Radiation is energy emitted from a source that travels through space and may interact with matter. In the context of dentistry we are considering a specific type of radiation known as ionising radiation. Ionising radiation is radiation that can produce charged particles or ions when it interacts with matter.
Dentists make use of radiation when they produce an X-ray image of the dentition. During this process the patient is directly exposed to a quantity of radiation. Radiation is also scattered from the patient and so to a lesser extent the operator of the X-ray equipment could be exposed. We make use of the properties of radiation to produce the image but we know that too much radiation can be detrimental to health. We need to strike a balance between using just enough radiation to get the image we want whilst limiting our exposure to radiation to minimise the harmful effects. This balancing act, therefore, is to ensure that the benefits outweigh the risks.
Preventing exposure
The concept of radiation protection is not to prevent radiation exposure in itself since without radiation exposure radiography as a diagnostic tool would be impossible. The goal is to ensure that over-exposure to radiation is minimised. Dentists must ensure that radiation exposures are maintained as low as reasonably practicable (the ALARP principle). In addition dentists must ensure that they are compliant with the radiation protection legislation that is in place in the UK. There are two main sets of legislation in the UK; the Ionising Radiations Regulations 1999 (IRR99) which are aimed at protecting the worker and the general public and the Ionising Radiations (Medical Exposure) Regulations 2000 (IR(ME)R2000), which are designed to protect patients undergoing X-ray exposures as part of their diagnosis or treatment.
Dentists who are using ionising radiation are required under regulation 13 of IRR99 to appoint and consult with a radiation protection adviser (RPA) for the purposes of advising the dentist (the radiation employer) on how to comply with the regulations. Specifically, the dentist must consult with an RPA on new plans and installations, designating controlled and supervised areas, calibration and checking of equipment used for monitoring levels of radiation and the periodic examination and testing of engineering controls, design features, safety features and warning devices and the regular checking of systems of work designed to restrict exposure to ionising radiation. This also includes advice on the content of radiation risk assessments, local rules for radiation safety, appointment of radiation protection supervisors (RPSs) and quality assurance programmes.
Under regulation 9 of the IR(ME)R2000 Regulations dentists are required to seek advice from a medical physics expert (MPE) on optimising medical exposures, patient dosimetry and quality assurance and to give advice on any other matters relating to radiation protection concerning medical exposures.
If radiation protection is not undertaken then there is an increased risk to patients, staff and members of the public from excessive exposure to ionising radiation. Inadequate radiation protection leading to non-compliance with any of the legislation could ultimately lead to prevention of work with X-rays and potentially to prosecution of the practice for breaches of health and safety legislation and could have an impact on a practice’s ability to deliver radiography to its patients.
Research
Research in to the use of ionising radiation for medical diagnosis is constantly on the move. Technological changes such as the move to digital imaging have made great strides in reducing radiation exposures, whilst delivering unprecedented image quality; they have also made imaging safer by removing the need for film processing facilities and the chemicals associated with the process. More recently we have begun to see the introduction of cone beam computed tomography (CBCT). This technology allows dental practices to produce almost hospital CT quality images from a system not much bigger than a conventional OPG unit.
Conclusion
The use of ionising radiation in medical diagnosis and treatment has been a great boon to society over the last 120 years or so. However, we must always be mindful of the risks to health from ionising radiation albeit those risks are small in the world of dental radiography. Good radiation protection practice not only shows a commitment to the safety of the dental practice staff and general public but also demonstrates that the practice considers the health and wellbeing of its patients to be paramount. Compliance with both IRR99 and IR(ME)R2000 cannot be understated.