Integrated

Management &

Educational

Consultancy

Services

  “Radiology Update Seminarfor The Dental Team”

  

 

Dr. Richard DeCann & Mr. Tim Reynolds IMECS Radiography Consultants Tel:07855 183117 email: info@imecs-cpd.co.uk

www.imecs-cpd.co.uk

What do dentists need to know?

• UK radiation dose distributions• Nature and effects of radiation• Clinical implications of IRR1999 and

IR(ME)R 2000• Patient safety and selection criteria• Optimisation of radiographic techniques• Quality assurance and record keeping

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What do nurses need to know?

• Principle foundations of dental radiographic techniques

• Equipment used• Methods of processing films and the

practice of digital radiography• Hazards of exposure to ionising radiations• Have an understanding of the regulatory

requirements

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What must nurses be able to do?

• Prepare the equipment and materials• Prepare and care for patients• Process radiographs• Properly mount radiographs• Undertake quality assurance measures in

processing

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The Discovery of X-Rays

Prof. W. RoentgenNovember 1895

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UK Dose Distribution

83%

17%

Comparison between dose sources in the UK

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Man Made Dose Distribution

90%

10%

• Medical dose compared with other man made sources

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Comparing Medical Doses

97%

3%

• General medical dose compared with dental

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Radiological Examinations in the UK

30%

70%

• Number of general medical examinations compared with dental

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Potential for Dose Saving

10%

45%

45%• Up to 50% of the medical dose delivered in

the UK is unnecessary

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Workshop

• List the characteristics of x-rays

e.g. travels in straight lines

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Nature of Ionising Radiation

• Travels in straight lines at the speed of light• Obeys the inverse square law• Penetrates, excites and ionises matter• Chemical and biological effect• Photographic and fluoroscopic effect• Unaffected by magnetic or electric fields

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Electromagnetic Spectrum

low high

Energy

radiowaves

visible light

cosmic rays

microwaves

X & gamma rays

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X-Ray Tube

anodecathode

target

X-ray beam

electron beam

Workshop

• What units are used to measure radiation exposure and dose ?

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Units of Radiation Measurement

• Exposure = COULOMBS PER KILOGRAM Kinetic Energy Released per unit Mass (KERMA)

• Absorbed Dose = GRAY Joules per Kilogram

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Dose Reference Levels

• PA DRLs DOH 4Mgy

HPA 2mGy

Recommended 1 – 1.5mGy

OPG DRLs DOH 66mGy

HPA 20mGy

Recommended 10 – 15mGy

Units of Radiation Measurement

• Exposure = COULOMBS PER KILOGRAM Kinetic Energy Released per unit Mass (KERMA)

• Absorbed Dose = GRAY Joules per Kilogram

• Dose Equivalent = SIEVERT Gray x Q (x-rays=1, protons=10, alpha=20)

• Effective Dose = SIEVERT Biological Effect (dose equivalent x tissue sensitivity)

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Dose Reference Levels

• PA DRLs DOH 4Mgy

HPA 2mGy

Recommended 1 – 1.5mGy

(Effective dose 0.002mSv)

OPG DRLs DOH 66mGy

HPA 20mGy

Recommended 10 – 15mGy

(Effective dose 0.007mSv)

Units of Radiation Measurement

• Exposure = COULOMBS PER KILOGRAM Kinetic Energy Released per unit Mass (KERMA)

• Absorbed Dose = GRAY Joules per Kilogram

• Dose Equivalent = SIEVERT Gray x Q (x-rays=1, protons=10, alpha=20)

• Effective Dose = SIEVERT Biological Effect (dose equivalent x tissue sensitivity)

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Round collimator at 6cms diameter = 29cm

DRL = mGy/cm2

DRL = mGy/cm2

Thyroid collars

Effective Dose and Kilo-voltage

• 60 kV 70kV

Excitation and Ionisation

Excitation and Ionisation

X-ray photon

Excitation and Ionisation

X-ray photon

Ionised electron

Excitation and Ionisation

Excitation and Ionisation

Excitation and Ionisation

Radiobiology

• Random interactions causing direct and indirect tissue damage

• Critical body macromolecules: protein, DNA (damage with incomplete or misrepair)

• H2O affected because of large size and content

• Ionised water becomes chemically reactive and can affect DNA by indirect action

• Formation of free radicals: HO2 (peroxyls) H2O2 (peroxides)

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Ionisation and free radicals

• RH + Radiation = RH+ + electron

R H

H2O HO H

RadiobiologyThe exposure of a cell to radiation may result in:

• The premature death of the cell• Prevention or delay in cell division• Changes in cell structure and/or functions

which may be passed on to daughter cells

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What is damaged?

• DNA

• Any of the cytoplasmic organelles

• I bet they say MITOCHONDRIA

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What Type of Damage Can Occur?

• Stochastic• Deterministic

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Who is Affected?

• Somatic• Genetic

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Variations with Age at Exposure

Detriment vs Age at Exposure

0 to 5years

5 to 10years

10 to 20years

20 to 30years

30 to 40years

40 to 50years

50 to 60years

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Integrated

Management &

Educational

Consultancy

Services

  “Radiology Update Seminarfor The Dental Team”

  

 

Dr. Richard DeCann & Mr. Tim Reynolds IMECS Radiography Consultants Tel:07855 183117 email: info@imecs-cpd.co.uk

www.imecs-cpd.co.uk

Legislative Framework

• Two sets of regulations have been introduced in the UK in the last 13 years

• Ionising Radiations Regulations 1999 (IRR 99)

• Ionising Radiations (Medical Exposures) Regulations 2000 (IR(ME)R 2000)

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IRR 1999

• Is about:– Environment– Workers – Members of the public

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Public Protection

IRR 1999

• Is about:– Environment– Workers – Members of the public– Management of radiationm protection

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IRR 1999

• HSE notification • Risk assessment

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Risk Assessment

Window

Exposure Switch

Mains isolator

4M

Surgery 2

Waiting room

Staff Risk Assessment

Staff Risk Assessment

IRR 1999

• HSE notification • Risk assessment• Contingency plans• Dose restriction/limitation• Training• RPS/RPA • Controlled areas

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Controlled areas

?Fire regulations

How MUCH Lead ?

IR(ME)R 2000

Is about:

• Patient protection

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Ionising Radiation (Medical Exposures) Regulations 2000

Summary

• Justification– Patient examination, identify clinical reason, written report

• Optimisation– Maximum yield with minimal dose

• Entitlement– Anyone can do anything as long as they are trained and it is agreed

and monitored

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Selection (Referral)Criteria

• SELECTIVE– Symptomatic to confirm or refute

• ROUTINE– Circumstantial evidence

• SCREENING– No evidence

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Optimisation

• Patient ID• Patient care• Check history, area• Admin• Justification• 70kV DC• Film holders

• Rectangular collimators• Film speed• Viewing• Maintenance & QA

– Equipment– Processor

• Audit• Training

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Digital Dental Radiography

• Direct– Charge Coupled Devices / CMOS – (wired systems)

• Indirect– Photo phosphor plates

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Digital Image Processing

• Analysis– Collect numeric information based on the image

• Enhancement– Improve appearance of image

• Encoding– Reduce information required to describe the image

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Ionising Radiation (Medical Exposures) Regulations 2000

Conceptual Framework• Clinical audit

– Radiographic and Radiological

• Expert advice– Medical Physics Expert

• Equipment inventory– Radiation Protection File

• Training– What, how and assessed

• Enforcement– Health & Safety @ Work

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Justification of an individual medical exposure

• No person shall carry out a medical exposure unless:

– It has been justified by a practitioner as showing sufficient net benefit.

– It has been authorised by a practitioner (where appropriate the operator)

– Has been authorised by the local research/ethics committee

– It is a part of an agreed medico-legal procedure

– In the case of a female of childbearing age, he has enquired whether she is pregnant, if relevant.

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Ionising Radiation (Medical Exposures) Regulations 2000

• Employer

• Referrer/Prescriber

• Practitioner

• Operator

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Duty of Role Holders

• Employer: to provide a framework for radiation protection of the patient through provision of standard operating procedures.

• Referrer/Prescriber: to provide sufficient relevant clinical information on the patient to enable the justification of the medical exposure.

• Practitioner: to justify each individual medical exposure.

• Operator: to undertake practical aspects of the medical exposure.

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Employer

• Any natural or legal person who, in the course of a trade, business or other undertaking, carries out (other than as an employee), or engages others to carry out, medical exposures or practical aspects, at a given radiological installation.

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Employer Procedures for Dentists

• Protocols and/or guidelines for:– Patient identification– Competencies of practitioners & operators– Medico-legal exposures– Women of childbearing age– Reduce accidental exposure to ALARP

• Expected doses and dose recording• Quality assurance

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Referrer

• A registered medical or dental practitioner, or other health care professional who is entitled in accordance with the employer’s procedures to refer individuals for a medical exposure to a practitioner.

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Practitioner

• A registered medical or dental practitioner, or other health professional who is entitled, in accordance with the employer’s procedures, to take responsibility for an individual medical exposure.

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Operator

• Any person who is entitled, in accordance with the employer’s procedures, to carry out practical aspects (including those to whom practical aspects have been allocated) except, when training, where they do so under the direct supervision of a person who is adequately trained.

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Adequate Training

• Practitioners and operators shall have successfully completed training, including theoretical knowledge and practical experience (in radiation protection and diagnostic or therapeutic techniques involving ionising radiation) appropriate to their specific area of practice.

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Quality AssurancePrimary FunctionsüConsistently high quality imagesüDoses to staff and patients are as low as reasonably practicable

Key Elementsü Darkroom, film and processingüX-ray equipmentü Working proceduresü Audits & Quality Targets

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Darkroom

• Film storage and stock rotation

• Light tight integrity (visual)

• Safelight (coin test)

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Quality Control:Equipment MonitoringWeekly clean with spirit based solution and checks for:

• Electrical: sockets, plugs, earthing, insulation, leads (mains, exposure), tube head (leaks).

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Quality Control:Equipment MonitoringWeekly clean with spirit based solution and checks for:

• Electrical: sockets, plugs, earthing, insulation, leads (mains, exposure), tube head (leaks).

• Mechanical: mountings, support, brakes, stability, fixtures and fittings (collimators).

• Radiation: output checks (annual), tube head (dents), mains isolation switch

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Trophy 70 Room 2 June 2010  5.6.10 12.6.10 19.6.10 26.6.10

Electrical        

Socket        

Plug        

Leads        

Tubes leaks        

Mechanical Security        

Wall support        

Tube arm        

Tube head        

Cone/collimators        

Radiation        

Tube dents        

Mains isolation        

Signature        

Date        

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Quality Control:Processor MonitoringWeekly clean with checks for:

• Electrical: sockets, plugs, leads, earthing and insulation.

• Lightproof: lid, feed cover, light screen (coin test)

• Transport: rollers and screens, daily cleaner.

• Image quality: temperature (heater, thermostat), activity (replenishment), wash, drainage, cleanliness, stepped wedge test.

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Velopex June 2006  5.6.06 12.6.06 19.6.06 26.6.06

Electrical        

Socket        

Plug        

Leads        

Lightproof        

Lid        

Sleeves        

Daily Cleaner        

Daily water drain        

Stepped wedge        

       

       

Signature        

Date        

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Stepped Wedge

This is what the wedge looks like

This is what a picture of it should look like

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Accessory Equipment

• Cassettes• Screens• Viewing boxes• Film holders

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Quality rating and quality standards for radiographs

Rating/Quality Basis

1. Excellent: No errors of exposure, positioning or processing. Not less than 70%.

2. Acceptable Some errors which do not detract from the diagnostic use. Not greater than 20%.

3. Unacceptable Errors which render the radiograph diagnostically unacceptable.

Not greater than 10%.www.imecs-cpd.co.uk

Guidelines for Image Critiques

• Area: film position and orientation

(axis, border, blip)

• Projection: beam centring and

angulation

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Critique• Projection: beam centring and angulation

• (no cone cut, crowns in profile/3mm border, no

interproximal overlap, bite block in profile)

3 mm

Guidelines for Image Critiques

• Area: film position and orientation (axis, border, blip)

• Projection: beam centring and angulation

• Density: level of blackness

• Contrast: difference in density for a range of structures

• Sharpness: level of detail

• Artifacts: something on the film that shouldn’t be there

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Orthopantomography

Plain Radiography

Scanography

Scanography

Plain Radiography

Tomography

Tomography

Focal Trough

Focal troughPivotal Plane

Principles of Radiation Protection

• Justification of the exposure• Positive identification of the patient• Reference to existing radiological records• Shielding: primary & secondary barriers• Distance• Beam restriction• Minimum number of personnel in the examination room• Quality assurance of all equipment and audit of activities• Choice of x-ray and imaging equipment

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www.imecs-cpd.co.ukinfo@imecs.co.uk

• Richard • admin@imecs.freeserve.co.uk• 07855 183117

• Tim• timreynolds1@aol.com• 07976 468504