Integrated
Management &
Educational
Consultancy
Services
“Radiology Update Seminarfor The Dental Team”
Dr. Richard DeCann & Mr. Tim Reynolds IMECS Radiography Consultants Tel:07855 183117 email: [email protected]
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: [email protected]
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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• Richard • [email protected]• 07855 183117
• Tim• [email protected]• 07976 468504