Dent RPA Frequently Asked Questions

We have provided a list of frequently asked questions divided in various categories.

Click the categories below to view the questions and answers.


    Q: What Regulations apply to the use of dental X-rays in the UK?

The Ionising Radiations Regulations 1999 (IRR99) aim to keep occupational exposures from ionising radiation to dentists, dental nurses, other staff and members of the public as low as reasonably practicable (ALARP). The Ionising Radiation (Medical Exposure) Regulations 2000 (IR(ME)R2000) aim to minimise patient radiation exposure from medical X-ray procedures.

Please see the FAQ below re changes in the regulations from early 2018.


    Q: Do I need to inform any authority before taking X-rays for the first time?

The Health and Safety Executive need to be notified at least 28 days before X-rays are used for the first time in a dental practice. The particulars to be notified are given at this link:

You can now notify the Health and Safety Executive of the intended use of ionising radiation online. Visit and select "Work with ionising radiation for the first time (other than the above)" from the drop-down box at the top of the page, then check the "Electrical Equipment" box. The remainder of the form is very straightforward to complete and simply asks basic details of the address of the premises, intended start date, etc.

Notification can also be done by post to the address of the local HSE office (see ) or by email to A proforma notification letter can be found in the Resources section of the website (under My Toolbox).

The practice of using electrically-generated X-rays for dental diagnosis is generically authorised and you do not need to wait for the HSE to grant permission to proceed.

Please see the FAQ below re changes in the regulations from early 2018.


    Q: How will dental practices be affected by the new Ionising Radiations Regulations 2017 and the Ionising Radiation (Medical Exposure) Regulations 2017?

The practical implications for dental practices using X-rays are expected to be fairly small following the implementation of the IRR2017 and IR(ME)R2017 regulations in early 2018. However, dental practices will need to register their use of X-rays with the Health and Safety Executive before 6th February 2018. This will be a simple online process involving a self-declaration and a one-off £25 registration fee. The registration website is now available at and clicking "notify, register or get consent from HSE." halfway down the page.

The online declaration involves answering a short series of questions covering areas including risk assessment, local rules, appointment of the RPA, staff doses, staff training and demarcation of controlled areas. Clients who follow Dent RPA's handbooks and other documentation/tools provided should already be compliant in these areas and the registration process should not present any concerns. Please contact us at if you need further advice on the registration process.

The implications of IR(ME)R2017 are expected to be small and our IR(ME)R procedures and protocols handbook will be updated in due course. There will be a requirement to inform patients of the doses, benefits and risks from ionising radiation and our existing advice sheet on patient doses (see My Toolbox/Advice Sheets) for details) can be used for this purpose e.g. by having copies available in the waiting rooms or surgeries.

There will be more emphasis on adequate training for IR(ME)R practitioners and operators and our clients are encouraged to ensure that the Dent RPA equipment-specific proformas are completed for all operators for each piece of X-ray and ancillary equipment that they use.

Our online radiation protection training will be updated in the light of the new regulations once the regulators have advised on their practical implementation (expected by end of 2018). Dentists and dental X-ray operators are unlikely to require immediate IR(ME)R training under the new IR(ME)R2017 if their current training is still in date.

Please check the Dent RPA homepage for updates and further practical information on the impact of the new regulations early in 2018.


    Q: Who is responsible for ensuring compliance with the Regulations?

IRR99 - The Employer has the overall responsibility for compliance with the regulations and this cannot be legally delegated. Normal practice is for a dentist or other senior person to be appointed as Radiation Protection Supervisor (RPS) for the practice with the duty of supervising radiation safety in accordance with the local rules.

IR(ME)R – These regulations require policies on identification of the following duty holders in the context of medical X-ray exposures:

Employer - This person that takes legal responsibility for compliance with IR(ME)R. The Employer must ensure that a framework of procedures for medical exposures is in place.

Referrer – An individual entitled by the Employer to refer a patient for an X-ray. Such persons must provide sufficient clinical information to enable justification of the exposure

Practitioner – A qualified medical practitioner i.e. dentist, who is responsible for providing the clinical justification for each individual exposure. The dentist must be able to demonstrate that all radiographs will provide useful medical information that will benefit the patient and outweigh the risks from the resultant radiation. In most dental practices the Practitioner and Referrer are the same person.

Operator – The person who performs the practical aspects of the exposure. The operator is usually a suitably-trained dentist or a dental nurse.
Please see the IRMER procedures template in the “Handbooks” section (under My Toolbox) of the website for further information.


    Q: How do I ensure that my medical exposures are optimised under IR(ME)R2000?

Adhering to published referral criteria such as “Selection Criteria for Dental Radiography”, (published by the Faculty of General Dental Practice (UK)) will help minimise the number of unnecessary X-rays and aid the justification process. Ensuring that the minimum patient dose is used depends on having suitable exposure charts, adequate processing conditions, a fast film system and a quality assurance programme in place. The equipment survey report from the Dent RPA technician will show how the exposures compare to national Diagnostic Reference Levels and have recommendations for remedial action where necessary.

    Q: Is there a legal requirement to have my X-ray equipment serviced?

Regulation 32 of the Ionising Radiations Regulations 1999 states that an employer that has responsibility for equipment related to medical exposures must have it ‘maintained’ so as to restrict dose as far as is reasonably practicable. Further to this, the Health and Safety Executive's Guidance Note PM77 (third edition) entitled "Equipment used in connection with medical exposure" states in the section on equipment maintenance: "Equipment used in connection with medical exposure should be under some form of maintenance/service contract, often with the manufacturer or installer. Alternatively, arrangements may be made with in-house engineers and technical staff. In this guidance, all reference to service engineers and service or maintenance includes such in-house arrangements. In any event, the employer has the legal responsibility for ensuring that equipment is properly maintained .....".

While document PM77 is not strictly legally binding, it can be used by the HSE to pursue a prosecution in a court of law where failure to follow its guidance has led to an incident or injury involving ionising radiation. As such, it is the interpretation of Dent RPA's Radiation Protection Advisers that servicing of X-ray equipment is effectively a legal requirement under IRR99. We would advise a minimum frequency of annually and this should include ancillary equipment such as CR plate readers and film processors.


    Q: Are "controlled area" warning signs necessary at the entrance to rooms and surgeries where intra-oral and panoramic X-ray sets are used?

In practice, the radiation controlled area for most dental X-ray facilities usually extends to around 1 to 2 metres from the patient. However, it is usual to designate the whole room or surgery as “controlled” because of the difficulties of demarcating the actual controlled area. Defining the whole room makes controlling access very straightforward. Technically, the area is only “controlled” when the equipment is in a state where it is capable of emitting X-rays (i.e. when the power is turned on). General X-ray departments overcome this by having a sign stating “Radiation Controlled Area when red light is on”, or similar. However, this system of work relies on the presence of a warning light that is wired into the X-ray equipment so that it illuminates during the prep and exposure and the benefit of doing this for most dental X-ray installations does not usually meet the expense. Another alternative is to have a reversible sign that can be turned around so that the “Controlled Area” text is not visible when the equipment is off. However, it is the experience of the Dent RPA technical team that such signs often go missing or are not turned around, negating their usefulness. As such, Dent RPA's Radiation Protection Advisers are of the view that the most workable solution is to have permanent controlled area signage. This simply means that access is controlled via the arrangements given in section 1.4 of the local rules.


    Q: Is there a legal requirement to appoint a Radiation Protection Adviser or can I take advice on an ad hoc basis?

Ionising Radiations Regulation 13 states "...every radiation employer shall consult such suitable radiation protection advisers as are necessary for the purpose of advising the radiation employer as to the observance of these Regulations..". The second part of this regulation states “....the radiation employer shall appoint that radiation protection adviser in writing and shall include in that appointment the scope of the advice ...”. It is therefore an explicit legal requirement that all users of X-ray equipment must have a current contract in place with a suitable RPA. The agreement must also be subject to an adequate service specification that ensures that the RPA provides advice on all areas required by the Regulations. Please see the Dent RPA homepage for details of an appropriate service specification.

    Q: Is it possible to complete IR(ME)R2000 training online?

Yes. It is perfectly acceptable to undertake online radiation protection training in preference to a classroom-based course. Dent RPA offer completely free five-yearly online radiation safety and IR(ME)R2000 training to all our customers to meet their statutory and professional radiation protection training requirements. Our online course comprises five hours of verifiable CPD in radiation protection and a certificate of completion is given.

The online training also includes the Health and Safety Executive’s Core of Competence for RPSs and serves as both initial and five-yearly update training for Radiation Protection Supervisors for dental practices.

Customers are sent activation codes for the online training as soon as a contract to provide Radiation Protection Adviser services has been set up.


    Q: Can a patient take their X-rays away with them?

There is no reason in principle that a patient can't take away their dental X-rays, as the notes resulting from the dentist's review of the X-ray constitute the legal record that your practice is obliged to keep. However, there are dangers of providing images to patients (self diagnosis, etc.), and a practice should only comply with the patient's wishes if they can give you reasonable grounds for their request. If you allow them to take away their film images (where there is likely to be only one copy), you should request that they keep the images safe and bring them to future appointments. You should also put in the patient's notes that they have taken away their X-ray images. Digital images can be taken away on CD (or other digital storage media) without restriction.


    Q: What do the Care Quality Commission look for when they inspect a dental practice?

The CQC inspect dental practices to ensure that they are safe, effective, caring, responsive and well-led. More specifically, they aim to ensure that the practice is compliant with current radiation protection legislation and you should ensure that you have appointed a Radiation Protection Adviser. They would look particularly at compliance with the Ionising Radiations Regulations 1999 and IR(ME)R2000. Dent RPA's services aim to fully facilitate our clients' adherence to UK radiation protection legislation and associated guidance. We provide audit tools to enable our clients to determine their level of compliance and help them take remedial action as necessary.

Full details of the CQC's inspection regime and expectations for dental practices can be found at:


    Q: What policies and procedures do I need in place to comply with the IR(ME)R2000 legislation?

IR(ME)R2000 legally requires you to have a set of procedures and policies that protect the patient from the potentially harmful effects of ionising radiation. These include policies on identification of referrers, practitioners and operators, availability of previous images, patient identification, radiography of females of child-bearing age, optimisation of radiation dose to patients, reporting of radiological examinations and retention of images. It also requires exposure protocols and a quality assurance programme to be in place. A template of such policies and procedures is available to Dent RPA customers to facilitate the process and this can be downloaded from the “Handbooks” section of My Toolbox.


    Q: Can I continue taking X-rays when I’m pregnant?

Normally, yes. It is extremely unusual for involvement in dental radiography to require a change in working practice during pregnancy. The Employer is required to carry out a risk assessment to ensure that the dose to the fetus does not exceed 1 mSv during the declared term of pregnancy. In practice this means the mother receiving a whole body dose of 2 mSv, which is almost impossible when the local rules are followed. This applies even for very high workloads and when the operator is using a cone beam CT unit. Bear in mind that pregnant employees should not hold patients during X-ray exposures.

    Q: Do staff working with dental X-rays need personal dose monitoring?

Usually not. Staff working in dental radiology do not routinely need to remain in a radiation controlled area during the exposure and therefore personal dosemeters are not generally required. However, it is the Employer’s duty to ensure that their employees are not at risk of approaching the classification level set out in IRR99 (i.e. a whole body dose exceeding 6 mSv per annum). Accordingly, a risk assessment should be carried out which may include provision of dosemeters to staff for a trial period. In practice, such a risk assessment need only be considered for those dental X-ray operators whose weekly workload exceeds 100 intra-oral or 50 panoramic exposures, or a pro-rata combination of each type of examination. Introduction of a new technology such as cone beam CT may warrant the introduction of personal dose monitoring for a trial period, especially if the workload is anticipated to be high.

    Q: What should be the content of the Local Rules for my practice?

Local rules for a dental practice are the safety instructions that should be followed to ensure that staff and the public are sufficiently protected from ionising radiation and are a legal requirement under IRR1999. They should comprise a description of the controlled area, arrangements to restrict access, conditions under which entry is allowed for members of the public, safe working instructions, dose investigation levels (where personal dose monitors are provided), contingency arrangements for foreseeable radiation accidents and the names of the Radiation Protection Supervisor and the Radiation Protection Adviser.

Local Rules for your practice can be generated automatically using the online tool in My Toolbox.


    Q: Is it acceptable for staff to hold patients who are undergoing an X-ray examination?

Yes, although it is generally preferable to ask a friend or relative (“comforters and carers” under IRR1999) of the patient to carry out this task if possible. If patients have to be held by a member of staff during radiography, it is not necessary to provide a monitor assuming the person holding does so only rarely. However, a record of the person's name should be kept. Pregnant staff should not hold patients.

    Q: Can the operator remain within the radiation controlled area during the X-ray exposure?

The radiation controlled area for standard dental X-rays (panoramic or intra-oral) usually extends to a distance of 1.5 metres from the patient and this is stated in the local rules. The purpose of designating a radiation controlled area is to prevent unauthorised persons from entering an area where they may be exposed to a hazard from X-rays. However, under the Ionising Radiations Regulations 1999 this does not include the operator as they are authorised to be present. As such, there is no explicit requirement for the operator to remain outside the controlled area during the exposure if they are suitably protected (with a lead coat, for example). The operator should, of course, remain outside the controlled area wherever practicable. In some situations this is not feasible, for example where handheld intra-oral X-ray units are used. However, there is a requirement under IRR99 to ensure that the doses to the operator remain as low as reasonably practicable. This is achieved through the use of a backscatter shield, which effectively reduces the exposure to the operator to nil.


    Q: Do I need to set a dose investigation level for staff exposures?

Dose investigation levels (DILs) for staff exposures are only applicable where staff wear personal dose monitors and the readings for the period can then be compared to investigation levels found in the local rules. However, where anticipated occupational doses are very low, such as general dental radiography, there is no need for personal monitoring and hence no DIL is required. Personal dose monitoring is only required to demonstrate that classification levels have not been exceeded (i.e. > 6 mSv whole body dose p.a.) and following the good practice guidance set out in the Dent RPA Ltd RPS Handbook and local rules also serves this purpose. For non-classified workers i.e. all dental staff, any DIL that may be set is effectively a dose constraint. The Health and Safety Executive clearly state in the Approved Code of Practice (para. 136): “Dose constraints are not likely to be appropriate for occupational exposures resulting from the following types of work with ionising radiation: (a) diagnostic radiology, nuclear medicine, most radiotherapy and other medical exposures;….”



    Q: Do I need to give my patient a lead apron when taking a dental X-ray?

Evidence has shown that a lead apron does not reduce the dose to patients undergoing a dental X-ray exposure (neither intra-oral or panoramic). It should therefore not be offered routinely to patients, even for their peace of mind, as this can perpetuate bad practice. The exception to this rule is for vertex occlusal examinations (or other-rarely used views that directly irradiate the abdomen) of pregnant patients. In this case the pregnant patient should be offered a lead apron, if available.

    Q: How do I set and monitor Diagnostic Reference Levels (DRLs) for dental X-ray examinations?

The DRL is a measure of the radiation dose to the patient which should not be exceeded under normal circumstances for standard patients. Due to the difficulties in measuring actual patient doses in dental radiography, the doses are measured by the technician during the 3-yearly equipment checks and the data presented in the survey report. The reference dose for an intra-oral dental X-ray unit is based on an adult mandibular molar exposure and is currently set at 1.7 mGy for a unit operating at 60-70kV with E-speed film (0.7 mGy for a child exposure). The reference level is 93 mGycm2 for a panoramic exposure. The equipment survey report from will detail your compliance with these levels and give advice on remedial action where local doses exceed these values.

    Q: Can I take an X-ray on a patient who is known to be pregnant?

Yes. Enquiries about whether a patient is pregnant are only necessary in dental radiography where primary radiation is directed at the abdomen. The risk from other dental X-rays to the fetus is effectively zero. Therefore the question of pregnancy will only become necessary in the case of a vertex occlusal or other rarely used views that directly irradiate the abdomen. Your IRMER file should have a procedure for dealing with potentially pregnant persons and this should reflect the information above.

    Q: Does a thyroid collar reduce the dose to the patient from a panoramic dental X-ray?

A thyroid collar can potentially cut the patient dose from a panoramic dental X-ray. However, they can be difficult to use and frequently cause artefacts where the collar attenuates the X-ray beam. As such, thyroid collars should not be used routinely.

    Q: What effect does rectangular collimation have on the patient dose from an intra-oral X-ray exposure?

Rectangular collimators can halve the patient dose from intra oral X-ray exposures and should be used where feasible.

    Q: Will I need to change my intra-oral exposure settings if I introduce a digital imaging system?

It is highly likely that your exposure times can be reduced for intra-oral radiography once a digital system has been introduced, although the optimum kV settings are unlikely to change. As a rough guide, the exposure time for a phosphor plate imaging system is likely to be around half that of E-speed film, and a solid state sensor is likely to require around a quarter of the exposure of E-speed film. You are advised to contact Dent RPA ( for advice before you commence using a new digital system. Where we have already completed your equipment surveys, we can usually advise on the optimum settings for a digital system without visiting the practice.


    Q: What training is required for operators of X-ray equipment?

Dental Practitioners registered with the General Dental Council must have an undergraduate degree conforming to the undergraduate dental curriculum in dental radiology and imaging as well as the core curriculum in dental radiography and radiology for undergraduate dental students. Refresher training on radiation safety must be integrated into the five-year re-certification cycle for dental Practitioners and Operators.

Dent RPA offer our customers completely free five-yearly online radiation safety training to our customers to meet this requirement. The course comprises five hours of verifiable CPD in radiation protection and a certificate of completion is given.

A nurse operating dental X-ray equipment will usually have completed the Certificate in Dental Radiography.

Equipment-specific training on each X-ray and processing unit used must also have taken place and this must be documented.


    Q: Is there a limit on the number of dental X-rays a single operator can perform?

No limit is placed on the maximum number of exposures. IRR1999 requires occupational exposures to be “as low as reasonably practicable” (ALARP) and in some rare cases personal dosimetry will be necessary to demonstrate this is being adhered to. However, this is not usually necessary if the workload for each staff member is fewer than 100 intra-oral exposures per week. Below this workload it is considered unlikely that any individual could exceed the 1 mSv annual dose limit for a member of the public. Radiography workload levels should be monitored by the Radiation Protection Supervisor to ensure that the weekly limit is not exceeded.

    Q: What training should be undertaken by a Radiation Protection Supervisor for a dental practice?

Radiation Protection Supervisors (RPSs) should undertake training to cover the relevant parts of the Health and Safety Executive's Core of Competence syllabus for RPSs (see the Resources:Training Guidance section of this website). This details the training requirements under the Ionising Radiations Regulations 1999. Training should be updated every five years.

Dent RPA offer free online radiation protection training to all our customers. This includes the Core of Competence for RPSs and serves as both initial and five-yearly update training. The online course lasts up to five hours and can be completed over several sessions. A certificate of completion is given.


    Q: Is it possible to complete IR(ME)R2000 training online?

Yes. It is perfectly acceptable to undertake online radiation protection training in preference to a classroom-based course. Dent RPA offer completely free five-yearly online radiation safety and IR(ME)R2000 training to all our customers to meet their statutory and professional radiation protection training requirements. Our online course comprises five hours of verifiable CPD in radiation protection and a certificate of completion is given.

The online training also includes the Health and Safety Executive’s Core of Competence for RPSs and serves as both initial and five-yearly update training for Radiation Protection Supervisors for dental practices.

Customers are sent activation codes for the online training as soon as a contract to provide Radiation Protection Adviser services has been set up.



    Q: What quality assurance do I need to carry out in my practice?

Quality audits should be performed on a representative batch of clinical images to assess film quality. HPA guidelines suggest that over 70% of all radiographs should be excellent, less than 20% clinically acceptable and less than 10% poor. Reference radiographs should be used for day-to-day comparison to identify any deterioration in image quality. Regular stepwedge images should be taken to assess processor performance and processing chemicals should be changed frequently.

Please consult the QA section of for the latest guidance on quality assurance for digital X-ray systems.

All safety features and warning devices such as shielding, collimation, and lamps must be checked regularly (not exceeding 3 years). Full details are given in the Quality Assurance section of the website under My Toolbox. Dent RPA provide a comprehensive QA package for scheduling, logging and analysing all the QA tests required by current legislation and guidance.


    Q: What in-house tests should I be doing on my phosphor plate (computed radiography) system?

There is no requirement to carry out any in-house testing of computed radiography (CR) plate reader systems. However, the reporting monitor/review workstation should be checked visually every week using the SMPTE test pattern. The process can be found in the QA section of and there is a log for recording that the check has been completed. If the SMPTE pattern is not available, there should be an equivalent test pattern that can be accessed or users could download the pattern from the internet.

The “Detector Condition” test is stipulated for direct digital systems under national guidance and is not specifically intended for CR. However, users could note any apparent deterioration to the phosphor plates and could use this function in the QA section of to record the data if they want to formalise the checks.

Each individual radiograph should also continue to be rated as excellent, diagnostically acceptable or poor, as with film.



    Q: Does a dental clinic using an intra oral X-ray unit need lead in the walls?

Generally, no. However, this will depend on the design, layout and workload of each dental practice. The Dent RPA Radiation Protection Adviser must be consulted to give guidance on the design of the facility and warning signage. For example, additional shielding in the walls may be required if factors such as distance, existing shielding from building materials, occupancy of adjoining rooms and workload mean that persons in adjacent areas may exceed the annual dose constraint to members of the public of 0.3 mSv p.a.

    Q: What warning signage is required for areas where X-rays are used?

This normally depends on the position of the equipment with the room or clinic and the extent of the controlled area. For panoramic X-ray equipment, a two stage warning light should normally be installed at the entrance to the room. This should state “X-rays - Controlled Area” when the unit is energized and “Do not enter” when X-rays are being emitted. Warning lights are not normally required for intra-oral dental equipment as it is unlikely that the door of the surgery will open into the controlled area. However, a warning sign stating "Controlled Area: X-rays" and "No Unauthorised Entry" should normally be affixed to the door to the surgery to indicate that X-rays are in use. The RPA can advise on warning signage on a case-by-case basis and the Dent RPA technician will check and advise on warning signage at the time of the equipment surveys.

    Q: Where can I get further advice and guidance?

You can contact a Dent RPA Radiation Protection Adviser at or via the “Ask the RPA” section of the website for advice on any other matter concerning radiation protection.

    Q: Is it possible to complete IR(ME)R2000 training online?

Yes. It is perfectly acceptable to undertake online radiation protection training in preference to a classroom-based course. Dent RPA offer completely free five-yearly online radiation safety and IR(ME)R2000 training to all our customers to meet their statutory and professional radiation protection training requirements. Our online course comprises five hours of verifiable CPD in radiation protection and a certificate of completion is given.

The online training also includes the Health and Safety Executive’s Core of Competence for RPSs and serves as both initial and five-yearly update training for Radiation Protection Supervisors for dental practices.

Customers are sent activation codes for the online training as soon as a contract to provide Radiation Protection Adviser services has been set up.



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