Towards Safer Radiotherapy

Chapter 3: Defining and classifying
radiotherapy errors
When discussing radiotherapy errors and incidents, it is essential to have a clear definition of these
terms to aid interpretation, reporting and comparison.
In the UK, following the report into the Exeter incident, 39,40 all radiotherapy centres were
encouraged to develop a quality management system; generally known as a ‘QART’ (quality
assurance in radiotherapy) system. One of the functions of the QART system is to record and report
errors, to examine what has gone wrong and why, to effect actions to correct the immediate
situation and prevent recurrence. Most, if not all, departments will analyse their statistics to identify
systematic problems, see what lessons can be learnt and improvements made. However, a major
difficulty arises when attempts are made to share and compare error data between centres due to
the individuality of the systems developed.
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Information on reportable radiotherapy errors is collected nationally via the statutory bodies (see
Chapter 6). However, analysis of errors of lesser magnitude and ‘near misses’, at anything other
than local level, is hampered by a lack of consistency in terminology and agreement on definitions
at national level.
There is a wealth of literature pertaining to error terminology in medical practice and the effect this
terminology has on how collected data are interpreted. A key point reflected by Tamuz et al 41 is that
the capacity for learning and the accumulation of knowledge is directly affected by how potentially
dangerous events are categorised and interpreted. There is also evidence that for effective analysis,
medical error should be defined in terms of failed processes that are clearly linked to adverse
outcomes. 42
An error classification system is thus proposed which seeks to:
1. Define the terms used to avoid ambiguity
2. Provide a decision grid to arrive at an outcome-based severity classification for each event
3. Provide a detailed radiotherapy pathway coding system, which enables definition and coding of
the point along the pathway at which the event occurred.
The overall objective is to enable departments to not only review their own practice, but also to
provide a framework that can be used to share data nationally, potentially via a database (see
Chapter 6). It is recognised that some departments already use a similar approach, but national
consistency is required for meaningful analysis and learning to be achieved.
3.1 Terminology and definitions
3.1.1 The problem
Confusion can occur because the same term is used with different meanings, and the same
event may be described using different terms. In his book Human Error, Reason defines an
error as ‘a failure of a planned sequence of (mental or physical) activities to achieve its
intended outcome when the failures cannot be attributed to chance’. 43
Towards Safer Radiotherapy