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radiography risk assessment



Trophy Trex IRIX 70 (Trophy CCX) in surgery 1
Trophy Trex IRIX 70 (Trophy CCX) in surgery 2


Routine and accidental exposure to ionising radiation arising from the use of dental x-ray equipment.  In our workplace, this is most likely to arise as a result of failure to follow systems of work so that people other than the patient are exposed to the primary beam OR failure of control systems so that exposure fails to terminate.

persons at risk

The following persons undertake work with x-ray equipment: Joanne Giddy and her Dental Nurse.

routine work

The estimated magnitude of the risk from routine exposure has been estimated as follows:

A. The estimated number of x-rays taken each week with the x-ray set in surgery 1 is 45* or fewer (the set in surgery 2 is now used as a backup only).
B. The number of working weeks per year is 48 or fewer.
C. The estimated maximum dose per radiograph to a member of staff standing at least 2 metres from the x-ray tube and from the patient and outside the primary beam is 0.125µSv.

Estimated maximum annual dose (A x B x C) = 45 x 48 x 0.125 = 270µSv

(If the figure exceeds 1000µSv per annum, contact Radiation Protection Adviser for advice)

*Between 3.9.2016 and 2.9.2017, 2,125 exposures were taken over 47 working weeks, resulting in an average of 45.2 exposures per week.


Potential accidents arise from failure of the exposure control system meaning that the unit continues to generate x-rays after the set time has elapsed.  In such cases the unit must be immediately isolated from the mains supply (refer to contingency plan in local rules).

compliance with Ionising Radiations Regulations 1999 (IRR99)

IRR regulation 6 – notification to Health & Safety Executive
Measures taken: HSE notified in writing on 10th July 2000
Further action: none required

IRR regulation 8 – restriction of exposure
Measures taken: Radiation doses to staff are kept as low as reasonable practicable because:
(1) x-rays are only taken where they are likely to yield diagnostically useful information
(2) staff stand outside the controlled area when the x-ray sets are in use (refer to local rules)
(3) safety features are fitted to the x-ray equipment
(4) contingency plans are in place (refer to local rules)
(5) non-clinical staff required to leave room when x-rays being taken
Further action: none required

IRR regulation 10 – equipment to be properly maintained & tested
Measures taken: All new x-ray generating equipment is installed (and tested before use) by competent service engineers and all existing x-ray generating equipment is inspected at 6 month intervals, serviced annually and tested every 3 years.  X-ray sensors are tested every 3 months and display screen equipment used to view x-ray images is tested every 3 months.
Further action: none required

IRR regulation 11 – staff doses limited to 20mSv per annum
Measures taken: Refer to regulation 8, above
Further action: none required

IRR regulation 12 – contingency plans to be in place in case of radiation accident
Measures taken: Detailed contingency plan already in place – refer to local rules
Further action: none required

IRR regulation 13 – Radiation Protection Adviser to be appointed and consulted
Measures taken: Public Health England Dental X-ray Protection Services (DXPS) appointed as RPA to Hygeia Dental Care (also appointed as Medical Physics Expert or MPE) – refer to local rules
Further action: none required

IRR regulation 14 – Provision of information, instruction and training
Measures taken: Employees working regularly with ionising radiation are provided with adequate training and information:
(1) Radiography has been a core item in the induction procedure for all new staff since August 2000
(2) Local rules are available to all persons working with ionising radiation
(3) RPS (Joanne Giddy) is up to date with radiography training
Further action: none required

IRR regulation 16 – Designation of controlled and supervised areas
Measures taken: The local rules already provide for this:
(1) Controlled areas have been designated
(2) No supervised areas exist
(3) No special procedures are required
Further action: none required

IRR regulation 17(1-3) – Local rules to be provided and observed
Measures taken:
(1) Local rules have been prepared
(2) Local rules are observed
(3) Local rules are brought to the attention of employees – eg new staff induction procedures and also published on website
Further action: none required

IRR regulation 17(4) – Radiation Protection Supervisor to be appointed
Measures taken: Joanne Giddy appointed as RPS
Further action: none required

IRR regulation 21 – Dose assessment
Measures taken:
(1) This regulation is not applicable to our practice since dosemeters are only required for operators who regularly exceed 150 intra oral or 50 panoramic radiographs per week. We do not have a panoramic x-ray machine and operators only take an average of 45 intra oral radiographs per week
(2) Should any member of staff receive an annual dose exceeding 1000µSv (1mSv) a formal investigation must be conducted in liaison with the RPA/MPE in order to establish why.  The result of any such investigation must be kept for a period of at least 2 years.
Further action: none required

IRR regulation 31(2) – Critical examination of new equipment
Measures taken: This has been done in respect of all new x-ray generating equipment installed at the practice
Further action: none required

IRR regulation 32(1) – Equipment used for medical exposures to minimise dose
Measures taken: Our equipment keeps patient doses as low as reasonably practicable; we know this because:
(1) It is CE marked
(2) It was installed by qualified engineers
(3) It was subjected to a critical examination before use
(4) We have installed a digital x-ray system that reduces patient dose by more than 50% compared to the old film-based systems
(5) We use rectangular beam collimator
(6) We routinely use beam alignment devices
Further action: none required

IRR regulation 32(3) – Quality assurance program
Measures taken: Measures have been taken to ensure consistent diagnostic performance and adequate control of patient doses:
(1) Dentists are responsible for monitoring the quality of radiographic images and must investigate any deterioration in quality in order to minimise unnecessary exposures
(2) If no obvious cause is found, RPS is responsible for testing/servicing and repair of x-ray equipment, as required
(3) Beam alignment devices in use to minimise the number of positioning errors and, therefore, the number of x-rays taken
(4) Audits of radiographic image quality and reject image analysis are carried out by the RPS at six monthly intervals to ensure that image quality targets are met and that, where errors or problems are identified, remedial action is taken (refer to local rules)
Further action: none required

IRR regulation 32(4) – Quality assurance program
Measures taken: Measures have been taken to ensure that equipment undergoes adequate testing before first use, at appropriate intervals and after major maintenance:
(1) Refer to regulation 31(2) above
(2) Refer to regulation 32(3) above
(3) Equipment is regularly tested and maintained (refer to local rules – see also Testing, Maintenance, Audit and Compliance Schedule and radiation safety reports in Equipment Maintenance & Testing file)
Further action: none required

IRR regulation 32(5-6) – Equipment failure and incidents
Measures taken: Steps have been taken to prevent equipment failure and to limit the consequences of any failure; provision also made for investigations if patient receives a larger dose than intended:
(1) Refer to regulation 32(4) above
(2) Refer to regulation 10 above
(3) Contingency plans in place (refer to local rules)
(4) Investigation requirements in place (refer to local rules)
Further action: none required

IRR regulation 34 – Employees to exercise reasonable care
Measures taken:
(1) Staff aware of obligation to exercise reasonable care – health & safety poster on display
(2) Staff aware of obligation to exercise reasonable care – express requirement in all contracts of employment and contracts for services
(3) Staff trained in radiography as part of induction process
(4) Dental nurses are supervised by dentists (nurses & hygienists do not use x-ray equipment here)
Further action: none required

Assessment undertaken by: Neil Phillips and Joanne Giddy

Web version 10: 3.9.2017
Date of Previous Assessments: 27.7.2006, 10.4.2008, 31.12.2010, 26.1.2012, 23.2.2012, 13.3.2013; 19.6.2014; 3.7.2015; 4.8.2016 (reviewed 1.9.2017)

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