Radiotherapy update.

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Abstract
In the United Kingdom, approximately 41.5 million radiographs are taken annually.1 Of these, approximately 52.7% are taken in the dental field.2 X-rays have been proven to contribute towards cancer, cataracts and even death.3 Therefore, it is vital that all dental staff reduce the risk of harm to themselves and to members of the public. Radiographs are a highly useful tool in dentistry for diagnosing patients and for detecting caries beneath the tooth surface. Most dental practices take routine radiographs every two years, but this may be more frequent if patients have dental problems such as periodontal issues, or if they require treatment such as an extraction or root canal treatment.4 X-rays are made up of photons which could be described as ‘packets of energy’. They are equivalent to one quantum of energy and are undetectable by human senses. Each X-ray beam is made up of millions of photons. When the exposure button is pressed, the photons are released, and are either absorbed or scattered. When a photon is scattered, it changes from the desired course and is deflected in other directions, including behind the X-ray tube head. It is advised that everyone except the patient stands away from the direct area of exposure. The control zone is 1.5 metres around the X-ray tube head and the patient.3 This refers to standing behind or beside the patient. It is strongly advised that people do not stand directly in the path of the X-ray beam. The so-called ‘safe distance’ is a lot further when standing directly in the path of the beam. This can be avoided with simple measures such as turning the patient's head or by more permanent options such as installing lead shielding in the walls. If it is possible, it is advised to stand further than 1.5 metres away from the X-ray tube head and the patient. It should be noted that the operator must still be able to see the patient directly or via a mirror, and that they should be able to reach the mains switch easily in case of prolonged exposure to the patient. X-rays have been linked to leukaemia, tumours, cataracts, and skin reddening. The reproductive organs are very sensitive to X-rays and it is largely advised that pregnant women do not have radiographs taken unless it is absolutely necessary. Routine X-rays are often deferred until after the pregnancy.5 The developing foetus is at risk of congenital abnormalities, mental deficiencies or even death if exposed to high amounts of radiation.3 Every patient who is considered for radiographs should be assessed through a process of justification. Due to the damage that X-rays can cause, clinicians must justify whether the benefit of taking the radiograph outweighs the risk of harm to the patient. This process of justification becomes more complicated when the patient needs a chaperone during exposure to X-rays; examples of this include child patients or adult patients with mental/learning difficulties. The patient goes through the normal process of justification; however, the exposure to X-rays does not benefit the chaperone. At this point, the clinician should write to the Radiation Protection Supervisor (RPS) who may refer them to the Radiation Protection Advisor (RPA). The clinician should explain the situation of why the patient requires a chaperone and why the patient needs to have the radiograph taken. The RPS will then usually write back with a response either allowing or refusing the use of a chaperone. The risks must then be explained clearly to the chaperone and also, the reasons for taking the radiograph. The chaperone must then be given the time to ask questions and the opportunity to refuse exposure. There is some conflict of opinions as to the role of the untrained dental nurse. Some clinicians do not agree that untrained dental nurses should be allowed to press the exposure button as they are effectively ‘taking’ the radiograph and thus, should assume responsibility for it. However, other clinicians feel that an untrained nurse can press the exposure button under their supervision if they have received basic in-house training.6 The official stance limits the taking of radiographs to dentists, dental therapists, dental hygienists and dental nurses with a radiography qualification. All dental staff must be conscientious to protect themselves, their colleagues, patients and members of the public from the danger of X-rays. Aim to stand in a safe place while the patient is being exposed and only take radiographs when it is clinically justified.