Dental x-rays are the most frequently taken x-rays in the whole of the UK. It is important to patients, the staff taking the x-ray and the rest of the staff at the practice that this is done in the safest and most effective ways possible. Everybody has a role to play and although the risks involved in ionising radiation are substantial, they can be kept to a minimum with proper training, good practice and quality control. This article is a brief reminder for those who are qualified in dental radiography and an introduction to those who are interested in increasing their responsibilities, furthering their career and their usefulness at their practice.

Legally speaking

Every person working in radiography for medical and dental purposes are working under the Ionising Radiation Regulations 1999, referred to as IRR99. They are concerned with the protection of workers and patients. A further regulation, the Ionising Radiation (Medical Exposure) Regulations 2000, takes patient protection further.

Every dental practice using ionising radiation (that is taking x-rays) in the UK must inform The Health and Safety Executive (HSE) of this. If the practice has a change of ownership or if the practice relocates, then the HSE should be informed of this too.

The room or rooms where dental x-rays are taken should have a controlled area around the dental x-ray equipment and nobody should be allowed to enter this area with the exception of the patient (and possibly an assistant if the patient is a child or needs help) when the radiograph is being taken. This area should be within 1.5 metres of the x-ray tube and it should not extend beyond the room or surgery. Staff, including the operator should stand outside the controlled area during the taking of the radiograph. Sometimes a protected area is provided for operators behind a special divide. The operator should be able to see the patient and the x-ray tube warning light while taking radiographs and be able to ensure that nobody comes through the door of the room during exposure.

See Box 1

What if something goes wrong?

If a patient has received an exposure much greater than intended (around 20 times the intended dose), the Legal person should consult an RPA immediately. If the cause of the overexposure is deemed to be an equipment malfunction, the local HSE should be notified. If the cause of the overexposure is due to clinical or operator error, the IRMER inspectorate should be notified.

Radiation Protection File

Every practice should have a Radiation Protection File. This should hold as much information as possible about the procedures that the practice uses to ensure radiation protection. This includes: Local rules and Written procedures for patient protection. It could also contain the information about the training of all members of the practice involved in taking radiographs. The Radiation Protection File should be kept up to date so that it continues to be useful and effective. The file should also include details of the arrangements for maintenance and testing of the x-ray equipment; significant findings of risk assessments; staff instructions; review programmes to keep local rules up to date and the arrangements for investigating and reporting incidents.

Local Rules

At the very minimum they should include:

  • The Radiation Protection Adviser's details

  • Identification of each controlled area and arrangements for restricting access

  • Summary of working instructions (eg stand behind protection panel or outside the controlled area)

  • Summary of contingency arrangements

  • Dose investigation level to decide whether personal monitoring is needed.

Other information that could be included are: the Legal person's details, the Radiation Protection Adviser's contact details, arrangements for personal dosimetry, arrangements for pregnant staff and a reminder to staff to report any faults or if there is an over-exposure.

Written Procedures

These are required to describe the protocols that are in place for patient protection; such as patient identification, identification of people entitled to act as referrer, IRMER practitioner or operator, ensuring a quality assurance programme is followed, assessment of patient dose, and others.

Training

Every IRMER practitioner and operator must be adequately trained and undertake continuing education to keep up to date. A training record should be maintained (may be kept in the Radiation Protection File) and be kept available for inspection.

Operators who are a dental nurse and are responsible for setting exposure parameters or positioning the film, patient and tube head, should possess a Certificate in Dental Radiography (see box to the right - how to obtain the NEBDN Certificate in Dental Radiography ). If the operator is a Hygienist or Therapist, they should have received an equivalent level of training. This knowledge should be up-dated at least every 5 years.

From 13 May 2005, all dental nurses who take radiographs must have a Certificate in Dental Radiography. Up to this time, all dental nurses who were competently taking dental radiographs prior to 13 May 2000 but had only received the ‘Core of Knowledge’ training may continue to take radiographs, but need to obtain a Certificate in Dental Radiography to continue taking radiographs after 13 May 2005.

It is preferable that people involved in film processing and quality assurance possess a Certificate in Dental Nursing or NVQ equivalent, or have documentation proving their training for the tasks that they undertake. This training may be provided in-house.

Non-clinical staff who are involved in some of the Operator tasks such as patient identification need to be aware of the need to avoid unnecessary personal exposure.

Protection

Patient protection

There is no need for patient protectors such as lead aprons and thyroid collars in routine dental radiographs where modern equipment and techniques ensure that the minimal amount of scatter is directed towards the body. Lead aprons do not protect against internal scatter.

Lead aprons may offer some protection for the vortex occlusal projection and should only be used if the patient is or may be pregnant. Staff members or any other person assisting should wear a lead apron if a handicapped patient or child need assistance during the taking of a radiograph. Lead aprons should be a lead equivalent of at least 0.25 mm and should not be folded when not in use but stored on hangers and inspected regularly. Thyroid collars should be used when the thyroid may be in the primary beam.

See Box 3

It is not usually necessary to ask a female patient if she is pregnant, as a dental radiograph does not expose the pelvic area and the dose is small. The risks to the foetus are negligible but patients should be given the option of delaying the radiograph if they wish. If the type of radiograph required means that the pelvic area might be irradiated and the patient is or may be pregnant; consider delaying the radiograph until after delivery. If the radiograph is proceeded with, use a lead apron on the patient and ensure that the foetal dose is minimum.

Staff protection

If a member of staff regularly takes over 100 intra-oral or 50 panoramic radiographs a week (or the equivalent pro-rata), it is good practice to wear a personal dosimeter. This records the personal dose of radiation over a given time (normally 3 months) and this should be kept on file for at least 2 years. Female employees involved in radiography must be aware of the risks to a foetus should they become pregnant.

Risk assessment

A risk assessment should be carried out with an RPA to anticipate the precautions that are needed to prevent exposure of operators, other staff and other patients. The results should be recorded and then reviewed regularly; more frequently if there are changes to practises or the equipment.

Quality assurance

Quality assurance (QA) is about consistently getting good diagnostic information in a radiograph while exposing patients to the lowest possible radiation dose. Someone in the practice should have responsibility for the QA programme which covers image quality, patient dose, equipment, film processing, training and audits.

The information for this article was taken from the British Dental Association's Advice Sheet A11, “Radiation in Dentistry”. Available from the BDA shop.

Radiography and Radiology for Dental Nurses is published in April 2005. Vital will be reviewing this in the Summer issue due out on June 11th.

Make sure you don't miss out, turn to page 54 to order a subscription.