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The Ionising Radiations Regulations 2017 (IRR17)

This article introduces the Ionising Radiations Regulations 2017 (IRR17) and discusses what is required when planning to work with x-ray equipment.

IRR17 aims to protect workers and others from the effects of exposure to ionising radiation in the workplace. The regulations are enforced by the Health and Safety Executive (HSE) and all work with dental X-ray equipment is subject to these regulations. Separate regulations exist which aim to protect patients undergoing medical exposures; these are covered in other parts of this course.

This article introduces those requirements of IRR17 that you must address when planning to work with X-ray equipment, or when you are thinking about getting new equipment.

The ‘Guidance Notes for Dental Practitioners on the Safe Use of X-ray Equipment – 2nd Edition’ was written by a UK working party led by PHE, and published in September 2020. The Dental GNs, as we will refer to them during the rest of this course, provide practical guidance on how to undertake dental radiography safely and comply with the radiation protection legislation. You can access the Dental GNs here.

Registration with HSE

In the UK, all employers working with dental X-ray equipment are required to obtain a registration from HSE to be able to carry out this work. Registration can be applied for via HSE’s on-line system (please note that a different system applies in Northern Ireland). When applying for registration, you will need to confirm that there are appropriate radiation protection arrangements in place and will be required to answer several questions. You do not, however, need to provide the numbers or the details of the X-ray sets in use. If you own more than one dental practice only one registration is needed (it is the employer who is registering).

Radiation Risk Assessment

IRR17 requires that a radiation risk assessment is carried out in a very specific way and documented in writing. The Dental GNs provide a template for this (see appendix B). Various matters must be considered, and the assessment helps you to decide a) what control measures are needed to restrict the radiation exposure of employees and b) how best to comply with the other requirements of the regulations. The assessment should cover both normal work and reasonably foreseeable accident scenarios. Some of the key decisions determined by the radiation risk assessment are:

  • The designation of controlled areas, and other requirements that relate to work in controlled areas
  • The need for local rules and contingency plans
  • The appointment of radiation protection supervisors (RPSs)
  • The training of RPSs

These, and other matters determined by the radiation risk assessment, will be covered in more detail in various steps later on in the course.

Expert Advice

The regulations require the employer to appoint and consult with a Radiation Protection adviser (RPA). The RPA is an appropriately certificated professional; or an organisation that has been formally recognised as an” RPA Body” by HSE. You can find the list of certificated RPAs here and the list of HSE recognised RPA bodies here.

The RPA must be consulted with regard to:

  • Controlled and supervised areas
  • Prior examination of plans for new installations
  • Calibration of radiation monitoring equipment
  • Examination and testing of engineering controls

In practice, RPAs generally advise on all the requirements of IRR17. More information about the role, and on the equivalent role of medical physics expert required under IRMER17, is provided later this week.

Critical Examination

A critical examination (CE) must be carried out following the installation, modification or relocation of an X-ray set. The purpose of the CE is to check that the safety and warning features work, that there is sufficient protection for persons from X-rays and that the user has been provided with proper information regarding use, maintenance and testing of the X-ray set.

The regulations place the responsibility for this on the equipment installer and an RPA must be consulted on the scope of the examination and the results. The RPA can be either the installer’s or the practice’s. The practice should check in advance with the installer what the arrangements for the CE are and obtain confirmation that a written report of the CE will be provided.

The practice should discuss any recommendations made in the CE report with its own RPA before use of the X-ray set commences. It should be noted that there is also a requirement for the practice to arrange acceptance testing of the equipment prior to first clinical use under the Ionising Radiation (Medical Exposures) Regulations 2017 (IRMER17), which is covered in step 2.3 of this course. Often the CE and the acceptance test are performed at the same time; the arrangements should be checked in advance with your MPE and the installer.

Radiation Protection Supervisor (RPS)

At least one suitable trained RPS needs to be appointed per practice. The role of the RPS is to ensure that staff follow the working procedures required to restrict exposure (these instructions are documented in local rules). Both the role of the RPS and the local rules will be discussed in detail later in the course.


All staff working with or near X-ray equipment must be provided with instruction or training to enable them to do so. Records should be kept of all instruction and training provided, whether external, online or in-house. All training should be refreshed at regular intervals; five yearly is advised.

IRMER17 also has detailed training requirements and more detail on the requirements under both IRR17 and IRMER is provided in step 2.5.

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Dental Radiography: Radiation Protection in Dental Practice

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