Towards Safer Radiotherapy

Near miss
Other non-conformance
A potential radiation incident that was detected and prevented
before treatment delivery. However, mistakes in plans, calculations
etc do not constitute near misses if they were detected and
corrected as part of the checking procedure before authorising for
clinical use. Notice that the term ‘miss’ is used in the context of
falling short of being an actual RI, rather than in the narrower
sense of a geometric miss.
None of the above; that is, non-compliance with some other
aspect of a documented procedure but not directly affecting
radiotherapy delivery.
3.1.3 Consistency with the WHO classification
20
The World Health Organization (WHO) has produced a list of preferred terms and definitions
in connection with patient safety. 44 The above uses of the terms ‘error’ and ‘incident’ are
consistent with the WHO definitions. In the WHO list, the term ‘near miss’ is defined as an
incident that did not cause harm. In the error classification grid (Figure 3.1), a ‘near miss’ is
shown as arising from a radiotherapy error that did not result in a radiation incident, which is
an apparent contradiction to the WHO definition. However, a near miss does indeed arise
from an incident (the commission of the radiotherapy error) which does not result in a
radiation incident (because, for instance, it is detected in time). Hence, the usage of the term
here is consistent with that of the WHO. The term ‘minor radiation incident’ is also a near
miss in the WHO parlance, since it is a radiation incident that did not cause harm.
Nevertheless, the term ‘minor radiation incident’ is used to distinguish between the near miss
that is not a radiation incident and that which is a radiation incident.
3.2 Correctable radiation incidents
3.2.1 When an error is detected after only a few fractions, an alteration in the field parameters or
the dose delivered can usually ensure that the final treatment delivered to the patient is
within tolerance of the intended dose. Examples of such calculations have been published
elsewhere. 45,46 The incident is then called a ‘correctable radiation incident’ as defined above.
3.2.2 However, if an error is not detected until late in a course of treatment complete
compensation may not be possible. In such cases, the exact radiobiological consequences of
an error can be difficult to establish due to the numerous factors involved. 47 In these
circumstances, external advice may be sought from an expert in clinical radiobiology. A
number of specialists in the UK currently offer advice, but the final decision and responsibility
as to the correct course of action rests with the practitioner who prescribed the treatment.
3.3 Radiotherapy error classification grid
A decision grid is proposed (Figure 3.1) that enables the error to be graded into one of five severity
classifications (Levels 1–5), using the definitions given above. Note that, while a level 1 reportable
radiation incident may not be clinically significant if it is correctable, it is nevertheless considered to
be of the highest severity by virtue of the requirement to report it to the appropriate statutory
authority.
Towards Safer Radiotherapy