Current UK legislation and guidelines for radiation protection of patients and staff

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Current UK legislation and guidelines for
radiation protection of patients and staff

• Prepared by Dr D. Mladenova

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General principles of the International
Commission on Radiological Protection (ICRP)
1.No practice shall be adopted unless its
introduction produces positive net benefit
(Justification)2.All exposures shall be kept
as low as reasonably practicable (ALARP)

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Principles of ICRP- contd

• Taking economic and social factors
• into account( Optimization)
• The dose equivalent to individuals shall
• not exceed the limits recommended by the
• ICRP (Limitation)

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Regulations for intraoral radiography

• Tube voltage should not be lower than 50
• kV preferably 70-90 kV
• Beam diameter should nor exceed 60 mm
• Rectangular collimation should be used

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Intraoral radiography-contd

• Total beam filtration ( inherent and added )
• -1.5 mm aluminium disc for sets operating
  bellow 70 kV
• - 2.5 mm aluminium for sets operating above
  70 kV

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Intraoral radiography-contd

• The focal spot should be marked on
• the outer casting of the tubehead
• Focal spot to skin distance ( FSD) should be at
  least 100 mm for sets operating below 60 kV and
  200 mm for sets operating above 60 kV.

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Intraoral radiography-contd

• Film speed controls and finely
• adjustable exposure time settings should be
  provided
• The fastest film available( E or F speed) that
  will produce satisfactory diagnostic images
  should be used

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Panoramic radiography

• Equipment should have a range of tube potential
  settings, preferably 60-90 kV.
• The beam height at the receiving slit of cassette
  holder should not be greater than

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Panoramic radiography-contd

• greater than the film in use (normally 125 mm or
  150 mm).
• The width of the beam should not be greater than
  5 mm

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Panoramic radiography-contd

• Equipment should be provided with adequate
  patient-positioning aids incorporating light beam
  markers
• New equipment should provide facilities for
  field-limitation techniques

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Cephalometric radiography

• Equipment must be able to ensure the precise
  alignment of X-ray beam, cassette and patient
• The beam should be collimated to include only the
  diagnostically relevant area

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Cephalometric radiography-contd

• To facilitate the imaging of the soft
• tissues, an aluminium wedge filter
• should be provided at the X-ray tube

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All equipment

• Should have a light on the control panel to show
  that the mains supply is switched on
• Should be fitted with a light and audible
  warnings that gives a clear and visible
  indication to the operator that an exposure is
  taking place

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All equipment-contd

• Exposure switches (timers) should only function
  while continuous pressure is maintained on the
  switch and terminate if pressure is released
• Exposure switches should be positioned so that
  the operator can

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All equipment-contd

• remain outside the controlled area
• and at least 2 m from the X-ray tube and patient

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Justification

• -the availability and/or findings of previous
  radiographs
• - the specific objectives of the exposure in
  relation to the history and examination of the
  patient

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Justification-contd

• the total potential diagnostic benefit to the
  patient
• - the radiation risk associated with the
  radiographic examination

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Justification-contd

• the efficacy, benefits and risks of
• alternative techniques having the
• same objective but no or less
• exposure to ionizing radiation

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Lead protection

• There is no justification for the routine use of
  lead aprons for the routine use of lead aprons
  for patients in dental radiography
• Thyroid collar to be used only in maxillary
  occlusal radiography

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Lead protection-contd

• Lead aprons do not protect against scattered
  radiation for adult who support a patient during
  exposure
• Lead aprons should not be folded

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Specific requirements for pregnant women

• Only radiographs that are absolutely necessary
  are taken
• ALARP and the patient is given the option to
  delay the radiography

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Selection criteria in Dental Radiography 1998

• No radiographs should be taken without a history
  and clinical examination
• New patient
• Child (primary and mixed dentition)- panoramic
  and bitewings radiographs

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Criteria for radiographs-contd

• Adult (dentate patient)-patient-specific
  radiographs depending on clinical examination
• Edentulous patients- panoramic and/or periapical
  radiographs in selected areas

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Dose limitations and annual dose

• Patients
• Radiation workers ( classified and non-
  classified)
• General public

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Radiographic investigations for patients

• Examinations directly associated with illness
• Systematic examinations
• Examinations for occupational, medico-legal or
  insurance purposes
• Examinations for medical research

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Annual dose limits-contd

• Non-classified workers 6 mSv
• General public 1 mSv
• Dose Constraints
• non-classified workers 1 mSv

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Annual dose limits-contd

• For employee not directly
• Involved with radiography and
• General public 0.3 mSv
• Pregnant staff member 1 mSv

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Source of radiation to dentist and their staff

• The primary beam, if they stands in its path
• Scattered radiation from the patients
• Radiation leakage form the tubehead

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Protective measures

• Personal monitoring is recommended
• for practice exceeding 100 intraoral or
• 50 panoramic film
• Staff should stand outside the controlled area
  and not in the line of the primary beam

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Protective measures-contd

• Safe use of equipment
• Safe use of radiographic techniques

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Main methods of monitoring and measuring
radiation dose

• Film badges
• Thermoluminescent dosemeters
• Ionizing chambers