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Prevention of accidental exposures in radiotherapy


When considering risks in radiotherapy, it should always be remembered that the patient is also gaining a major potential benefit from the therapy. However, accidents do occur, and in order to prevent future accidents in radiotherapy it is necessary to learn from accidents that have occurred in the past. When aiming to learn from these past accidents, it is of value to analyze the specific case histories and find the causes, contributing factors, actual circumstances of discovering the accident as well as methods for future prevention. Complementing this retrospective approach, it is also of great benefit to use prospective approaches, such as Probabilistic Safety Analysis (PSA) and risk matrices, in order to prevent accidents that have not yet happened, been reported, or where lessons to learn have not been made available.

Important Principles

A patient receiving therapy with ionizing radiation will be exposed to many potential sources of harm throughout the medical procedures. While the probability of harm occurring might be low, the consequences of that harm can be very serious for the individual patient, considering the high doses involved in radiotherapy and the serious malignant conditions treated in many cases. The combination of the probability of harm occurring and the consequence of that harm, constitutes the risk for the patient. A review of lessons learned from accidents in radiotherapy, indicate that many of these accidents have occurred under certain conditions, which can be grouped into four categories: (1) Working with awareness and alertness: Accidental exposures have occurred due to inattention to details, and lack of alertness and awareness. This condition could also be made worse if the health professionals have to work in circumstances prone to distractions; (2) Procedures: Accidental exposures have occurred when there is a lack of procedures and checks, or when they are not sufficiently comprehensive, properly documented or fully implemented; (3) Training and understanding: Accidental exposures have occurred when there is a lack of qualified and well-trained staff, with necessary educational background and specialised training; (4) Responsibilities: Accidental exposures have occurred when there are gaps and ambiguities in the functions of personnel along the lines of authority and responsibility. In these cases, safety-critical tasks have been insufficiently covered.

Introduction to References

The Radiation Protection of Patients (RPoP) website contains information to help health professionals prevent accidental exposures in external beam radiotherapy and brachytherapy. This website also contains training material on this topic.

There has also been much guidance and information published by the IAEA on specific radiotherapy safety issues over the last number of years, such as several booklets with information on lessons to learn from specific radiotherapy accidents and safety reports on radiotherapy, all of which are available on the Internet. Furthermore, there are many other publications on this topic, two of which are referred to below.

The key standards in this area are the International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, also known as the International BSS. These standards mark the culmination of efforts that have continued over the past several decades towards the harmonization of radiation protection and safety standards internationally.