The risk of radiation

06 April 2020 | Blog
The risk of radiation

Public Health England’s (PHE) latest review of intra-oral digital imaging in 2017 in UK dental practices found that 72% of dentists used this technology, against just 27% in 2010. The PHE also estimated nearly 50% of dental practices had panoramic x-ray facilities, further demonstrating the steady growth of digital imaging in practice.

Supporting this trend, the latest BDIA Technology and Trends Survey in 2019 showed that nearly 10% of dentists intend to purchase Cone Beam Computed Tomography (CBCT) in the next 12 months, an increase from around five percent in just two years. It also showed an increase for the intended purchase of general digital equipment and modern technologies, including that of buying a 3D printer nearly tripling.

While reducing paper in the practice and moving to digital devices has obvious benefits and environmental savings, there are still potential risks to your health and that of your patients, so it’s worth a reminder of the guidance that supports these risks.

Dental x-rays

X-rays are obviously vital tools in a dental setting. They are used daily to identify problems such as infections, decay and bone loss, as well other potential problems in the future.

Dental x-ray imaging procedures include:

  • Intra-oral: bitewings, periapical and occlusal.
  • Extra-oral:
  1. 3D Panoramic (Orthopantomogram - OPG)
  2. Cephalometric
  3. Computed Tomography (CT) and Cone Beam Computed Tomography (CBCT).

The move to using digital x-rays has multiple benefits such as no development time, being able to view the images on the surgery’s computer screen, enabling them to be enlarged and sharing and comparing them. And perhaps most importantly, a lower dose of radiation - in some cases 80% less than the film method. It’s worth noting however that the doses delivered to patients during CBCT are typically much higher than those from other digital dental radiography.

CT scanning wasn’t utilised in dentistry because of its high cost, limited access and high radiation levels, but CBCT has changed that. With conventional CT scanning, each scan produces a single slice image, so several images are usually required, exposing the patient, and the dental professional conducting the scan, to several doses of radiation. With CBCT, an x-ray tube rotates around the patient’s head so you can gain a complete volume image in a single rotation, reducing exposure time. However, it’s worth remembering that it is a higher dose than other digital x-rays and as it offers such accurate and informative images, there may be a temptation to use it more frequently and on patients with a wider variety of oral health conditions. Being selective about its use is important, not just for the protection of patients but also the staff operating the device.

Radiation safe limits

UK dentists reported taking over 16 and a half thousand radiographs of adults in the BDIA 2019 survey, an increase of over three per cent from 2017-18.

PHE last year when reviewing the data on patient doses and equipment trends of digital x-ray imaging procedures between 2014 and 2017, noted a steady increase in the numbers of hand-held x-ray sets used in the general dental practice for routine intra-oral radiography.

Radiation dose is measured by how much energy you absorb when you are x-rayed; the term ‘effective dose’ describes the amount of radiation each of your organs are exposed to, as each vary in their sensitivity and propensity to absorb the radiation and therefore develop cancer or genetic effects.

In the UK, National Diagnostic Reference Levels (NDRLs) set by PHE are for intra-oral, panoramic radiography and CBCT.

National DRLs for dental radiology of Adults from August 2019 are:

Intra-oral mandibular molar         1.2 mGy per radiograph

Panoramic (full jaw)                    81 DAP per radiograph (mGy cm2)

Lateral cephalometric                  35 DAP per radiograph (mGy cm2)

Dental CBCT                               265 per radiograph (mGy cm2) (imaging prior to placement of a maxillary molar implant) * Lower levels are given for children

For conventional radiography you usually stand 1.5m away from (and behind) the x-ray tubehead but with CBCT they suggest the operator and all other staff are positioned outside the room or behind a shielded area. If the patient needs support during the procedure, the member of staff should wear a lead apron for protection, which needs to be stored carefully after each use, to avoid damage by creasing or cracking.

Radiation health risks

Whilst there is a very low risk of the effects of radiation within a dental setting there remains a degree of risk, and because radiation has a latent effect and links with cancer it should be used responsibly and only in the amounts required for the task at hand. While the evidence linking occupational radiation exposure to cancers remains unclear, the impact on health of excessive doses has been well documented, so it’s clear that keeping exposure to a minimum is strongly recommended.

The evidence of the link between cancer and radiation exposure was reported in a paper in 2018 that reviewed twenty-one papers that studied a correlation between dental diagnostic x-rays and overall health, among them eighteen papers that assessed a correlation between them and diseases of the head and neck that included ten relating to brain cancer, five for thyroid cancer and three on the head and neck areas, which are obviously close to the oral cavity, and they identified a link.

Not necessarily related to radiation exposure but certainly significant, Dentists’ Provident 2018 claim statistics show that cancer was responsible for nearly 15 per cent of all claims paid to females and nearly five per cent to males. This equated to paying nearly £345,000 of sickness benefits to dentists, including over £35,000 for brain tumours and nearly £6,000 for parts of the face and throat.

Professional guidance

The CQC expect you to have evidence of documentation of the radiation protection arrangements in the practice, to have appointed a radiation protection adviser (RPA) and medical physics expert (MPE), to regularly test and service all radiography equipment, and to ensure all staff using the equipment are appropriately trained. They also ask you to be able to show your certificate of registration with the Health and Safety Executive (HSE) – see below.

PHE’s guidance on the use of hand-held dental x-ray equipment in practice was last updated in February 2016.

The regulations

New regulations came into force on 1 January 2018 which meant that the practice principal (the person responsible for enforcing the Health and Social Care at Work Act within the practice), must register with the HSE to say that they have x-ray equipment in the practice.

These new regulations saw IRR17 replace IRR99, with a new three-point risk-based system of regulatory control being introduced with 1. notification (for low-level risk activities), 2. registration (for the operation of radiation generators) and 3. consent (for the highest risks). Dental practices fit into level 2.

The dedicated legislation and professional guidelines governing the use of dental x-ray equipment includes:

  • Ionising Radiation (Medical Exposure) Regulations 2000/2018 [IRMER2000/2018] for the protection of the patient.
  • Ionising Radiations Regulations 2017 [IRR2017] for the protection of workers and the public.
  • Guidance Notes for Dental Practitioners on the Safe Use of X-ray Equipment (Department of Health 2001)
  • Institute of Physics and Engineering in Medicine (IPEM) in 2018 provided dental guidance notes.

(Direct links to the documents can be found on the CQC website under Dental mythbuster 3: Dental radiography and X-rays.)

 As well as the legislation and guidelines listed above, when they inspect a practice, the CQC consider x-ray provisions in relation to the Health and Social Care Act 2008 (Regulated Activities) Regulations 2014 under Regulation 12: ’The intention of this regulation is to prevent people from receiving unsafe care and treatment and prevent avoidable harm or risk of harm…,’ and Regulation 15: ’The intention of this regulation is to make sure that the premises where care and treatment are delivered are clean, suitable for the intended purpose, maintained and where required, appropriately located, and that the equipment that is used to deliver care and treatment is clean, suitable for the intended purpose, maintained, stored securely and used properly….’

There are a whole host of regulations and regulators to protect patients and staff from the health risks of radiation, so it’s periodically worth reviewing your knowledge and documentation to ensure you comply.

References available on request.

This article is intended for general information only, it is not designed to provide financial, health or other advice, nor is it intended to make any recommendations regarding the suitability of any plans for any particular individual. Nothing in this article constitutes an invitation, inducement or offer to subscribe for membership or additional benefits of Dentists’ Provident.

No responsibility or liability is assumed by Dentists’ Provident or any copyright owner for any injury or damage to persons or property as a consequence of the reading, use or interpretation of its published content. Whilst every effort is made to ensure accuracy, Dentists’ Provident, the authors, Editors and copyright owners cannot be held responsible for published errors.

Dentists’ Provident exercises editorial control only over material published and/or produced by it.  No responsibility or liability is assumed by Dentists’ Provident for any articles produced or reproduced in third party publications and/or websites.

The views or opinions expressed do not necessarily reflect views of Dentists’ Provident or copyright owners. Inclusion of any advertising material does not constitute a guarantee or endorsement of any products or services or the claims made by any manufacturer.

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