Current UK legislation and
guidelines for radiation protection
of patients and staff
Prepared by: Dr D. Mladenova
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)
Principles of ICRP- cont’d
Taking economic and social factors
into account( Optimization)
• The dose equivalent to individuals
shall
not exceed the limits recommended
by the
ICRP (Limitation)
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
Intraoral radiography-cont’d
• 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
Intraoral radiography-cont’d
• 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.
Intraoral radiography-cont’d
• 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
Panoramic radiography
• Equipment should have a range of
tube potential settings, preferably 6090 kV.
• The beam height at the receiving slit
of cassette holder should not be
greater than
Panoramic radiography-cont’d
• greater than the film in use (normally
125 mm or 150 mm).
• The width of the beam should not be
greater than 5 mm
Panoramic radiography-cont’d
• Equipment should be provided with
adequate patient-positioning aids
incorporating light beam markers
• New equipment should provide
facilities for field-limitation techniques
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
Cephalometric radiography-cont’d
• To facilitate the imaging of the soft
tissues, an aluminium wedge filter
should be provided at the X-ray tube
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
All equipment-cont’d
• 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
All equipment-cont’d
• remain outside the controlled area
and at least 2 m from the X-ray tube
and patient
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
Justification-cont’d
- the total potential diagnostic benefit to
the patient
- the radiation risk associated with the
radiographic examination
Justification-cont’d
• the efficacy, benefits and risks of
alternative techniques having the
same objective but no or less
exposure to ionizing radiation
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
Lead protection-cont’d
• Lead aprons do not protect against
scattered radiation for adult who
support a patient during exposure
• Lead aprons should not be folded
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
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
Criteria for radiographs-cont’d
- Adult (dentate patient)-patient-specific
radiographs depending on clinical
examination
- Edentulous patients- panoramic
and/or periapical radiographs in
selected areas
Dose limitations and annual dose
• Patients
• Radiation workers ( classified and
non- classified)
• General public
Radiographic investigations for
patients
• Examinations directly associated with
illness
• Systematic examinations
• Examinations for occupational,
medico-legal or insurance purposes
• Examinations for medical research
Annual dose limits-cont’d
- Non-classified workers
- General public
6 mSv
1 mSv
• Dose Constraints
- non-classified workers
1 mSv
Annual dose limits-cont’d
- For employee not directly
Involved with radiography and
General public
0.3 mSv
- Pregnant staff member
1 mSv
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
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
Protective measures-cont’d
• Safe use of equipment
• Safe use of radiographic techniques
Main methods of monitoring
and measuring radiation dose
• Film badges
• Thermoluminescent dosemeters
• Ionizing chambers