maxillofacial surgery

(diagnosis and treatment planning of (diagnosis and treatment planning of tumours, fractures and neuropathies)tumours, fractures and neuropathies)

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Magnetic resonance Magnetic resonance imaging (MRI)imaging (MRI)

Gives better soft tissue images than CT scansGives better soft tissue images than CT scans No radiation - uses magnetic field and sound No radiation - uses magnetic field and sound

waveswaves Very good diagnostic informationVery good diagnostic information Used in oral maxillofacial surgery (diagnosis Used in oral maxillofacial surgery (diagnosis

and treatment planning of tumours, fractures and treatment planning of tumours, fractures and neuropathies, gold standard for TMJ and neuropathies, gold standard for TMJ imaging) imaging)

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UltrasoundUltrasound

Limited uses for dental careLimited uses for dental care

Salivary gland tumoursSalivary gland tumours

Possibly TMJPossibly TMJ

Locating foreign object in soft tissueLocating foreign object in soft tissue

Soft tissue cystsSoft tissue cysts

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Radiation UnitsRadiation Units

ExposureExposure Absorbed doseAbsorbed dose Dose EquivalentDose Equivalent

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Radiation UnitsRadiation Units

Exposure: Exposure: amount of radiation in a beam of x-raysamount of radiation in a beam of x-rays ionization in airionization in air Coulomb per kgCoulomb per kg

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Radiation UnitsRadiation Units

Absorbed dose: Absorbed dose: amount of radiation absorbed by the amount of radiation absorbed by the

tissuestissues amount of energy deposited in 1 kgamount of energy deposited in 1 kg Gray, Gy (1 joule/kg)Gray, Gy (1 joule/kg) Rad (radiation absorbed dose) equal to Rad (radiation absorbed dose) equal to

0.01 J/kg0.01 J/kg

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Radiation UnitsRadiation Units

Dose Equivalent: Dose Equivalent: amount of radiation absorbed by the amount of radiation absorbed by the

tissues x Quality Factor (QF)tissues x Quality Factor (QF) QF relates to biological damageQF relates to biological damage Sievert, Sv equals 1 GySievert, Sv equals 1 Gy

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Radiation ProtectionRadiation Protection

Good technique to avoid re-takes:Good technique to avoid re-takes: use of correct film for the view intendeduse of correct film for the view intended use of appropriate film holderuse of appropriate film holder correct film placement within film holdercorrect film placement within film holder correct placement (angulation) of film holder correct placement (angulation) of film holder

in patient’s mouthin patient’s mouth correct tube angulationcorrect tube angulation correct exposure timecorrect exposure time

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Radiation ProtectionRadiation Protection

Protect patient, public and staffProtect patient, public and staff Remember dose is cumulativeRemember dose is cumulative Benefit/risk ratioBenefit/risk ratio Dose reduction = Dose reduction = time, distance, shieldingtime, distance, shielding

High speed filmHigh speed film Long exp. cableLong exp. cable Lead coats toLead coats toreduced exp. time so dentist steps away stop scatter radiationreduced exp. time so dentist steps away stop scatter radiation

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ConclusionConclusion

X-rays is essential in dentistryX-rays is essential in dentistry Dose is cumulativeDose is cumulative Follow radiation protection principlesFollow radiation protection principles Each X-ray exam should be justifiedEach X-ray exam should be justified

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ReferencesReferences

Whaites E (1996) Whaites E (1996) Essentials of dental Essentials of dental radiography and radiology,radiography and radiology, 2 2ndnd edition, edition, Churchill LivingstoneChurchill Livingstone

de Lrye and Johnson, de Lrye and Johnson, Essentials of Essentials of dental radiography for dental assistantsdental radiography for dental assistants

Goaz and White, Goaz and White, Oral radiologyOral radiology: : Principles and interpretation,Principles and interpretation, CV Mosby CV Mosby